<?php
/**
 * C-Relay-PG Admin — PDO database connection helper.
 *
 * Provides a singleton PDO connection to the relay's PostgreSQL database.
 * All admin pages use db() to get the connection.
 */

require_once __DIR__ . '/config.php';

function db(): PDO {
    static $pdo = null;
    if ($pdo === null) {
        $cfg = require __DIR__ . '/config.php';
        // Build DSN — supports both TCP (host=localhost) and Unix socket
        // (host=/var/run/postgresql). Omit password if empty (peer auth).
        $dsn = sprintf(
            'pgsql:host=%s;port=%d;dbname=%s;user=%s',
            $cfg['db_host'],
            $cfg['db_port'],
            $cfg['db_name'],
            $cfg['db_user']
        );
        if (!empty($cfg['db_password'])) {
            $dsn .= ';password=' . $cfg['db_password'];
        }
        try {
            $pdo = new PDO($dsn, null, null, [
                PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
                PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                PDO::ATTR_EMULATE_PREPARES   => false,
            ]);
        } catch (PDOException $e) {
            http_response_code(500);
            die('Database connection failed: ' . htmlspecialchars($e->getMessage()));
        }
    }
    return $pdo;
}

/** Get a config value from the admin config file. */
function cfg(string $key, $default = null) {
    static $cfg = null;
    if ($cfg === null) {
        $cfg = require __DIR__ . '/config.php';
    }
    return $cfg[$key] ?? $default;
}