const express = require('express');
const cookieParser = require('cookie-parser');
const jwt = require('jsonwebtoken');
const bcrypt = require('bcryptjs');
const fs = require('fs');
const path = require('path');
const archiver = require('archiver');
const db = require('./database');

const app = express();
const JWT_SECRET = process.env.JWT_SECRET || 'mischkomposition-super-secret-key-change-me';
const FULLS_DIR = path.join(__dirname, '../public/images/fulls');
const IMAGE_RE = /\.(jpg|jpeg|png|gif|webp)$/i;

app.use(express.json());
app.use(express.urlencoded({ extended: true }));
app.use(cookieParser());

// ==================== MIDDLEWARE ====================

function authMiddleware(req, res, next) {
    const token = req.cookies.token;
    if (!token) { req.user = null; return next(); }
    jwt.verify(token, JWT_SECRET, (err, decoded) => {
        if (err) { req.user = null; return next(); }
        // Client-Ablauf pruefen (30 Tage)
        if (decoded.role === 'client' && decoded.created_at) {
            const expires = new Date(decoded.created_at);
            expires.setDate(expires.getDate() + 30);
            if (new Date() > expires) {
                res.clearCookie('token');
                req.user = null;
                return next();
            }
        }
        req.user = decoded;
        next();
    });
}

function requireAuth(req, res, next) {
    if (!req.user) return res.status(401).json({ error: 'Not logged in' });
    next();
}

function requireAdmin(req, res, next) {
    if (!req.user || req.user.role !== 'admin') {
        return res.status(403).json({ error: 'Forbidden' });
    }
    next();
}

app.use(authMiddleware);

// ==================== HELPER ====================

function listImagesInDir(dir) {
    try {
        const files = fs.readdirSync(dir);
        return files.filter(f => IMAGE_RE.test(f) && fs.statSync(path.join(dir, f)).isFile());
    } catch (e) {
        return [];
    }
}

function listSubfolders(dir) {
    try {
        return fs.readdirSync(dir).filter(f => {
            try { return fs.statSync(path.join(dir, f)).isDirectory(); }
            catch (e) { return false; }
        });
    } catch (e) {
        return [];
    }
}

// ==================== AUTH API ====================

app.post('/api/auth/login', (req, res) => {
    const { username, password } = req.body;
    db.get('SELECT * FROM users WHERE username = ?', [username], (err, user) => {
        if (err) return res.status(500).json({ error: 'DB Error' });
        if (!user || !bcrypt.compareSync(password, user.password_hash)) {
            return res.status(401).json({ error: 'Invalid credentials' });
        }
        // Client-Ablauf pruefen
        if (user.role === 'client' && user.created_at) {
            const expires = new Date(user.created_at);
            expires.setDate(expires.getDate() + 30);
            if (new Date() > expires) {
                return res.status(401).json({ error: 'Account abgelaufen' });
            }
        }
        const token = jwt.sign(
            { id: user.id, username: user.username, role: user.role, created_at: user.created_at },
            JWT_SECRET, { expiresIn: '7d' }
        );
        res.cookie('token', token, { httpOnly: true, sameSite: 'strict', maxAge: 7 * 24 * 60 * 60 * 1000 });
        res.json({ success: true, role: user.role });
    });
});

app.post('/api/auth/logout', (req, res) => {
    res.clearCookie('token');
    res.json({ success: true });
});

app.get('/api/auth/me', (req, res) => {
    if (!req.user) return res.status(401).json({ error: 'Not logged in' });
    res.json(req.user);
});

app.post('/api/auth/change-password', requireAuth, (req, res) => {
    const { old_password, new_password } = req.body;
    if (!new_password || new_password.length < 4) {
        return res.status(400).json({ error: 'Passwort muss mindestens 4 Zeichen lang sein' });
    }
    db.get('SELECT * FROM users WHERE id = ?', [req.user.id], (err, user) => {
        if (err || !user) return res.status(500).json({ error: 'DB Error' });
        if (!bcrypt.compareSync(old_password, user.password_hash)) {
            return res.status(401).json({ error: 'Altes Passwort ist falsch' });
        }
        const hash = bcrypt.hashSync(new_password, 10);
        db.run('UPDATE users SET password_hash = ? WHERE id = ?', [hash, user.id], (err) => {
            if (err) return res.status(500).json({ error: 'DB Error' });
            res.json({ success: true });
        });
    });
});

// ==================== IMAGE LISTING ====================

app.get('/images/fulls/', (req, res) => {
    // Root-Bilder sind immer oeffentlich
    const rootImages = listImagesInDir(FULLS_DIR).map(name => ({
        name, type: 'file', folder: null
    }));

    // Nicht eingeloggt: nur Root-Bilder
    if (!req.user) return res.json(rootImages);

    const folders = listSubfolders(FULLS_DIR);

    // Admin: Nur Root-Bilder (damit die Startseite sauber bleibt)
    if (req.user.role === 'admin') {
        return res.json(rootImages);
    }

    // User/Client: NUR zugewiesene Ordner (keine Root-Bilder untermischen)
    db.all('SELECT folder_name FROM user_folders WHERE user_id = ?', [req.user.id], (err, rows) => {
        const assignedFolders = err ? [] : rows.map(r => r.folder_name);
        const result = [];
        assignedFolders.forEach(folder => {
            if (folders.includes(folder)) {
                listImagesInDir(path.join(FULLS_DIR, folder)).forEach(name => {
                    result.push({ name, type: 'file', folder });
                });
            }
        });
        return res.json(result);
    });
});

// ==================== ADMIN API ====================

app.get('/api/admin/users', requireAdmin, (req, res) => {
    db.all('SELECT id, username, role, created_at FROM users', (err, rows) => {
        if (err) {
            console.error('User-Abfrage fehlgeschlagen:', err.message);
            // Fallback: einfache Abfrage ohne neue Spalten
            return db.all('SELECT * FROM users', (err2, rows2) => {
                if (err2) return res.status(500).json({ error: 'DB Error: ' + err2.message });
                res.json(rows2.map(u => ({ id: u.id, username: u.username, role: u.role || 'client', created_at: u.created_at || null })));
            });
        }
        // Ablaufdatum berechnen fuer Clients
        const result = rows.map(u => {
            const out = { ...u };
            if (u.role === 'client' && u.created_at) {
                const expires = new Date(u.created_at);
                expires.setDate(expires.getDate() + 30);
                out.expires_at = expires.toISOString();
                out.expired = new Date() > expires;
            }
            return out;
        });
        res.json(result);
    });
});

app.post('/api/admin/users', requireAdmin, (req, res) => {
    const { username, password, role } = req.body;
    if (!username || !password) return res.status(400).json({ error: 'Username und Passwort erforderlich' });
    const validRoles = ['admin', 'user', 'client'];
    const userRole = validRoles.includes(role) ? role : 'client';
    const hash = bcrypt.hashSync(password, 10);
    db.run('INSERT INTO users (username, password_hash, role) VALUES (?, ?, ?)', [username, hash, userRole], function(err) {
        if (err) return res.status(400).json({ error: err.message });
        res.json({ success: true, id: this.lastID });
    });
});

app.delete('/api/admin/users/:id', requireAdmin, (req, res) => {
    const userId = parseInt(req.params.id);
    // Sich selbst loeschen verhindern
    if (userId === req.user.id) {
        return res.status(400).json({ error: 'Du kannst dich nicht selbst loeschen' });
    }
    db.run('DELETE FROM users WHERE id = ?', [userId], (err) => {
        if (err) return res.status(500).json({ error: 'DB Error' });
        db.run('DELETE FROM user_folders WHERE user_id = ?', [userId]);
        res.json({ success: true });
    });
});

app.put('/api/admin/users/:id/password', requireAdmin, (req, res) => {
    const { new_password } = req.body;
    if (!new_password || new_password.length < 4) {
        return res.status(400).json({ error: 'Passwort muss mindestens 4 Zeichen lang sein' });
    }
    const hash = bcrypt.hashSync(new_password, 10);
    db.run('UPDATE users SET password_hash = ? WHERE id = ?', [hash, parseInt(req.params.id)], (err) => {
        if (err) return res.status(500).json({ error: 'DB Error' });
        res.json({ success: true });
    });
});

// Ordner-Verwaltung
app.get('/api/admin/folders', requireAdmin, (req, res) => {
    res.json(listSubfolders(FULLS_DIR));
});

app.get('/api/admin/assign', requireAdmin, (req, res) => {
    const userId = req.query.user_id;
    if (userId) {
        db.all('SELECT folder_name FROM user_folders WHERE user_id = ?', [userId], (err, rows) => {
            res.json(err ? [] : rows.map(r => r.folder_name));
        });
    } else {
        db.all('SELECT * FROM user_folders', (err, rows) => {
            res.json(err ? [] : rows);
        });
    }
});

app.post('/api/admin/assign', requireAdmin, (req, res) => {
    const { user_id, folders } = req.body;
    if (!user_id) return res.status(400).json({ error: 'user_id erforderlich' });
    const folderList = Array.isArray(folders) ? folders : [];
    db.serialize(() => {
        db.run('DELETE FROM user_folders WHERE user_id = ?', [user_id]);
        const stmt = db.prepare('INSERT INTO user_folders (user_id, folder_name) VALUES (?, ?)');
        folderList.forEach(name => stmt.run(user_id, name));
        stmt.finalize();
        res.json({ success: true });
    });
});

// ==================== DOWNLOAD API ====================

function isValidName(name) {
    return name && !name.includes('/') && !name.includes('\\') && !name.includes('..');
}

app.post('/api/download/selected', (req, res) => {
    const { images } = req.body;
    if (!Array.isArray(images) || images.length === 0) {
        return res.status(400).json({ error: 'Keine Bilder ausgewaehlt' });
    }

    // Alle Bilder validieren und Zugriff pruefen
    let pending = images.length;
    const verified = [];
    let responded = false;

    images.forEach((img, idx) => {
        if (responded) return;
        const name = img.name;
        const folder = img.folder || null;

        // Dateiname + Ordnername validieren
        if (!isValidName(name) || !IMAGE_RE.test(name) || (folder && !isValidName(folder))) {
            responded = true;
            return res.status(400).json({ error: 'Ungueltiger Dateiname' });
        }

        const checkAccess = (ok) => {
            if (responded) return;
            if (!ok) {
                responded = true;
                return res.status(403).json({ error: 'Kein Zugriff auf: ' + name });
            }
            verified[idx] = img;
            pending--;
            if (pending === 0) sendFiles();
        };

        if (!folder) {
            // Root-Bild: fuer alle zugaenglich
            const filePath = path.join(FULLS_DIR, name);
            checkAccess(fs.existsSync(filePath));
        } else {
            // Ordner-Bild: nur wenn User den Ordner zugewiesen hat
            if (!req.user) return checkAccess(false);
            db.get('SELECT 1 FROM user_folders WHERE user_id = ? AND folder_name = ?',
                [req.user.id, folder], (err, row) => {
                    if (err || !row) return checkAccess(false);
                    const filePath = path.join(FULLS_DIR, folder, name);
                    checkAccess(fs.existsSync(filePath));
                });
        }
    });

    function sendFiles() {
        if (verified.length <= 3) {
            // Einzelne Downloads: URLs zurueckgeben
            const urls = verified.map(img => {
                const prefix = img.folder ? encodeURIComponent(img.folder) + '/' : '';
                return '/images/fulls/' + prefix + encodeURIComponent(img.name);
            });
            return res.json({ mode: 'individual', urls });
        }

        // 4+ Bilder: ZIP streamen
        res.setHeader('Content-Type', 'application/zip');
        res.setHeader('Content-Disposition', 'attachment; filename="mischkomposition-auswahl.zip"');
        const archive = archiver('zip', { zlib: { level: 5 } });
        archive.on('error', () => {
            if (!res.headersSent) res.status(500).json({ error: 'ZIP-Fehler' });
        });
        archive.pipe(res);
        verified.forEach(img => {
            const filePath = img.folder
                ? path.join(FULLS_DIR, img.folder, img.name)
                : path.join(FULLS_DIR, img.name);
            archive.file(filePath, { name: img.name });
        });
        archive.finalize();
    }
});

app.get('/api/download/folder/:folderName', (req, res) => {
    const folderName = req.params.folderName;
    if (!isValidName(folderName)) {
        return res.status(400).json({ error: 'Ungueltiger Ordnername' });
    }
    if (!req.user) {
        return res.status(401).json({ error: 'Nicht eingeloggt' });
    }
    db.get('SELECT 1 FROM user_folders WHERE user_id = ? AND folder_name = ?',
        [req.user.id, folderName], (err, row) => {
            if (err || !row) {
                return res.status(403).json({ error: 'Kein Zugriff auf diesen Ordner' });
            }
            const folderPath = path.join(FULLS_DIR, folderName);
            const images = listImagesInDir(folderPath);
            if (images.length === 0) {
                return res.status(404).json({ error: 'Keine Bilder im Ordner' });
            }
            res.setHeader('Content-Type', 'application/zip');
            res.setHeader('Content-Disposition', 'attachment; filename="' + encodeURIComponent(folderName) + '.zip"');
            const archive = archiver('zip', { zlib: { level: 5 } });
            archive.on('error', () => {
                if (!res.headersSent) res.status(500).json({ error: 'ZIP-Fehler' });
            });
            archive.pipe(res);
            images.forEach(name => {
                archive.file(path.join(folderPath, name), { name });
            });
            archive.finalize();
        });
});

// ==================== STATIC FILES ====================

app.use(express.static(path.join(__dirname, '../public')));

app.get('*', (req, res) => {
    res.sendFile(path.join(__dirname, '../public/index.html'));
});

const PORT = 8090;
app.listen(PORT, () => {
    console.log(`Mischkomposition Backend on port ${PORT}`);
});