import * as http from 'http';
import * as os from 'os';
import * as nodePath from 'path';
import checkLocalCache from './funcs/checkLocalCache';
import createDirRecursively from './funcs/createDirRecursively';
import saveResponse from './funcs/saveResponse';

/** Downloads the given URL and saves it to disk. Throws error if download fails. */
export default function downloadUrlContents({ host, path, size }: {host: string, path: string, size: number}): Promise<string> {
  return new Promise((resolve, reject) => {
    //Generate file name we want to save it under
    //e.g. on Linux: /tmp/patcher/patch/assets_swtor_main/assets_swtor_main_-1to0/assets_swtor_main_-1to0.zip
    const tempFileName = nodePath.join(os.tmpdir(), 'patcher', host, path);

    //Create parent directory recursively
    const folderName = nodePath.dirname(tempFileName);
    createDirRecursively(folderName).then(() => {
      //Check if file already exists locally
      checkLocalCache(tempFileName, size).then((cacheStatus) => {
        if (cacheStatus) {
          return resolve(tempFileName);
        }

        //Create HTTP request
        const request = http.request({
          family: 4,
          hostname: host,
          path,
        }, saveResponse.bind(null, tempFileName, resolve, (reason: string) => { request.abort(); reject(reason); }));

        //In case of connection errors, exit early
        request.on('error', (error) => {
          request.abort();
          reject(error);
        });

        request.end();
      });
    });
  });
}