import { existsSync } from 'fs'
import path from 'path'
import { config } from '../../config/app.config'

export type YtdlpParams = {
  url: string
  uuid: string
  format: string
  quality: string
  subtitles: boolean
  subtitleLangs: string[] | null
  clipStart: number | null
  clipEnd: number | null
  audioQuality: string | null
  extraArgs: string | null
}

export function resolveYtdlpBin(): string {
  const local = path.join(config.BIN_DIR, 'yt-dlp')
  return existsSync(local) ? local : 'yt-dlp'
}

export type YtdlpCommand = { command: string; args: string[] }

// bin/yt-dlp is a pure-Python zipapp, not a standalone binary: it has no bundled
// interpreter or native libs to extract/mmap, so it works on hosts with a
// noexec /tmp (unlike yt-dlp's PyInstaller-built binaries). It relies on a
// `#!/usr/bin/env python3` shebang, which spawn() can't honor on Windows and
// which resolves to whatever `python3` happens to be on PATH elsewhere (on
// o2switch that's an unsupported 3.6) — so it's always invoked explicitly
// through PYTHON_BIN. A system-wide `yt-dlp` (PATH fallback) already has its
// own proper launcher and is run directly.
export function buildYtdlpCommand(args: string[]): YtdlpCommand {
  const bin = resolveYtdlpBin()
  const isBundledScript = bin !== 'yt-dlp'

  if (isBundledScript) {
    return { command: config.PYTHON_BIN, args: [bin, ...args] }
  }

  return { command: bin, args }
}

export function buildYtdlpArgs(params: YtdlpParams): string[] {
  const {
    url,
    uuid,
    format,
    quality,
    subtitles,
    subtitleLangs,
    clipStart,
    clipEnd,
    audioQuality,
    extraArgs,
  } = params
  const outputTemplate = path.join(config.STORAGE_PATH, `${uuid}.%(ext)s`)

  const args: string[] = ['--no-playlist', '-o', outputTemplate]

  // bin/ffmpeg is a Linux ELF binary bundled for o2switch prod deploy; it can't
  // run on Windows, so local dev instead looks for a bin/ffmpeg.exe.
  const ffmpegBin = path.join(config.BIN_DIR, process.platform === 'win32' ? 'ffmpeg.exe' : 'ffmpeg')
  if (existsSync(ffmpegBin)) {
    args.push('--ffmpeg-location', ffmpegBin)
  }

  if (format === 'mp3') {
    args.push('-x', '--audio-format', 'mp3')
    args.push('--audio-quality', audioQuality && audioQuality !== 'best' ? `${audioQuality}K` : '0')
  } else {
    const heightFilter = quality !== 'best' ? `[height<=?${quality.replace('p', '')}]` : ''
    args.push('-f', `bestvideo${heightFilter}+bestaudio/best${heightFilter}`)
    args.push('--merge-output-format', format)
  }

  if (subtitles) {
    const langs = subtitleLangs?.length ? subtitleLangs.join(',') : 'fr,en'
    args.push('--write-subs', '--write-auto-subs', '--sub-lang', langs)
  }

  if (clipStart != null || clipEnd != null) {
    args.push('--download-sections', `*${clipStart ?? 0}-${clipEnd ?? ''}`)
  }

  if (extraArgs) {
    try {
      const extra = JSON.parse(extraArgs) as string[]
      args.push(...extra)
    } catch {
      // malformed extraArgs — skip silently
    }
  }

  args.push(url)
  return args
}