import { spawn } from 'node:child_process'
import { randomInt } from 'node:crypto'
import { mkdir, readFile, unlink, writeFile } from 'node:fs/promises'
import { tmpdir } from 'node:os'
import { dirname, join } from 'node:path'
import { eq } from 'drizzle-orm'
import ffmpegPath from 'ffmpeg-static'
import { uploads } from '../db/schema'

export const uploadDir = () => join(process.cwd(), 'public', 'uploads')
export const avatarDir = () => join(uploadDir(), 'avatars')

const ID_ALPHABET = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'

export function generateUploadId() {
  return Array.from({ length: 8 }, () => ID_ALPHABET[randomInt(ID_ALPHABET.length)]).join('')
}

export async function newUploadId(db: ReturnType<typeof useDb>) {
  for (let i = 0; i < 10; i++) {
    const id = generateUploadId()
    const rows = await db.select({ id: uploads.id }).from(uploads).where(eq(uploads.id, id)).limit(1)
    if (!rows.length) return id
  }
  throw createError({ statusCode: 500, statusMessage: 'ID konnte nicht generiert werden' })
}

export const IMAGE_EXT = /\.(avif|bmp|gif|jpe?g|png|svg|webp)$/i
export const VIDEO_EXT = /\.(m4v|mov|mp4|ogg|ogv|webm)$/i
export const AUDIO_EXT = /\.(flac|mp3)$/i

export type UploadType = 'image' | 'video' | 'audio' | 'youtube' | 'twitch' | 'link'

export function classifyUrl(url: string): UploadType {
  if (getYoutubeId(url)) return 'youtube'
  if (getTwitchTarget(url)) return 'twitch'
  const path = new URL(url).pathname
  if (IMAGE_EXT.test(path)) return 'image'
  if (VIDEO_EXT.test(path)) return 'video'
  if (AUDIO_EXT.test(path)) return 'audio'
  return 'link'
}

export const MAX_UPLOAD_SIZE = 200 * 1024 * 1024 // 200 MB

export interface DownloadedMedia {
  data: Buffer
  mimeType: string
  type: 'image' | 'video' | 'audio'
}

// Direkte Medien-URLs werden lokal gespeichert wie ein echter Upload —
// mit SSRF-Schutz (interne Hosts blockiert, auch nach Redirects), Timeout
// und Größenlimit, das beim Streamen erzwungen wird
export async function downloadExternalMedia(url: string): Promise<DownloadedMedia> {
  if (isBlockedHost(new URL(url).hostname)) {
    throw createError({ statusCode: 400, statusMessage: 'Diese URL ist nicht erlaubt' })
  }
  let res: Response
  try {
    res = await fetch(url, {
      signal: AbortSignal.timeout(60_000),
      redirect: 'follow',
      headers: {
        'user-agent': 'Mozilla/5.0 (compatible; 4Brett-MediaDownload/1.0)',
        'accept': 'image/*,video/*,audio/*',
      },
    })
  }
  catch {
    throw createError({ statusCode: 502, statusMessage: 'Datei konnte nicht geladen werden' })
  }
  if (isBlockedHost(new URL(res.url).hostname)) {
    throw createError({ statusCode: 400, statusMessage: 'Diese URL ist nicht erlaubt' })
  }
  if (!res.ok || !res.body) {
    throw createError({ statusCode: 502, statusMessage: `Download fehlgeschlagen (${res.status})` })
  }

  const mimeType = (res.headers.get('content-type') ?? '').split(';')[0]!.trim().toLowerCase()
  const type = mimeType.startsWith('image/') ? 'image' as const
    : mimeType.startsWith('video/') ? 'video' as const
      : mimeType.startsWith('audio/') ? 'audio' as const
        : null
  if (!type) {
    throw createError({ statusCode: 415, statusMessage: 'URL liefert keine Bild-, Video- oder Audiodatei' })
  }

  const contentLength = Number(res.headers.get('content-length') ?? 0)
  if (contentLength > MAX_UPLOAD_SIZE) {
    throw createError({ statusCode: 413, statusMessage: 'Datei ist zu groß (max. 200 MB)' })
  }

  const chunks: Buffer[] = []
  let total = 0
  const reader = res.body.getReader()
  for (;;) {
    const { done, value } = await reader.read()
    if (done) break
    total += value.byteLength
    if (total > MAX_UPLOAD_SIZE) {
      await reader.cancel()
      throw createError({ statusCode: 413, statusMessage: 'Datei ist zu groß (max. 200 MB)' })
    }
    chunks.push(Buffer.from(value))
  }

  return { data: Buffer.concat(chunks), mimeType, type }
}

const PREVIEW_MIME_EXT: Record<string, string> = {
  'image/jpeg': '.jpg',
  'image/png': '.png',
  'image/gif': '.gif',
  'image/webp': '.webp',
  'image/avif': '.avif',
}

// Link-/Twitch-Vorschaubilder werden zur Upload-Zeit lokal gespeichert —
// entfernte URLs sind veränderlich (z. B. Twitch-Live-Previews zeigen sonst
// nach Stream-Ende nur noch einen Platzhalter)
export async function savePreviewImage(key: string, url: string): Promise<string | null> {
  try {
    const media = await downloadExternalMedia(url)
    const ext = media.type === 'image' ? PREVIEW_MIME_EXT[media.mimeType] : null
    if (!ext || !/^[A-Za-z0-9/_-]+$/.test(key)) return null
    const filePath = join(uploadDir(), 'thumbs', `${key}${ext}`)
    await mkdir(dirname(filePath), { recursive: true })
    await writeFile(filePath, media.data)
    return `/uploads/thumbs/${key}${ext}`
  }
  catch {
    return null
  }
}

const COVER_MIME_EXT: Record<string, string> = {
  'image/jpeg': '.jpg',
  'image/png': '.png',
  'image/gif': '.gif',
  'image/webp': '.webp',
}

export interface AudioMetaInfo {
  title: string | null
  artist: string | null
  album: string | null
  codec: string | null
  bitrate: number | null
  sampleRate: number | null
  bitsPerSample: number | null
  lossless: boolean
}

// Eingebettete Audio-Metadaten auslesen: Cover (ID3v2 APIC / FLAC PICTURE)
// wird lokal als Vorschaubild gespeichert, Text-/Qualitätsmetadaten gehen
// als JSON in die DB
export async function extractAudioMeta(uploadId: string, data: Buffer, mimeType: string): Promise<{ cover: string | null, meta: AudioMetaInfo | null }> {
  try {
    const { parseBuffer } = await import('music-metadata')
    // MIME-Hint kann falsch sein (per Endung abgeleitet) — im Fehlerfall
    // ohne Hint parsen lassen, dann sniffed music-metadata die Magic Bytes
    const parsed = await parseBuffer(data, { mimeType }, { duration: false })
      .catch(() => parseBuffer(data, undefined, { duration: false }))

    const pic = parsed.common.picture?.[0]
    const ext = pic ? COVER_MIME_EXT[pic.format] ?? null : null
    let cover: string | null = null
    if (pic && ext) {
      const filePath = join(uploadDir(), 'thumbs', 'covers', `${uploadId}${ext}`)
      await mkdir(dirname(filePath), { recursive: true })
      await writeFile(filePath, pic.data)
      cover = `/uploads/thumbs/covers/${uploadId}${ext}`
    }

    const fmt = parsed.format
    const meta: AudioMetaInfo = {
      title: parsed.common.title ?? null,
      artist: parsed.common.artist ?? parsed.common.artists?.[0] ?? null,
      album: parsed.common.album ?? null,
      codec: fmt.codec ?? fmt.container ?? null,
      bitrate: fmt.bitrate ? Math.round(fmt.bitrate) : null,
      sampleRate: fmt.sampleRate ?? null,
      bitsPerSample: fmt.bitsPerSample ?? null,
      lossless: fmt.lossless ?? false,
    }
    const hasAny = meta.title || meta.artist || meta.album || meta.codec || meta.bitrate
    return { cover, meta: hasAny ? meta : null }
  }
  catch {
    return { cover: null, meta: null }
  }
}

// Sprachnachrichten kommen als WebM/Opus o.ä. rein — MediaRecorder kann selbst
// kein MP3 encodieren, daher serverseitig per ffmpeg nach MP3 transkodieren.
export async function transcodeVoiceToMp3(data: Buffer): Promise<Buffer | null> {
  if (!ffmpegPath) return null
  const base = join(tmpdir(), `voice-${Date.now()}-${Math.random().toString(36).slice(2)}`)
  const inPath = `${base}.webm`
  const outPath = `${base}.mp3`
  try {
    await writeFile(inPath, data)
    await new Promise<void>((resolve, reject) => {
      const proc = spawn(ffmpegPath, [
        '-hide_banner', '-loglevel', 'error', '-y',
        '-i', inPath,
        '-codec:a', 'libmp3lame', '-q:a', '4',
        outPath,
      ])
      proc.on('error', reject)
      proc.on('close', code => (code === 0 ? resolve() : reject(new Error(`ffmpeg exit ${code}`))))
    })
    return await readFile(outPath)
  }
  catch {
    return null
  }
  finally {
    await unlink(inPath).catch(() => {})
    await unlink(outPath).catch(() => {})
  }
}