import { Request, Response, NextFunction } from "express";
import { GenerateImageResponse } from "../types/api";

/**
 * Global error handler for the Express application
 */
export const errorHandler = (
  error: Error,
  req: Request,
  res: Response,
  next: NextFunction,
) => {
  const timestamp = new Date().toISOString();
  const requestId = req.requestId || "unknown";

  // Log the error
  console.error(`[${timestamp}] [${requestId}] ERROR:`, {
    message: error.message,
    stack: error.stack,
    path: req.path,
    method: req.method,
    body: req.body,
    query: req.query,
  });

  // Don't send error response if headers already sent
  if (res.headersSent) {
    return next(error);
  }

  // Determine error type and status code
  let statusCode = 500;
  let errorMessage = "Internal server error";
  let errorType = "INTERNAL_ERROR";

  if (error.name === "ValidationError") {
    statusCode = 400;
    errorMessage = error.message;
    errorType = "VALIDATION_ERROR";
  } else if (
    error.message.includes("API key") ||
    error.message.includes("authentication")
  ) {
    statusCode = 401;
    errorMessage = "Authentication failed";
    errorType = "AUTH_ERROR";
  } else if (
    error.message.includes("not found") ||
    error.message.includes("404")
  ) {
    statusCode = 404;
    errorMessage = "Resource not found";
    errorType = "NOT_FOUND";
  } else if (
    error.message.includes("timeout") ||
    error.message.includes("503")
  ) {
    statusCode = 503;
    errorMessage = "Service temporarily unavailable";
    errorType = "SERVICE_UNAVAILABLE";
  } else if (
    error.message.includes("overloaded") ||
    error.message.includes("rate limit")
  ) {
    statusCode = 429;
    errorMessage = "Service overloaded, please try again later";
    errorType = "RATE_LIMITED";
  }

  // Create error response
  const errorResponse: GenerateImageResponse = {
    success: false,
    message: "Request failed",
    error: errorMessage,
  };

  // Add additional debug info in development
  if (process.env["NODE_ENV"] === "development") {
    (errorResponse as any).debug = {
      originalError: error.message,
      errorType,
      requestId,
      timestamp,
    };
  }

  console.log(
    `[${timestamp}] [${requestId}] Sending error response: ${statusCode} - ${errorMessage}`,
  );

  res.status(statusCode).json(errorResponse);
};

/**
 * 404 handler for unmatched routes
 */
export const notFoundHandler = (req: Request, res: Response) => {
  const timestamp = new Date().toISOString();
  const requestId = req.requestId || "unknown";

  console.log(
    `[${timestamp}] [${requestId}] 404 - Route not found: ${req.method} ${req.path}`,
  );

  const notFoundResponse: GenerateImageResponse = {
    success: false,
    message: "Route not found",
    error: `The requested endpoint ${req.method} ${req.path} does not exist`,
  };

  res.status(404).json(notFoundResponse);
};

/**
 * Async error wrapper to catch errors in async route handlers
 */
export const asyncHandler =
  (fn: Function) => (req: Request, res: Response, next: NextFunction) => {
    Promise.resolve(fn(req, res, next)).catch(next);
  };