import { existsSync, writeFileSync, mkdirSync, unlinkSync } from 'fs';
import { basename, join, extname } from 'path';
import { load as cheerioLoad } from 'cheerio';
import { upsertMediaFile, removeMediaFile } from '../db.js';

const UA = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36';

const VIDEO_EXTS = new Set(['.mp4', '.mov', '.avi', '.webm', '.mkv', '.m4v']);

export function parseMediaUrl(url) {
  const parsed = new URL(url);
  const base = `${parsed.protocol}//${parsed.hostname}`;
  // Support /model/{id} or /media/{id} (fapello.to JSON API)
  const m = parsed.pathname.match(/\/(?:model|media)\/(\d+)/);
  if (m) return { base, userId: m[1], mode: 'api' };
  // Support fapello.com profile slug URLs like /josie-hamming-41/
  const slugMatch = parsed.pathname.match(/^\/([a-zA-Z0-9_-]+)\/?$/);
  if (slugMatch) return { base, userId: slugMatch[1], mode: 'html' };
  throw new Error(`Can't parse URL. Expected: https://fapello.to/model/12345 or https://fapello.com/username/`);
}

// Fetch JSON from the API endpoint
// API: GET /api/media/{userId}/{page}/{order}
// Requires X-Requested-With and Referer headers to avoid 403
async function fetchApiPage(base, userId, page, order, logFn) {
  const apiUrl = `${base}/api/media/${userId}/${page}/${order}`;
  try {
    const resp = await fetch(apiUrl, {
      headers: {
        'User-Agent': UA,
        'Accept': 'application/json, text/javascript, */*; q=0.01',
        'X-Requested-With': 'XMLHttpRequest',
        'Referer': `${base}/model/${userId}`,
      },
      signal: AbortSignal.timeout(15000),
    });
    if (!resp.ok) {
      if (resp.status === 404) return null;
      logFn(`API error (${resp.status}): ${apiUrl}`);
      return null;
    }
    const data = await resp.json();
    return data;
  } catch (err) {
    logFn(`API fetch error: ${err.message}`);
    return null;
  }
}

// Collect all media items by paginating through the API
export async function fetchAllMedia(base, userId, maxPages, delay, logFn, checkCancelled) {
  const allItems = [];
  const seen = new Set();

  for (let page = 1; page <= maxPages; page++) {
    if (checkCancelled()) break;

    logFn(`Fetching page ${page}...`);
    const data = await fetchApiPage(base, userId, page, 1, logFn);

    if (!data || data.length === 0) {
      logFn(`Page ${page}: no more items — done`);
      break;
    }

    let newCount = 0;
    for (const item of data) {
      if (seen.has(item.id)) continue;
      seen.add(item.id);
      newCount++;

      // type "2" = video (newUrl is mp4), type "1" = image (newUrl is full-size jpg)
      const isVideo = item.type === '2' || item.type === 2;
      const fullUrl = item.newUrl;
      if (!fullUrl) continue;

      allItems.push({
        id: item.id,
        url: fullUrl,
        thumbUrl: item.newUrlThumb || null,
        type: isVideo ? 'video' : 'image',
      });
    }

    if (newCount === 0) {
      logFn(`Page ${page}: all duplicates — stopping`);
      break;
    }

    logFn(`Page ${page}: ${data.length} items (${newCount} new, ${allItems.length} total)`);

    if (page < maxPages && !checkCancelled()) {
      await new Promise(r => setTimeout(r, delay));
    }
  }

  return allItems;
}

// --- HTML-based scraping (fapello.com profile pages) ---

function parseMediaFromHtml(html, base) {
  const $ = cheerioLoad(html);
  const items = [];

  // Find all image thumbnails in the grid
  $('img[src*="_300px."]').each((_, el) => {
    const thumbUrl = $(el).attr('src');
    if (!thumbUrl) return;
    // Convert thumbnail to full-size: remove _300px
    const fullUrl = thumbUrl.replace(/_300px\./, '.');
    const absUrl = fullUrl.startsWith('http') ? fullUrl : `${base}${fullUrl}`;
    items.push({ url: absUrl, type: 'image' });
  });

  // Find video elements (source tags with .mp4)
  $('video source[src*=".mp4"], video[src*=".mp4"]').each((_, el) => {
    const src = $(el).attr('src');
    if (!src) return;
    const absUrl = src.startsWith('http') ? src : `${base}${src}`;
    items.push({ url: absUrl, type: 'video' });
  });

  return items;
}

export async function fetchAllMediaFromHtml(base, slug, maxPages, delay, logFn, checkCancelled) {
  const allItems = [];
  const seen = new Set();
  let totalPages = maxPages;

  // Phase 1: Fetch initial profile page to get data-max
  logFn(`Fetching profile page: ${base}/${slug}/`);
  try {
    const resp = await fetch(`${base}/${slug}/`, {
      headers: { 'User-Agent': UA },
      signal: AbortSignal.timeout(15000),
    });
    if (!resp.ok) {
      logFn(`Profile page error (${resp.status})`);
      return allItems;
    }
    const html = await resp.text();
    const $ = cheerioLoad(html);

    // Get max pages from data-max attribute
    const dataMax = $('#showmore').attr('data-max');
    if (dataMax) {
      totalPages = Math.min(parseInt(dataMax, 10) || maxPages, maxPages);
      logFn(`Detected ${totalPages} pages`);
    }

    // Parse initial page content
    const initialItems = parseMediaFromHtml(html, base);
    for (const item of initialItems) {
      if (!seen.has(item.url)) {
        seen.add(item.url);
        allItems.push({ ...item, id: seen.size });
      }
    }
    logFn(`Page 1: ${initialItems.length} items (${allItems.length} total)`);
  } catch (err) {
    logFn(`Error fetching profile: ${err.message}`);
    return allItems;
  }

  // Phase 2: Paginate through AJAX pages
  for (let page = 2; page <= totalPages; page++) {
    if (checkCancelled()) break;

    const ajaxUrl = `${base}/ajax/model/${slug}/page-${page}/`;
    try {
      const resp = await fetch(ajaxUrl, {
        headers: {
          'User-Agent': UA,
          'X-Requested-With': 'XMLHttpRequest',
          'Referer': `${base}/${slug}/`,
        },
        signal: AbortSignal.timeout(15000),
      });
      if (!resp.ok) {
        if (resp.status === 404) {
          logFn(`Page ${page}: 404 — done`);
          break;
        }
        logFn(`Page ${page}: error (${resp.status})`);
        continue;
      }
      const html = await resp.text();
      if (!html || html.trim().length === 0) {
        logFn(`Page ${page}: empty — done`);
        break;
      }

      const pageItems = parseMediaFromHtml(html, base);
      let newCount = 0;
      for (const item of pageItems) {
        if (!seen.has(item.url)) {
          seen.add(item.url);
          allItems.push({ ...item, id: seen.size });
          newCount++;
        }
      }

      if (newCount === 0) {
        logFn(`Page ${page}: all duplicates — stopping`);
        break;
      }

      logFn(`Page ${page}: ${pageItems.length} items (${newCount} new, ${allItems.length} total)`);
    } catch (err) {
      logFn(`Page ${page}: error — ${err.message}`);
    }

    if (page < totalPages && !checkCancelled()) {
      await new Promise(r => setTimeout(r, delay));
    }
  }

  return allItems;
}

// Helper: derive filename from URL, with fallback
function filenameFromUrl(url, item) {
  try {
    const name = basename(new URL(url).pathname);
    if (name && name !== '/') return name;
  } catch {}
  return `${item.id}.${item.type === 'video' ? 'mp4' : 'jpg'}`;
}

// Helper: add _md suffix before extension
function mdFilename(filename) {
  const ext = extname(filename);
  return filename.slice(0, -ext.length) + '_md' + ext;
}

// Helper: try fetching a URL, return buffer or null
async function tryFetch(url, referer) {
  if (!url) return null;
  try {
    const resp = await fetch(url, {
      headers: { 'User-Agent': UA, 'Referer': referer || 'https://fapello.to/' },
      signal: AbortSignal.timeout(60000),
    });
    if (!resp.ok) return null;
    const buf = Buffer.from(await resp.arrayBuffer());
    if (buf.length < 500) return null;
    return buf;
  } catch {
    return null;
  }
}

// Download all collected media items with concurrency
// Fallback: if full-res URL fails, download medium (thumbUrl) with _md suffix.
// Upgrade: if _md file exists, try full-res again; replace _md on success.
export async function downloadMedia(items, outputDir, workers, logFn, progressFn, checkCancelled, referer) {
  mkdirSync(outputDir, { recursive: true });

  let completed = 0;
  let errors = 0;
  let skipped = 0;
  let upgraded = 0;
  let index = 0;

  async function processNext() {
    while (index < items.length) {
      if (checkCancelled()) return;

      const current = index++;
      const item = items[current];

      const filename = filenameFromUrl(item.url, item);
      const filepath = join(outputDir, filename);
      const mdName = mdFilename(filename);
      const mdPath = join(outputDir, mdName);

      // Full-res already exists — skip
      if (existsSync(filepath)) {
        skipped++;
        progressFn(completed + skipped, errors, items.length);
        continue;
      }

      // Medium version exists — try to upgrade to full-res
      if (existsSync(mdPath)) {
        const buf = await tryFetch(item.url, referer);
        if (buf) {
          writeFileSync(filepath, buf);
          try { unlinkSync(mdPath); } catch {}
          const folderName = basename(outputDir);
          const fileType = VIDEO_EXTS.has(extname(filename).toLowerCase()) ? 'video' : 'image';
          try { removeMediaFile(folderName, mdName); } catch {}
          try { upsertMediaFile(folderName, filename, fileType, buf.length, Date.now(), null); } catch {}
          upgraded++;
          completed++;
          logFn(`[${completed}/${items.length}] ${filename} (upgraded from _md, ${(buf.length / 1024).toFixed(1)} KB)`);
          progressFn(completed + skipped, errors, items.length);
        } else {
          skipped++;
          progressFn(completed + skipped, errors, items.length);
        }
        continue;
      }

      // Neither exists — try full-res, then fallback to medium
      const buf = await tryFetch(item.url, referer);
      if (buf) {
        writeFileSync(filepath, buf);
        const folderName = basename(outputDir);
        const fileType = VIDEO_EXTS.has(extname(filename).toLowerCase()) ? 'video' : 'image';
        try { upsertMediaFile(folderName, filename, fileType, buf.length, Date.now(), null); } catch {}
        completed++;
        logFn(`[${completed}/${items.length}] ${filename} (${(buf.length / 1024).toFixed(1)} KB)`);
        progressFn(completed + skipped, errors, items.length);
        continue;
      }

      // Full-res failed — try medium (thumbUrl)
      if (item.thumbUrl) {
        const mdBuf = await tryFetch(item.thumbUrl, referer);
        if (mdBuf) {
          writeFileSync(mdPath, mdBuf);
          const folderName = basename(outputDir);
          const fileType = VIDEO_EXTS.has(extname(mdName).toLowerCase()) ? 'video' : 'image';
          try { upsertMediaFile(folderName, mdName, fileType, mdBuf.length, Date.now(), null); } catch {}
          completed++;
          logFn(`[${completed}/${items.length}] ${mdName} (medium fallback, ${(mdBuf.length / 1024).toFixed(1)} KB)`);
          progressFn(completed + skipped, errors, items.length);
          continue;
        }
      }

      // Both failed
      logFn(`FAILED: ${filename} — full-res and medium both unavailable`);
      errors++;
      progressFn(completed + skipped, errors, items.length);
    }
  }

  const workerPromises = [];
  for (let i = 0; i < Math.min(workers, items.length); i++) {
    workerPromises.push(processNext());
  }
  await Promise.all(workerPromises);

  if (upgraded > 0) logFn(`Upgraded ${upgraded} files from medium to full resolution`);
  return { completed, errors, skipped, total: items.length };
}