import { existsSync, writeFileSync, mkdirSync } from 'fs';
import { basename, join, extname } from 'path';
import { upsertMediaFile } 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}
  const m = parsed.pathname.match(/\/(?:model|media)\/(\d+)/);
  if (!m) throw new Error(`Can't parse URL. Expected: https://fapello.to/model/12345`);
  return { base, userId: m[1] };
}

// 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,
        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;
}

// Download all collected media items with concurrency
export async function downloadMedia(items, outputDir, workers, logFn, progressFn, checkCancelled) {
  mkdirSync(outputDir, { recursive: true });

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

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

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

      let filename;
      try {
        filename = basename(new URL(item.url).pathname);
        if (!filename || filename === '/') {
          filename = `${item.id}.${item.type === 'video' ? 'mp4' : 'jpg'}`;
        }
      } catch {
        filename = `${item.id}.${item.type === 'video' ? 'mp4' : 'jpg'}`;
      }

      let filepath = join(outputDir, filename);
      if (existsSync(filepath)) {
        skipped++;
        progressFn(completed + skipped, errors, items.length);
        continue;
      }

      try {
        const resp = await fetch(item.url, {
          headers: {
            'User-Agent': UA,
            'Referer': 'https://fapello.to/',
          },
          signal: AbortSignal.timeout(60000),
        });
        if (!resp.ok) {
          logFn(`FAILED (${resp.status}): ${filename}`);
          errors++;
          progressFn(completed + skipped, errors, items.length);
          continue;
        }

        const buf = Buffer.from(await resp.arrayBuffer());
        if (buf.length < 500) {
          skipped++;
          progressFn(completed + skipped, errors, items.length);
          continue;
        }

        // Handle filename collision
        if (existsSync(filepath)) {
          const ext = extname(filename);
          const name = filename.slice(0, -ext.length);
          let i = 1;
          while (existsSync(filepath)) {
            filepath = join(outputDir, `${name}_${i}${ext}`);
            i++;
          }
        }

        writeFileSync(filepath, buf);
        const savedName = basename(filepath);
        const folderName = basename(outputDir);
        const fileExt = extname(savedName).toLowerCase();
        const fileType = VIDEO_EXTS.has(fileExt) ? 'video' : 'image';
        try { upsertMediaFile(folderName, savedName, fileType, buf.length, Date.now(), null); } catch {}

        completed++;
        const sizeKb = (buf.length / 1024).toFixed(1);
        logFn(`[${completed}/${items.length}] ${savedName} (${sizeKb} KB)`);
        progressFn(completed + skipped, errors, items.length);
      } catch (err) {
        logFn(`FAILED: ${filename} - ${err.message}`);
        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);

  return { completed, errors, skipped, total: items.length };
}