const express = require("express");
const { join: joinPath } = require("path");
const homeDir = require("os").homedir();
const fs = require("fs/promises");
const sass = require("sass");

const FACTORIO_DATA_DIR = process.env["FACTORIO_DATA_DIR"] ?? `${homeDir}/.steam/steam/steamapps/common/Factorio/data`;

const exists = path => fs.stat(path).then(() => true, () => false);

const app = express();

app.use(express.json());

app.use(express.static("public"));

app.get("/data.json", (_req, res) => {
  res.sendFile(joinPath(__dirname, "build/data.json"));
});

app.get(/.*\.css$/, async (req, res) => {
  const strippedFilepath = joinPath("public", req.path.slice(0, -4));
  const isScss = await exists(strippedFilepath + ".scss");
  const isSass = await exists(strippedFilepath + ".sass");

  try {
    if (isScss) {
      res.type('css').send(sass.compile(strippedFilepath + ".scss").css);
      return;
    }

    if (isSass) {
      res.type('css').send(sass.compile(strippedFilepath + ".sass").css);
      return;
    }
  } catch(e) {
    console.error(e);
  }

  res.type('css').send("body { background: red; }");
});

app.get(/__.*__/, async (req, res) => {
  const [ , mod, path ] = /^\/__(.+?)__\/(.+)/.exec(req.path);
  const data = await fs.readFile(joinPath(FACTORIO_DATA_DIR, mod, path));
  res.type('png').send(data);
})

app.listen(
    Number(process.env["PORT"] ?? 8080),
    function () {
      return console.log(`listening on ${this.address().port}`);
    }
);