import type { HttpContext } from '@adonisjs/core/http'
import env from '#start/env'
import NzbService from '#services/nzb_service'
import SearchService from '#services/search_service'
import AccessService, { AccessDenied } from '#services/access_service'
import { capsXml, errorXml, expandCategories, resultsXml, type NewznabServer } from '#lib/newznab/index'

const LIMITS = { max: 100, default: 50 }

/** Search functions and the category each defaults to when `cat` is absent. */
const SEARCH_FUNCTIONS: Record<string, number | undefined> = {
  'search': undefined,
  'tvsearch': 5000,
  'tv-search': 5000,
  'movie': 2000,
  'movie-search': 2000,
  'music': 3000,
  'audio': 3000,
  'book': 7000,
}

/** The configured key, if any. */
function configuredApiKey(): string | undefined {
  const value: any = env.get('NEWZNAB_API_KEY')
  const key = typeof value === 'string' ? value : value?.release()
  return key || undefined
}

function int(value: unknown): number | undefined {
  return typeof value === 'string' && /^\d+$/.test(value) ? Number(value) : undefined
}

/**
 * Newznab API for Prowlarr, Sonarr, Radarr and the like (from voyager 1):
 * GET /api?t=caps|search|tvsearch|movie|music|book|get&apikey=…
 * Releases with readable names (or an inner name from the prober, which then is the title) that aren't known to miss files.
 */
export default class NewznabController {
  async handle(ctx: HttpContext) {
    const xml = (body: string, type = 'application/xml') => {
      ctx.response.header('Content-Type', `${type}; charset=utf-8`)
      return ctx.response.send(body)
    }
    try {
      return await this.answer(ctx, xml)
    } catch (error) {
      if (error instanceof AccessDenied) return xml(errorXml(error.newznabCode, error.message))
      throw error
    }
  }

  private async answer(ctx: HttpContext, xml: (body: string, type?: string) => void) {
    const { request, response } = ctx
    const qs = request.qs()
    const t = String(qs.t ?? '')

    // With accounts the key is a user's (AccessService); else the one configured, if any.
    const grant = await AccessService.authorize(ctx, qs.apikey)
    const apiKey = grant ? grant.user.apiKey : configuredApiKey()
    if (!grant && apiKey && qs.apikey !== apiKey) return xml(errorXml(100, 'Incorrect user credentials'))
    const server = this.server(request, apiKey)
    if (t === 'caps') return xml(capsXml(server, LIMITS, { available: AccessService.accounts && AccessService.signup !== 'closed', open: AccessService.accounts && AccessService.signup === 'open' }))

    if (t === 'get') {
      const id = int(qs.id)
      if (id === undefined) return xml(errorXml(200, 'Missing parameter (id)'))
      // Unknown ids and releases past the tier's retention aren't counted.
      if (!(await AccessService.checkRelease(grant, id))) return xml(errorXml(300, 'No such item'))
      await AccessService.charge(grant, 'grab')
      const nzb = await NzbService.build(id)
      if (!nzb) return xml(errorXml(300, 'No such item'))
      const filename = `${nzb.name.replace(/[^\w.\-()[\] ]+/g, '_').slice(0, 180) || 'release'}.nzb`
      response.header('Content-Disposition', `attachment; filename="${filename}"`)
      return xml(nzb.xml, 'application/x-nzb')
    }

    if (!(t in SEARCH_FUNCTIONS)) return xml(errorXml(202, `No such function (${t || 'none'})`))
    await AccessService.charge(grant, 'api')

    const requested = String(qs.cat ?? '')
      .split(',')
      .map((c) => int(c.trim()))
      .filter((c): c is number => c !== undefined)
    const fallback = SEARCH_FUNCTIONS[t]
    const categories = expandCategories(requested.length ? requested : fallback ? [fallback] : [])
    const limit = Math.min(int(qs.limit) ?? LIMITS.default, LIMITS.max)
    const offset = int(qs.offset) ?? 0

    // ID-only lookups (tvdbid, imdbid, …) aren't supported: an empty result rather than everything.
    const q = typeof qs.q === 'string' ? qs.q.trim() : ''
    const idOnly = !q && ['tvdbid', 'tvmazeid', 'rid', 'imdbid', 'tmdbid'].some((p) => qs[p])
    const result = idOnly
      ? null
      : await SearchService.search({
          q,
          categories,
          readable: true,
          notIncomplete: true,
          maxAgeDays: AccessService.maxAgeDays(grant, int(qs.maxage)),
          season: int(qs.season),
          episode: int(qs.season) !== undefined ? int(qs.ep) : undefined,
          sort: 'newest',
          perPage: limit,
          offset,
        })

    const items = (result?.releases ?? []).map((r) => {
      const tv = /(?:^|[._ -])S(\d{1,2})E(\d{1,3})/i.exec(r.name)
      return {
        id: r.id,
        // An obfuscated release by what the prober found inside, without its extension (what clients parse).
        title: r.readable || !r.innerName ? r.name : r.innerName.replace(/\.[a-z0-9]{2,4}$/i, ''),
        category: r.category ?? 8010,
        size: r.size,
        files: r.fileCount,
        postedAt: r.postedAt ? new Date(r.postedAt) : null,
        poster: r.poster,
        groups: r.groups ?? [],
        // From the prober (phase 2): encrypted archive entries or headers.
        password: r.passworded === true,
        season: tv ? `S${tv[1].padStart(2, '0')}` : undefined,
        episode: tv ? `E${tv[2].padStart(2, '0')}` : undefined,
      }
    })
    // What's left of the day, for clients that show it (newznab:apilimits).
    const limits = grant && {
      apiCurrent: grant.usage.apiHits,
      apiMax: grant.limits.apiHits,
      grabCurrent: grant.usage.grabs,
      grabMax: grant.limits.grabs,
    }
    return xml(resultsXml(server, items, offset, result?.total ?? 0, limits || undefined), 'application/rss+xml')
  }

  /** Download links carry the caller's key. */
  private server(request: HttpContext['request'], apiKey: string | undefined): NewznabServer {
    const proto = request.header('x-forwarded-proto') ?? 'http'
    const host = request.header('x-forwarded-host') ?? request.header('host') ?? 'localhost'
    return { title: 'Voyager 2', baseUrl: `${proto}://${host}`, apiKey }
  }
}