const express = require('express');
const cors = require('cors');
const fs = require('fs');
const path = require('path');
const crypto = require('crypto');
const config = require('./config');
const db = require('./db');

const app = express();
app.use(cors());
app.use(express.json({ limit: '100mb' }));

app.use((req, res, next) => {
  const start = Date.now();
  res.on('finish', () => {
    const ms = Date.now() - start;
    const user = req.body?.username ? ` user=${req.body.username}` : '';
    console.log(`[${new Date().toISOString()}] ${req.method} ${req.path} → ${res.statusCode} (${ms}ms)${user}`);
  });
  next();
});

function getPhotosPath() {
  const p = config.getPhotosPath();
  if (!p) throw new Error('Photos path not configured. Set it in nas_config.txt');
  if (!fs.existsSync(p)) {
    fs.mkdirSync(p, { recursive: true });
  }
  return p;
}

function sanitizeUsername(username) {
  return username.trim().replace(/[^a-zA-Z0-9_\-.]/g, '_');
}

// ─── Health ──────────────────────────────────────────────────

app.get('/api/health', (req, res) => {
  res.json({ status: 'ok', timestamp: new Date().toISOString() });
});

// ─── User Registration ──────────────────────────────────────
// Device sends its username; NAS registers and creates user folder

app.post('/api/register', (req, res) => {
  try {
    const { username } = req.body;
    if (!username || typeof username !== 'string' || username.trim().length === 0) {
      return res.status(400).json({ error: 'Username is required' });
    }
    const sanitized = sanitizeUsername(username);
    const userId = db.ensureUser(sanitized);
    const photosPath = getPhotosPath();
    const userDir = path.join(photosPath, sanitized);
    if (!fs.existsSync(userDir)) {
      fs.mkdirSync(userDir, { recursive: true });
    }
    res.json({ success: true, userId, username: sanitized });
  } catch (err) {
    console.error('[/api/register] Error:', err.message, err.stack);
    res.status(500).json({ error: err.message });
  }
});

// ─── Index (NAS builds its database) ────────────────────────

app.post('/api/index', (req, res) => {
  try {
    const { username } = req.body;
    if (!username) return res.status(400).json({ error: 'Username is required' });

    const photosPath = getPhotosPath();
    const sanitized = sanitizeUsername(username);

    const removed = db.removeOrphanedEntries(sanitized, photosPath);
    const result = db.indexPhotosForUser(sanitized, photosPath);

    res.json({
      success: true,
      username: sanitized,
      indexed: result.indexed,
      skipped: result.skipped,
      errors: result.errors,
      totalFiles: result.total,
      orphansRemoved: removed,
    });
  } catch (err) {
    console.error('[/api/index] Error:', err.message, err.stack);
    res.status(500).json({ error: err.message });
  }
});

// ─── Photo List (POST fetch cycle) ─────────────────────────

app.post('/api/photos', (req, res) => {
  try {
    const { username } = req.body;
    if (!username) return res.status(400).json({ error: 'Username is required' });

    const sanitized = sanitizeUsername(username);
    const photos = db.getPhotoIndex(sanitized);

    res.json({
      success: true,
      username: sanitized,
      count: photos.length,
      photos: photos.map(p => ({
        id: p.id,
        filename: p.filename,
        sha256Hash: p.sha256_hash,
        fileSize: p.file_size,
        mimeType: p.mime_type,
        indexedAt: p.indexed_at,
      })),
    });
  } catch (err) {
    console.error('[/api/photos] Error:', err.message, err.stack);
    res.status(500).json({ error: err.message });
  }
});

// ─── Fetch Single Photo as Base64 with hash ─────────────────

app.post('/api/photo/fetch', (req, res) => {
  try {
    const { photoId, hash } = req.body;
    if (!photoId && !hash) {
      return res.status(400).json({ error: 'photoId or hash is required' });
    }

    let photo;
    if (photoId) {
      photo = db.getPhotoById(photoId);
    } else {
      photo = db.getPhotoByHash(hash);
    }

    if (!photo) return res.status(404).json({ error: 'Photo not found' });
    if (!fs.existsSync(photo.filepath)) {
      return res.status(404).json({ error: 'Photo file missing from disk' });
    }

    const fileBuffer = fs.readFileSync(photo.filepath);
    const base64Data = fileBuffer.toString('base64');
    const transportHash = crypto.createHash('sha256').update(base64Data).digest('hex');

    res.json({
      success: true,
      photo: {
        id: photo.id,
        filename: photo.filename,
        mimeType: photo.mime_type,
        fileSize: photo.file_size,
        sha256Hash: photo.sha256_hash,
        transportHash,
        base64: base64Data,
      },
    });
  } catch (err) {
    console.error('[/api/photo/fetch] Error:', err.message, err.stack);
    res.status(500).json({ error: err.message });
  }
});

// ─── Upload Photo from Device to NAS ────────────────────────

app.post('/api/photo/upload', (req, res) => {
  try {
    const { username, filename, base64, transportHash } = req.body;
    if (!username || !filename || !base64) {
      return res.status(400).json({ error: 'username, filename, and base64 are required' });
    }

    if (transportHash) {
      const computed = crypto.createHash('sha256').update(base64).digest('hex');
      if (computed !== transportHash) {
        return res.status(400).json({ error: 'Transport integrity check failed' });
      }
    }

    const sanitized = sanitizeUsername(username);
    const photosPath = getPhotosPath();
    const userDir = path.join(photosPath, sanitized);
    if (!fs.existsSync(userDir)) {
      fs.mkdirSync(userDir, { recursive: true });
    }

    const safeFilename = filename.replace(/[^a-zA-Z0-9_\-.]/g, '_');
    const destPath = path.join(userDir, safeFilename);

    const buffer = Buffer.from(base64, 'base64');
    fs.writeFileSync(destPath, buffer);

    db.ensureUser(sanitized);
    const result = db.indexPhotosForUser(sanitized, photosPath);

    res.json({ success: true, filename: safeFilename, indexed: result.indexed });
  } catch (err) {
    console.error('[/api/photo/upload] Error:', err.message, err.stack);
    res.status(500).json({ error: err.message });
  }
});

// ─── Delete Photo from NAS ──────────────────────────────────

app.post('/api/photo/delete', (req, res) => {
  try {
    const { photoId } = req.body;
    if (!photoId) return res.status(400).json({ error: 'photoId is required' });
    const result = db.deletePhoto(photoId);
    res.json(result);
  } catch (err) {
    console.error('[/api/photo/delete] Error:', err.message, err.stack);
    res.status(500).json({ error: err.message });
  }
});

// ─── Refresh (re-index + return list) ───────────────────────

app.post('/api/refresh', (req, res) => {
  try {
    const { username } = req.body;
    if (!username) return res.status(400).json({ error: 'Username is required' });

    const sanitized = sanitizeUsername(username);
    const photosPath = getPhotosPath();

    db.ensureUser(sanitized);
    db.removeOrphanedEntries(sanitized, photosPath);
    db.indexPhotosForUser(sanitized, photosPath);
    const photos = db.getPhotoIndex(sanitized);

    res.json({
      success: true,
      username: sanitized,
      count: photos.length,
      photos: photos.map(p => ({
        id: p.id,
        filename: p.filename,
        sha256Hash: p.sha256_hash,
        fileSize: p.file_size,
        mimeType: p.mime_type,
        indexedAt: p.indexed_at,
      })),
    });
  } catch (err) {
    console.error('[/api/refresh] Error:', err.message, err.stack);
    res.status(500).json({ error: err.message });
  }
});

// ─── Album Endpoints ────────────────────────────────────────

app.post('/api/albums', (req, res) => {
  try {
    const { username } = req.body;
    if (!username) return res.status(400).json({ error: 'Username is required' });
    const sanitized = sanitizeUsername(username);
    const albums = db.getAlbums(sanitized);
    res.json({ success: true, albums });
  } catch (err) {
    console.error('[/api/albums] Error:', err.message, err.stack);
    res.status(500).json({ error: err.message });
  }
});

app.post('/api/album/create', (req, res) => {
  try {
    const { username, name } = req.body;
    if (!username || !name) return res.status(400).json({ error: 'username and name are required' });
    const sanitized = sanitizeUsername(username);
    const result = db.createAlbum(sanitized, name.trim());
    res.json(result);
  } catch (err) {
    console.error('[/api/album/create] Error:', err.message, err.stack);
    res.status(500).json({ error: err.message });
  }
});

app.post('/api/album/photos', (req, res) => {
  try {
    const { albumId } = req.body;
    if (!albumId) return res.status(400).json({ error: 'albumId is required' });
    const photos = db.getAlbumPhotos(albumId);
    res.json({
      success: true,
      photos: photos.map(p => ({
        id: p.id,
        filename: p.filename,
        sha256Hash: p.sha256_hash,
        fileSize: p.file_size,
        mimeType: p.mime_type,
        indexedAt: p.indexed_at,
      })),
    });
  } catch (err) {
    console.error('[/api/album/photos] Error:', err.message, err.stack);
    res.status(500).json({ error: err.message });
  }
});

app.post('/api/album/add-photo', (req, res) => {
  try {
    const { albumId, photoId } = req.body;
    if (!albumId || !photoId) return res.status(400).json({ error: 'albumId and photoId are required' });
    const result = db.addPhotoToAlbum(albumId, photoId);
    res.json(result);
  } catch (err) {
    console.error('[/api/album/add-photo] Error:', err.message, err.stack);
    res.status(500).json({ error: err.message });
  }
});

app.post('/api/album/remove-photo', (req, res) => {
  try {
    const { albumId, photoId } = req.body;
    if (!albumId || !photoId) return res.status(400).json({ error: 'albumId and photoId are required' });
    const result = db.removePhotoFromAlbum(albumId, photoId);
    res.json(result);
  } catch (err) {
    console.error('[/api/album/remove-photo] Error:', err.message, err.stack);
    res.status(500).json({ error: err.message });
  }
});

app.post('/api/album/delete', (req, res) => {
  try {
    const { albumId } = req.body;
    if (!albumId) return res.status(400).json({ error: 'albumId is required' });
    const result = db.deleteAlbum(albumId);
    res.json(result);
  } catch (err) {
    console.error('[/api/album/delete] Error:', err.message, err.stack);
    res.status(500).json({ error: err.message });
  }
});

app.post('/api/album/rename', (req, res) => {
  try {
    const { albumId, name } = req.body;
    if (!albumId || !name) return res.status(400).json({ error: 'albumId and name are required' });
    const result = db.renameAlbum(albumId, name.trim());
    res.json(result);
  } catch (err) {
    console.error('[/api/album/rename] Error:', err.message, err.stack);
    res.status(500).json({ error: err.message });
  }
});

// ─── Users ──────────────────────────────────────────────────

app.get('/api/users', (req, res) => {
  try {
    const users = db.getAllUsers();
    res.json({ success: true, users });
  } catch (err) {
    console.error('[/api/users] Error:', err.message, err.stack);
    res.status(500).json({ error: err.message });
  }
});

// ─── Error handling ─────────────────────────────────────────

app.use((err, req, res, _next) => {
  console.error('Server error:', err.message);
  res.status(500).json({ error: 'Internal server error' });
});

app.use((req, res) => {
  res.status(404).json({ error: 'Not found', path: req.path });
});

// ─── Lifecycle ──────────────────────────────────────────────

function startServer(port) {
  const p = port || config.DEFAULT_PORT;
  app.listen(p, '0.0.0.0', () => {
    console.log(`[NAS Server] Running on http://0.0.0.0:${p}`);
    console.log(`[NAS Server] Photos path: ${config.getPhotosPath() || 'NOT SET'}`);
  });
}

if (require.main === module) {
  const photosPath = config.getPhotosPath();
  if (!photosPath) {
    console.error('ERROR: Photos path not set. Write the path to your photos directory in nas_config.txt');
    process.exit(1);
  }
  // Auto-create the photos directory if it doesn't exist yet
  if (!fs.existsSync(photosPath)) {
    fs.mkdirSync(photosPath, { recursive: true });
    console.log(`[NAS Server] Created photos directory: ${photosPath}`);
  }
  startServer();
}

process.on('SIGINT', () => {
  console.log('\nShutting down...');
  db.closeDb();
  process.exit(0);
});

module.exports = { app, startServer };