import { query } from './db.js';
import { normalizeRut } from './util.js';

// Extract a 6-char uppercase alphanumeric code from transfer description
function extractCode(description) {
  if (!description) return null;
  const m = description.toUpperCase().match(/\b([A-Z0-9]{6})\b/);
  return m ? m[1] : null;
}

/**
 * Try to match an inbound payment against a pending intent.
 * Returns { intent, confidence } or null.
 *
 * Priority:
 *   1. Reference code in description — strongest signal, unambiguous
 *   2. Exact amount + sender RUT — reliable when RUT is available
 *   3. Exact amount only (same account) — weaker, flagged as 'amount_only'
 */
export async function matchInbound(inbound) {
  // 1. Reference code
  const code = extractCode(inbound.description);
  if (code) {
    const { rows } = await query(
      `SELECT * FROM payment_intents WHERE reference_code = $1 AND status = 'pending'`,
      [code]
    );
    if (rows[0]) return { intent: rows[0], confidence: 'reference_code' };
  }

  // 2. Exact amount + sender RUT
  const senderRut = normalizeRut(inbound.sender_rut);
  if (senderRut) {
    const { rows } = await query(
      `SELECT * FROM payment_intents
       WHERE exact_amount = $1
         AND status = 'pending'
         AND (
           sender_rut IS NULL
           OR replace(lower(sender_rut), '.', '') = $2
         )
         AND ($3::text IS NULL OR account_id = $3)`,
      [inbound.amount, senderRut, inbound.account_id ?? null]
    );
    if (rows[0]) return { intent: rows[0], confidence: 'exact_amount_rut' };
  }

  // 3. Exact amount on same account (weakest — no RUT confirmation)
  if (inbound.account_id) {
    const { rows } = await query(
      `SELECT * FROM payment_intents
       WHERE exact_amount = $1 AND account_id = $2 AND status = 'pending'`,
      [inbound.amount, inbound.account_id]
    );
    if (rows[0]) return { intent: rows[0], confidence: 'amount_only' };
  }

  return null;
}