<?php
/**
 * Authentication — App Key Validation
 */

require_once __DIR__ . '/../config.php';

class Auth
{
    /**
     * Validate the app_key from request.
     * Supports both Flutter app key and Caller device key.
     *
     * @param string|null $key      The key provided in request
     * @param string      $required Which key type is required: 'app' | 'device' | 'any'
     * @return bool
     */
    public static function validate(?string $key, string $required = 'any'): bool
    {
        if ($key === null || $key === '') {
            return false;
        }

        switch ($required) {
            case 'app':
                return hash_equals(APP_KEY, $key);
            case 'device':
                return hash_equals(DEVICE_KEY, $key);
            case 'any':
                return hash_equals(APP_KEY, $key) || hash_equals(DEVICE_KEY, $key);
            default:
                return false;
        }
    }

    /**
     * Extract app_key from request (header or body).
     */
    public static function getKeyFromRequest(): ?string
    {
        // Check header first
        $headerKey = $_SERVER['HTTP_X_APP_KEY']
            ?? $_SERVER['HTTP_APP_KEY']
            ?? null;

        if ($headerKey !== null) {
            return $headerKey;
        }

        // Check JSON body
        $body = json_decode(file_get_contents('php://input'), true);
        if (is_array($body) && isset($body['app_key'])) {
            return $body['app_key'];
        }

        // Check POST data
        if (isset($_POST['app_key'])) {
            return $_POST['app_key'];
        }

        return null;
    }

    /**
     * Require authentication — sends 401 and exits on failure.
     */
    public static function requireAuth(string $required = 'any'): void
    {
        $key = self::getKeyFromRequest();
        if (!self::validate($key, $required)) {
            http_response_code(401);
            header('Content-Type: application/json');
            echo json_encode([
                'success' => false,
                'message' => 'invalid_app_key',
            ]);
            exit;
        }
    }

    /**
     * Determine if the provided key is the device key.
     */
    public static function isDeviceKey(?string $key): bool
    {
        return $key !== null && hash_equals(DEVICE_KEY, $key);
    }

    /**
     * Determine if the provided key is the app key.
     */
    public static function isAppKey(?string $key): bool
    {
        return $key !== null && hash_equals(APP_KEY, $key);
    }
}