"use strict";

const express = require("express"),
  fs = require("fs"),
  url = require("url");

const router = express.Router();

/* List of filename extensions we know are "potential" file extensions for
* assets we don"t want to return "index.html" for */
const extensions = [
  "html", "js", "css", "eot", "gif", "ico", "jpeg", "jpg", "mp4",
  "md", "ttf", "txt", "woff", "woff2", "yml", "svg"
];

/* Build the extension match RegExp from the list of extensions */
const extensionMatch = new RegExp("^.*?(" + extensions.join("|") + ")$", "i");

/* To handle dynamic routes, we return index.html to every request that
 * gets this far -- so this needs to be the last route.
 *
 * However, that introduces site development problems when assets are
 * referenced which don't yet exist (due to bugs, or sequence of adds) --
 * the server would return HTML content instead of the 404.
 *
 * So, check to see if the requested path is for an asset with a recognized
 * file extension.
 *
 * If so, 404 because the asset isn't there. otherwise assume it is a
 * dynamic client side route and *then* return index.html.
 */
router.get("/*", function(req, res, next) {
  const parts = url.parse(req.url),
    basePath = req.app.get("basePath");

  /* If req.user isn't set yet (authentication hasn't happened) then
   * only allow / to be loaded--everything else chains to the next 
   * handler */
  if (!req.user && req.url != "/") {
    return next();
  }
  
  if (extensionMatch.exec(parts.pathname)) {
    return res.status(404).send({
      message: "File not found", 
      status: 404 
    });
  }

  let source;
  console.log(JSON.stringify(parts, null, 2));
  switch (parts.pathname) {
  case "/":
    source = "frontend/index.html";
    break;
  case "/identities":
    source = "./index.html";
    break;
  }

  if (source) {
    console.log("Returning " + source + " for " + req.url);
    /* Replace <script>'<base href="/BASEPATH/">';</script> in index.html with
     * the basePath */
    const index = fs.readFileSync(source, "utf8");

    return res.send(index.replace(
      /<script>'<base href="BASEPATH">';<\/script>/,
      "<base href='" + basePath + "'>"));
  }

  console.log("Page not found: " + req.url);
  return res.status(404).json({
    message: "Page not found",
    status: 404
  });
});

module.exports = router;