import { gunzipSync } from 'node:zlib'
import db from '@adonisjs/lucid/services/db'
import { decodeChunk, type ChunkFile } from '#lib/chunks/index'
import { buildNzb } from '#lib/nzb/index'

/**
 * A release's files and NZB (REBUILD.md, part 9), from its chunks in the
 * chunk store: every chunk decoded, its files in name order. A file stored
 * twice (the same name and first article, e.g. a range read again) is taken
 * once.
 */
class NzbService {
  async files(releaseId: number): Promise<ChunkFile[]> {
    const chunks = await db.from('release_chunks').where('release_id', releaseId).orderBy('id').select('payload')
    const files = new Map<string, ChunkFile>()
    for (const chunk of chunks) {
      for (const file of decodeChunk(chunk.payload)) files.set(`${file.name}\n${file.segments[0]?.[1] ?? ''}`, file)
    }
    return [...files.values()].sort((a, b) => a.name.localeCompare(b.name))
  }

  async build(releaseId: number): Promise<{ name: string; xml: string } | null> {
    const release = await db.from('releases').where('id', releaseId).select('name', 'source').first()
    if (!release) return null
    // A release a spot made of its own (no files matched the header pass's): the spot's NZB as read.
    if (release.source === 'spot') {
      const spot = await db.from('spots').where('release_id', releaseId).whereNotNull('nzb').select('nzb').first()
      if (spot) return { name: release.name, xml: gunzipSync(spot.nzb).toString('utf8') }
    }
    const xml = buildNzb(
      (await this.files(releaseId)).map((f) => ({
        name: f.name,
        poster: f.poster,
        date: f.postedAt ?? 0,
        groups: f.groups,
        segments: f.segments.map(([number, id, size]) => ({ number, id, size })),
      })),
      { title: release.name }
    )
    return { name: release.name, xml }
  }
}

export default new NzbService()