dataflow/api/routes/rules.js

/**
 * Rules Routes
 * Manage transformation rules
 */

const express = require('express');

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

    // List all rules for a source
    router.get('/source/:source_name', async (req, res, next) => {
        try {
            const result = await pool.query(
                'SELECT * FROM rules WHERE source_name = $1 ORDER BY sequence, name',
                [req.params.source_name]
            );
            res.json(result.rows);
        } catch (err) {
            next(err);
        }
    });

    // Preview an ad-hoc pattern against real records (no saved rule needed)
    router.get('/preview', async (req, res, next) => {
        try {
            const { source, field, pattern, flags, function_type = 'extract', replace_value = '', limit = 20 } = req.query;

            if (!source || !field || !pattern) {
                return res.status(400).json({ error: 'source, field, and pattern are required' });
            }

            const fullPattern = (flags ? `(?${flags})` : '') + pattern;

            const query = function_type === 'replace'
                ? `SELECT
                    id,
                    data->>$1 AS raw_value,
                    to_jsonb(regexp_replace(data->>$1, $2, $3)) AS extracted_value
                   FROM records
                   WHERE source_name = $4 AND data ? $1
                   ORDER BY id DESC LIMIT $5`
                : `SELECT
                    r.id,
                    r.data->>$1 AS raw_value,
                    CASE
                        WHEN m.match IS NULL THEN NULL
                        WHEN cardinality(m.match) = 1 THEN to_jsonb(m.match[1])
                        ELSE to_jsonb(m.match)
                    END AS extracted_value
                   FROM records r
                   CROSS JOIN LATERAL (SELECT regexp_match(r.data->>$1, $2) AS match) m
                   WHERE r.source_name = $3 AND r.data ? $1
                   ORDER BY r.id DESC LIMIT $4`;

            const params = function_type === 'replace'
                ? [field, fullPattern, replace_value, source, parseInt(limit)]
                : [field, fullPattern, source, parseInt(limit)];

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

    // Test a rule against real records
    router.get('/:id/test', async (req, res, next) => {
        try {
            const { limit = 20 } = req.query;

            const ruleResult = await pool.query(
                'SELECT * FROM rules WHERE id = $1',
                [req.params.id]
            );

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

            const rule = ruleResult.rows[0];

            const pattern = (rule.flags ? `(?${rule.flags})` : '') + rule.pattern;
            const result = await pool.query(
                `SELECT
                    r.id,
                    r.data->>$1 AS raw_value,
                    CASE
                        WHEN m.match IS NULL THEN NULL
                        WHEN cardinality(m.match) = 1 THEN to_jsonb(m.match[1])
                        ELSE to_jsonb(m.match)
                    END AS extracted_value
                 FROM records r
                 CROSS JOIN LATERAL (SELECT regexp_match(r.data->>$1, $2) AS match) m
                 WHERE r.source_name = $3
                   AND r.data ? $1
                 ORDER BY r.id DESC
                 LIMIT $4`,
                [rule.field, pattern, rule.source_name, parseInt(limit)]
            );

            res.json({
                rule: { id: rule.id, name: rule.name, field: rule.field, pattern: rule.pattern, output_field: rule.output_field },
                results: result.rows
            });
        } catch (err) {
            next(err);
        }
    });

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

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

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

    // Create rule
    router.post('/', async (req, res, next) => {
        try {
            const { source_name, name, field, pattern, output_field, function_type, flags, replace_value, enabled, sequence } = req.body;

            if (!source_name || !name || !field || !pattern || !output_field) {
                return res.status(400).json({
                    error: 'Missing required fields: source_name, name, field, pattern, output_field'
                });
            }

            if (function_type && !['extract', 'replace'].includes(function_type)) {
                return res.status(400).json({ error: 'function_type must be "extract" or "replace"' });
            }

            const result = await pool.query(
                `INSERT INTO rules (source_name, name, field, pattern, output_field, function_type, flags, replace_value, enabled, sequence)
                 VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)
                 RETURNING *`,
                [source_name, name, field, pattern, output_field, function_type || 'extract', flags || '', replace_value || '', enabled !== false, sequence || 0]
            );

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

    // Update rule
    router.put('/:id', async (req, res, next) => {
        try {
            const { name, field, pattern, output_field, function_type, flags, replace_value, enabled, sequence } = req.body;

            if (function_type && !['extract', 'replace'].includes(function_type)) {
                return res.status(400).json({ error: 'function_type must be "extract" or "replace"' });
            }

            const result = await pool.query(
                `UPDATE rules
                 SET name = COALESCE($2, name),
                     field = COALESCE($3, field),
                     pattern = COALESCE($4, pattern),
                     output_field = COALESCE($5, output_field),
                     function_type = COALESCE($6, function_type),
                     flags = COALESCE($7, flags),
                     replace_value = COALESCE($8, replace_value),
                     enabled = COALESCE($9, enabled),
                     sequence = COALESCE($10, sequence)
                 WHERE id = $1
                 RETURNING *`,
                [req.params.id, name, field, pattern, output_field, function_type, flags, replace_value, enabled, sequence]
            );

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

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

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

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

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

    return router;
};