import {Request, Response, NextFunction} from "express";
import * as mm from "micromatch";

function getProxys(proxyMap: {[key: string]: any} | Array<{context: string[] | string}> | Function) {
  if (typeof proxyMap === "function") {
    proxyMap = proxyMap();
  }
  if (Array.isArray(proxyMap)) {
    proxyMap = proxyMap.reduce((pre, cur) => {
      const url = cur.context;
      if (typeof url === "string") {
        pre[url] = true;
      } else {
        for (const key of url) {
          pre[key] = true;
        }
      }
      return pre;
    }, {});
  }
  return Object.keys(proxyMap);
}

export default function middleware(htmlTpl: string, mainModule: {default: (path: string) => Promise<{ssrInitStoreKey: string; data: any; html: string}>}, proxyMap: {[key: string]: any} | Array<{context: string[] | string}> | Function = {}) {
  const passUrls = getProxys(proxyMap);
  const arr = htmlTpl.match(/<!--\s*{react-coat-init-env}\s*-->\s*<script>\s*function\s+(\w+)\s*\(([^)]+)\)[^{]+{([\s\S]+)}\s*<\/script>/m);
  global[arr![1]] = new Function(arr![2], arr![3]);
  const htmlChunks = htmlTpl.split(/<!--\s*{react-coat-response-chunk}\s*-->/);
  return (req: Request, res: Response, next: NextFunction) => {
    if (passUrls.some(reg => mm.isMatch(req.url, reg))) {
      next();
    } else {
      const errorHandler = (err: any) => {
        if (err.code === "301" || err.code === "302") {
          if (res.headersSent) {
            res.write(`<a data-type="${parseInt(err.code, 10)}" href="${err.detail}">跳转中。。。</a></body><script>window.location.href="${err.detail}"</script></html>`);
            res.end();
          } else {
            res.redirect(parseInt(err.code, 10), err.detail);
          }
        } else {
          console.error(err);
          if (res.headersSent) {
            res.write(`<h1 style="font-size:16px;top:0;left:0;position:fixed;z-index:999999;color:red">${err.message || "服务器错误！"}</h1></body></html>`);
            res.end();
          } else {
            res.send(err.message || "服务器错误！");
          }
        }
      };
      if (htmlChunks[1]) {
        res.write(htmlChunks[0]);
      }
      try {
        mainModule
          .default(req.url)
          .then(result => {
            const {ssrInitStoreKey, data, html} = result;
            if (res.headersSent) {
              res.write(htmlChunks[1].replace(/[^>]*<!--\s*{react-coat-html}\s*-->[^<]*/m, `${html}`).replace(/<!--\s*{react-coat-script}\s*-->/, `<script>window.${ssrInitStoreKey} = ${JSON.stringify(data)};</script>`));
              res.end();
            } else {
              res.send(htmlChunks[0].replace(/[^>]*<!--\s*{react-coat-html}\s*-->[^<]*/m, `${html}`).replace(/<!--\s*{react-coat-script}\s*-->/, `<script>window.${ssrInitStoreKey} = ${JSON.stringify(data)};</script>`));
            }
          })
          .catch(errorHandler);
      } catch (err) {
        errorHandler(err);
      }
    }
  };
}