/**
 * Mappings Routes
 * Manage value mappings
 */

const express = require('express');

module.exports = (pool) => {
    const router = express.Router();

    // List all mappings for a source
    router.get('/source/:source_name', async (req, res, next) => {
        try {
            const { rule_name } = req.query;

            let query = 'SELECT * FROM mappings WHERE source_name = $1';
            const params = [req.params.source_name];

            if (rule_name) {
                query += ' AND rule_name = $2';
                params.push(rule_name);
            }

            query += ' ORDER BY rule_name, input_value';

            const result = await pool.query(query, params);
            res.json(result.rows);
        } catch (err) {
            next(err);
        }
    });

    // Get unmapped values
    router.get('/source/:source_name/unmapped', async (req, res, next) => {
        try {
            const { rule_name } = req.query;

            const result = await pool.query(
                'SELECT * FROM get_unmapped_values($1, $2)',
                [req.params.source_name, rule_name || null]
            );

            res.json(result.rows);
        } catch (err) {
            next(err);
        }
    });

    // Get single mapping
    router.get('/:id', async (req, res, next) => {
        try {
            const result = await pool.query(
                'SELECT * FROM mappings WHERE id = $1',
                [req.params.id]
            );

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

            res.json(result.rows[0]);
        } catch (err) {
            next(err);
        }
    });

    // Create mapping
    router.post('/', async (req, res, next) => {
        try {
            const { source_name, rule_name, input_value, output } = req.body;

            if (!source_name || !rule_name || !input_value || !output) {
                return res.status(400).json({
                    error: 'Missing required fields: source_name, rule_name, input_value, output'
                });
            }

            const result = await pool.query(
                `INSERT INTO mappings (source_name, rule_name, input_value, output)
                 VALUES ($1, $2, $3, $4)
                 RETURNING *`,
                [source_name, rule_name, JSON.stringify(input_value), JSON.stringify(output)]
            );

            res.status(201).json(result.rows[0]);
        } catch (err) {
            if (err.code === '23505') {  // Unique violation
                return res.status(409).json({ error: 'Mapping already exists' });
            }
            if (err.code === '23503') {  // Foreign key violation
                return res.status(404).json({ error: 'Source or rule not found' });
            }
            next(err);
        }
    });

    // Bulk create mappings
    router.post('/bulk', async (req, res, next) => {
        const client = await pool.connect();
        try {
            const { mappings } = req.body;

            if (!Array.isArray(mappings)) {
                return res.status(400).json({ error: 'Expected array of mappings' });
            }

            await client.query('BEGIN');

            const results = [];
            for (const mapping of mappings) {
                const { source_name, rule_name, input_value, output } = mapping;

                const result = await client.query(
                    `INSERT INTO mappings (source_name, rule_name, input_value, output)
                     VALUES ($1, $2, $3, $4)
                     ON CONFLICT (source_name, rule_name, input_value)
                     DO UPDATE SET output = EXCLUDED.output
                     RETURNING *`,
                    [source_name, rule_name, JSON.stringify(input_value), JSON.stringify(output)]
                );

                results.push(result.rows[0]);
            }

            await client.query('COMMIT');
            res.status(201).json({ count: results.length, mappings: results });
        } catch (err) {
            await client.query('ROLLBACK');
            next(err);
        } finally {
            client.release();
        }
    });

    // Update mapping
    router.put('/:id', async (req, res, next) => {
        try {
            const { input_value, output } = req.body;

            const result = await pool.query(
                `UPDATE mappings
                 SET input_value = COALESCE($2, input_value),
                     output = COALESCE($3, output)
                 WHERE id = $1
                 RETURNING *`,
                [req.params.id, input_value, output ? JSON.stringify(output) : null]
            );

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

            res.json(result.rows[0]);
        } catch (err) {
            next(err);
        }
    });

    // Delete mapping
    router.delete('/:id', async (req, res, next) => {
        try {
            const result = await pool.query(
                'DELETE FROM mappings WHERE id = $1 RETURNING id',
                [req.params.id]
            );

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

            res.json({ success: true, deleted: result.rows[0].id });
        } catch (err) {
            next(err);
        }
    });

    return router;
};