<?php
/**
 * Reads server-side application configuration without bundling secrets.
 * The deploy layout places a .env symlink beside backend/, outside public/.
 */
final class AppConfig
{
    private static $loaded = false;

    public static function loadEnvironment()
    {
        if (self::$loaded) {
            return;
        }

        $path = getenv('APP_ENV_FILE');
        if ($path === false || $path === '') {
            $path = dirname(__DIR__) . DIRECTORY_SEPARATOR . '.env';
        }

        if (!is_file($path) || !is_readable($path)) {
            throw new RuntimeException('Server environment file is missing or unreadable');
        }

        $lines = file($path, FILE_IGNORE_NEW_LINES);
        if ($lines === false) {
            throw new RuntimeException('Unable to read server environment file');
        }

        foreach ($lines as $lineNumber => $line) {
            $line = trim($line);
            if ($line === '' || $line[0] === '#') {
                continue;
            }

            if (!preg_match('/^([A-Z][A-Z0-9_]*)\s*=\s*(.*)$/', $line, $matches)) {
                throw new RuntimeException('Invalid environment entry on line ' . ($lineNumber + 1));
            }

            $name = $matches[1];
            $value = trim($matches[2]);
            if (strlen($value) >= 2) {
                $first = $value[0];
                $last = substr($value, -1);
                if (($first === '"' && $last === '"') || ($first === "'" && $last === "'")) {
                    $value = substr($value, 1, -1);
                }
            }

            // Explicit process environment values override the file.
            if (getenv($name) === false) {
                putenv($name . '=' . $value);
                $_ENV[$name] = $value;
            }
        }

        self::$loaded = true;
    }

    public static function required($name)
    {
        self::loadEnvironment();
        $value = getenv($name);
        if ($value === false || $value === '') {
            throw new RuntimeException('Required server setting is missing: ' . $name);
        }
        return $value;
    }

    public static function integer($name, $default)
    {
        self::loadEnvironment();
        $value = getenv($name);
        if ($value === false || $value === '') {
            return (int) $default;
        }

        $parsed = filter_var($value, FILTER_VALIDATE_INT);
        if ($parsed === false) {
            throw new RuntimeException('Server setting must be an integer: ' . $name);
        }
        return $parsed;
    }
}