import { Request, Response, NextFunction } from 'express';
import { ZodSchema } from 'zod';
import { ApiResponse } from '@ehandyhire/shared';

export function paramId(value: string | string[]): string {
  return Array.isArray(value) ? value[0] : value;
}

export class AppError extends Error {
  statusCode: number;
  isOperational: boolean;

  constructor(message: string, statusCode = 400) {
    super(message);
    this.statusCode = statusCode;
    this.isOperational = true;
    Error.captureStackTrace(this, this.constructor);
  }
}

export function validate(schema: ZodSchema) {
  return (req: Request, _res: Response, next: NextFunction) => {
    try {
      schema.parse({
        body: req.body,
        query: req.query,
        params: req.params,
      });
      next();
    } catch (error: unknown) {
      next(error);
    }
  };
}

export function asyncHandler(
  fn: (req: Request, res: Response, next: NextFunction) => Promise<void>
) {
  return (req: Request, res: Response, next: NextFunction) => {
    Promise.resolve(fn(req, res, next)).catch(next);
  };
}

export function sendSuccess<T>(
  res: Response,
  data: T,
  message?: string,
  statusCode = 200,
  meta?: ApiResponse['meta']
) {
  const response: ApiResponse<T> = { success: true, data, message, meta };
  res.status(statusCode).json(response);
}

export function sendError(res: Response, message: string, statusCode = 400) {
  const response: ApiResponse = { success: false, error: message };
  res.status(statusCode).json(response);
}

export function getPagination(query: Record<string, unknown>) {
  const page = Math.max(1, parseInt(String(query.page || '1'), 10));
  const limit = Math.min(100, Math.max(1, parseInt(String(query.limit || '20'), 10)));
  const skip = (page - 1) * limit;
  return { page, limit, skip };
}

export function buildPaginationMeta(total: number, page: number, limit: number) {
  return {
    page,
    limit,
    total,
    totalPages: Math.ceil(total / limit),
  };
}