const express = require('express');
const cors = require('cors');
const Database = require('better-sqlite3');
const { v4: uuidv4 } = require('uuid');
const path = require('path');
const fs = require('fs');

const app = express();
const PORT = process.env.PORT || 3000;

const MAX_PROFILES = 5;
const DEFAULT_PROFILE_NAMES = {
  1: 'Profil 1',
  2: 'Profil 2',
  3: 'Profil 3',
  4: 'Profil 4',
  5: 'Profil 5'
};

const screenshotDir = path.join(__dirname, 'data', 'screenshots');
if (!fs.existsSync(screenshotDir)) {
  fs.mkdirSync(screenshotDir, { recursive: true });
}

// Middleware - Enhanced CORS for extension
app.use(cors({
  origin: '*',
  methods: ['GET', 'POST', 'PUT', 'DELETE', 'OPTIONS'],
  allowedHeaders: ['Content-Type', 'Authorization'],
  credentials: true
}));
// Allow larger payloads because screenshots from high-res monitors can easily exceed 10 MB
app.use(express.json({ limit: '30mb' }));

// Additional CORS headers for extension compatibility
app.use((req, res, next) => {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS');
  res.header('Access-Control-Allow-Headers', 'Content-Type, Authorization');
  next();
});

// Database setup
const dbPath = path.join(__dirname, 'data', 'tracker.db');
const db = new Database(dbPath);

function clampTargetCount(value) {
  const parsed = parseInt(value, 10);
  if (Number.isNaN(parsed)) {
    return 1;
  }
  return Math.min(MAX_PROFILES, Math.max(1, parsed));
}

function validateTargetCount(value) {
  const parsed = parseInt(value, 10);
  if (Number.isNaN(parsed) || parsed < 1 || parsed > MAX_PROFILES) {
    return null;
  }
  return parsed;
}

function sanitizeProfileNumber(value) {
  const parsed = parseInt(value, 10);
  if (Number.isNaN(parsed) || parsed < 1 || parsed > MAX_PROFILES) {
    return null;
  }
  return parsed;
}

function getProfileName(profileNumber) {
  return DEFAULT_PROFILE_NAMES[profileNumber] || `Profil ${profileNumber}`;
}

function getRequiredProfiles(targetCount) {
  const count = clampTargetCount(targetCount);
  return Array.from({ length: count }, (_, index) => index + 1);
}

function buildProfileStatuses(requiredProfiles, checks) {
  const validChecks = checks
    .map(check => {
      const profileNumber = sanitizeProfileNumber(check.profile_number);
      if (!profileNumber) {
        return null;
      }
      return {
        ...check,
        profile_number: profileNumber,
        profile_name: getProfileName(profileNumber)
      };
    })
    .filter(Boolean);

  const completedSet = new Set(validChecks.map(check => check.profile_number));
  const checkByProfile = new Map(validChecks.map(check => [check.profile_number, check]));

  const statuses = requiredProfiles.map((profileNumber, index) => {
    const prerequisites = requiredProfiles.slice(0, index);
    const prerequisitesMet = prerequisites.every(num => completedSet.has(num));
    const isChecked = completedSet.has(profileNumber);
    return {
      profile_number: profileNumber,
      profile_name: getProfileName(profileNumber),
      status: isChecked ? 'done' : (prerequisitesMet ? 'available' : 'locked'),
      checked_at: isChecked && checkByProfile.get(profileNumber)
        ? checkByProfile.get(profileNumber).checked_at
        : null
    };
  });

  return {
    statuses,
    completedChecks: validChecks,
    completedSet
  };
}

function recalcCheckedCount(postId) {
  const post = db.prepare('SELECT id, target_count FROM posts WHERE id = ?').get(postId);
  if (!post) {
    return null;
  }

  const checks = db.prepare('SELECT id, profile_number, checked_at FROM checks WHERE post_id = ?').all(postId);
  const requiredProfiles = getRequiredProfiles(post.target_count);
  const { statuses } = buildProfileStatuses(requiredProfiles, checks);
  const checkedCount = statuses.filter(status => status.status === 'done').length;

  db.prepare('UPDATE posts SET checked_count = ? WHERE id = ?').run(checkedCount, postId);
  if (post.target_count !== requiredProfiles.length) {
    db.prepare('UPDATE posts SET target_count = ? WHERE id = ?').run(requiredProfiles.length, postId);
  }

  return checkedCount;
}

// Initialize database tables
db.exec(`
  CREATE TABLE IF NOT EXISTS posts (
    id TEXT PRIMARY KEY,
    url TEXT NOT NULL UNIQUE,
    title TEXT,
    target_count INTEGER NOT NULL,
    checked_count INTEGER DEFAULT 0,
    screenshot_path TEXT,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
  );
`);

db.exec(`
  CREATE TABLE IF NOT EXISTS checks (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    post_id TEXT NOT NULL,
    profile_number INTEGER,
    checked_at DATETIME DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (post_id) REFERENCES posts(id)
  );
`);

db.exec(`
  CREATE TABLE IF NOT EXISTS profile_state (
    id INTEGER PRIMARY KEY CHECK (id = 1),
    profile_number INTEGER NOT NULL
  );
`);

const ensureColumn = (table, column, definition) => {
  const columns = db.prepare(`PRAGMA table_info(${table})`).all();
  if (!columns.some(col => col.name === column)) {
    db.exec(`ALTER TABLE ${table} ADD COLUMN ${definition}`);
  }
};

ensureColumn('posts', 'checked_count', 'checked_count INTEGER DEFAULT 0');
ensureColumn('posts', 'screenshot_path', 'screenshot_path TEXT');

const checkIndexes = db.prepare("PRAGMA index_list('checks')").all();
for (const idx of checkIndexes) {
  if (idx.unique) {
    // Skip auto indexes created from PRIMARY KEY/UNIQUE constraints; SQLite refuses to drop them
    if (idx.origin !== 'c' || (idx.name && idx.name.startsWith('sqlite_autoindex'))) {
      continue;
    }

    const info = db.prepare(`PRAGMA index_info('${idx.name}')`).all();
    const columns = info.map(i => i.name).join(',');
    if (columns === 'post_id,profile_number' || columns === 'profile_number,post_id') {
      db.exec(`DROP INDEX IF EXISTS "${idx.name}"`);
    }
  }
}

const profileStateRow = db.prepare('SELECT profile_number FROM profile_state WHERE id = 1').get();
if (!profileStateRow) {
  db.prepare('INSERT INTO profile_state (id, profile_number) VALUES (1, 1)').run();
}

function mapPostRow(post) {
  if (!post) {
    return null;
  }

  const checks = db.prepare('SELECT id, profile_number, checked_at FROM checks WHERE post_id = ? ORDER BY checked_at ASC').all(post.id);
  const requiredProfiles = getRequiredProfiles(post.target_count);
  const { statuses, completedChecks } = buildProfileStatuses(requiredProfiles, checks);
  const checkedCount = statuses.filter(status => status.status === 'done').length;
  const screenshotFile = post.screenshot_path ? path.join(screenshotDir, post.screenshot_path) : null;
  const screenshotPath = screenshotFile && fs.existsSync(screenshotFile)
    ? `/api/posts/${post.id}/screenshot`
    : null;

  if (post.checked_count !== checkedCount) {
    db.prepare('UPDATE posts SET checked_count = ? WHERE id = ?').run(checkedCount, post.id);
  }

  if (post.target_count !== requiredProfiles.length) {
    db.prepare('UPDATE posts SET target_count = ? WHERE id = ?').run(requiredProfiles.length, post.id);
  }

  const nextRequired = statuses.find(status => status.status === 'available');

  return {
    ...post,
    target_count: requiredProfiles.length,
    checked_count: checkedCount,
    checks: completedChecks,
    is_complete: checkedCount >= requiredProfiles.length,
    screenshot_path: screenshotPath,
    required_profiles: requiredProfiles,
    profile_statuses: statuses,
    next_required_profile: nextRequired ? nextRequired.profile_number : null
  };
}

// Get all posts
app.get('/api/posts', (req, res) => {
  try {
    const posts = db.prepare(`
      SELECT *
      FROM posts
      ORDER BY created_at DESC
    `).all();

    res.json(posts.map(mapPostRow));
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// Get post by URL
app.get('/api/posts/by-url', (req, res) => {
  try {
    const { url } = req.query;
    if (!url) {
      return res.status(400).json({ error: 'URL parameter required' });
    }

    const post = db.prepare('SELECT * FROM posts WHERE url = ?').get(url);

    if (!post) {
      return res.json(null);
    }

    res.json(mapPostRow(post));
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

app.get('/api/profile-state', (req, res) => {
  try {
    const row = db.prepare('SELECT profile_number FROM profile_state WHERE id = 1').get();
    res.json({ profile_number: row ? row.profile_number : 1 });
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

app.post('/api/profile-state', (req, res) => {
  try {
    const { profile_number } = req.body;
    if (typeof profile_number === 'undefined') {
      return res.status(400).json({ error: 'profile_number is required' });
    }

    const parsed = parseInt(profile_number, 10);
    if (Number.isNaN(parsed) || parsed < 1 || parsed > 5) {
      return res.status(400).json({ error: 'profile_number must be between 1 and 5' });
    }

    db.prepare('UPDATE profile_state SET profile_number = ? WHERE id = 1').run(parsed);

    res.json({ profile_number: parsed });
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

app.post('/api/posts/:postId/screenshot', (req, res) => {
  try {
    const { postId } = req.params;
    const { imageData } = req.body;

    const post = db.prepare('SELECT * FROM posts WHERE id = ?').get(postId);
    if (!post) {
      return res.status(404).json({ error: 'Post not found' });
    }

    if (!imageData || typeof imageData !== 'string') {
      return res.status(400).json({ error: 'imageData is required' });
    }

    const match = imageData.match(/^data:(image\/\w+);base64,(.+)$/);
    if (!match) {
      return res.status(400).json({ error: 'Invalid image data format' });
    }

    const mimeType = match[1];
    const base64 = match[2];
    const extension = mimeType === 'image/jpeg' ? 'jpg' : 'png';
    const buffer = Buffer.from(base64, 'base64');
    const fileName = `${postId}.${extension}`;
    const filePath = path.join(screenshotDir, fileName);

    if (post.screenshot_path && post.screenshot_path !== fileName) {
      const existingPath = path.join(screenshotDir, post.screenshot_path);
      if (fs.existsSync(existingPath)) {
        try {
          fs.unlinkSync(existingPath);
        } catch (error) {
          console.warn('Failed to remove previous screenshot:', error.message);
        }
      }
    }

    fs.writeFileSync(filePath, buffer);
    db.prepare('UPDATE posts SET screenshot_path = ? WHERE id = ?').run(fileName, postId);

    const updatedPost = db.prepare('SELECT * FROM posts WHERE id = ?').get(postId);
    res.json(mapPostRow(updatedPost));
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

app.get('/api/posts/:postId/screenshot', (req, res) => {
  try {
    const { postId } = req.params;
    const post = db.prepare('SELECT screenshot_path FROM posts WHERE id = ?').get(postId);

    if (!post || !post.screenshot_path) {
      return res.status(404).json({ error: 'Screenshot not found' });
    }

    const filePath = path.join(screenshotDir, post.screenshot_path);
    if (!fs.existsSync(filePath)) {
      return res.status(404).json({ error: 'Screenshot not found' });
    }

    res.set('Cache-Control', 'no-store');
    res.sendFile(filePath);
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// Create new post
app.post('/api/posts', (req, res) => {
  try {
    const { url, title, target_count } = req.body;

    const validatedTargetCount = validateTargetCount(target_count);

    if (!url || !validatedTargetCount) {
      return res.status(400).json({ error: 'URL and target_count are required (1-5)' });
    }

    const id = uuidv4();

    const stmt = db.prepare('INSERT INTO posts (id, url, title, target_count, checked_count, screenshot_path) VALUES (?, ?, ?, ?, 0, NULL)');
    stmt.run(id, url, title || '', validatedTargetCount);

    const post = db.prepare('SELECT * FROM posts WHERE id = ?').get(id);

    res.json(mapPostRow(post));
  } catch (error) {
    if (error.message.includes('UNIQUE constraint failed')) {
      res.status(409).json({ error: 'Post with this URL already exists' });
    } else {
      res.status(500).json({ error: error.message });
    }
  }
});

app.put('/api/posts/:postId', (req, res) => {
  try {
    const { postId } = req.params;
    const { target_count, title } = req.body || {};

    const updates = [];
    const params = [];

    if (typeof target_count !== 'undefined') {
      const validatedTargetCount = validateTargetCount(target_count);
      if (!validatedTargetCount) {
        return res.status(400).json({ error: 'target_count must be between 1 and 5' });
      }
      updates.push('target_count = ?');
      params.push(validatedTargetCount);
    }

    if (typeof title !== 'undefined') {
      updates.push('title = ?');
      params.push(title || '');
    }

    if (!updates.length) {
      return res.status(400).json({ error: 'No valid fields to update' });
    }

    params.push(postId);

    const stmt = db.prepare(`UPDATE posts SET ${updates.join(', ')} WHERE id = ?`);
    const result = stmt.run(...params);

    if (result.changes === 0) {
      return res.status(404).json({ error: 'Post not found' });
    }

    recalcCheckedCount(postId);

    const updatedPost = db.prepare('SELECT * FROM posts WHERE id = ?').get(postId);
    res.json(mapPostRow(updatedPost));
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// Check a post for a profile
app.post('/api/posts/:postId/check', (req, res) => {
  try {
    const { postId } = req.params;
    const { profile_number } = req.body;

    const post = db.prepare('SELECT * FROM posts WHERE id = ?').get(postId);
    if (!post) {
      return res.status(404).json({ error: 'Post not found' });
    }

    const requiredProfiles = getRequiredProfiles(post.target_count);
    if (post.target_count !== requiredProfiles.length) {
      db.prepare('UPDATE posts SET target_count = ? WHERE id = ?').run(requiredProfiles.length, postId);
      post.target_count = requiredProfiles.length;
    }

    let profileValue = sanitizeProfileNumber(profile_number);
    if (!profileValue) {
      const stateRow = db.prepare('SELECT profile_number FROM profile_state WHERE id = 1').get();
      profileValue = sanitizeProfileNumber(stateRow ? stateRow.profile_number : null) || requiredProfiles[0];
    }

    if (!requiredProfiles.includes(profileValue)) {
      return res.status(409).json({ error: 'Dieses Profil ist für diesen Beitrag nicht erforderlich.' });
    }

    const existingCheck = db.prepare(
      'SELECT id FROM checks WHERE post_id = ? AND profile_number = ?'
    ).get(postId, profileValue);

    if (existingCheck) {
      const existingPost = db.prepare('SELECT * FROM posts WHERE id = ?').get(postId);
      return res.json(mapPostRow(existingPost));
    }

    if (requiredProfiles.length > 0) {
      const prerequisiteProfiles = requiredProfiles.slice(0, requiredProfiles.indexOf(profileValue));
      if (prerequisiteProfiles.length) {
        const completedRows = db.prepare('SELECT profile_number FROM checks WHERE post_id = ?').all(postId);
        const completedSet = new Set(
          completedRows
            .map(row => sanitizeProfileNumber(row.profile_number))
            .filter(Boolean)
        );

        const missingPrerequisites = prerequisiteProfiles.filter(num => !completedSet.has(num));
        if (missingPrerequisites.length) {
          return res.status(409).json({
            error: 'Vorherige Profile müssen zuerst bestätigen.',
            missing_profiles: missingPrerequisites
          });
        }
      }
    }

    const insertStmt = db.prepare('INSERT INTO checks (post_id, profile_number) VALUES (?, ?)');
    insertStmt.run(postId, profileValue);
    recalcCheckedCount(postId);

    const updatedPost = db.prepare('SELECT * FROM posts WHERE id = ?').get(postId);

    res.json(mapPostRow(updatedPost));
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// Check by URL (for web interface auto-check)
app.post('/api/check-by-url', (req, res) => {
  try {
    const { url, profile_number } = req.body;

    if (!url) {
      return res.status(400).json({ error: 'URL is required' });
    }

    const post = db.prepare('SELECT * FROM posts WHERE url = ?').get(url);
    if (!post) {
      return res.status(404).json({ error: 'Post not found' });
    }

    const requiredProfiles = getRequiredProfiles(post.target_count);
    if (post.target_count !== requiredProfiles.length) {
      db.prepare('UPDATE posts SET target_count = ? WHERE id = ?').run(requiredProfiles.length, post.id);
      post.target_count = requiredProfiles.length;
    }

    let profileValue = sanitizeProfileNumber(profile_number);
    if (!profileValue) {
      const stateRow = db.prepare('SELECT profile_number FROM profile_state WHERE id = 1').get();
      profileValue = sanitizeProfileNumber(stateRow ? stateRow.profile_number : null) || requiredProfiles[0];
    }

    if (!requiredProfiles.includes(profileValue)) {
      return res.status(409).json({ error: 'Dieses Profil ist für diesen Beitrag nicht erforderlich.' });
    }

    const existingCheck = db.prepare(
      'SELECT id FROM checks WHERE post_id = ? AND profile_number = ?'
    ).get(post.id, profileValue);

    if (existingCheck) {
      const updatedPost = db.prepare('SELECT * FROM posts WHERE id = ?').get(post.id);
      return res.json(mapPostRow(updatedPost));
    }

    if (requiredProfiles.length > 0) {
      const prerequisiteProfiles = requiredProfiles.slice(0, requiredProfiles.indexOf(profileValue));
      if (prerequisiteProfiles.length) {
        const completedRows = db.prepare('SELECT profile_number FROM checks WHERE post_id = ?').all(post.id);
        const completedSet = new Set(
          completedRows
            .map(row => sanitizeProfileNumber(row.profile_number))
            .filter(Boolean)
        );

        const missingPrerequisites = prerequisiteProfiles.filter(num => !completedSet.has(num));
        if (missingPrerequisites.length) {
          return res.status(409).json({
            error: 'Vorherige Profile müssen zuerst bestätigen.',
            missing_profiles: missingPrerequisites
          });
        }
      }
    }

    db.prepare('INSERT INTO checks (post_id, profile_number) VALUES (?, ?)').run(post.id, profileValue);
    recalcCheckedCount(post.id);

    const updatedPost = db.prepare('SELECT * FROM posts WHERE id = ?').get(post.id);

    res.json(mapPostRow(updatedPost));
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// Delete post
app.delete('/api/posts/:postId', (req, res) => {
  try {
    const { postId } = req.params;

    const post = db.prepare('SELECT screenshot_path FROM posts WHERE id = ?').get(postId);

    db.prepare('DELETE FROM checks WHERE post_id = ?').run(postId);
    const result = db.prepare('DELETE FROM posts WHERE id = ?').run(postId);

    if (result.changes === 0) {
      return res.status(404).json({ error: 'Post not found' });
    }

    if (post && post.screenshot_path) {
      const filePath = path.join(screenshotDir, post.screenshot_path);
      if (fs.existsSync(filePath)) {
        try {
          fs.unlinkSync(filePath);
        } catch (error) {
          console.warn('Failed to remove screenshot:', error.message);
        }
      }
    }

    res.json({ success: true });
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// Health check
app.get('/health', (req, res) => {
  res.json({ status: 'ok' });
});

app.listen(PORT, '0.0.0.0', () => {
  console.log(`Server running on port ${PORT}`);
});