/*
 * @Description: 框架服务跨域处理模块
 * @version: 1.0.0
 * @Company: saganlab
 * @Author: vcbear
 * @Date: 2022-08-24 19:01:06
 * @LastEditors: vcbear
 * @LastEditTime: 2022-08-24 21:22:28
 */

import { IncomingMessage } from 'http';
import vary from 'vary';
export default async (app) => {
  const corsConfig = app.config.cors;

  // 如果没有配置，默认不可以跨域
  if(!corsConfig) return;
  const cors = (options) => {
    const defaults = {
      allowMethods: 'GET,HEAD,PUT,POST,DELETE,PATCH',
    };

    options = {
      ...defaults,
      ...options,
    };

    // 设定Access-Control-Expose-Headers
    if (Array.isArray(options.exposeHeaders)) {
      options.exposeHeaders = options.exposeHeaders.join(',');
    }

    // 设定Access-Control-Allow-Methods
    if (Array.isArray(options.allowMethods)) {
      options.allowMethods = options.allowMethods.join(',');
    }

    // 设定Access-Control-Allow-Headers
    if (Array.isArray(options.allowHeaders)) {
      options.allowHeaders = options.allowHeaders.join(',');
    }

    // 设定Access-Control-Max-Age
    if (options.maxAge) {
      options.maxAge = String(options.maxAge);
    }

    options.keepHeadersOnError = options.keepHeadersOnError === undefined || !!options.keepHeadersOnError;

    return async function cors(ctx, next) {

      const requestOrigin = ctx.get('Origin');
      ctx.vary('Origin');

      if (!requestOrigin) return await next();

      let origin;
      if (typeof options.origin === 'function') {
        origin = options.origin(ctx);
        if (origin instanceof Promise) origin = await origin;
        if (!origin) return await next();
      } else {
        origin = options.origin || requestOrigin;
      }

      let credentials;
      if (typeof options.credentials === 'function') {
        credentials = options.credentials(ctx);
        if (credentials instanceof Promise) credentials = await credentials;
      } else {
        credentials = !!options.credentials;
      }

      const headersSet = {};

      function set(key, value) {
        ctx.set(key, value);
        headersSet[key] = value;
      }

      if (ctx.method !== 'OPTIONS') {
        set('Access-Control-Allow-Origin', origin);

        if (credentials === true) {
          set('Access-Control-Allow-Credentials', 'true');
        }

        if (options.exposeHeaders) {
          set('Access-Control-Expose-Headers', options.exposeHeaders);
        }

        if (!options.keepHeadersOnError) {
          return await next();
        }
        try {
          return await next();
        } catch (err) {
          const errHeadersSet = (err as IncomingMessage).headers || {};
          const varyWithOrigin = vary.append(errHeadersSet.vary || errHeadersSet.Vary || '', 'Origin');
          delete errHeadersSet.Vary;

          (err as IncomingMessage).headers = {
            ...errHeadersSet,
            ...headersSet,
            ...{ vary: varyWithOrigin },
          };
          throw err;
        }
      } else {
        if (!ctx.get('Access-Control-Request-Method')) {
          return await next();
        }

        ctx.set('Access-Control-Allow-Origin', origin);

        if (credentials === true) {
          ctx.set('Access-Control-Allow-Credentials', 'true');
        }

        if (options.maxAge) {
          ctx.set('Access-Control-Max-Age', options.maxAge);
        }

        if (options.allowMethods) {
          ctx.set('Access-Control-Allow-Methods', options.allowMethods);
        }

        let allowHeaders = options.allowHeaders;
        if (!allowHeaders) {
          allowHeaders = ctx.get('Access-Control-Request-Headers');
        }
        if (allowHeaders) {
          ctx.set('Access-Control-Allow-Headers', allowHeaders);
        }

        ctx.status = 204;
      }
    };
  };
  app.use(cors(corsConfig))
}