/**
 * Sources Routes
 * Manage data sources
 */

const express = require('express');
const multer = require('multer');
const { parse } = require('csv-parse/sync');

const upload = multer({ storage: multer.memoryStorage() });

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

    // List all sources
    router.get('/', async (req, res, next) => {
        try {
            const result = await pool.query(
                'SELECT * FROM sources ORDER BY name'
            );
            res.json(result.rows);
        } catch (err) {
            next(err);
        }
    });

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

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

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

    // Suggest source definition from CSV
    router.post('/suggest', upload.single('file'), async (req, res, next) => {
        try {
            if (!req.file) {
                return res.status(400).json({ error: 'No file uploaded' });
            }

            const records = parse(req.file.buffer, {
                columns: true,
                skip_empty_lines: true,
                trim: true
            });

            if (records.length === 0) {
                return res.status(400).json({ error: 'CSV file is empty' });
            }

            const sample = records[0];
            const fields = Object.keys(sample).map(key => {
                const val = sample[key];
                let type = 'text';

                if (!isNaN(parseFloat(val)) && isFinite(val) && val.charAt(0) !== '0') {
                    type = 'numeric';
                } else if (Date.parse(val) > Date.parse('1950-01-01') && Date.parse(val) < Date.parse('2050-01-01')) {
                    type = 'date';
                }

                return { name: key, type };
            });

            res.json({
                name: '',
                dedup_fields: [],
                fields
            });
        } catch (err) {
            next(err);
        }
    });

    // Create source
    router.post('/', async (req, res, next) => {
        try {
            const { name, dedup_fields, config } = req.body;

            if (!name || !dedup_fields || !Array.isArray(dedup_fields)) {
                return res.status(400).json({
                    error: 'Missing required fields: name, dedup_fields (array)'
                });
            }

            const result = await pool.query(
                `INSERT INTO sources (name, dedup_fields, config)
                 VALUES ($1, $2, $3)
                 RETURNING *`,
                [name, dedup_fields, config || {}]
            );

            res.status(201).json(result.rows[0]);
        } catch (err) {
            if (err.code === '23505') {  // Unique violation
                return res.status(409).json({ error: 'Source already exists' });
            }
            next(err);
        }
    });

    // Update source
    router.put('/:name', async (req, res, next) => {
        try {
            const { dedup_fields, config } = req.body;

            const result = await pool.query(
                `UPDATE sources
                 SET dedup_fields = COALESCE($2, dedup_fields),
                     config = COALESCE($3, config),
                     updated_at = CURRENT_TIMESTAMP
                 WHERE name = $1
                 RETURNING *`,
                [req.params.name, dedup_fields, config]
            );

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

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

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

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

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

    // Import CSV data
    router.post('/:name/import', upload.single('file'), async (req, res, next) => {
        try {
            if (!req.file) {
                return res.status(400).json({ error: 'No file uploaded' });
            }

            // Parse CSV
            const records = parse(req.file.buffer, {
                columns: true,
                skip_empty_lines: true,
                trim: true
            });

            // Import records
            const result = await pool.query(
                'SELECT import_records($1, $2) as result',
                [req.params.name, JSON.stringify(records)]
            );

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

    // Get import log
    router.get('/:name/import-log', async (req, res, next) => {
        try {
            const result = await pool.query(
                `SELECT * FROM import_log
                 WHERE source_name = $1
                 ORDER BY imported_at DESC`,
                [req.params.name]
            );
            res.json(result.rows);
        } catch (err) {
            next(err);
        }
    });

    // Apply transformations
    router.post('/:name/transform', async (req, res, next) => {
        try {
            const result = await pool.query(
                'SELECT apply_transformations($1) as result',
                [req.params.name]
            );

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

    // Get all known field names for a source
    router.get('/:name/fields', async (req, res, next) => {
        try {
            const result = await pool.query(`
                SELECT key, array_agg(DISTINCT origin ORDER BY origin) AS origins
                FROM (
                    SELECT f->>'name' AS key, 'schema' AS origin
                    FROM sources, jsonb_array_elements(config->'fields') f
                    WHERE name = $1 AND config ? 'fields'
                    UNION ALL
                    SELECT jsonb_object_keys(data) AS key, 'raw' AS origin
                    FROM records WHERE source_name = $1
                    UNION ALL
                    SELECT output_field AS key, 'rule: ' || name AS origin
                    FROM rules WHERE source_name = $1
                    UNION ALL
                    SELECT jsonb_object_keys(output) AS key, 'mapping' AS origin
                    FROM mappings WHERE source_name = $1
                ) keys
                GROUP BY key
                ORDER BY key
            `, [req.params.name]);
            res.json(result.rows);
        } catch (err) {
            next(err);
        }
    });

    // Generate output view
    router.post('/:name/view', async (req, res, next) => {
        try {
            const result = await pool.query(
                'SELECT generate_source_view($1) as result',
                [req.params.name]
            );
            res.json(result.rows[0].result);
        } catch (err) {
            next(err);
        }
    });

    // Reprocess all records
    router.post('/:name/reprocess', async (req, res, next) => {
        try {
            const result = await pool.query(
                'SELECT reprocess_records($1) as result',
                [req.params.name]
            );

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

    // Get statistics
    router.get('/:name/stats', async (req, res, next) => {
        try {
            const result = await pool.query(
                `SELECT
                    COUNT(*) as total_records,
                    COUNT(*) FILTER (WHERE transformed IS NOT NULL) as transformed_records,
                    COUNT(*) FILTER (WHERE transformed IS NULL) as pending_records
                 FROM records
                 WHERE source_name = $1`,
                [req.params.name]
            );

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

    return router;
};