const express = require('express');
const router = express.Router();
const commentService = require('../services/comments');
const contentService = require('../services/content');
const pageCache = require('../middleware/cache');
const { loadSiteConfig } = require('../config');

// Helper to parse cookies from headers without requiring extra npm dependencies
function parseCookies(req) {
  const list = {};
  const rc = req.headers.cookie;
  if (rc) {
    rc.split(';').forEach(cookie => {
      const parts = cookie.split('=');
      const key = parts.shift().trim();
      const val = parts.join('=').trim();
      try {
        list[key] = decodeURIComponent(val);
      } catch (_) {
        list[key] = val;
      }
    });
  }
  return list;
}

function getExpectedAdminKey() {
  const config = loadSiteConfig();
  return process.env.ADMIN_SECRET || config.admin?.secret || config.site?.admin_secret || 'admin';
}

// Admin authentication middleware
function requireAdminAuth(req, res, next) {
  const expectedKey = getExpectedAdminKey();
  const cookies = parseCookies(req);
  const providedKey = req.query.key || req.headers['x-admin-key'] || cookies.admin_key;

  if (providedKey && providedKey === expectedKey) {
    // If authenticated via query param, set cookie for convenience
    if (req.query.key) {
      res.setHeader('Set-Cookie', `admin_key=${encodeURIComponent(expectedKey)}; Path=/; HttpOnly; SameSite=Lax`);
    }
    return next();
  }

  // Render clean login prompt if unauthorized
  res.status(401);
  return res.render('pages/admin-login', {
    title: 'Admin Authorization',
    error: providedKey ? 'Incorrect admin password.' : null,
    redirect: req.originalUrl
  });
}

// Explicit 404 for legacy /admin routes to prevent leakage and bust browser 301 cache
router.all(['/admin', '/admin/*'], (req, res) => {
  res.setHeader('Cache-Control', 'no-store, no-cache, must-revalidate');
  res.status(404).render('pages/error', {
    title: '404 - Page Not Found',
    errorCode: 404,
    errorMessage: "The page you are looking for doesn't exist or has moved."
  });
});

// Redirect /guanli root to comments
router.get('/guanli', (req, res) => {
  res.redirect('/guanli/comments');
});

// Login GET endpoint (clean access)
router.get('/guanli/login', (req, res) => {
  res.render('pages/admin-login', {
    title: 'Admin Authorization',
    error: null,
    redirect: req.query.redirect || '/guanli/comments'
  });
});

// Login POST endpoint
router.post('/guanli/login', (req, res) => {
  const expectedKey = getExpectedAdminKey();
  const providedKey = (req.body.key || '').trim();
  const redirectUrl = req.body.redirect || '/guanli/comments';

  if (providedKey === expectedKey) {
    res.setHeader('Set-Cookie', `admin_key=${encodeURIComponent(expectedKey)}; Path=/; HttpOnly; SameSite=Lax`);
    return res.redirect(redirectUrl);
  }

  res.status(401).render('pages/admin-login', {
    title: 'Admin Authorization',
    error: 'Incorrect admin password. Please try again.',
    redirect: redirectUrl
  });
});

// Logout endpoint
router.get('/guanli/logout', (req, res) => {
  res.setHeader('Set-Cookie', 'admin_key=; Path=/; Expires=Thu, 01 Jan 1970 00:00:00 GMT');
  res.redirect('/guanli/comments');
});

const dbService = require('../services/db');

// 0. Posts Read-Only Overview Dashboard
router.get('/guanli/posts', requireAdminAuth, (req, res) => {
  const q = (req.query.q || '').trim().toLowerCase();
  const activeCategory = (req.query.category || '').trim();

  const allPosts = contentService.getAllPosts();
  let filteredPosts = allPosts;

  if (activeCategory) {
    filteredPosts = filteredPosts.filter(p => (p.category || '').toLowerCase() === activeCategory.toLowerCase());
  }

  if (q) {
    filteredPosts = filteredPosts.filter(p => 
      (p.title || '').toLowerCase().includes(q) ||
      (p.slug || '').toLowerCase().includes(q) ||
      (p.tags || []).some(t => t.toLowerCase().includes(q))
    );
  }

  const taxonomy = contentService.getTaxonomy();
  const commentStats = dbService.getPostCommentStats();
  const stats = dbService.getAdminStats();

  res.render('pages/admin-posts', {
    title: 'Posts Overview - Site Administration',
    posts: allPosts,
    filteredPosts,
    categories: taxonomy.categories,
    activeCategory,
    q: req.query.q || '',
    commentStats,
    stats
  });
});

// Hot Content Re-index & Cache Flush endpoint
router.post('/guanli/reindex', requireAdminAuth, (req, res) => {
  try {
    const { CONTENT_DIR } = require('../config');
    contentService.init(CONTENT_DIR);
    pageCache.clear();
    const totalPosts = contentService.getAllPosts().length;
    const totalPages = contentService.pagesBySlug.size;
    res.json({ success: true, totalPosts, totalPages });
  } catch (err) {
    console.error('[Admin] Hot re-index failed:', err);
    res.status(500).json({ success: false, error: err.message });
  }
});

// 1. Comment Moderation Dashboard
router.get('/guanli/comments', requireAdminAuth, (req, res) => {
  const status = req.query.status || 'all';
  const q = req.query.q || '';
  const page = parseInt(req.query.page, 10) || 1;
  const limit = 15;

  const paginated = dbService.getPaginatedComments({ status, q, page, limit });
  const counts = dbService.getCommentCounts();
  const adminKey = getExpectedAdminKey();
  const stats = dbService.getAdminStats();

  res.render('pages/admin-comments', {
    title: 'Comment Moderation Dashboard',
    comments: paginated.comments,
    totalComments: paginated.total,
    page: paginated.page,
    totalPages: paginated.totalPages,
    status,
    q,
    counts,
    adminKey,
    stats
  });
});

// 2a. Single Moderation Action Endpoint
router.post('/guanli/comments/:action/:id', requireAdminAuth, (req, res) => {
  const { action, id } = req.params;

  if (action === 'approve') {
    commentService.approveComment(Number(id));
    pageCache.clear();
  } else if (action === 'reject' || action === 'spam') {
    commentService.rejectComment(Number(id));
    pageCache.clear();
  } else if (action === 'delete') {
    commentService.deleteComment(Number(id));
    pageCache.clear();
  }

  const isAjax = req.xhr || req.headers['content-type'] === 'application/json' || req.headers.accept?.includes('application/json');
  if (isAjax) {
    const counts = dbService.getCommentCounts();
    const stats = dbService.getAdminStats();
    return res.json({ success: true, action, id: Number(id), counts, stats });
  }

  const returnUrl = req.headers.referer || '/guanli/comments';
  res.redirect(returnUrl);
});

// 2b. Batch Moderation Action Endpoint
router.post('/guanli/comments/batch', requireAdminAuth, (req, res) => {
  const action = req.body.action;
  let ids = req.body.ids;

  if (typeof ids === 'string') {
    ids = ids.split(',').map(s => Number(s.trim())).filter(Boolean);
  } else if (Array.isArray(ids)) {
    ids = ids.map(Number).filter(Boolean);
  } else {
    ids = [];
  }

  if (ids.length > 0) {
    if (action === 'approve') {
      commentService.batchApproveComments(ids);
      pageCache.clear();
    } else if (action === 'reject' || action === 'spam') {
      commentService.batchRejectComments(ids);
      pageCache.clear();
    } else if (action === 'delete') {
      commentService.batchDeleteComments(ids);
      pageCache.clear();
    }
  }

  const isAjax = req.xhr || req.headers['content-type'] === 'application/json' || req.headers.accept?.includes('application/json');
  if (isAjax) {
    const counts = dbService.getCommentCounts();
    const stats = dbService.getAdminStats();
    return res.json({ success: true, action, ids, count: ids.length, counts, stats });
  }

  const returnUrl = req.headers.referer || '/guanli/comments';
  res.redirect(returnUrl);
});

// 3. Dynamic SEO Analyzer Dashboard
router.get('/guanli/seo', requireAdminAuth, (req, res) => {
  const posts = contentService.getAllPosts();
  const adminKey = getExpectedAdminKey();
  const stats = dbService.getAdminStats();
  const report = [];

  for (const post of posts) {
    const raw = post.rawContent || '';
    const internalLinks = (raw.match(/\[[^\]]+\]\((\/[^)]+)\)/g) || []).length;
    const externalLinks = (raw.match(/\[[^\]]+\]\((https?:\/\/[^)]+)\)/g) || []).length;
    const imagesMissingAlt = (raw.match(/!\[\s*\]\([^)]+\)/g) || []).length;
    const totalImages = (raw.match(/!\[[^\]]*\]\([^)]+\)/g) || []).length;
    
    // Check heading hierarchy
    const headings = post.toc || [];
    let headingIssues = [];
    let lastLevel = 1;
    for (const h of headings) {
      if (h.level > lastLevel + 1) {
        headingIssues.push(`Skipped heading level: from h${lastLevel} to h${h.level} ("${h.title}")`);
      }
      lastLevel = h.level;
    }

    const wordCount = raw.trim().split(/\s+/).length;
    const titleLength = post.title.length;

    report.push({
      type: 'post',
      slug: post.slug,
      title: post.title,
      wordCount,
      titleLength,
      titleOk: titleLength >= 20 && titleLength <= 70,
      internalLinks,
      externalLinks,
      totalImages,
      imagesMissingAlt,
      headingIssues,
      hasExcerpt: Boolean(post.excerpt && post.excerpt.length > 50)
    });
  }

  res.render('pages/admin-seo', {
    title: 'SEO Analyzer & Content Audit',
    report,
    adminKey,
    stats
  });
});

// 4. Search Analytics Dashboard
router.get('/guanli/search', requireAdminAuth, (req, res) => {
  const adminKey = getExpectedAdminKey();
  const stats = dbService.getAdminStats();
  const searchLogs = dbService.getAllSearchLogs(100);
  const recommendations = dbService.getTopSearchRecommendations(20);

  res.render('pages/admin-search', {
    title: 'Search Analytics & Query Logs',
    adminKey,
    stats,
    searchLogs,
    recommendations
  });
});

module.exports = router;