'use strict';

const http = require('node:http');
const path = require('node:path');
const fs = require('node:fs');

const api = new Map();

const apiPath = './api/';

const cacheFile = (name) => {
  const filePath = apiPath + name;
  const key = path.basename(filePath, '.js');
  try {
    const libPath = require.resolve(filePath);
    delete require.cache[libPath];
  } catch {
    return;
  }
  try {
    const method = require(filePath);
    api.set(key, method);
  } catch {
    api.delete(key);
  }
};

const cacheFolder = (path) => {
  fs.readdir(path, (err, files) => {
    if (err) return;
    files.forEach(cacheFile);
  });
};

const watch = (path) => {
  fs.watch(path, (event, file) => {
    cacheFile(file);
  });
};

cacheFolder(apiPath);
watch(apiPath);

setTimeout(() => {
  console.dir({ api });
}, 1000);

const receiveArgs = async (req) => {
  const buffers = [];
  for await (const chunk of req) buffers.push(chunk);
  const data = Buffer.concat(buffers).toString();
  return JSON.parse(data);
};

const httpError = (res, status, message) => {
  res.statusCode = status;
  res.end(`"${message}"`);
};

const controller = async (req, res) => {
  const url = req.url === '/' ? '/index.html' : req.url;
  const [first, second] = url.substring(1).split('/');
  if (first === 'api') {
    const method = api.get(second);
    const args = await receiveArgs(req);
    try {
      const result = await method(...args);
      if (!result) {
        httpError(res, 500, 'Server error');
        return;
      }
      res.end(JSON.stringify(result));
    } catch (err) {
      console.dir({ err });
      httpError(res, 500, 'Server error');
    }
  } else {
    const path = `./static/${first}`;
    try {
      const data = await fs.promises.readFile(path);
      res.end(data);
    } catch {
      httpError(res, 404, 'File is not found');
    }
  }
};

http.createServer(controller).listen(8000);