import { Request, Response, NextFunction } from '../interfaces';
import { get, isArray, isEqual } from 'lodash';
import { response } from '../utils';

export default function(req: Request, res, next: NextFunction): void {
  if (get(this, 'options')) {
    const ips: string[] = get(this, 'options.cors.ips');
    const origins: string[] = get(this, 'options.cors.origins');
    const methods: string[] = get(this, 'options.cors.methods');
    const headers: string[] = get(this, 'options.cors.headers');
    const clientIP = req.connection.remoteAddress || req.headers['x-forwarded-for'];
    const clientMethod = req.method;
    let access: boolean = false;

    if (ips && isArray(ips)) {
      for (let i = 0, ip; ip = ips[i]; i++) {
        if (isEqual(ip, clientIP)) {
          access = true;
        }
      }
    }
    
    if (!access) return response(res, 403, null, { 
      message: `No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin '${get(req, 'headers.origin') || null}' is therefore not allowed access.`
    });

    if (origins && isArray(origins)) {
      for (let i = 0, origin; origin = origins[i]; i++) {
        if (req.headers.origin && req.headers.origin.indexOf(origin) > -1) {
          res.header('Access-Control-Allow-Origin', origin);
        }
      }
    }
    
    access = false;
    if (methods && isArray(methods)) {
      let string: string = '';

      for (let i = 0, method; method = methods[i]; i++) {
        if (isEqual(method, clientMethod)) access = true;

        if (i == (methods.length - 1)) {
          string += method;
        } else {
          string += `${method}, `;
        } 
      }

      res.header("Access-Control-Allow-Methods", string);
    }
    
    if (!access) return response(res, 403, null, { 
      message: `No 'Access-Control-Allow-Methods' header is present on the requested resource. Method '${clientMethod || null}' is therefore not allowed access.`
    });
    
    if (headers && isArray(headers)) {
      let string: string = '';

      for (let i = 0, header; header = headers[i]; i++) {
        if (i == (headers.length - 1)) {
          string += header;
        } else {
          string += `${header}, `;
        }
      }

      res.header("Access-Control-Allow-Headers", string);
    }

    res.header('Access-Control-Allow-Credentials', true);
  }

  next();
}