import express from 'express';
import pool from '../database.js';

const router = express.Router();

// GET all students
router.get('/', async (req, res) => {
    try {
        const [rows] = await pool.execute(`
      SELECT id, name, class, parent_name as parentName, parent_phone as parentPhone, shift, face_descriptor as faceDescriptor 
      FROM students 
      ORDER BY class, name
    `);
        res.json(rows);
    } catch (error) {
        console.error('Error fetching students:', error);
        res.status(500).json({ error: 'Failed to fetch students' });
    }
});

// GET single student
router.get('/:id', async (req, res) => {
    try {
        const [rows] = await pool.execute(`
      SELECT id, name, class, parent_name as parentName, parent_phone as parentPhone, shift, face_descriptor as faceDescriptor 
      FROM students 
      WHERE id = ?
    `, [req.params.id]);

        if (rows.length === 0) {
            return res.status(404).json({ error: 'Student not found' });
        }
        res.json(rows[0]);
    } catch (error) {
        console.error('Error fetching student:', error);
        res.status(500).json({ error: 'Failed to fetch student' });
    }
});

// POST create student
router.post('/', async (req, res) => {
    try {
        const { id, name, class: studentClass, parentName, parentPhone, shift } = req.body;

        await pool.execute(`
      INSERT INTO students (id, name, class, parent_name, parent_phone, shift)
      VALUES (?, ?, ?, ?, ?, ?)
    `, [id, name, studentClass, parentName, parentPhone, shift || 'Siang']);

        res.status(201).json({ status: 'success', message: 'Student created' });
    } catch (error) {
        console.error('Error creating student:', error);
        res.status(500).json({ error: 'Failed to create student' });
    }
});

// PUT update student
router.put('/:id', async (req, res) => {
    try {
        const { name, class: studentClass, parentName, parentPhone, shift, faceDescriptor } = req.body;

        await pool.execute(`
      UPDATE students 
      SET name = ?, class = ?, parent_name = ?, parent_phone = ?, shift = ?, face_descriptor = ?
      WHERE id = ?
    `, [name, studentClass, parentName, parentPhone, shift, faceDescriptor, req.params.id]);

        res.json({ status: 'success', message: 'Student updated' });
    } catch (error) {
        console.error('Error updating student:', error);
        res.status(500).json({ error: 'Failed to update student' });
    }
});

// DELETE student
router.delete('/:id', async (req, res) => {
    try {
        await pool.execute('DELETE FROM students WHERE id = ?', [req.params.id]);
        res.json({ status: 'success', message: 'Student deleted' });
    } catch (error) {
        console.error('Error deleting student:', error);
        res.status(500).json({ error: 'Failed to delete student' });
    }
});

// GET class statistics for promotion
router.get('/stats/classes', async (req, res) => {
    try {
        const [rows] = await pool.execute(`
            SELECT class, COUNT(*) as count 
            FROM students 
            GROUP BY class 
            ORDER BY class
        `);
        res.json(rows);
    } catch (error) {
        console.error('Error fetching class stats:', error);
        res.status(500).json({ error: 'Failed to fetch class stats' });
    }
});

// POST promote students to next class
router.post('/promote', async (req, res) => {
    const connection = await pool.getConnection();
    try {
        await connection.beginTransaction();

        // Get promotion mapping: X -> XI, XI -> XII, XII -> LULUS (delete)
        const promotionRules = [
            { from: 'X', to: 'XI' },
            { from: 'XI', to: 'XII' },
        ];

        let promoted = 0;
        let graduated = 0;

        // First, handle graduates (XII -> Lulus/Delete)
        // Count XII students first
        const [xiiStudents] = await connection.execute(
            "SELECT COUNT(*) as count FROM students WHERE class LIKE 'XII%'"
        );
        graduated = xiiStudents[0].count;

        // Archive XII students before deletion (optional - can create alumni table later)
        // For now, just delete them
        await connection.execute("DELETE FROM students WHERE class LIKE 'XII%'");

        // Promote XI to XII
        const [xiResult] = await connection.execute(`
            UPDATE students 
            SET class = REPLACE(class, 'XI-', 'XII-')
            WHERE class LIKE 'XI-%'
        `);

        // Also handle XI without dash
        await connection.execute(`
            UPDATE students 
            SET class = REPLACE(class, 'XI', 'XII')
            WHERE class = 'XI' OR (class LIKE 'XI%' AND class NOT LIKE 'XII%')
        `);

        // Promote X to XI  
        const [xResult] = await connection.execute(`
            UPDATE students 
            SET class = REPLACE(class, 'X-', 'XI-')
            WHERE class LIKE 'X-%' AND class NOT LIKE 'XI%' AND class NOT LIKE 'XII%'
        `);

        // Also handle X without dash
        await connection.execute(`
            UPDATE students 
            SET class = 'XI'
            WHERE class = 'X'
        `);

        // Count promoted students
        const [countResult] = await connection.execute('SELECT COUNT(*) as count FROM students');
        promoted = countResult[0].count;

        await connection.commit();

        res.json({
            status: 'success',
            message: 'Kenaikan kelas berhasil!',
            graduated,
            totalRemaining: promoted
        });
    } catch (error) {
        await connection.rollback();
        console.error('Error promoting students:', error);
        res.status(500).json({ error: 'Failed to promote students' });
    } finally {
        connection.release();
    }
});

// POST graduate specific class (manual)
router.post('/graduate/:classPrefix', async (req, res) => {
    try {
        const { classPrefix } = req.params;
        const [result] = await pool.execute(
            'DELETE FROM students WHERE class LIKE ?',
            [`${classPrefix}%`]
        );
        res.json({
            status: 'success',
            message: `Siswa kelas ${classPrefix} telah diluluskan`,
            count: result.affectedRows
        });
    } catch (error) {
        console.error('Error graduating students:', error);
        res.status(500).json({ error: 'Failed to graduate students' });
    }
});

// POST promote individual students with mapping
router.post('/promote-mapping', async (req, res) => {
    const { mappings } = req.body; // Array of { studentId, newClass }

    if (!mappings || !Array.isArray(mappings) || mappings.length === 0) {
        return res.status(400).json({ error: 'Data mapping diperlukan' });
    }

    const connection = await pool.getConnection();
    try {
        await connection.beginTransaction();

        let success = 0;
        let failed = 0;
        const errors = [];
        const graduatedIds = [];

        for (const mapping of mappings) {
            const { studentId, newClass } = mapping;

            if (!studentId) {
                failed++;
                errors.push(`ID siswa tidak valid`);
                continue;
            }

            try {
                if (newClass === 'LULUS' || newClass === 'lulus' || newClass === '') {
                    // Graduate this student (delete)
                    await connection.execute(
                        'DELETE FROM students WHERE id = ?',
                        [studentId]
                    );
                    graduatedIds.push(studentId);
                    success++;
                } else {
                    // Update class
                    const [result] = await connection.execute(
                        'UPDATE students SET class = ? WHERE id = ?',
                        [newClass, studentId]
                    );

                    if (result.affectedRows > 0) {
                        success++;
                    } else {
                        failed++;
                        errors.push(`Siswa ${studentId} tidak ditemukan`);
                    }
                }
            } catch (err) {
                failed++;
                errors.push(`Error untuk siswa ${studentId}: ${err.message}`);
            }
        }

        await connection.commit();

        res.json({
            status: 'success',
            message: `Proses selesai: ${success} berhasil, ${failed} gagal`,
            success,
            failed,
            graduated: graduatedIds.length,
            errors: errors.slice(0, 10) // Limit error messages
        });
    } catch (error) {
        await connection.rollback();
        console.error('Error in promote-mapping:', error);
        res.status(500).json({ error: 'Gagal memproses kenaikan kelas' });
    } finally {
        connection.release();
    }
});

// GET available classes for dropdown
router.get('/available-classes', async (req, res) => {
    try {
        const [rows] = await pool.execute(`
            SELECT DISTINCT class 
            FROM students 
            ORDER BY class
        `);

        // Generate next level classes
        const currentClasses = rows.map(r => r.class);
        const allClasses = new Set(currentClasses);

        // Add common class patterns for next level
        currentClasses.forEach(c => {
            // Extract level and suffix (e.g., "X-A" -> "X", "A")
            const match = c.match(/^(X|XI|XII)-?(.*)$/i);
            if (match) {
                const level = match[1].toUpperCase();
                const suffix = match[2];

                if (level === 'X') {
                    allClasses.add(`XI-${suffix}`);
                    allClasses.add(`XI${suffix}`);
                } else if (level === 'XI') {
                    allClasses.add(`XII-${suffix}`);
                    allClasses.add(`XII${suffix}`);
                }
            }
        });

        // Sort and return unique classes
        const sortedClasses = Array.from(allClasses).sort();
        res.json(sortedClasses);
    } catch (error) {
        console.error('Error fetching available classes:', error);
        res.status(500).json({ error: 'Failed to fetch classes' });
    }
});

export default router;