//! The edge's indexing: lib/edge/scan.ts (SegmentScanner, scanOverviewText) and lib/files/aggregator.ts as in the
//! TypeScript, then voyager 3's window (REBUILD.md, "Voyager 3: window indexing", 2): files and releases are
//! finished when the frontier (the median Date of the last FRONTIER_ARTICLES plausible ones) is WINDOW_MS past
//! their last part, or at the block's end (provisionally, as edges), and written once.

use crate::codec::{encode_chunk, ChunkFile};
use crate::js::{self, sha1_hex};
use crate::names::{self, is_random_file, looks_scrambled, JudgedFile, Release, Rules, Verdict};
use rustc_hash::{FxHashMap, FxHashSet};
use serde::{Deserialize, Serialize};
use std::rc::Rc;

pub static mut PROF: [u64; 8] = [0; 8];

pub struct FileMeta {
    pub file_key: String,
    pub name: String,
    pub poster: String,
    pub subject: String,
    pub total_parts: u32,
    pub groups: Vec<String>,
    pub release: Release,
}

pub struct Seg {
    pub file: Rc<FileMeta>,
    pub number: u32,
    pub message_id: String,
    pub bytes: i64,
    pub article: i64,
    pub posted_at: Option<i64>,
}

pub struct ReleaseChunk {
    pub key: String,
    pub upload: usize,
    pub name: String,
    pub source: &'static str,
    pub file_total: Option<i64>,
    pub poster: String,
    pub groups: Vec<String>,
    pub posted_at: Option<i64>,
    pub posted_last: Option<i64>,
    pub files: usize,
    pub segments: usize,
    pub bytes: i64,
    pub first_article: i64,
    pub last_article: i64,
    pub readable: bool,
    pub has_par2: bool,
    /// The window closed on it (false: still open at the block's end, written provisionally).
    pub finished: bool,
    /// Open at the block's end, or within the window of its start: the block merger's.
    pub edge: bool,
    /// A file misses parts.
    pub partial: bool,
    /// The upload tool from the first article's message-id (names::upload_tool), for an unnamed release: with the
    /// group its signature, what the pending ladder learns verdicts by. None for a named one.
    pub tool: Option<&'static str>,
    /// The files' names and segments (codec); empty for an unnamed release (decision f: nothing in the catalog
    /// without a usable name; the pending store keeps its keys and probe targets until a probe names it).
    pub payload: Vec<u8>,
    /// The first files' subjects (at most SUBJECTS): edge-bench's --releases dump for the grouping sweeps.
    pub subjects: Vec<String>,
}

pub const SUBJECTS: usize = 3;

pub struct Candidate {
    pub release_key: String,
    pub upload: usize,
    pub kind: &'static str,
    pub message_id: String,
    pub file: String,
}

#[derive(Default)]
pub struct Batch {
    pub from: i64,
    pub next: i64,
    pub headers: u64,
    /// postedLow / postedHigh: the batch's posting times without the earliest and latest 1% (postedSpan).
    pub posted_low: Option<i64>,
    pub posted_high: Option<i64>,
    pub releases: Vec<ReleaseChunk>,
    pub samples: Vec<(ReleaseChunk, &'static str, String)>,
    pub candidates: Vec<Candidate>,
    /// (rule, key) → (articles, files)
    pub counts: Vec<(&'static str, String, u64, u64)>,
}

struct Counter {
    index: usize,
    length: usize,
    segment: i64,
    total: i64,
}

/// The last "(k/N)" after `after` (anywhere when None: JS -1), scanning back from the end (findCounter).
fn find_counter(subject: &[u8], after: Option<usize>) -> Option<Counter> {
    let mut open = subject.len();
    loop {
        // lastIndexOf('(', open - 1): at most open - 1.
        if open == 0 {
            return None;
        }
        open = subject[..open].iter().rposition(|&c| c == b'(')?;
        if after.is_some_and(|a| open <= a) {
            return None;
        }
        let mut i = open + 1;
        let mut segment: i64 = 0;
        let mut digits = 0;
        while let Some(c) = subject.get(i).filter(|c| c.is_ascii_digit()) {
            segment = segment * 10 + (c - b'0') as i64;
            digits += 1;
            i += 1;
        }
        if digits == 0 || subject.get(i) != Some(&b'/') {
            continue;
        }
        i += 1;
        let mut total: i64 = 0;
        digits = 0;
        while let Some(c) = subject.get(i).filter(|c| c.is_ascii_digit()) {
            total = total * 10 + (c - b'0') as i64;
            digits += 1;
            i += 1;
        }
        if digits == 0 || subject.get(i) != Some(&b')') {
            continue;
        }
        return Some(Counter { index: open, length: i + 1 - open, segment, total });
    }
}

fn xref_groups(xref: &str, group: &str) -> Vec<String> {
    let mut groups = Vec::new();
    for token in js::split_spaces(js::trim(xref)).into_iter().skip(1) {
        if let Some(colon) = token.rfind(':') {
            if colon > 0 {
                groups.push(token[..colon].to_string());
            }
        }
    }
    if groups.is_empty() {
        groups.push(group.to_string());
    }
    groups
}

#[derive(Default)]
struct Scanner {
    files: FxHashMap<String, Option<Rc<FileMeta>>>,
    key: String,
}

impl Scanner {
    fn owner<'a>(&self, xref: &'a str, group: &'a str, priorities: &FxHashMap<String, u32>) -> &'a str {
        let b = xref.as_bytes();
        let Some(mut at) = xref.find(' ') else { return group };
        let mut owner: Option<&str> = None;
        let mut best = u32::MAX;
        loop {
            while b.get(at) == Some(&b' ') {
                at += 1;
            }
            if at >= b.len() {
                break;
            }
            let end = xref[at..].find(' ').map(|i| i + at);
            // lastIndexOf(':', end ?? length): a colon at or before `end`.
            let limit = end.unwrap_or(b.len());
            let colon = xref[..limit.min(b.len())].rfind(':');
            if let Some(colon) = colon.filter(|&c| c > at) {
                let name = &xref[at..colon];
                if let Some(&p) = priorities.get(name) {
                    if p < best {
                        best = p;
                        owner = Some(name);
                    }
                }
            }
            match end {
                Some(e) => at = e,
                None => break,
            }
        }
        owner.unwrap_or(group)
    }

    #[allow(clippy::too_many_arguments)]
    fn segment(&mut self, article: i64, subject: &str, from: &str, date: &str, message_id: &str, bytes: &str, xref: &str, group: &str) -> Option<Seg> {
        if subject.is_empty() || message_id.is_empty() {
            return None;
        }
        let sb = subject.as_bytes();
        // After the last quote; without one, anywhere (unquoted_name finds the file name).
        let name_end = subject.rfind('"');
        let counter = find_counter(sb, name_end)?;
        self.key.clear();
        self.key.push_str(from);
        self.key.push('\u{1}');
        self.key.push_str(&subject[..counter.index]);
        self.key.push('\u{0}');
        self.key.push_str(&subject[counter.index + counter.length..]);
        let file = match self.files.get(self.key.as_str()) {
            Some(f) => f.clone(),
            None => {
                let f = describe(subject, name_end, &counter, from, xref, group).map(Rc::new);
                self.files.insert(self.key.clone(), f.clone());
                f
            }
        };
        let file = file?;
        if counter.segment < 1 || counter.segment > file.total_parts as i64 {
            return None;
        }
        let id = if message_id.starts_with('<') { message_id.get(1..message_id.len().saturating_sub(1)).unwrap_or("") } else { message_id };
        Some(Seg {
            number: counter.segment as u32,
            message_id: id.to_string(),
            bytes: js::parse_int(bytes).unwrap_or(0),
            article,
            posted_at: js::parse_date(date),
            file,
        })
    }
}

fn describe(subject: &str, name_end: Option<usize>, counter: &Counter, from: &str, xref: &str, group: &str) -> Option<FileMeta> {
    let quoted = match name_end {
        Some(end) if end > 0 => subject[..end].rfind('"').map(|start| subject[start + 1..end].to_string()),
        _ => None,
    };
    let name = match quoted {
        Some(name) => name_beside_quotes(&name, &subject[..counter.index]).unwrap_or(name),
        None => unquoted_name(&subject[..counter.index])?,
    };
    let name = name.as_str();
    if name.is_empty() || counter.total < 1 {
        return None;
    }
    let joined = format!("{}{}", &subject[..counter.index], &subject[counter.index + counter.length..]);
    let base = js::trim(&js::collapse_spaces(&joined)).to_string();
    let file_key = sha1_hex(&format!("{from}\n{base}\n{}", counter.total));
    let release = names::release_identity(from, &base, name);
    Some(FileMeta {
        file_key,
        name: name.to_string(),
        poster: from.to_string(),
        subject: base,
        total_parts: counter.total as u32,
        groups: xref_groups(xref, group),
        release,
    })
}

/// EXTENSION: /[^.\s]\.[A-Za-z0-9]{2,4}$/
fn has_extension(s: &str) -> bool {
    let Some(dot) = s.rfind('.') else { return false };
    let ext = &s.as_bytes()[dot + 1..];
    if !(2..=4).contains(&ext.len()) || !ext.iter().all(|c| c.is_ascii_alphanumeric()) {
        return false;
    }
    s[..dot].chars().last().is_some_and(|c| c != '.' && !js::is_space(c))
}

/// The first / - \d{1,3} - / in `text`: the index of its " - ".
fn first_track(text: &str) -> Option<usize> {
    let b = text.as_bytes();
    let mut from = 0;
    while let Some(i) = text[from..].find(" - ").map(|i| i + from) {
        let digits = b[i + 3..].iter().take_while(|c| c.is_ascii_digit()).count();
        if (1..=3).contains(&digits) && b[i + 3 + digits..].starts_with(b" - ") {
            return Some(i);
        }
        from = i + 1;
    }
    None
}

/// postedSpan: posting times without the earliest and latest 1% (floor(n / 100) at each end).
pub fn posted_span(mut dates: Vec<i64>) -> (Option<i64>, Option<i64>) {
    if dates.is_empty() {
        return (None, None);
    }
    dates.sort_unstable();
    let k = dates.len() / 100;
    (Some(dates[k]), Some(dates[dates.len() - 1 - k]))
}

/// nameBesideQuotes (lib/headers/subject.ts): a file name elsewhere when the quoted text has no extension.
pub fn name_beside_quotes(quoted: &str, before_counter: &str) -> Option<String> {
    if has_extension(quoted) {
        return None;
    }
    // A stray quote took the last pair: the last quoted part that is a file name.
    let mut named = None;
    let mut rest = before_counter;
    while let Some(open) = rest.find('"') {
        let Some(close) = rest[open + 1..].find('"') else { break };
        let part = &rest[open + 1..open + 1 + close];
        if has_extension(part) {
            named = Some(part);
        }
        rest = &rest[open + 1 + close + 1..];
    }
    if let Some(part) = named {
        return Some(part.to_string());
    }
    // .replace(/"[^"]*"/g, ' ')
    let mut text = String::with_capacity(before_counter.len());
    let mut rest = before_counter;
    while let Some(open) = rest.find('"') {
        match rest[open + 1..].find('"') {
            Some(close) => {
                text.push_str(&rest[..open]);
                text.push(' ');
                rest = &rest[open + 1 + close + 1..];
            }
            None => break,
        }
    }
    text.push_str(rest);
    unquoted_name(&text).filter(|n| has_extension(n))
}

/// unquotedName (lib/headers/subject.ts): the file name of a subject without a quoted one, from the text before its counter.
/// /\.(jpe?g|png|gif|bmp|webp|tiff?)$/i
fn is_image_name(name: &str) -> bool {
    let lower = name.to_ascii_lowercase();
    [".jpg", ".jpeg", ".png", ".gif", ".bmp", ".webp", ".tif", ".tiff"].iter().any(|e| lower.ends_with(e))
}

/// DATE_ONLY (lib/headers/subject.ts): a file name that is a date alone ("15_07_2015.rar").
fn date_only(name: &str) -> bool {
    static DATE_ONLY: std::sync::LazyLock<regex::Regex> = std::sync::LazyLock::new(|| {
        regex::Regex::new(r"^(?:[0-9]{1,2}[-_.][0-9]{1,2}[-_.](?:19|20)[0-9]{2}|(?:19|20)[0-9]{2}[-_.][0-9]{1,2}[-_.][0-9]{1,2})\.[A-Za-z0-9]{2,4}$").unwrap()
    });
    DATE_ONLY.is_match(name)
}

pub fn unquoted_name(before_counter: &str) -> Option<String> {
    let mut text = before_counter.trim_end_matches(js::is_space);
    if text.len() >= 4 && text.is_char_boundary(text.len() - 4) && text[text.len() - 4..].eq_ignore_ascii_case("yenc") {
        text = text[..text.len() - 4].trim_end_matches(js::is_space);
    }
    if let Some(quote) = text.find('"') {
        if text[quote + 1..].contains('"') {
            return None;
        }
        let before = &text[..quote];
        if let Some(bracket) = before.rfind('[') {
            let inside = js::trim(&before[bracket + 1..]);
            // replace(/^\d+\/\d+ +/, '')
            let b = inside.as_bytes();
            let mut i = 0;
            while i < b.len() && b[i].is_ascii_digit() {
                i += 1;
            }
            let mut stripped = inside;
            if i > 0 && b.get(i) == Some(&b'/') {
                let mut j = i + 1;
                while j < b.len() && b[j].is_ascii_digit() {
                    j += 1;
                }
                if j > i + 1 && b.get(j) == Some(&b' ') {
                    while j < b.len() && b[j] == b' ' {
                        j += 1;
                    }
                    stripped = &inside[j..];
                }
            }
            if has_extension(stripped) {
                return Some(stripped.to_string());
            }
        }
        let word = &before[before.rfind(' ').map_or(0, |i| i + 1)..];
        return has_extension(word).then(|| word.to_string());
    }
    // A single-quoted name at the end: /'([^']*[^.\s']\.[A-Za-z0-9]{2,4})'$/
    if let Some(inner) = text.strip_suffix('\'') {
        if let Some(open) = inner.rfind('\'') {
            let part = &inner[open + 1..];
            if has_extension(part) {
                return Some(part.to_string());
            }
        }
    }
    if has_extension(text) {
        let bracket = text.rfind("] ").map_or(0, |i| i + 2);
        // A track or part number (/ - \d{1,3} - /): the name starts there; else after the last " - ".
        let dash = first_track(text).or_else(|| text.rfind(" - ")).map_or(0, |i| i + 3);
        // Or after an arrow ("… -> Exclusive-tgirls_000000-lg.jpg").
        let arrow = text.rfind("-> ").map_or(0, |i| i + 3);
        let cut = bracket.max(dash).max(arrow);
        // A date alone after the cut ("… [ettv] 15_07_2015.rar"): the whole text is the name.
        let name = if date_only(js::trim(&text[cut..])) { js::trim(text) } else { js::trim(&text[cut..]) };
        // An image after numbered text without a separator: its last word ("<abm> … AB: part2 0573-1002 043.jpg").
        // Not an index alone ("Teen Tease Self Shooter sad1 (10).jpg").
        if cut == 0 && is_image_name(name) && name.contains(' ') {
            let space = name.rfind(' ').unwrap();
            let last = &name[space + 1..];
            if name[..space].trim_end_matches(js::is_space).ends_with(|c: char| c.is_ascii_digit()) && !last.starts_with('(') {
                return Some(last.to_string());
            }
        }
        // Ending in a host is no file name: the one in brackets or a word follows.
        if !is_host(name) {
            return (!name.is_empty() && has_extension(name)).then(|| name.to_string());
        }
    }
    // A name in brackets: the last /\[([^[\]]*[^.\s[\]]\.[A-Za-z0-9]{2,4})\]/.
    let mut bracketed = None;
    for (open, _) in text.match_indices('[') {
        let inside = &text[open + 1..];
        let Some(close) = inside.find(']') else { break };
        let part = &inside[..close];
        if !part.contains('[') && has_extension(part) {
            bracketed = Some(part);
        }
    }
    if let Some(part) = bracketed {
        return Some(part.to_string());
    }
    text.split(' ').find(|w| has_extension(w) && !is_host(w)).map(str::to_string)
}

/// /www\./i: a host ("www.libranews.nl"), whose ".nl" is no extension.
fn is_host(s: &str) -> bool {
    s.to_ascii_lowercase().contains("www.")
}

/// One line of an XOVER reply: number, subject, from, date, message-id, bytes, xref (scanOverviewText).
fn scan_overview_text(text: &str, mut line: impl FnMut(Option<i64>, &str, &str, &str, &str, &str, &str)) {
    let b = text.as_bytes();
    let mut start = 0;
    while start < b.len() {
        let end = memchr::memchr(b'\n', &b[start..]).map(|i| i + start).unwrap_or(b.len());
        let stop = if end > start && b[end - 1] == b'\r' { end - 1 } else { end };
        if stop > start {
            let l = &text[start..stop];
            let lb = l.as_bytes();
            let mut tabs = [usize::MAX; 9];
            let mut n = 0;
            for i in memchr::memchr_iter(b'\t', lb) {
                tabs[n] = i;
                n += 1;
                if n == 9 {
                    break;
                }
            }
            if n >= 5 {
                let field = |a: usize, b: usize| -> &str {
                    if a == usize::MAX {
                        ""
                    } else {
                        &l[a + 1..if b == usize::MAX { l.len() } else { b }]
                    }
                };
                let mut xref = if n >= 8 { field(tabs[7], tabs[8]) } else { "" };
                if let Some(rest) = xref.strip_prefix("Xref:") {
                    xref = rest.strip_prefix(' ').unwrap_or(rest);
                }
                line(js::parse_int(&l[..tabs[0]]), &l[tabs[0] + 1..tabs[1]], field(tabs[1], tabs[2]), field(tabs[2], tabs[3]), field(tabs[3], tabs[4]), field(tabs[5], tabs[6]), xref);
            }
        }
        start = end + 1;
    }
}

/// A re-upload's copy of a file is kept apart (FileAggregator, uploadGapMs); a file joins the open release of its
/// key posted within this gap of it, else starts one (uploadsOf, online).
pub const UPLOAD_GAP_MS: i64 = 3 * 60 * 60 * 1000;
/// The window (REBUILD.md, "Voyager 3: window indexing", 2): a file still missing parts, and a release, are finished
/// once the frontier is this far past their last part.
pub const WINDOW_MS: i64 = 24 * 60 * 60 * 1000;
/// The frontier is the median Date of the last this many plausibly dated articles: enough that a minority of skewed
/// dates can't move it, few enough that it trails the newest article by little even in a quiet group (half the
/// ring: a day at 500 articles a day).
pub const FRONTIER_ARTICLES: usize = 1024;
/// A Date further than this from the frontier isn't believed (clock skew, bogus years); FRONTIER_ARTICLES of them
/// in a row that agree among themselves move it (the group paused for longer).
pub const PLAUSIBLE_MS: i64 = 7 * 24 * 60 * 60 * 1000;
/// The frontier is established once this many dated articles were seen (a lone bogus date doesn't set it).
const FRONTIER_MIN: usize = 64;
/// Albums (REBUILD.md, "Voyager 3: window indexing", 3): a poster's single-file releases whose file names differ only
/// by number sequences, posted within WINDOW_MS of the album's first, written as one release (`source: "album"`); an
/// album holds at most this many files (a dump of 38k pictures a day is a few albums, not one).
pub const ALBUM_MAX_FILES: usize = 1000;
/// A counter total this large, shared by this many releases of one poster, is a batch counter (Yenc-PP-A&A's
/// [n/68067] over thousands of different programs), not a file count: those releases get no file total.
pub const BATCH_COUNTER_MIN_TOTAL: i64 = 100;
pub const BATCH_COUNTER_RELEASES: u32 = 20;
/// Batches after which a poster's counter total is forgotten (BATCH_COUNTER_RELEASES must come within them).
const BATCH_COUNTER_BATCHES: u64 = 100;

fn median(dates: &mut [i64]) -> i64 {
    let mid = dates.len() / 2;
    *dates.select_nth_unstable(mid).1
}

/// Where the block is in posting time: the median Date of the last FRONTIER_ARTICLES plausible ones. Date headers
/// alone aren't trusted: a date more than PLAUSIBLE_MS from the frontier is set aside, and only FRONTIER_ARTICLES
/// such dates in a row, agreeing among themselves, move the frontier there.
#[derive(Default, Serialize, Deserialize)]
pub struct Frontier {
    ring: Vec<i64>,
    at: usize,
    value: Option<i64>,
    /// The frontier when first established: the block's start in posting time (releases within WINDOW_MS of it are edges).
    start: Option<i64>,
    /// Dates set aside since the last plausible one.
    aside: Vec<i64>,
    pending: usize,
}

impl Frontier {
    pub fn add(&mut self, t: i64) {
        if let Some(f) = self.value {
            if (t - f).abs() > PLAUSIBLE_MS {
                self.aside.push(t);
                if self.aside.len() >= FRONTIER_ARTICLES {
                    let m = median(&mut self.aside.clone());
                    if self.aside.iter().filter(|&&d| (d - m).abs() <= PLAUSIBLE_MS).count() * 2 >= self.aside.len() {
                        self.ring = self.aside.iter().copied().filter(|&d| (d - m).abs() <= PLAUSIBLE_MS).collect();
                        self.ring.truncate(FRONTIER_ARTICLES);
                        self.at = self.ring.len() % FRONTIER_ARTICLES;
                        self.value = Some(m);
                    }
                    self.aside.clear();
                }
                return;
            }
            self.aside.clear();
        }
        if self.ring.len() < FRONTIER_ARTICLES {
            self.ring.push(t);
        } else {
            self.ring[self.at] = t;
        }
        self.at = (self.at + 1) % FRONTIER_ARTICLES;
        self.pending += 1;
    }

    /// Recomputes the frontier (once per chunk: a median of FRONTIER_ARTICLES isn't for every article).
    pub fn update(&mut self) {
        if self.pending == 0 || (self.value.is_none() && self.ring.len() < FRONTIER_MIN) {
            return;
        }
        self.pending = 0;
        let m = median(&mut self.ring.clone());
        self.value = Some(m);
        if self.start.is_none() {
            self.start = Some(m);
        }
    }

    /// At the block's end: whatever dates there are set the frontier (a small block never reached FRONTIER_MIN).
    pub fn settle(&mut self) {
        if self.value.is_none() && !self.ring.is_empty() {
            self.pending = 1;
            let m = median(&mut self.ring.clone());
            self.value = Some(m);
            self.start = Some(m);
        } else {
            self.update();
        }
    }

    pub fn value(&self) -> Option<i64> {
        self.value
    }

    pub fn start(&self) -> Option<i64> {
        self.start
    }

    /// The posting time before which a last part means the window closed.
    fn closed_before(&self) -> Option<i64> {
        self.value.map(|f| f - WINDOW_MS)
    }
}

struct OpenFile {
    parts: Vec<Seg>,
    seen: FxHashSet<u32>,
    total: u32,
    touched: u64,
    /// Posting times seen.
    earliest: Option<i64>,
    latest: Option<i64>,
}

// The snapshot (REBUILD.md, "Voyager 3: window indexing", 5): the window's state between two batches, serialized
// (bincode, gzip by the worker) and kept by the coordinator, restored by the group's next holder. Segments share
// their file's FileMeta through an Rc; in the snapshot the files are a table and a segment points at its index.
#[derive(Serialize, Deserialize)]
struct SegSnap {
    file: u32,
    number: u32,
    message_id: String,
    bytes: i64,
    article: i64,
    posted_at: Option<i64>,
}

#[derive(Serialize, Deserialize)]
struct OpenFileSnap {
    parts: Vec<SegSnap>,
    total: u32,
    touched: u64,
    earliest: Option<i64>,
    latest: Option<i64>,
}

#[derive(Serialize, Deserialize)]
struct OpenReleaseSnap {
    upload: usize,
    files: Vec<Vec<SegSnap>>,
    first: Option<i64>,
    last: Option<i64>,
    touched: u64,
}

#[derive(Serialize, Deserialize)]
struct OpenAlbumSnap {
    upload: usize,
    members: Vec<(String, OpenReleaseSnap)>,
    first: Option<i64>,
    last: Option<i64>,
    touched: u64,
}

/// A file's details in the snapshot (FileMeta, its release identity's source as text: a &'static str in memory).
#[derive(Serialize, Deserialize)]
struct FileMetaSnap {
    file_key: String,
    name: String,
    poster: String,
    subject: String,
    total_parts: u32,
    groups: Vec<String>,
    release_key: String,
    release_name: String,
    release_source: String,
    release_file_total: Option<i64>,
}

/// The sources release_identity gives (lib/release/source.ts), as the static strings the code compares.
fn source_static(source: &str) -> &'static str {
    match source {
        "subject" => "subject",
        "post" => "post",
        "stem" => "stem",
        "album" => "album",
        "weak-stem" => "weak-stem",
        _ => "stem",
    }
}

#[derive(Serialize, Deserialize)]
pub struct Snapshot {
    pub version: u32,
    pub group: String,
    /// The article the window stands at: the next one to index (a batch boundary).
    pub next: i64,
    frontier: Frontier,
    files: Vec<FileMetaSnap>,
    aggregator: Vec<(String, Vec<OpenFileSnap>)>,
    aggregator_batch: u64,
    open: Vec<(String, Vec<OpenReleaseSnap>)>,
    albums: Vec<(String, Vec<OpenAlbumSnap>)>,
    uploads: Vec<(String, usize)>,
    batch_totals: Vec<(String, i64, u32, u64)>,
}

/// The snapshot's format version: raised when the state's shape changes (an older snapshot is refused: the group
/// continues at its resume point, one seam).
pub const SNAPSHOT_VERSION: u32 = 1;

/// The files of a snapshot as they are taken: each FileMeta once, by its Rc.
#[derive(Default)]
struct FileTable {
    index: FxHashMap<*const FileMeta, u32>,
    files: Vec<Rc<FileMeta>>,
}

impl FileTable {
    fn seg(&mut self, s: &Seg) -> SegSnap {
        let ptr = Rc::as_ptr(&s.file);
        let file = match self.index.get(&ptr) {
            Some(&i) => i,
            None => {
                let i = self.files.len() as u32;
                self.index.insert(ptr, i);
                self.files.push(s.file.clone());
                i
            }
        };
        SegSnap { file, number: s.number, message_id: s.message_id.clone(), bytes: s.bytes, article: s.article, posted_at: s.posted_at }
    }

    fn segs(&mut self, segs: &[Seg]) -> Vec<SegSnap> {
        segs.iter().map(|s| self.seg(s)).collect()
    }

    fn release(&mut self, u: &OpenRelease) -> OpenReleaseSnap {
        OpenReleaseSnap { upload: u.upload, files: u.files.iter().map(|f| self.segs(f)).collect(), first: u.first, last: u.last, touched: u.touched }
    }

    /// The table's files as the snapshot stores them.
    fn into_files(self) -> Vec<FileMetaSnap> {
        self.files
            .iter()
            .map(|f| FileMetaSnap {
                file_key: f.file_key.clone(),
                name: f.name.clone(),
                poster: f.poster.clone(),
                subject: f.subject.clone(),
                total_parts: f.total_parts,
                groups: f.groups.clone(),
                release_key: f.release.key.clone(),
                release_name: f.release.name.clone(),
                release_source: f.release.source.to_string(),
                release_file_total: f.release.file_total,
            })
            .collect()
    }
}

fn file_of(f: FileMetaSnap) -> FileMeta {
    FileMeta {
        file_key: f.file_key,
        name: f.name,
        poster: f.poster,
        subject: f.subject,
        total_parts: f.total_parts,
        groups: f.groups,
        release: Release { key: f.release_key, name: f.release_name, source: source_static(&f.release_source), file_total: f.release_file_total },
    }
}

fn seg_of(s: SegSnap, files: &[Rc<FileMeta>]) -> Seg {
    Seg { file: files[s.file as usize].clone(), number: s.number, message_id: s.message_id, bytes: s.bytes, article: s.article, posted_at: s.posted_at }
}

fn release_of(u: OpenReleaseSnap, files: &[Rc<FileMeta>]) -> OpenRelease {
    OpenRelease { upload: u.upload, files: u.files.into_iter().map(|f| f.into_iter().map(|s| seg_of(s, files)).collect()).collect(), first: u.first, last: u.last, touched: u.touched }
}

impl OpenFile {
    fn distance(&self, t: Option<i64>) -> i64 {
        match (t, self.earliest, self.latest) {
            (Some(t), Some(e), Some(l)) => 0.max(e - t).max(t - l),
            _ => 0,
        }
    }
}

#[derive(Default)]
struct Aggregator {
    /// Per file key its open copies, oldest first.
    open: FxHashMap<String, Vec<OpenFile>>,
    batch: u64,
}

impl Aggregator {
    fn add(&mut self, segments: Vec<Seg>) -> Vec<Vec<Seg>> {
        self.batch += 1;
        let batch = self.batch;
        let mut touched: Vec<String> = Vec::new();
        let mut touched_set: FxHashSet<String> = FxHashSet::default();
        for s in segments {
            let key = s.file.file_key.clone();
            if !touched_set.contains(key.as_str()) {
                touched_set.insert(key.clone());
                touched.push(key.clone());
            }
            let copies = self.open.entry(key).or_default();
            let t = s.posted_at;
            // A copy lacking the part, the nearest in time.
            let mut chosen: Option<usize> = None;
            let mut best = i64::MAX;
            for (i, copy) in copies.iter().enumerate() {
                if copy.seen.contains(&s.number) {
                    continue;
                }
                let d = copy.distance(t);
                if d < best {
                    best = d;
                    chosen = Some(i);
                }
            }
            let index = match chosen {
                Some(i) => i,
                None => {
                    if let Some(near) = copies.iter_mut().find(|c| c.distance(t) <= UPLOAD_GAP_MS) {
                        near.touched = batch;
                        continue;
                    }
                    copies.push(OpenFile { parts: Vec::new(), seen: FxHashSet::default(), total: s.file.total_parts, touched: batch, earliest: None, latest: None });
                    copies.len() - 1
                }
            };
            let file = &mut copies[index];
            file.seen.insert(s.number);
            if let Some(t) = t {
                if file.earliest.is_none_or(|e| t < e) {
                    file.earliest = Some(t);
                }
                if file.latest.is_none_or(|l| t > l) {
                    file.latest = Some(t);
                }
            }
            file.touched = batch;
            file.parts.push(s);
        }
        let mut complete = Vec::new();
        for key in touched {
            let copies = self.open.get_mut(&key).unwrap();
            let mut i = 0;
            while i < copies.len() {
                if (copies[i].parts.len() as u32) < copies[i].total {
                    i += 1;
                    continue;
                }
                let mut f = copies.remove(i);
                f.parts.sort_by_key(|s| s.number);
                complete.push(f.parts);
            }
            if copies.is_empty() {
                self.open.remove(&key);
            }
        }
        complete
    }

    /// Files the window closed on, still missing parts: those whose last part is before `closed_before`, undated ones
    /// idle for `idle` batches (all when `all`). Their segments, part order.
    fn evict(&mut self, closed_before: Option<i64>, idle: u64, all: bool) -> Vec<Vec<Seg>> {
        let batch = self.batch;
        let mut out = Vec::new();
        let keys: Vec<String> = self.open.keys().cloned().collect();
        for key in keys {
            let copies = self.open.get_mut(&key).unwrap();
            let mut i = 0;
            while i < copies.len() {
                let c = &copies[i];
                let closed = match c.latest {
                    Some(l) => closed_before.is_some_and(|before| l < before),
                    None => idle > 0 && batch - c.touched >= idle,
                };
                if !all && !closed {
                    i += 1;
                    continue;
                }
                let mut f = copies.remove(i);
                f.parts.sort_by_key(|s| s.number);
                out.push(f.parts);
            }
            if copies.is_empty() {
                self.open.remove(&key);
            }
        }
        out
    }
}

/// A release still open in the window: the files of one upload of its key (one after another, as they finished).
struct OpenRelease {
    upload: usize,
    files: Vec<Vec<Seg>>,
    first: Option<i64>,
    last: Option<i64>,
    touched: u64,
}

impl OpenRelease {
    /// How far a file's posting span is from the release's (0 when either is undated).
    fn distance(&self, first: Option<i64>, last: Option<i64>) -> i64 {
        match (first, last, self.first, self.last) {
            (Some(ff), Some(fl), Some(rf), Some(rl)) => 0.max(rf - fl).max(ff - rl),
            _ => 0,
        }
    }
}

/// An album still open: the closed singles of one poster and name template (ALBUM_MAX_FILES at most), with their
/// release keys, so a lone member is written as the release it was.
struct OpenAlbum {
    upload: usize,
    members: Vec<(String, OpenRelease)>,
    first: Option<i64>,
    last: Option<i64>,
    touched: u64,
}

/// The template a file name joins an album by: every digit run as "#" ("1481439079025_014.jpg.data" →
/// "#_#.jpg.data"); none for a name without a number, a random one, an archive, a volume or a sidecar.
pub fn album_template(name: &str) -> Option<String> {
    let (stem, ext) = split_extension(name);
    // A numbered extension is a volume ("acs5152s1.11"), and a stray suffix hides none of the above ("x.par2.temp").
    let volume = |n: &str| names::is_par2(n) || names::is_archive_start(n) || names::is_later_volume(n);
    if is_random_file(name) || names::is_sidecar(name) || volume(name) || volume(stem) || (ext.len() > 1 && ext.bytes().skip(1).all(|c| c.is_ascii_digit())) {
        return None;
    }
    let mut out = String::with_capacity(name.len());
    let mut runs = 0;
    let mut in_digits = false;
    for c in stem.chars() {
        if c.is_ascii_digit() {
            if !in_digits {
                out.push('#');
                runs += 1;
                in_digits = true;
            }
        } else {
            in_digits = false;
            out.push(c);
        }
    }
    out.push_str(ext);
    (runs > 0).then_some(out)
}

/// A name's stem and its extension (a last ".xxx" of 1–5 letters and digits, "mp4"'s 4 no number sequence).
fn split_extension(name: &str) -> (&str, &str) {
    match name.rfind('.') {
        Some(dot) if dot > 0 && (1..=5).contains(&(name.len() - dot - 1)) && name[dot + 1..].bytes().all(|c| c.is_ascii_alphanumeric()) => (&name[..dot], &name[dot..]),
        _ => (name, ""),
    }
}

/// A name's runs of digits and of other characters, in order.
fn digit_runs(name: &str) -> Vec<(bool, &str)> {
    let mut out = Vec::new();
    let mut start = 0;
    let b = name.as_bytes();
    let mut i = 0;
    while i < b.len() {
        let digits = b[i].is_ascii_digit();
        let mut j = i + 1;
        while j < b.len() && b[j].is_ascii_digit() == digits {
            j += 1;
        }
        out.push((digits, &name[start..j]));
        start = j;
        i = j;
    }
    out
}

/// An album's name: its members' shared name, with the numbers that vary among them as "#" and the ones they share
/// kept ("1481439079025_#.jpg.data" for one timestamp's pictures).
pub fn album_name(names: &[&str]) -> String {
    let (stem, ext) = split_extension(names[0]);
    let first = digit_runs(stem);
    let mut varies = vec![false; first.len()];
    for name in &names[1..] {
        let runs = digit_runs(split_extension(name).0);
        if runs.len() != first.len() {
            return album_template(names[0]).unwrap_or_else(|| names[0].to_string());
        }
        for (i, (digits, text)) in runs.iter().enumerate() {
            if *digits && first[i].1 != *text {
                varies[i] = true;
            }
        }
    }
    let mut out = String::with_capacity(names[0].len());
    for (i, (digits, text)) in first.iter().enumerate() {
        if *digits && varies[i] {
            out.push('#');
        } else {
            out.push_str(text);
        }
    }
    out.push_str(ext);
    out
}

pub struct RangeIndexer {
    group: String,
    rules: Rules,
    end: i64,
    priorities: FxHashMap<String, u32>,
    idle: u64,
    scanner: Scanner,
    aggregator: Aggregator,
    frontier: Frontier,
    /// Per release key its open uploads, oldest first.
    open: FxHashMap<String, Vec<OpenRelease>>,
    /// Per album key its open albums, oldest first.
    albums: FxHashMap<String, Vec<OpenAlbum>>,
    /// The next upload number per key (distinct within a batch: the store's slot is the key and the upload).
    uploads: FxHashMap<String, usize>,
    /// Per (poster, counter total ≥ BATCH_COUNTER_MIN_TOTAL) the releases started under it and the batch of the last.
    batch_totals: FxHashMap<(String, i64), (u32, u64)>,
    batch: Batch,
    counts: FxHashMap<(&'static str, String), (u64, u64)>,
    count_order: Vec<(&'static str, String)>,
    /// Posting times of this batch's segments (posted_span at take).
    dates: Vec<i64>,
    pending_files: usize,
}

impl RangeIndexer {
    /// `resume_at`: where this worker starts (a range taken over midway); its first batch starts there. `idle`: batches
    /// (chunks) after which an undated file or release is given up.
    pub fn new(group: &str, _start: i64, end: i64, resume_at: i64, rules: Rules, idle: u64) -> Self {
        RangeIndexer {
            group: group.to_string(),
            end,
            priorities: rules.priorities.clone(),
            rules,
            idle,
            scanner: Scanner::default(),
            aggregator: Aggregator::default(),
            frontier: Frontier::default(),
            open: FxHashMap::default(),
            albums: FxHashMap::default(),
            uploads: FxHashMap::default(),
            batch_totals: FxHashMap::default(),
            batch: Batch { from: resume_at, next: resume_at, ..Default::default() },
            counts: FxHashMap::default(),
            count_order: Vec::new(),
            dates: Vec::new(),
            pending_files: 0,
        }
    }

    /// A worker's indexer for a group it holds (REBUILD.md design 1): ranges come one after another (begin_range),
    /// the window carried between them; the batch starts at the first range's resume point.
    pub fn for_group(group: &str, rules: Rules, idle: u64) -> Self {
        Self::new(group, 0, 0, 0, rules, idle)
    }

    /// The next range of the group: the batch starts at its resume point (after a gap too), the range's end is known.
    pub fn begin_range(&mut self, next: i64, end: i64) {
        self.end = end;
        if self.batch.headers == 0 && self.batch.releases.is_empty() && self.batch.candidates.is_empty() {
            self.batch.from = next;
            self.batch.next = next;
        }
    }

    /// The article the window stands at: the next one to index (right after a take, a batch boundary).
    pub fn next(&self) -> i64 {
        self.batch.next
    }

    /// The window's state between two batches (right after a take; the batch must be empty), serialized (bincode).
    pub fn snapshot(&self) -> Result<Vec<u8>, String> {
        if self.batch.headers != 0 || !self.batch.releases.is_empty() || !self.batch.candidates.is_empty() {
            return Err("a snapshot is taken right after a batch, not with one open".to_string());
        }
        let mut table = FileTable::default();
        let aggregator: Vec<(String, Vec<OpenFileSnap>)> = self
            .aggregator
            .open
            .iter()
            .map(|(key, copies)| {
                (key.clone(), copies.iter().map(|c| OpenFileSnap { parts: table.segs(&c.parts), total: c.total, touched: c.touched, earliest: c.earliest, latest: c.latest }).collect())
            })
            .collect();
        let open: Vec<(String, Vec<OpenReleaseSnap>)> = self.open.iter().map(|(key, uploads)| (key.clone(), uploads.iter().map(|u| table.release(u)).collect())).collect();
        let albums: Vec<(String, Vec<OpenAlbumSnap>)> = self
            .albums
            .iter()
            .map(|(key, list)| {
                (
                    key.clone(),
                    list.iter()
                        .map(|a| OpenAlbumSnap { upload: a.upload, members: a.members.iter().map(|(k, u)| (k.clone(), table.release(u))).collect(), first: a.first, last: a.last, touched: a.touched })
                        .collect(),
                )
            })
            .collect();
        let snapshot = Snapshot {
            version: SNAPSHOT_VERSION,
            group: self.group.clone(),
            next: self.batch.next,
            frontier: Frontier { ring: self.frontier.ring.clone(), at: self.frontier.at, value: self.frontier.value, start: self.frontier.start, aside: self.frontier.aside.clone(), pending: self.frontier.pending },
            files: table.into_files(),
            aggregator,
            aggregator_batch: self.aggregator.batch,
            open,
            albums,
            uploads: self.uploads.iter().map(|(k, &n)| (k.clone(), n)).collect(),
            batch_totals: self.batch_totals.iter().map(|((poster, total), (n, touched))| (poster.clone(), *total, *n, *touched)).collect(),
        };
        bincode::serialize(&snapshot).map_err(|e| e.to_string())
    }

    /// A worker's indexer for a group from its snapshot (the rules fresh from the lease).
    pub fn restore(bytes: &[u8], rules: Rules, idle: u64) -> Result<Self, String> {
        let snapshot: Snapshot = bincode::deserialize(bytes).map_err(|e| format!("snapshot: {e}"))?;
        if snapshot.version != SNAPSHOT_VERSION {
            return Err(format!("snapshot version {} (this build writes {SNAPSHOT_VERSION})", snapshot.version));
        }
        let files: Vec<Rc<FileMeta>> = snapshot.files.into_iter().map(|f| Rc::new(file_of(f))).collect();
        let mut ix = Self::for_group(&snapshot.group, rules, idle);
        ix.frontier = snapshot.frontier;
        ix.aggregator.batch = snapshot.aggregator_batch;
        for (key, copies) in snapshot.aggregator {
            ix.aggregator.open.insert(
                key,
                copies
                    .into_iter()
                    .map(|c| {
                        let parts: Vec<Seg> = c.parts.into_iter().map(|s| seg_of(s, &files)).collect();
                        let seen = parts.iter().map(|s| s.number).collect();
                        OpenFile { parts, seen, total: c.total, touched: c.touched, earliest: c.earliest, latest: c.latest }
                    })
                    .collect(),
            );
        }
        for (key, uploads) in snapshot.open {
            ix.open.insert(key, uploads.into_iter().map(|u| release_of(u, &files)).collect());
        }
        for (key, list) in snapshot.albums {
            ix.albums.insert(
                key,
                list.into_iter().map(|a| OpenAlbum { upload: a.upload, members: a.members.into_iter().map(|(k, u)| (k, release_of(u, &files))).collect(), first: a.first, last: a.last, touched: a.touched }).collect(),
            );
        }
        ix.uploads = snapshot.uploads.into_iter().collect();
        ix.batch_totals = snapshot.batch_totals.into_iter().map(|(poster, total, n, touched)| ((poster, total), (n, touched))).collect();
        ix.batch = Batch { from: snapshot.next, next: snapshot.next, ..Default::default() };
        Ok(ix)
    }

    pub fn add_text(&mut self, text: &str, next: i64) {
        let mut segments: Vec<Seg> = Vec::new();
        let mut crossposts: Vec<String> = Vec::new();
        let mut obfuscated = 0u64;
        let mut headers = 0u64;
        {
            let group = self.group.clone();
            let scanner = &mut self.scanner;
            let priorities = &self.priorities;
            scan_overview_text(text, |n, subject, from, date, message_id, bytes, xref| {
                let Some(n) = n else { return };
                if message_id.is_empty() {
                    return;
                }
                headers += 1;
                let owner = if xref.is_empty() { group.as_str() } else { scanner.owner(xref, &group, priorities) };
                if owner != group {
                    crossposts.push(owner.to_string());
                    return;
                }
                match scanner.segment(n, subject, from, date, message_id, bytes, xref, &group) {
                    Some(s) => segments.push(s),
                    None => obfuscated += 1,
                }
            });
        }
        self.batch.headers += headers;
        for t in segments.iter().filter_map(|s| s.posted_at) {
            self.dates.push(t);
            self.frontier.add(t);
        }
        for owner in crossposts {
            self.count("crosspost", owner, 1, 0);
        }
        if obfuscated > 0 {
            self.count("obfuscated", String::new(), obfuscated, 0);
        }
        self.end_chunk(segments, next);
    }

    fn end_chunk(&mut self, segments: Vec<Seg>, next: i64) {
        let t = std::time::Instant::now();
        let done = self.aggregator.add(segments);
        unsafe { PROF[3] += t.elapsed().as_nanos() as u64; }
        self.files(done, false);
        self.frontier.update();
        let t = std::time::Instant::now();
        let gone = self.aggregator.evict(self.frontier.closed_before(), self.idle, false);
        self.files(gone, false);
        self.close(false);
        unsafe { PROF[4] += t.elapsed().as_nanos() as u64; }
        self.batch.next = next;
    }

    /// The block's end: every file and release left is written, finished when the window closed on it, else
    /// provisionally and as an edge (the block merger finishes it with the neighbour block's part).
    pub fn finish(&mut self) {
        self.frontier.settle();
        let gone = self.aggregator.evict(None, 0, true);
        self.files(gone, true);
        self.close(true);
        self.batch.next = self.end + 1;
    }

    /// The next range of a group starts after a gap (edge-bench --group, the corpus holding some ranges only): a fresh
    /// batch starts there, not at the previous range's end; the window carries on. Nothing when the batch has anything.
    pub fn skip_to(&mut self, article: i64) {
        if self.batch.headers == 0 && self.batch.releases.is_empty() && self.batch.candidates.is_empty() && self.batch.from < article {
            self.batch.from = article;
            self.batch.next = article;
        }
    }

    /// Files in the releases finished since the last take (RangeIndexer.pending).
    pub fn pending(&self) -> usize {
        self.pending_files
    }

    /// Where the block is in posting time (None until FRONTIER_MIN dated articles were read).
    pub fn frontier(&self) -> Option<i64> {
        self.frontier.value()
    }

    /// Releases the window still holds (edge-bench's progress line).
    pub fn open_releases(&self) -> usize {
        self.open.values().map(|u| u.len()).sum::<usize>() + self.albums.values().map(|a| a.len()).sum::<usize>()
    }

    /// Files still short of parts, or complete and not yet in a release.
    pub fn open_files(&self) -> usize {
        self.aggregator.open.values().map(|f| f.len()).sum()
    }

    pub fn take(&mut self) -> Batch {
        self.scanner.files.clear();
        let next = self.batch.next;
        let mut out = std::mem::replace(&mut self.batch, Batch { from: next, next, ..Default::default() });
        (out.posted_low, out.posted_high) = posted_span(std::mem::take(&mut self.dates));
        for id in self.count_order.drain(..) {
            let (articles, files) = self.counts.remove(&id).unwrap();
            out.counts.push((id.0, id.1, articles, files));
        }
        self.pending_files = 0;
        // Upload numbers only have to be distinct within a batch: those of keys with nothing open go.
        let (open, albums) = (&self.open, &self.albums);
        self.uploads.retain(|key, _| open.contains_key(key) || albums.contains_key(key));
        let batch = self.aggregator.batch;
        self.batch_totals.retain(|_, (_, touched)| batch - *touched < BATCH_COUNTER_BATCHES);
        out
    }

    /// Finished files (complete, or the window closed on them) into the open release of their key and upload; `at_end`
    /// when the block ends on them.
    fn files(&mut self, files: Vec<Vec<Seg>>, at_end: bool) {
        let batch = self.aggregator.batch;
        for file in files {
            let lone = file.len() == 1 && (file[0].number != 1 || file[0].file.total_parts > 1);
            // A scrambled name only before the block's end, where the rest of a file can still be in the next block.
            if lone && (is_random_file(&file[0].file.name) || (!at_end && looks_scrambled(&file[0].file.name))) {
                // One article of a multi-part random file (its upload per article: ngPost's, nyuu's, and a random poster's
                // per article, 160k in alt.binaries.storage; LOG.md (122)): not a release.
                let tool = names::upload_tool(&file[0].message_id);
                self.count("per-article", tool.to_string(), 1, 0);
                continue;
            }
            let key = release_key_of(&file[0]);
            let first = posted_of(&file);
            let last = file.iter().filter_map(|s| s.posted_at).max();
            let uploads = self.open.entry(key.clone()).or_default();
            let near = uploads.iter_mut().filter(|u| u.distance(first, last) <= UPLOAD_GAP_MS).min_by_key(|u| u.distance(first, last));
            let release = match near {
                Some(u) => u,
                None => {
                    let n = self.uploads.entry(key).or_insert(0);
                    let upload = *n;
                    *n += 1;
                    if let Some(total) = file[0].file.release.file_total_truthy().filter(|&t| t >= BATCH_COUNTER_MIN_TOTAL) {
                        let e = self.batch_totals.entry((file[0].file.poster.clone(), total)).or_insert((0, batch));
                        e.0 += 1;
                        e.1 = batch;
                    }
                    uploads.push(OpenRelease { upload, files: Vec::new(), first: None, last: None, touched: batch });
                    uploads.last_mut().unwrap()
                }
            };
            if let Some(f) = first {
                if release.first.is_none_or(|r| f < r) {
                    release.first = Some(f);
                }
            }
            if let Some(l) = last {
                if release.last.is_none_or(|r| l > r) {
                    release.last = Some(l);
                }
            }
            release.touched = batch;
            release.files.push(file);
        }
    }

    /// Releases the window closed on (their last part before the frontier less WINDOW_MS; undated ones idle for
    /// `idle` batches): judged and written. At the end (`all`), the rest too: provisionally, as edges.
    fn close(&mut self, all: bool) {
        let before = self.frontier.closed_before();
        let start = self.frontier.start();
        let batch = self.aggregator.batch;
        let idle = self.idle;
        let mut done: Vec<(String, OpenRelease, bool)> = Vec::new();
        let keys: Vec<String> = self.open.keys().cloned().collect();
        for key in keys {
            let uploads = self.open.get_mut(&key).unwrap();
            let mut i = 0;
            while i < uploads.len() {
                let u = &uploads[i];
                let closed = match u.last {
                    Some(l) => before.is_some_and(|b| l < b),
                    None => idle > 0 && batch - u.touched >= idle,
                };
                if !all && !closed {
                    i += 1;
                    continue;
                }
                done.push((key.clone(), uploads.remove(i), closed));
            }
            if uploads.is_empty() {
                self.open.remove(&key);
            }
        }
        // An edge: still open at the block's end, or posted within the window of the block's start (its other
        // part may be in the neighbour block); undated ones can't be placed, so they are edges too.
        let near_start = |first: Option<i64>| match (start, first) {
            (Some(s), Some(f)) => f < s + WINDOW_MS,
            _ => true,
        };
        // In posting order, so an album's members join it from its first file on (the keys' order is a hash's).
        done.sort_by(|a, b| a.1.first.cmp(&b.1.first).then_with(|| a.0.cmp(&b.0)));
        for (key, u, closed) in done {
            // A single the window closed on waits in its album (a lone one is written as it is when that closes).
            if closed {
                if let Some(template) = album_candidate(&u) {
                    self.album(key, u, template);
                    continue;
                }
            }
            let edge = !closed || near_start(u.first);
            self.emit(&key, u, closed, edge);
        }
        // Albums: closed once every single that could join (posted within WINDOW_MS of the first) has closed too.
        let mut done_albums: Vec<(String, OpenAlbum, bool)> = Vec::new();
        let keys: Vec<String> = self.albums.keys().cloned().collect();
        for key in keys {
            let list = self.albums.get_mut(&key).unwrap();
            let mut i = 0;
            while i < list.len() {
                let a = &list[i];
                let closed = match a.first {
                    Some(f) => before.is_some_and(|b| f + WINDOW_MS < b),
                    None => idle > 0 && batch - a.touched >= idle,
                };
                if !all && !closed {
                    i += 1;
                    continue;
                }
                done_albums.push((key.clone(), list.remove(i), closed));
            }
            if list.is_empty() {
                self.albums.remove(&key);
            }
        }
        for (key, mut a, closed) in done_albums {
            let edge = !closed || near_start(a.first);
            if a.members.len() < 2 {
                let (release_key, u) = a.members.remove(0);
                self.emit(&release_key, u, closed, edge);
                continue;
            }
            let names: Vec<&str> = a.members.iter().map(|(_, u)| u.files[0][0].file.name.as_str()).collect();
            let name = album_name(&names);
            let files: Vec<Vec<Seg>> = a.members.into_iter().flat_map(|(_, u)| u.files).collect();
            self.write(&key, a.upload, files, closed, edge, Some(name));
        }
    }

    /// A closed single into the open album of its poster and template posted within WINDOW_MS of its first file
    /// (with room), else a new one.
    fn album(&mut self, release_key: String, u: OpenRelease, template: String) {
        let batch = self.aggregator.batch;
        let poster = &u.files[0][0].file.poster;
        let poster = if names::random_poster(poster) { "" } else { poster.as_str() };
        let key = sha1_hex(&format!("album\n{poster}\n{template}"));
        let albums = self.albums.entry(key.clone()).or_default();
        let fits = |a: &OpenAlbum| {
            a.members.len() < ALBUM_MAX_FILES
                && match (a.first, u.first) {
                    (Some(af), Some(f)) => f >= af && f < af + WINDOW_MS,
                    _ => true,
                }
        };
        let index = match albums.iter().position(fits) {
            Some(i) => i,
            None => {
                let n = self.uploads.entry(key).or_insert(0);
                let upload = *n;
                *n += 1;
                albums.push(OpenAlbum { upload, members: Vec::new(), first: None, last: None, touched: batch });
                albums.len() - 1
            }
        };
        let a = &mut albums[index];
        if let Some(f) = u.first {
            if a.first.is_none_or(|r| f < r) {
                a.first = Some(f);
            }
        }
        if let Some(l) = u.last {
            if a.last.is_none_or(|r| l > r) {
                a.last = Some(l);
            }
        }
        a.touched = batch;
        a.members.push((release_key, u));
    }

    fn emit(&mut self, key: &str, release: OpenRelease, finished: bool, edge: bool) {
        self.write(key, release.upload, release.files, finished, edge, None);
    }

    /// A release (or an album, under its name) judged and written to the batch.
    fn write(&mut self, key: &str, upload: usize, list: Vec<Vec<Seg>>, finished: bool, edge: bool, album: Option<String>) {
        let judged: Vec<JudgedFile> = list
            .iter()
            .map(|f| JudgedFile {
                name: &f[0].file.name,
                total_parts: f[0].file.total_parts,
                groups: &f[0].file.groups,
                first_message_id: &f[0].message_id,
                poster: &f[0].file.poster,
                segments: f.len() as u32,
                bytes: f.iter().map(|s| s.bytes.max(0) as u64).sum(),
            })
            .collect();
        // Settled for the single-archive rules: the window closed on it (a par2 can still join an open one). The
        // start edge (posted within the window of the block's start) doesn't count: a par2 comes after its rar, so
        // one in the previous block is rare (0 par2 siblings of 3,000 catalog hits, LOG.md (125)), and 7% of the
        // catalog's releases are start edges, which would escape the rule.
        match names::judge(key, &judged, finished, &self.rules) {
            Verdict::Keep => {
                let candidates = candidates_of(key, &list, upload);
                let mut chunk = chunk_of(key, &list, upload);
                chunk.finished = finished;
                chunk.edge = edge;
                let album_none = album.is_none();
                if let Some(name) = album {
                    chunk.name = name;
                    chunk.source = "album";
                    chunk.file_total = None;
                }
                if !chunk.readable {
                    // Unnamed: no chunk (its segments are read again once a probe names it), the tool for its signature.
                    chunk.tool = Some(names::upload_tool(&list[0][0].message_id));
                    chunk.payload = encode_chunk(&[]);
                }
                if chunk.readable {
                    self.pending_files += chunk.files;
                }
                if let Some(total) = chunk.file_total.filter(|&t| album_none && t >= BATCH_COUNTER_MIN_TOTAL && (chunk.files as i64) < t) {
                    // A batch counter: no file total (the release is as complete as its files are).
                    if self.batch_totals.get(&(chunk.poster.clone(), total)).is_some_and(|(n, _)| *n >= BATCH_COUNTER_RELEASES) {
                        chunk.file_total = None;
                    }
                }
                self.batch.releases.push(chunk);
                self.batch.candidates.extend(candidates);
            }
            Verdict::Drop { rule, key: rule_key, sample } => {
                let segments: usize = list.iter().map(|f| f.len()).sum();
                self.count(rule, rule_key.clone(), segments as u64, list.len() as u64);
                if sample {
                    self.batch.samples.push((chunk_of(key, &list, upload), rule, rule_key));
                }
            }
        }
    }

    fn count(&mut self, rule: &'static str, key: String, articles: u64, files: u64) {
        match self.counts.get_mut(&(rule, key.clone())) {
            Some(c) => {
                c.0 += articles;
                c.1 += files;
            }
            None => {
                self.count_order.push((rule, key.clone()));
                self.counts.insert((rule, key), (articles, files));
            }
        }
    }
}

/// A closed release that may be an album's member: one file, named by its stem or its post (no release name in the
/// subject), with a number in its name (album_template).
fn album_candidate(u: &OpenRelease) -> Option<String> {
    if u.files.len() != 1 {
        return None;
    }
    let meta = &u.files[0][0].file;
    if !matches!(meta.release.source, "stem" | "post") {
        return None;
    }
    album_template(&meta.name)
}

fn release_key_of(s: &Seg) -> String {
    // A named file always has a release (releaseIdentity isn't null unless weak).
    s.file.release.key.clone()
}

fn posted_of(segments: &[Seg]) -> Option<i64> {
    segments.iter().filter_map(|s| s.posted_at).min()
}

fn chunk_of(key: &str, files: &[Vec<Seg>], upload: usize) -> ReleaseChunk {
    let first = &files[0][0].file;
    let chunk_files: Vec<ChunkFile> = files
        .iter()
        .map(|f| {
            let m = &f[0].file;
            ChunkFile { name: &m.name, poster: &m.poster, subject: &m.subject, posted_at: posted_of(f), groups: &m.groups, segments: f.iter().map(|s| (s.number, s.message_id.as_str(), s.bytes)).collect() }
        })
        .collect();
    let mut segments = 0;
    let mut bytes = 0;
    let mut first_article = i64::MAX;
    let mut last_article = 0;
    let mut posted_at: Option<i64> = None;
    let mut posted_last: Option<i64> = None;
    for f in files {
        for s in f {
            if let Some(t) = s.posted_at {
                if posted_last.is_none_or(|p| t > p) {
                    posted_last = Some(t);
                }
            }
            segments += 1;
            bytes += s.bytes;
            first_article = first_article.min(s.article);
            last_article = last_article.max(s.article);
        }
        if let Some(t) = posted_of(f) {
            if posted_at.is_none_or(|p| t < p) {
                posted_at = Some(t);
            }
        }
    }
    ReleaseChunk {
        key: key.to_string(),
        upload,
        name: first.release.name.clone(),
        source: first.release.source,
        file_total: files.iter().find_map(|f| f[0].file.release.file_total_truthy()),
        poster: first.poster.clone(),
        groups: first.groups.clone(),
        posted_at,
        posted_last,
        files: files.len(),
        segments,
        bytes,
        first_article,
        last_article,
        readable: chunk_files.iter().any(|f| !is_random_file(f.name)),
        has_par2: chunk_files.iter().any(|f| names::is_par2(f.name)),
        finished: true,
        edge: false,
        partial: files.iter().any(|f| (f.len() as u32) < f[0].file.total_parts),
        tool: None,
        payload: encode_chunk(&chunk_files),
        subjects: chunk_files.iter().take(SUBJECTS).map(|f| f.subject.to_string()).collect(),
    }
}

fn candidates_of(key: &str, files: &[Vec<Seg>], upload: usize) -> Vec<Candidate> {
    let mut out = Vec::new();
    let mut tail: Option<(i64, &Vec<Seg>)> = None;
    let c = |kind, s: &Seg| Candidate { release_key: key.to_string(), upload, kind, message_id: s.message_id.clone(), file: s.file.name.clone() };
    for f in files {
        let name = &f[0].file.name;
        let volume = names::seven_zip_volume(name);
        if let Some(volume) = volume.filter(|&v| v > 1) {
            if tail.is_none_or(|(v, _)| volume > v) {
                tail = Some((volume, f));
            }
            continue;
        }
        // An unsplit 7z of more than one segment: its listing is in its last one.
        if volume == Some(0) && f.len() > 1 && tail.is_none() {
            tail = Some((0, f));
        }
        if names::is_archive_start(name) {
            out.push(c("archive", &f[0]));
        } else if names::is_par2(name) && !names::is_later_volume(name) {
            out.push(c("par2", &f[0]));
        }
    }
    if let Some((_, f)) = tail {
        out.push(Candidate { release_key: key.to_string(), upload, kind: "7z-tail", message_id: f.last().unwrap().message_id.clone(), file: f[0].file.name.clone() });
    }
    if out.is_empty() && files.len() == 1 && is_random_file(&files[0][0].file.name) {
        out.push(c("lone", &files[0][0]));
    }
    out.truncate(4);
    out
}

#[cfg(test)]
mod tests {
    use super::*;

    const GROUP: &str = "alt.binaries.test";

    fn line(n: i64, subject: &str, minutes: i64) -> String {
        let date = chrono::DateTime::from_timestamp_millis(1_791_194_400_000 + minutes * 60_000).unwrap().format("%a, %d %b %Y %H:%M:%S +0000");
        format!("{n}\t{subject}\tp <p@x>\t{date}\t<u{n}@test>\t\t1000\t10\tXref: news.example {GROUP}:{n}")
    }

    #[test]
    fn uploads_split_as_in_the_typescript() {
        let mut priorities = FxHashMap::default();
        priorities.insert(GROUP.to_string(), 1);
        let mut ix = RangeIndexer::new(GROUP, 1, 10_000, 1, Rules::defaults(priorities), 5);
        let mut lines: Vec<String> = (0..5).map(|i| line(100 + i, &format!(r#"Big.Release [1/2] - "Big.Release.mkv" yEnc ({}/5)"#, i + 1), i * 60)).collect();
        lines.push(line(200, r#"Big.Release [2/2] - "Big.Release.par2" yEnc (1/1)"#, 245));
        lines.extend((0..5).map(|i| line(300 + i, &format!(r#"Big.Release [1/2] - "Big.Release.mkv" yEnc ({}/5)"#, i + 1), 1440 + i)));
        ix.add_text(&lines.join("\r\n"), 10_001);
        ix.finish();
        let batch = ix.take();
        let got: Vec<(usize, usize)> = batch.releases.iter().map(|r| (r.upload, r.files)).collect();
        assert_eq!(got, vec![(0, 2), (1, 1)]);
        assert_eq!(batch.releases[0].posted_last.unwrap() - batch.releases[0].posted_at.unwrap(), 245 * 60_000);
        assert_eq!(batch.releases[0].key, batch.releases[1].key);
        // A day of posting in all: the window never closed on them, so at the end they are provisional edges.
        assert!(batch.releases.iter().all(|r| !r.finished && r.edge && !r.partial));
    }

    /// `n` single-part filler files posted `minutes` apart from `start`: dated articles that move the frontier.
    fn fillers(from: i64, n: i64, start: i64, minutes: i64) -> Vec<String> {
        (0..n).map(|i| line(from + i, &format!(r#"Filler.{} [1/1] - "filler.{}.jpg" yEnc (1/1)"#, from + i, from + i), start + i * minutes)).collect()
    }

    #[test]
    fn the_window_finishes_releases_and_keeps_incomplete_files() {
        let mut priorities = FxHashMap::default();
        priorities.insert(GROUP.to_string(), 1);
        let mut ix = RangeIndexer::new(GROUP, 1, 1_000_000, 1, Rules::defaults(priorities), 5);
        let day = 24 * 60;
        // Chunk 1: a release at the block's start (two of three parts of its file), and 100 dated articles after it.
        let mut lines = vec![
            line(10, r#"Early.Show [1/1] - "Early.Show.mkv" yEnc (1/3)"#, 0),
            line(11, r#"Early.Show [1/1] - "Early.Show.mkv" yEnc (2/3)"#, 1),
        ];
        lines.extend(fillers(100, 100, 2, 1));
        ix.add_text(&lines.join("
"), 1000);
        assert!(ix.frontier().is_some());
        let b1 = ix.take();
        assert!(b1.releases.iter().all(|r| r.name.starts_with("Filler")));
        // Chunk 2, three days on (more articles than before, so the median moves there): the window closed on the
        // early show (its file still short a part) and on the first fillers.
        let mut lines = vec![line(2000, r#"Later.Show [1/1] - "Later.Show.mkv" yEnc (1/1)"#, 3 * day)];
        lines.extend(fillers(2100, 300, 3 * day + 1, 1));
        ix.add_text(&lines.join("
"), 3000);
        let b2 = ix.take();
        let early = b2.releases.iter().find(|r| r.name == "Early Show").expect("the early show is written");
        assert!(early.finished && early.edge && early.partial, "finished {} edge {} partial {}", early.finished, early.edge, early.partial);
        assert_eq!((early.files, early.segments), (1, 2));
        assert!(!b2.releases.iter().any(|r| r.name == "Later Show"));
        // Chunk 3, three more days: the later show is finished, and not an edge (a day past the block's start).
        ix.add_text(&fillers(4000, 500, 6 * day, 1).join("
"), 5000);
        let b3 = ix.take();
        let later = b3.releases.iter().find(|r| r.name == "Later Show").expect("the later show is written");
        assert!(later.finished && !later.edge && !later.partial);
        // The end: the last fillers are still inside the window, so they are provisional edges.
        ix.finish();
        let b4 = ix.take();
        assert_eq!(b4.releases.len(), 500);
        assert!(b4.releases.iter().all(|r| !r.finished && r.edge));
        assert_eq!(b4.next, 1_000_001);
    }

    #[test]
    fn singles_of_one_template_become_an_album() {
        let mut priorities = FxHashMap::default();
        priorities.insert(GROUP.to_string(), 1);
        let mut ix = RangeIndexer::new(GROUP, 1, 1_000_000, 1, Rules::defaults(priorities), 5);
        let day = 24 * 60;
        // A dump's pictures of one timestamp (a stem each: ".data" is no image), two scans, a lone document, and dated fillers.
        let mut lines: Vec<String> = (1..=14).map(|i| line(1000 + i, &format!(r#"<IMGBANK> [1/1] "1481439079025_{i:03}.jpg.data" yEnc (1/1)"#), i)).collect();
        lines.push(line(2001, r#"[1/1] "Scan_001.pdf" yEnc (1/1)"#, 20));
        lines.push(line(2002, r#"[1/1] "Scan_002.pdf" yEnc (1/1)"#, 21));
        lines.push(line(2003, r#"[1/1] "Lonely_007.pdf" yEnc (1/1)"#, 22));
        lines.extend(fillers(3000, 100, 23, 1));
        ix.add_text(&lines.join("\n"), 4000);
        let b1 = ix.take();
        assert!(b1.releases.iter().all(|r| r.name.starts_with("Filler")));
        // Three days on: the window closed on the singles, and on their albums.
        ix.add_text(&fillers(5000, 300, 3 * day, 1).join("\n"), 6000);
        let b2 = ix.take();
        let mut albums: Vec<(&str, &str, usize, bool)> = b2.releases.iter().filter(|r| !r.name.starts_with("Filler")).map(|r| (r.name.as_str(), r.source, r.files, r.finished)).collect();
        albums.sort();
        assert_eq!(albums, vec![("1481439079025_#.jpg.data", "album", 14, true), ("Lonely_007", "stem", 1, true), ("Scan_#.pdf", "album", 2, true)]);
        let album = b2.releases.iter().find(|r| r.source == "album" && r.files == 14).unwrap();
        // Posted within the window of the block's start: an edge, like any release there.
        assert!(album.file_total.is_none() && album.edge && !album.partial && album.readable);
        assert_eq!(album.segments, 14);
        assert_eq!(b2.candidates.len(), 0);
        assert!(ix.albums.is_empty());
    }

    #[test]
    fn an_unnamed_release_keeps_no_chunk_but_its_tool_and_probe_target() {
        let mut priorities = FxHashMap::default();
        priorities.insert(GROUP.to_string(), 1);
        let mut ix = RangeIndexer::new(GROUP, 1, 10_000, 1, Rules::defaults(priorities), 5);
        let lines: Vec<String> = (0..4).map(|i| line(100 + i, &format!(r#"[1/1] - "q3B9OrpKiCxUnzgtUGnp.part01.rar" yEnc ({}/4)"#, i + 1), i)).collect();
        ix.add_text(&lines.join("\n"), 10_001);
        ix.finish();
        let batch = ix.take();
        assert_eq!(batch.releases.len(), 1);
        let r = &batch.releases[0];
        assert!(!r.readable && r.tool == Some("other") && r.files == 1 && r.segments == 4);
        assert_eq!(r.payload, encode_chunk(&[]));
        assert_eq!(batch.candidates.iter().map(|c| c.kind).collect::<Vec<_>>(), vec!["archive"]);
        assert_eq!(ix.pending(), 0);
    }

    #[test]
    fn album_templates_and_names() {
        assert_eq!(album_template("1481439079025_014.jpg.data").as_deref(), Some("#_#.jpg.data"));
        assert_eq!(album_template("ActiCalc 1.06.rar"), None);
        assert_eq!(album_template("Scan_001.vol00+01.par2"), None);
        assert_eq!(album_template("Scan_001.nfo"), None);
        assert_eq!(album_template("NoNumber.mp4"), None);
        assert_eq!(album_template("acs5152s1.11"), None);
        assert_eq!(album_template("Broforce.vol00+01.par2.temp"), None);
        assert_eq!(album_template("Starship For Rent 3 (2024).epub").as_deref(), Some("Starship For Rent # (#).epub"));
        assert_eq!(album_template("c3453cdd2a3645a8f3cf3d22319abe63"), None);
        assert_eq!(album_name(&["1481439079025_001.jpg.data", "1481439079025_014.jpg.data"]), "1481439079025_#.jpg.data");
        assert_eq!(album_name(&["1481439079025_001.jpg.data", "1481439080000_001.jpg.data"]), "#_001.jpg.data");
        assert_eq!(album_name(&["Scan_001.pdf", "Scan_002.pdf", "Scan_003.pdf"]), "Scan_#.pdf");
    }

    #[test]
    fn a_batch_counter_is_no_file_total() {
        let mut priorities = FxHashMap::default();
        priorities.insert(GROUP.to_string(), 1);
        let mut ix = RangeIndexer::new(GROUP, 1, 1_000_000, 1, Rules::defaults(priorities), 5);
        let day = 24 * 60;
        // 25 different programs of one poster under one running counter, and one upload with a counter of its own.
        let mut lines: Vec<String> = (0..25).map(|i| line(100 + i, &format!(r#"[{}/68067] - "Program.Number.{i}.v1.0.rar" yEnc (1/1)"#, 1000 + i), i)).collect();
        lines.push(line(200, r#"[1/120] - "Real.Upload.part001.rar" yEnc (1/1)"#, 30));
        lines.extend(fillers(300, 100, 31, 1));
        ix.add_text(&lines.join("\n"), 1000);
        ix.add_text(&fillers(2000, 300, 3 * day, 1).join("\n"), 3000);
        let batch = ix.take();
        let programs: Vec<&ReleaseChunk> = batch.releases.iter().filter(|r| r.name.starts_with("Program")).collect();
        assert_eq!(programs.len(), 25);
        assert!(programs.iter().all(|r| r.file_total.is_none() && r.files == 1));
        let real = batch.releases.iter().find(|r| r.name.starts_with("Real")).unwrap();
        assert_eq!(real.file_total, Some(120));
    }

    #[test]
    fn a_snapshot_restores_the_window_between_two_ranges() {
        let rules = || {
            let mut priorities = FxHashMap::default();
            priorities.insert(GROUP.to_string(), 1);
            Rules::defaults(priorities)
        };
        let day = 24 * 60;
        // Range 1: a release whose last file comes in range 2, a day later; an album's first member; fillers.
        let mut first = vec![
            line(10, r#"Two.Ranges [1/2] - "Two.Ranges.part1.rar" yEnc (1/1)"#, 0),
            line(11, r#"[1/1] "Scan_001.pdf" yEnc (1/1)"#, 1),
        ];
        first.extend(fillers(100, 100, 2, 1));
        // The second file within the upload gap of the first (3 h), the album's second member within its window.
        let mut second = vec![
            line(1000, r#"Two.Ranges [2/2] - "Two.Ranges.part2.rar" yEnc (1/1)"#, 100),
            line(1001, r#"[1/1] "Scan_002.pdf" yEnc (1/1)"#, 101),
        ];
        second.extend(fillers(2000, 300, 3 * day, 1));
        let summary = |batches: Vec<Batch>| {
            let mut got: Vec<(String, &str, usize, bool)> = batches.iter().flat_map(|b| b.releases.iter()).filter(|r| !r.name.starts_with("Filler")).map(|r| (r.name.clone(), r.source, r.files, r.finished)).collect();
            got.sort();
            got
        };
        // In one go.
        let mut whole = RangeIndexer::for_group(GROUP, rules(), 5);
        whole.begin_range(1, 999);
        whole.add_text(&first.join("\n"), 1000);
        let w1 = whole.take();
        whole.begin_range(1000, 1_000_000);
        whole.add_text(&second.join("\n"), 1_000_001);
        let w2 = whole.take();
        // With a snapshot between the ranges, restored into a fresh indexer.
        let mut before = RangeIndexer::for_group(GROUP, rules(), 5);
        before.begin_range(1, 999);
        before.add_text(&first.join("\n"), 1000);
        let s1 = before.take();
        assert_eq!(before.next(), 1000);
        let bytes = before.snapshot().unwrap();
        assert!(bytes.len() > 1000);
        let mut after = RangeIndexer::restore(&bytes, rules(), 5).unwrap();
        assert_eq!(after.next(), 1000);
        assert_eq!(after.open_releases(), before.open_releases());
        assert_eq!(after.open_files(), before.open_files());
        after.begin_range(1000, 1_000_000);
        after.add_text(&second.join("\n"), 1_000_001);
        let s2 = after.take();
        assert_eq!(summary(vec![s1, s2]), summary(vec![w1, w2]));
        let got = summary(vec![after.take()]);
        assert!(got.is_empty());
        // The two-range release is one, finished, with both files; the album joined its second member.
        let mut a2 = RangeIndexer::for_group(GROUP, rules(), 5);
        a2.begin_range(1, 999);
        a2.add_text(&first.join("\n"), 1000);
        let _ = a2.take();
        let restored = RangeIndexer::restore(&a2.snapshot().unwrap(), rules(), 5).unwrap();
        let _ = restored;
        let s2b = {
            let mut r = RangeIndexer::restore(&bytes, rules(), 5).unwrap();
            r.begin_range(1000, 1_000_000);
            r.add_text(&second.join("\n"), 1_000_001);
            r.take()
        };
        let two = s2b.releases.iter().find(|r| r.name == "Two Ranges").expect("the two-range release");
        assert!(two.finished && two.files == 2);
        assert!(s2b.releases.iter().any(|r| r.source == "album" && r.files == 2));
        // A snapshot with a batch open is refused; one of another version too.
        let mut open = RangeIndexer::for_group(GROUP, rules(), 5);
        open.begin_range(1, 999);
        open.add_text(&first.join("\n"), 1000);
        assert!(open.snapshot().is_err());
    }

    #[test]
    fn the_frontier_ignores_implausible_dates_and_follows_a_pause() {
        let hour = 3_600_000i64;
        let mut f = Frontier::default();
        for i in 0..200 {
            f.add(i * hour / 10);
        }
        f.update();
        let settled = f.value().unwrap();
        assert!((settled - 10 * hour).abs() <= hour);
        assert_eq!(f.start(), Some(settled));
        // A bogus year, and one a year back: set aside.
        for _ in 0..100 {
            f.add(4_000_000_000_000);
            f.add(-400 * 24 * hour);
        }
        f.update();
        assert_eq!(f.value(), Some(settled));
        // The group paused for a month: FRONTIER_ARTICLES agreeing dates move the frontier there.
        let later = 30 * 24 * hour;
        for i in 0..FRONTIER_ARTICLES as i64 {
            f.add(later + i * 1000);
        }
        f.update();
        assert!(f.value().unwrap() >= later);
        assert_eq!(f.start(), Some(settled));
    }

    #[test]
    fn archive_candidates_as_in_the_typescript() {
        let mut priorities = FxHashMap::default();
        priorities.insert(GROUP.to_string(), 1);
        let mut ix = RangeIndexer::new(GROUP, 1, 10_000, 1, Rules::defaults(priorities), 5);
        let file = |at: i64, release: &str, name: &str, n: usize, parts: i64| -> Vec<String> {
            (0..parts).map(|i| line(at + i, &format!(r#"{release} [{n}/3] - "{name}" yEnc ({}/{parts})"#, i + 1), 0)).collect()
        };
        let mut lines = Vec::new();
        // A split 7z: its start, and the end of its highest volume.
        lines.extend(file(100, "Split.Seven", "Split.Seven.7z.001", 1, 2));
        lines.extend(file(110, "Split.Seven", "Split.Seven.7z.003", 3, 2));
        lines.extend(file(120, "Split.Seven", "Split.Seven.7z.002", 2, 2));
        // An unsplit 7z of 3 segments: its start and its end.
        lines.extend(file(200, "Whole.Seven", "Whole.Seven.7z", 1, 3));
        // A ZIP: its start.
        lines.extend(file(300, "Some.Zip", "Some.Zip.zip", 1, 2));
        ix.add_text(&lines.join("\r\n"), 10_001);
        ix.finish();
        let batch = ix.take();
        let mut got: Vec<(&str, &str, &str)> = batch.candidates.iter().map(|c| (c.kind, c.file.as_str(), c.message_id.as_str())).collect();
        got.sort();
        assert_eq!(
            got,
            vec![
                ("7z-tail", "Split.Seven.7z.003", "u111@test"),
                ("7z-tail", "Whole.Seven.7z", "u202@test"),
                ("archive", "Some.Zip.zip", "u300@test"),
                ("archive", "Split.Seven.7z.001", "u100@test"),
                ("archive", "Whole.Seven.7z", "u200@test"),
            ]
        );
    }

    #[test]
    fn copies_and_fills_as_in_the_typescript() {
        let hour = 3_600_000i64;
        let meta = Rc::new(FileMeta {
            file_key: "a".into(),
            name: "a.bin".into(),
            poster: "p".into(),
            subject: "s".into(),
            total_parts: 3,
            groups: vec![],
            release: names::release_identity("p", "s", "a.bin"),
        });
        let at = |number: u32, h: f64, id: &str| Seg { file: meta.clone(), number, message_id: id.into(), bytes: 100, article: 0, posted_at: Some((h * hour as f64) as i64) };
        let mut agg = Aggregator::default();
        assert!(agg.add(vec![at(1, 10.0, "a1"), at(2, 10.0, "a2"), at(1, 10.1, "resend")]).is_empty());
        assert!(agg.add(vec![at(1, 34.0, "b1"), at(2, 34.0, "b2")]).is_empty());
        assert_eq!(agg.open.get("a").unwrap().len(), 2);
        let second = agg.add(vec![at(3, 34.2, "b3")]);
        assert_eq!(second[0].iter().map(|s| s.message_id.as_str()).collect::<Vec<_>>(), vec!["b1", "b2", "b3"]);
        let first = agg.add(vec![at(3, 58.0, "a3")]);
        assert_eq!(first[0].iter().map(|s| s.message_id.as_str()).collect::<Vec<_>>(), vec!["a1", "a2", "a3"]);
        assert!(agg.open.is_empty());
    }

#[cfg(test)]
mod unquoted_tests {
    use super::unquoted_name;

    #[test]
    fn file_names_of_subjects_without_a_quoted_one() {
        let cases = [
            ("DVDFab 8.2.0.5.rar ", Some("DVDFab 8.2.0.5.rar")),
            ("q3B9OrpKiCxUnzgtUGnp.part023.rar ", Some("q3B9OrpKiCxUnzgtUGnp.part023.rar")),
            ("New_Super_Mario_Bros._[Keygen].exe ", Some("New_Super_Mario_Bros._[Keygen].exe")),
            ("Emily_18_-_Bed.part01.rar Emily 18 bed video FULL NUDE ", Some("Emily_18_-_Bed.part01.rar")),
            ("[33/117] 674a37548b09.dat ", Some("674a37548b09.dat")),
            ("A Strange Light from the East - Eastern Influenced Western Music (1965-72) - CD2 - 07 - Rascals - Sattva.mp3 ", Some("07 - Rascals - Sattva.mp3")),
            ("pal!    [Mivina high(1).wmv\" yEnc] ", Some("Mivina high(1).wmv")),
            ("[03/21 Geroellheimer - S03E16.part01.rar\" yEnc ", Some("Geroellheimer - S03E16.part01.rar")),
            ("<Group> FP -> {EXL01~P~004} -> Alexia (3) -> VF -> [0001 of 0076] -> Exclusive-tgirls_000000-lg.jpg ", Some("Exclusive-tgirls_000000-lg.jpg")),
            ("Ballers.2014.S01E01.HDTV.x264-KILLERS[ettv] 15_07_2015.rar ", Some("Ballers.2014.S01E01.HDTV.x264-KILLERS[ettv] 15_07_2015.rar")),
            ("Computer Bild - Ausgabe 152015 - 15_07_2015.rar ", Some("Computer Bild - Ausgabe 152015 - 15_07_2015.rar")),
            ("<abm> <Duke> here's a little thanksgiving present: AB: part2 0573-1002 043.jpg ", Some("043.jpg")),
            ("xlady post You, Me And Dupree www.x2l.nl [001/106] 'You, Me And Dupree.nfo'", Some("You, Me And Dupree.nfo")),
            ("[01/77][LIBRATEAM_M2219009.par2] Onbeperkt downloaden met een snelheid van 1,22 MB p.s. en dat voor maar 7,95 p.m. www.libranews.nl", Some("LIBRATEAM_M2219009.par2")),
            ("patensas post -^-[Mnozil Brass - Seven.nzb]-^-www.usenet2day.cc -^-[000/107]-^-www.libranews.nl-^- yEnc", Some("Mnozil Brass - Seven.nzb")),
            ("[7w] - 9BbEV2MrTi59GBTEFlVrssBrXNwXf2SK9cQEeDjg yEnc ", None),
            ("Re: Will somebody answer the question? ", None),
        ];
        for (text, want) in cases {
            assert_eq!(unquoted_name(text).as_deref(), want, "{text}");
        }
    }
}

#[cfg(test)]
mod beside_quotes_tests {
    use super::name_beside_quotes;

    #[test]
    fn a_name_beside_a_quoted_word() {
        assert_eq!(name_beside_quotes("Official", "My \"Official\" remaining set's of Inna, Please help up to #69 if you can 025.jpg [25/74] - yEnc ").as_deref(), Some("025.jpg"));
        assert_eq!(name_beside_quotes("Dr. Lust", "\"Dr. Lust\" - Lily Marlene, Vanessa Del Rio, Scorpio? - yEnc - [12/21] - Ed_DRL_VDR_LM.part09.rar ").as_deref(), Some("Ed_DRL_VDR_LM.part09.rar"));
        assert_eq!(name_beside_quotes("1f0554e5fec14b8b05ca", "77cd6d03d19281a775f5bdc5 [2/8] - \"1f0554e5fec14b8b05ca\" yEnc ").as_deref(), None);
        assert_eq!(name_beside_quotes("x.rar", "\"x.rar\" other.zip ").as_deref(), None);
    }
}
}

#[cfg(test)]
mod posted_span_tests {
    use super::posted_span;

    #[test]
    fn without_the_earliest_and_latest_percent() {
        assert_eq!(posted_span(vec![]), (None, None));
        let mut dates: Vec<i64> = (0..200).map(|i| 1_000_000 + i).collect();
        dates.push(5);
        dates.push(9_999_999_999);
        // 202 dates: 2 trimmed at each end, so the two wild ones go (postedSpan).
        assert_eq!(posted_span(dates), (Some(1_000_001), Some(1_000_198)));
    }
}