// Luna bus access.
//
// Talks to PalmServiceBridge directly rather than pulling in webOSTV.js: it is
// the same object webOSTV.js wraps, it is injected into every webOS app, and
// it means there is no third-party file to keep in sync.
//
// Opened in a desktop browser the bridge is absent, so everything falls back
// to a small mock. That is what makes the UI developable without a TV.

(function (global) {
  'use strict';

  var SERVICE = 'luna://org.webosbrew.audiocap.service/';
  var HBCHANNEL = 'luna://org.webosbrew.hbchannel.service/';

  var haveBridge = typeof global.PalmServiceBridge !== 'undefined';

  // A call in flight. `cancel()` tears down a subscription.
  function Request(bridge) {
    this.bridge = bridge;
    this.cancelled = false;
  }

  Request.prototype.cancel = function () {
    this.cancelled = true;
    if (this.bridge && this.bridge.cancel) {
      this.bridge.cancel();
    }
  };

  // Low-level call. `onReply` fires once per reply, so subscriptions keep
  // calling it until cancelled.
  function call(uri, params, onReply, onError) {
    if (!haveBridge) {
      return global.LunaMock.call(uri, params, onReply, onError);
    }

    var bridge = new global.PalmServiceBridge();
    var request = new Request(bridge);

    bridge.onservicecallback = function (raw) {
      if (request.cancelled) {
        return;
      }
      var reply;
      try {
        reply = JSON.parse(raw);
      } catch (e) {
        if (onError) {
          onError('Malformed reply from ' + uri);
        }
        return;
      }
      // Luna reports both its own failures and ours through returnValue.
      if (reply.returnValue === false) {
        if (onError) {
          onError(reply.errorText || reply.errorMessage || 'Call to ' + uri + ' failed');
        }
        return;
      }
      if (onReply) {
        onReply(reply);
      }
    };

    try {
      bridge.call(uri, JSON.stringify(params || {}));
    } catch (e) {
      if (onError) {
        onError(String(e));
      }
    }
    return request;
  }

  var Luna = {
    available: haveBridge,

    // --- our service -------------------------------------------------------
    start: function (patch, ok, fail) {
      return call(SERVICE + 'start', patch || {}, ok, fail);
    },
    stop: function (ok, fail) {
      return call(SERVICE + 'stop', {}, ok, fail);
    },
    subscribeStatus: function (ok, fail) {
      return call(SERVICE + 'getStatus', { subscribe: true }, ok, fail);
    },
    getConfig: function (ok, fail) {
      return call(SERVICE + 'getConfig', {}, ok, fail);
    },
    setConfig: function (patch, ok, fail) {
      return call(SERVICE + 'setConfig', { settings: patch }, ok, fail);
    },
    resetConfig: function (ok, fail) {
      return call(SERVICE + 'resetConfig', {}, ok, fail);
    },
    listBackends: function (ok, fail) {
      return call(SERVICE + 'listBackends', {}, ok, fail);
    },
    listSinks: function (ok, fail) {
      return call(SERVICE + 'listSinks', {}, ok, fail);
    },
    getDiagnostics: function (ok, fail) {
      return call(SERVICE + 'getDiagnostics', {}, ok, fail);
    },
    // Ends the service process. Any later call starts a fresh one, which is
    // how the service picks up new bus permissions after being elevated.
    quit: function (ok, fail) {
      return call(SERVICE + 'quit', {}, ok, fail);
    },
    // `clear` empties the ring buffer after reading it, so the reply is the
    // last thing anyone sees of those lines.
    getLogs: function (clear, ok, fail) {
      return call(SERVICE + 'getLogs', { clear: !!clear }, ok, fail);
    },

    // --- Homebrew Channel --------------------------------------------------
    // Used for the boot symlink. Needs the Homebrew Channel installed, which
    // it will be on any TV that can run this app.
    exec: function (command, ok, fail) {
      return call(HBCHANNEL + 'exec', { command: command }, ok, fail);
    },

    // --- system ------------------------------------------------------------
    getNetworkStatus: function (ok, fail) {
      return call('luna://com.palm.connectionmanager/getStatus', {}, ok, fail);
    },
  };

  global.Luna = Luna;
})(window);