(function () {
  'use strict';

  /** Orchestration default channel; stable is fallback for promoted releases. */
  var OTA_CHANNELS = ['staging', 'stable'];

  function setStatus(msg) {
    var el = document.getElementById('hub-download-apk-status');
    if (el) {
      el.textContent = msg;
    }
  }

  function fetchJson(url) {
    return fetch(url, { cache: 'no-store' }).then(function (r) {
      if (!r.ok) {
        throw new Error('HTTP ' + r.status + ' for ' + url);
      }
      return r.json();
    });
  }

  function resolveApkFromChannel(channelName) {
    return fetchJson('/v0/ota/channel/' + encodeURIComponent(channelName) + '.json')
      .then(function (channel) {
        var manifestUrl = channel && channel.manifestUrl;
        if (!manifestUrl) {
          throw new Error(channelName + ' missing manifestUrl');
        }
        return fetchJson(manifestUrl);
      })
      .then(function (manifest) {
        var url =
          (manifest && (manifest.browserApkUrl || manifest.apkUrl)) || '';
        if (!url) {
          throw new Error('manifest missing browserApkUrl/apkUrl');
        }
        if (!manifest.browserApkUrl && /\.otapkg(\?|$)/.test(url)) {
          url = url.replace(/\.otapkg(\?|$)/, '.apk$1');
        }
        var nameMatch = url.match(/\/([^/?#]+\.apk)(?:\?|$)/i);
        var filename = nameMatch ? nameMatch[1] : 'android_cast-latest.apk';
        return { url: url, filename: filename, channel: channelName };
      });
  }

  function resolveApkUrl() {
    var chain = Promise.reject(new Error('no channel'));
    OTA_CHANNELS.forEach(function (ch) {
      chain = chain.catch(function () {
        return resolveApkFromChannel(ch);
      });
    });
    return chain;
  }

  function triggerDownload(url, filename) {
    if (/\.apk(\?|$)/i.test(url)) {
      var a = document.createElement('a');
      a.href = url;
      a.download = filename;
      a.rel = 'noopener';
      document.body.appendChild(a);
      a.click();
      a.remove();
      return Promise.resolve();
    }
    return fetch(url, { cache: 'no-store' })
      .then(function (r) {
        if (!r.ok) {
          throw new Error('download HTTP ' + r.status);
        }
        return r.blob();
      })
      .then(function (blob) {
        var blobUrl = URL.createObjectURL(blob);
        var link = document.createElement('a');
        link.href = blobUrl;
        link.download = filename;
        link.rel = 'noopener';
        document.body.appendChild(link);
        link.click();
        link.remove();
        setTimeout(function () {
          URL.revokeObjectURL(blobUrl);
        }, 60000);
      });
  }

  function wireApkButton() {
    var btn = document.getElementById('hub-download-apk');
    if (!btn) {
      return;
    }
    btn.addEventListener('click', function () {
      btn.disabled = true;
      setStatus('Resolving OTA channel…');
      resolveApkUrl()
        .then(function (resolved) {
          setStatus('Downloading ' + resolved.filename + ' (' + resolved.channel + ')…');
          return triggerDownload(resolved.url, resolved.filename);
        })
        .catch(function (err) {
          setStatus(
            'APK unavailable — run builder with OTA publish (staging). ' +
              (err.message || err)
          );
        })
        .finally(function () {
          btn.disabled = false;
        });
    });
  }

  if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', wireApkButton);
  } else {
    wireApkButton();
  }
})();