// services/sqlPool.js
// MSSQL connection pool(s) for all portal stores' direct-SQL access to SAP
// tables. ONE POOL PER DATABASE NAME — the SQL Server login (SQL_USER/
// SQL_PASSWORD) is a single server-level credential that can reach every SAP
// B1 company database on that server (unlike SAP Service Layer, where each
// company has its own OUSR table with its own per-company password — see
// [[per-company-sap-login]]), so only the DATABASE a pool points at needs to
// vary, not the credentials. getPool() with no argument keeps its original
// behavior (the .env SQL_DATABASE default) for 100% backward compat with
// every existing caller; pass a companyDB to get/create a pool for that
// specific database instead.
//
// Bug this fixes (2026-08-04): getPool() used to be a SINGLE global pool
// hardcoded to .env's SQL_DATABASE with no way to target any other company at
// all — every direct-SQL route (routes/sap.js's item/warehouse/etc. lookups,
// routes/workOrders.js, reports, dashboards, GST, general ledger…) silently
// queried the same one database regardless of which company a user selected
// or was restricted to. Using ConnectionPool directly (not the global
// sql.connect() singleton) avoids conflicts between concurrently-initialising
// pools for different databases.
'use strict';
const sql = require('mssql');

const _pools       = new Map();   // dbName → { pool, connecting, waiters }
const DEFAULT_DB   = process.env.SQL_DATABASE;

function buildConfig(database) {
  return {
    server:            process.env.SQL_SERVER_NAME || process.env.SQL_HOST,
    port:              parseInt(process.env.SQL_PORT) || 1433,
    user:              process.env.SQL_USER,
    password:          process.env.SQL_PASSWORD,
    database,
    connectionTimeout: 30000,
    requestTimeout:    60000,
    pool: { max: 10, min: 0, idleTimeoutMillis: 30000 },
    options: {
      encrypt:                true,
      trustServerCertificate: true,
      enableArithAbort:       true,
      // SQL Server 2017 on this host requires TLS 1.0.
      // Node.js 17+ disables TLS 1.0 by default — re-enable it for this pool.
      cryptoCredentialsDetails: { minVersion: 'TLSv1' },
    },
  };
}

async function getPool(companyDB) {
  const db = companyDB || DEFAULT_DB;
  let entry = _pools.get(db);
  if (!entry) { entry = { pool: null, connecting: false, waiters: [] }; _pools.set(db, entry); }

  // Return healthy pool immediately
  if (entry.pool && entry.pool.connected) return entry.pool;

  // Queue if already connecting
  if (entry.connecting) {
    return new Promise((resolve, reject) => entry.waiters.push({ resolve, reject }));
  }

  entry.connecting = true;
  try {
    const pool = new sql.ConnectionPool(buildConfig(db));

    // Reset on pool-level errors so the next caller reconnects
    pool.on('error', err => {
      console.error(`[SQL-POOL] Pool error (${db}) — resetting:`, err.message);
      entry.pool = null;
    });

    await pool.connect();
    entry.pool = pool;
    console.log(`[SQL-POOL] ✅ Connected  ${db} @ ${process.env.SQL_HOST}`);
    entry.waiters.forEach(w => w.resolve(entry.pool));
    return entry.pool;
  } catch (err) {
    entry.pool = null;
    console.error(`[SQL-POOL] ❌ Connection failed (${db}):`, err.message);
    entry.waiters.forEach(w => w.reject(err));
    throw err;
  } finally {
    entry.connecting = false;
    entry.waiters    = [];
  }
}

// Parameterised query helper — use ? as placeholder, works like the legacy per-store exec()
async function query(sqlText, params = [], companyDB) {
  const pool = await getPool(companyDB);
  const req  = pool.request();
  let i = 0;
  const text = sqlText.replace(/\?/g, () => {
    const name = `p${i}`;
    req.input(name, params[i]);
    i++;
    return `@${name}`;
  });
  const result = await req.query(text);
  return result.recordset || [];
}

module.exports = { getPool, query };