const fs = require('fs');
const path = require('path');
const crypto = require('crypto');
const { request } = require('undici');

const BASE_URL = 'https://vidmoly.me';
const USER_AGENT = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36';
const UPLOAD_TIMEOUT = 1800000; // 30 min
const RESULT_POLL_ATTEMPTS = 10;
const RESULT_POLL_DELAY_MS = 2000;

/**
 * XFileSharing-based upload for Vidmoly (login + form upload)
 */
class VidmolyUploader {
  constructor() {
    this.cookies = new Map();
  }

  _cookieHeader() {
    return Array.from(this.cookies.entries())
      .map(([k, v]) => `${k}=${v}`)
      .join('; ');
  }

  _parseCookiesFromHeaders(headers) {
    // Handle both undici response headers and fetch Headers
    let setCookies;
    if (typeof headers.getSetCookie === 'function') {
      setCookies = headers.getSetCookie();
    } else if (headers['set-cookie']) {
      setCookies = Array.isArray(headers['set-cookie']) ? headers['set-cookie'] : [headers['set-cookie']];
    } else {
      return;
    }
    for (const raw of setCookies) {
      const pair = raw.split(';')[0];
      const eq = pair.indexOf('=');
      if (eq > 0) {
        this.cookies.set(pair.substring(0, eq).trim(), pair.substring(eq + 1).trim());
      }
    }
  }

  /**
   * Simple GET/POST using built-in fetch (handles redirects)
   */
  async _fetch(url, opts = {}, _redirectCount = 0) {
    const MAX_REDIRECTS = 10;
    const headers = {
      'User-Agent': USER_AGENT,
      ...(opts.headers || {})
    };
    if (this.cookies.size > 0) {
      headers['Cookie'] = this._cookieHeader();
    }

    const res = await fetch(url, {
      ...opts,
      headers,
      redirect: 'manual' // handle manually to capture cookies from redirect responses
    });

    this._parseCookiesFromHeaders(res.headers);

    // Follow redirects manually (to capture cookies at each hop)
    if ([301, 302, 303, 307, 308].includes(res.status)) {
      // Drain body to prevent connection leak
      try { await res.text(); } catch {}
      if (_redirectCount >= MAX_REDIRECTS) {
        throw new Error('Zu viele Redirects');
      }
      const location = res.headers.get('location');
      if (location) {
        const nextUrl = new URL(location, url).href;
        return this._fetch(nextUrl, { ...opts, method: 'GET', body: undefined }, _redirectCount + 1);
      }
    }

    return res;
  }

  /**
   * Login to Vidmoly
   */
  async login(username, password) {
    // First GET the main page to get initial cookies
    const initRes = await this._fetch(BASE_URL);
    await initRes.text();

    // POST login
    const loginData = new URLSearchParams({
      op: 'login',
      login: username,
      password: password,
      redirect: ''
    });

    const res = await this._fetch(BASE_URL, {
      method: 'POST',
      body: loginData.toString(),
      headers: {
        'Content-Type': 'application/x-www-form-urlencoded',
        'Referer': BASE_URL
      }
    });

    const body = await res.text();

    if (body.includes('Incorrect Login or Password')) {
      throw new Error('Vidmoly Login fehlgeschlagen: Falscher Username oder Passwort');
    }

    // Check for login cookie
    const hasSession = this.cookies.has('login') || this.cookies.has('xfsts') ||
      this.cookies.size > 1;
    if (!hasSession) {
      throw new Error('Vidmoly Login fehlgeschlagen: Keine Session erhalten');
    }
  }

  /**
   * Get upload form parameters from the upload page
   */
  async getUploadParams() {
    const res = await this._fetch(`${BASE_URL}/?op=upload`);
    const html = await res.text();

    // Parse hidden form fields from XFS upload form
    const params = {};

    const inputRegex = /<input[^>]*type=["']hidden["'][^>]*>/gi;
    let match;
    while ((match = inputRegex.exec(html)) !== null) {
      const tag = match[0];
      const nameMatch = tag.match(/name=["']([^"']+)["']/);
      const valueMatch = tag.match(/value=["']([^"']*?)["']/);
      if (nameMatch) {
        params[nameMatch[1]] = valueMatch ? valueMatch[1] : '';
      }
    }

    // Extract form action
    const formMatch = html.match(/<form[^>]*id=["']?file_upload["']?[^>]*action=["']([^"']+)["']/i)
      || html.match(/<form[^>]*enctype=["']multipart\/form-data["'][^>]*action=["']([^"']+)["']/i)
      || html.match(/<form[^>]*action=["']([^"']+)["'][^>]*enctype=["']multipart\/form-data["']/i);

    let uploadUrl = null;
    if (formMatch) {
      uploadUrl = formMatch[1];
    } else if (params.srv_tmp_url) {
      uploadUrl = params.srv_tmp_url;
    }

    if (!uploadUrl) {
      const cgiMatch = html.match(/(https?:\/\/[^"'\s]+\/cgi-bin\/upload\.cgi[^"'\s]*)/i)
        || html.match(/(https?:\/\/[^"'\s]+\/upload\/\d+)/i);
      if (cgiMatch) uploadUrl = cgiMatch[1];
    }

    if (!uploadUrl) {
      throw new Error('Vidmoly Upload-URL nicht gefunden. Bist du eingeloggt?');
    }

    let fileFieldName = 'file';
    const fileInputMatch = html.match(/<input[^>]*type=["']file["'][^>]*name=["']([^"']+)["']/i)
      || html.match(/<input[^>]*name=["']([^"']+)["'][^>]*type=["']file["']/i);
    if (fileInputMatch && fileInputMatch[1]) {
      fileFieldName = fileInputMatch[1].trim();
    }

    return { uploadUrl, params, fileFieldName };
  }

  /**
   * Upload a file to Vidmoly (uses undici.request for streaming progress)
   */
  async upload(filePath, onProgress, signal, throttle) {
    const fileName = path.basename(filePath);
    const fileSize = fs.statSync(filePath).size;
    const baselineCodes = await this._captureVmFileCodes();

    const { uploadUrl, params, fileFieldName } = await this.getUploadParams();

    const boundary = '----FormBoundary' + crypto.randomBytes(16).toString('hex');

    // XFS form fields
    const formFields = {};
    for (const [k, v] of Object.entries(params)) {
      if (!/^file(?:_\d+)?$/i.test(k)) {
        formFields[k] = v;
      }
    }

    // Build multipart
    let preamble = '';
    for (const [key, value] of Object.entries(formFields)) {
      preamble += `--${boundary}\r\n`;
      preamble += `Content-Disposition: form-data; name="${key}"\r\n\r\n`;
      preamble += `${value}\r\n`;
    }
    preamble += `--${boundary}\r\n`;
    preamble += `Content-Disposition: form-data; name="${fileFieldName || 'file'}"; filename="${fileName}"\r\n`;
    preamble += `Content-Type: application/octet-stream\r\n\r\n`;

    const epilogue = `\r\n--${boundary}--\r\n`;

    const preambleBuf = Buffer.from(preamble, 'utf-8');
    const epilogueBuf = Buffer.from(epilogue, 'utf-8');
    const totalSize = preambleBuf.length + fileSize + epilogueBuf.length;

    let bytesRead = 0;
    const CHUNK_SIZE = 256 * 1024;

    async function* generate() {
      yield preambleBuf;
      const fileStream = fs.createReadStream(filePath, { highWaterMark: CHUNK_SIZE });
      for await (const chunk of fileStream) {
        if (throttle) await throttle.consume(chunk.length, signal);
        bytesRead += chunk.length;
        yield chunk;
        if (onProgress) onProgress(bytesRead, fileSize);
      }
      yield epilogueBuf;
    }

    // Use undici.request for the upload (streaming body for progress)
    const { body, statusCode, headers } = await request(uploadUrl, {
      method: 'POST',
      body: generate(),
      signal,
      headers: {
        'User-Agent': USER_AGENT,
        'Cookie': this._cookieHeader(),
        'Content-Type': `multipart/form-data; boundary=${boundary}`,
        'Content-Length': String(totalSize),
        'Referer': `${BASE_URL}/upload.html`
      },
      headersTimeout: UPLOAD_TIMEOUT,
      bodyTimeout: UPLOAD_TIMEOUT
    });

    this._parseCookiesFromHeaders(headers || {});

    // Check if upload response is a redirect (XFS often redirects to result page)
    let resultHtml;
    if ([301, 302, 303].includes(statusCode)) {
      const location = headers && headers.location;
      // Always drain the original body to prevent connection leak
      try { await body.text(); } catch {}
      if (location) {
        const resultRes = await this._fetch(new URL(location, uploadUrl).href);
        resultHtml = await resultRes.text();
      } else {
        resultHtml = '';
      }
    } else {
      resultHtml = await body.text();
    }

    // Try JSON first (some XFS versions return JSON)
    try {
      const json = JSON.parse(resultHtml);
      if (json.files && json.files.length > 0) {
        const f = json.files[0];
        const code = f.filecode || f.file_code;
        return {
          download_url: code ? `${BASE_URL}/w/${code}` : null,
          embed_url: code ? `${BASE_URL}/embed-${code}.html` : null,
          file_code: code
        };
      }
      if (json.result) {
        const r = Array.isArray(json.result) ? json.result[0] : json.result;
        const code = r.filecode || r.file_code;
        return {
          download_url: r.download_url || (code ? `${BASE_URL}/w/${code}` : null),
          embed_url: r.embed_url || (code ? `${BASE_URL}/embed-${code}.html` : null),
          file_code: code
        };
      }
    } catch {}

    try {
      return this._parseUploadResult(resultHtml);
    } catch (primaryErr) {
      const fallback = await this._resolveUploadedFileFromVmApi(fileName, baselineCodes, signal);
      if (fallback) return fallback;
      throw primaryErr;
    }
  }

  _normalizeTitle(value) {
    return String(value || '')
      .toLowerCase()
      .normalize('NFKD')
      .replace(/[^a-z0-9]+/g, '');
  }

  _scoreVmCandidate(file, expectedTitle) {
    if (!file || !file.file_code) return -1;
    if (!expectedTitle) return 0;

    const title = this._normalizeTitle(file.full_title || file.title_txt || '');
    if (!title) return -1;
    if (title === expectedTitle) return 120;
    if (title.startsWith(expectedTitle) || expectedTitle.startsWith(title)) return 90;
    if (title.includes(expectedTitle) || expectedTitle.includes(title)) return 70;
    return 0;
  }

  _buildUrlsFromCode(fileCode) {
    const code = String(fileCode || '').trim();
    if (!code) return null;

    return {
      download_url: `${BASE_URL}/w/${code}`,
      embed_url: `${BASE_URL}/embed-${code}.html`,
      file_code: code
    };
  }

  async _captureVmFileCodes() {
    try {
      const files = await this._fetchVmList();
      return new Set(
        files
          .map((f) => String(f.file_code || '').trim())
          .filter(Boolean)
      );
    } catch {
      return new Set();
    }
  }

  async _fetchVmList() {
    const params = new URLSearchParams({
      op: 'vm',
      api: 'list',
      page: '1',
      per: '100',
      sort: 'date',
      order: 'desc',
      fld_id: '0'
    });

    const res = await this._fetch(`${BASE_URL}/?${params.toString()}`);
    const body = await res.text();

    let payload;
    try {
      payload = JSON.parse(body);
    } catch {
      throw new Error('Vidmoly VM API lieferte kein JSON');
    }

    if (!payload || !Array.isArray(payload.files)) return [];
    return payload.files;
  }

  async _resolveUploadedFileFromVmApi(fileName, baselineCodes, signal) {
    const expectedTitle = this._normalizeTitle(path.parse(fileName).name);

    for (let attempt = 0; attempt < RESULT_POLL_ATTEMPTS; attempt++) {
      if (signal && signal.aborted) {
        const err = new Error('Aborted');
        err.name = 'AbortError';
        throw err;
      }

      let files = [];
      try {
        files = await this._fetchVmList();
      } catch {
        files = [];
      }

      const withCode = files.filter((f) => f && typeof f.file_code === 'string' && f.file_code.trim());
      const newFiles = withCode.filter((f) => !baselineCodes.has(f.file_code));

      if (newFiles.length > 0) {
        let best = null;
        let bestScore = -1;

        for (const file of newFiles) {
          const score = this._scoreVmCandidate(file, expectedTitle);
          if (score > bestScore) {
            bestScore = score;
            best = file;
          }
        }

        if (best && (bestScore > 0 || newFiles.length === 1)) {
          return this._buildUrlsFromCode(best.file_code);
        }
      }

      if (expectedTitle) {
        let bestMatch = null;
        let bestScore = -1;

        for (const file of withCode) {
          const score = this._scoreVmCandidate(file, expectedTitle);
          if (score > bestScore) {
            bestScore = score;
            bestMatch = file;
          }
        }

        if (bestMatch && bestScore >= 90) {
          return this._buildUrlsFromCode(bestMatch.file_code);
        }
      }

      if (attempt < RESULT_POLL_ATTEMPTS - 1) {
        await this._sleep(RESULT_POLL_DELAY_MS, signal);
      }
    }

    return null;
  }

  _sleep(ms, signal) {
    return new Promise((resolve, reject) => {
      const timer = setTimeout(() => {
        if (signal) signal.removeEventListener('abort', onAbort);
        resolve();
      }, ms);

      function onAbort() {
        clearTimeout(timer);
        if (signal) signal.removeEventListener('abort', onAbort);
        const err = new Error('Aborted');
        err.name = 'AbortError';
        reject(err);
      }

      if (signal) {
        if (signal.aborted) return onAbort();
        signal.addEventListener('abort', onAbort);
      }
    });
  }

  _parseUploadResult(html) {
    let download_url = null;
    let embed_url = null;
    let file_code = null;

    const fnMatch = html.match(/<(?:input|textarea)[^>]*name=["']fn["'][^>]*(?:value=["']([^"']+)["'])?[^>]*>([^<]*)/i);
    if (fnMatch) {
      const codeFromFn = (fnMatch[1] || fnMatch[2] || '').trim();
      if (/^[a-z0-9]{8,16}$/i.test(codeFromFn)) {
        file_code = codeFromFn;
      }
    }

    if (!file_code) {
      const fnAltMatch = html.match(/(?:^|[?&])fn=([a-z0-9]{8,16})(?:&|$)/i);
      if (fnAltMatch) file_code = fnAltMatch[1];
    }

    // Vidmoly URL patterns - includes /w/ path format
    const linkPatterns = [
      /https?:\/\/vidmoly\.[a-z]+\/w\/[a-z0-9]{12}/gi,
      /https?:\/\/vidmoly\.[a-z]+\/embed-[a-z0-9]{12}[^\s"']*/gi,
      /https?:\/\/vidmoly\.[a-z]+\/[a-z0-9]{12}\.html/gi,
      /https?:\/\/vidmoly\.[a-z]+\/[a-z0-9]{12}/gi
    ];

    for (const pattern of linkPatterns) {
      const matches = html.match(pattern);
      if (matches) {
        for (const url of matches) {
          if (url.includes('/embed-') || url.includes('/embed/')) {
            if (!embed_url) embed_url = url;
          } else {
            if (!download_url) download_url = url;
          }
        }
      }
    }

    // Extract file code from URLs
    const codeMatch = (download_url || embed_url || '').match(/\/(?:w\/)?([a-z0-9]{12})/i)
      || (download_url || embed_url || '').match(/embed-([a-z0-9]{12})/i);
    if (codeMatch) {
      file_code = codeMatch[1];
    }

    // Try input/textarea fields
    if (!download_url) {
      const inputMatch = html.match(/<(?:input|textarea)[^>]*value=["'](https?:\/\/vidmoly[^"']+)["']/i);
      if (inputMatch) {
        download_url = inputMatch[1];
        const code = download_url.match(/\/(?:w\/)?([a-z0-9]{12})/i);
        if (code) file_code = code[1];
      }
    }

    // Try to find file code in any filecode reference
    if (!file_code) {
      const codeInPage = html.match(/filecode['":\s]+['"]?([a-z0-9]{12})['"]?/i)
        || html.match(/file_code['":\s]+['"]?([a-z0-9]{12})['"]?/i);
      if (codeInPage) file_code = codeInPage[1];
    }

    // Build URLs from file_code
    if (file_code && !download_url) {
      download_url = `${BASE_URL}/w/${file_code}`;
    }
    if (file_code && !embed_url) {
      embed_url = `${BASE_URL}/embed-${file_code}.html`;
    }

    if (!download_url && !file_code) {
      const errMatch = html.match(/class=["']err["'][^>]*>([^<]+)/i);
      const errMsg = errMatch ? errMatch[1].trim() : 'Kein Download-Link gefunden';
      throw new Error(`Vidmoly Upload-Ergebnis: ${errMsg}`);
    }

    return { download_url, embed_url, file_code };
  }
}

module.exports = VidmolyUploader;