import { Request, Response, NextFunction } from 'express';

export class AppError extends Error {
  constructor(
    message: string,
    public readonly statusCode: number,
    public readonly code: string,
    public readonly isOperational = true,
  ) {
    super(message);
    this.name = this.constructor.name;
    Error.captureStackTrace(this, this.constructor);
  }
}

export class ValidationError extends AppError {
  constructor(message: string, public readonly details?: unknown) {
    super(message, 400, 'VALIDATION_ERROR');
  }
}

export class AuthenticationError extends AppError {
  constructor(message = 'Unauthorized') {
    super(message, 401, 'AUTHENTICATION_ERROR');
  }
}

export class ForbiddenError extends AppError {
  constructor(message = 'Forbidden') {
    super(message, 403, 'FORBIDDEN');
  }
}

export class NotFoundError extends AppError {
  constructor(resource: string) {
    super(`${resource} not found`, 404, 'NOT_FOUND');
  }
}

export class ConflictError extends AppError {
  constructor(message: string) {
    super(message, 409, 'CONFLICT');
  }
}

export class RateLimitError extends AppError {
  constructor() {
    super('Too many requests', 429, 'RATE_LIMIT');
  }
}

export function globalErrorHandler(
  err: Error,
  req: Request,
  res: Response,
  _next: NextFunction,
): void {
  const logger = (req as Request & { log?: { warn: Function; error: Function } }).log;

  if (err instanceof AppError && err.isOperational) {
    if (logger) {
      logger.warn({ err, statusCode: err.statusCode }, err.message);
    }
    const body: Record<string, unknown> = { error: err.message, code: err.code };
    if (err instanceof ValidationError && err.details !== undefined) {
      body['details'] = err.details;
    }
    res.status(err.statusCode).json(body);
    return;
  }

  if (logger) {
    logger.error({ err }, 'Unhandled error');
  } else {
    console.error('Unhandled error', err);
  }

  res.status(500).json({
    error: process.env['NODE_ENV'] === 'production' ? 'Internal server error' : err.message,
    code: 'INTERNAL_ERROR',
  });
}