import { Request, Response, NextFunction } from 'express';
import { AppError, ValidationError } from '../errors';
import { logger } from './requestLogger';

/**
 * Global error handler middleware.
 * Catches all errors, logs unexpected ones with Pino, and returns safe JSON responses.
 * Must be registered AFTER all routes.
 */
export const errorHandler = (
    err: Error,
    req: Request,
    res: Response,
    _next: NextFunction
) => {
    if (err instanceof AppError) {
        return res.status(err.statusCode).json({
            status: 'error',
            message: err.message,
            ...(err instanceof ValidationError && err.errors ? { errors: err.errors } : {}),
        });
    }

    // Log unexpected errors
    logger.error({
        error: err.message,
        stack: err.stack,
        url: req.url,
        method: req.method,
    });

    // Don't leak error details in production
    const message =
        process.env.NODE_ENV === 'production'
            ? 'Internal server error'
            : err.message;

    res.status(500).json({
        status: 'error',
        message,
    });
};