import { spawn } from 'node:child_process'
import { promises as fs, createWriteStream, constants as fsConst } from 'node:fs'
import path from 'node:path'
import https from 'node:https'
import http from 'node:http'
import { getMcCustomDir } from '../shared/paths.js'

/**
 * 리소스팩 간편설치기는 Windows .exe 로 배포되므로 yt-dlp.exe 한 종류만 사용.
 * 경로: %appdata%/.mc_custom/yt-dlp.exe
 */
export function getYtDlpExePath(): string {
  return path.join(getMcCustomDir(), 'yt-dlp.exe')
}

const YT_DLP_DOWNLOAD_URL =
  'https://github.com/yt-dlp/yt-dlp/releases/latest/download/yt-dlp.exe'

let installPromise: Promise<string> | null = null

/**
 * %appdata%/.mc_custom/yt-dlp.exe 가 없거나 실행 불가능하면 GitHub Releases
 * 의 최신 yt-dlp.exe 를 받아 설치하고, 그 절대경로를 돌려준다.
 */
export async function ensureYtDlpExe(
  log?: (line: string) => void
): Promise<string> {
  const target = getYtDlpExePath()
  if (await canExecute(target)) {
    log?.(`yt-dlp.exe 이미 있음: ${target}`)
    return target
  }
  if (installPromise) return installPromise

  installPromise = (async () => {
    try {
      await fs.mkdir(path.dirname(target), { recursive: true })
      log?.(`yt-dlp.exe 다운로드 중: ${YT_DLP_DOWNLOAD_URL}`)
      await downloadToFile(YT_DLP_DOWNLOAD_URL, target)
      const okVersion = await probeVersion(target)
      if (!okVersion) {
        throw new Error('yt-dlp.exe 다운로드는 됐지만 실행 검증에 실패했습니다.')
      }
      log?.(`yt-dlp.exe 준비 완료: ${target}`)
      return target
    } catch (err) {
      // 부분 다운로드 흔적 정리
      try { await fs.unlink(target) } catch { /* noop */ }
      throw new Error(
        'yt-dlp.exe 자동 설치 실패: ' +
          (err instanceof Error ? err.message : String(err))
      )
    } finally {
      installPromise = null
    }
  })()
  return installPromise
}

async function canExecute(filePath: string): Promise<boolean> {
  try {
    await fs.access(filePath, fsConst.F_OK)
  } catch {
    return false
  }
  return probeVersion(filePath)
}

function probeVersion(bin: string): Promise<boolean> {
  return new Promise((resolve) => {
    const child = spawn(bin, ['--version'], { stdio: ['ignore', 'pipe', 'pipe'] })
    let ok = false
    child.stdout.on('data', () => { ok = true })
    child.on('error', () => resolve(false))
    child.on('close', (code) => resolve(ok && code === 0))
  })
}

/** GitHub Releases 의 latest URL 은 302 리다이렉트를 사용하므로 따라가며 받음. */
function downloadToFile(url: string, dest: string, redirects = 0): Promise<void> {
  return new Promise((resolve, reject) => {
    if (redirects > 8) {
      reject(new Error('redirect 가 너무 많습니다.'))
      return
    }
    const lib = url.startsWith('https://') ? https : http
    const req = lib.get(url, {
      headers: { 'user-agent': 'mc-music-quiz-rp-installer' }
    }, (res) => {
      const code = res.statusCode || 0
      if (code >= 300 && code < 400 && res.headers.location) {
        res.resume()
        downloadToFile(res.headers.location, dest, redirects + 1).then(resolve, reject)
        return
      }
      if (code !== 200) {
        res.resume()
        reject(new Error(`HTTP ${code} (${url})`))
        return
      }
      const out = createWriteStream(dest)
      res.pipe(out)
      out.on('finish', () => out.close((err) => err ? reject(err) : resolve()))
      out.on('error', reject)
      res.on('error', reject)
    })
    req.on('error', reject)
  })
}