const path = require('path');
const fs = require('fs');
const get = require('simple-get');
const pump = require('pump');
const tfs = require('tar-fs');
const zlib = require('zlib');
const util = require('./util');
const error = require('./error');
const proxy = require('./proxy');
const mkdirp = require('mkdirp-classic');

function downloadPrebuild(downloadUrl, opts, cb) {
  let cachedPrebuild = util.cachedPrebuild(downloadUrl);
  const localPrebuild = util.localPrebuild(downloadUrl, opts);
  const tempFile = util.tempFile(cachedPrebuild);
  const log = opts.log || util.noopLogger;

  if (opts.nolocal) return download();

  log.info('looking for local prebuild @', localPrebuild);
  fs.access(localPrebuild, fs.R_OK | fs.W_OK, function (err) {
    if (err && err.code === 'ENOENT') {
      return download();
    }

    log.info('found local prebuild');
    cachedPrebuild = localPrebuild;
    unpack();
  });

  function download() {
    ensureNpmCacheDir(function (err) {
      if (err) return onerror(err);

      log.info('looking for cached prebuild @', cachedPrebuild);
      fs.access(cachedPrebuild, fs.R_OK | fs.W_OK, function (err) {
        if (!(err && err.code === 'ENOENT')) {
          log.info('found cached prebuild');
          return unpack();
        }

        log.http('request', 'GET ' + downloadUrl);
        const reqOpts = proxy({ url: downloadUrl }, opts);

        if (opts.token) {
          reqOpts.headers = {
            'User-Agent': 'simple-get',
            Accept: 'application/octet-stream',
            Authorization: 'token ' + opts.token,
          };
        }

        const req = get(reqOpts, function (err, res) {
          if (err) return onerror(err);
          log.http(res.statusCode, downloadUrl);
          if (res.statusCode !== 200) return onerror();
          mkdirp(util.prebuildCache(), function () {
            log.info('downloading to @', tempFile);
            pump(res, fs.createWriteStream(tempFile), function (err) {
              if (err) return onerror(err);
              fs.rename(tempFile, cachedPrebuild, function (err) {
                if (err) return cb(err);
                log.info('renaming to @', cachedPrebuild);
                unpack();
              });
            });
          });
        });

        req.setTimeout(30 * 1000, function () {
          req.abort();
        });
      });

      function onerror(err) {
        fs.unlink(tempFile, function () {
          cb(err || error.noPrebuilts(opts));
        });
      }
    });
  }

  function unpack() {
    let binaryName;

    const updateName =
      opts.updateName ||
      function (entry) {
        if (/\.node$/i.test(entry.name)) binaryName = entry.name;
      };

    log.info('unpacking @', cachedPrebuild);

    const options = {
      readable: true,
      writable: true,
      hardlinkAsFilesFallback: true,
    };
    const extract = tfs.extract(opts.path, options).on('entry', updateName);

    pump(
      fs.createReadStream(cachedPrebuild),
      zlib.createGunzip(),
      extract,
      function (err) {
        if (err) return cb(err);

        let resolved;
        if (binaryName) {
          try {
            resolved = path.resolve(opts.path || '.', binaryName);
          } catch (err) {
            return cb(err);
          }
          log.info('unpack', 'resolved to ' + resolved);

          if (
            opts.runtime === 'node' &&
            opts.platform === process.platform &&
            opts.abi === process.versions.modules &&
            opts.arch === process.arch
          ) {
            try {
              require(resolved);
            } catch (err) {
              return cb(err);
            }
            log.info('unpack', 'required ' + resolved + ' successfully');
          }
        }

        cb(null, resolved);
      }
    );
  }

  function ensureNpmCacheDir(cb) {
    const cacheFolder = util.npmCache();
    fs.access(cacheFolder, fs.R_OK | fs.W_OK, function (err) {
      if (err && err.code === 'ENOENT') {
        return makeNpmCacheDir();
      }
      cb(err);
    });

    function makeNpmCacheDir() {
      log.info('npm cache directory missing, creating it...');
      mkdirp(cacheFolder, cb);
    }
  }
}

module.exports = downloadPrebuild;