/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";

const { classes: Cc, interfaces: Ci, utils: Cu, results: Cr } = Components;

Cu.import("resource://gre/modules/Services.jsm");
Cu.import("resource://gre/modules/XPCOMUtils.jsm");
Cu.import("resource:///modules/devtools/ViewHelpers.jsm");
Cu.import("resource:///modules/devtools/gDevTools.jsm");

// Override DOM promises with Promise.jsm helpers
const { defer, all } = Cu.import("resource://gre/modules/Promise.jsm", {}).Promise;

const { Task } = Cu.import("resource://gre/modules/Task.jsm", {});
const require = Cu.import("resource://gre/modules/devtools/Loader.jsm", {}).devtools.require;
const EventEmitter = require("devtools/toolkit/event-emitter");
const STRINGS_URI = "chrome://browser/locale/devtools/webaudioeditor.properties"
const L10N = new ViewHelpers.L10N(STRINGS_URI);
const Telemetry = require("devtools/shared/telemetry");
const telemetry = new Telemetry();

let { console } = Cu.import("resource://gre/modules/devtools/Console.jsm", {});

// The panel's window global is an EventEmitter firing the following events:
const EVENTS = {
  // Fired when the first AudioNode has been created, signifying
  // that the AudioContext is being used and should be tracked via the editor.
  START_CONTEXT: "WebAudioEditor:StartContext",

  // On node creation, connect and disconnect.
  CREATE_NODE: "WebAudioEditor:CreateNode",
  CONNECT_NODE: "WebAudioEditor:ConnectNode",
  DISCONNECT_NODE: "WebAudioEditor:DisconnectNode",

  // When a node gets GC'd.
  DESTROY_NODE: "WebAudioEditor:DestroyNode",

  // On a node parameter's change.
  CHANGE_PARAM: "WebAudioEditor:ChangeParam",

  // When the devtools theme changes.
  THEME_CHANGE: "WebAudioEditor:ThemeChange",

  // When the UI is reset from tab navigation.
  UI_RESET: "WebAudioEditor:UIReset",

  // When a param has been changed via the UI and successfully
  // pushed via the actor to the raw audio node.
  UI_SET_PARAM: "WebAudioEditor:UISetParam",

  // When a node is to be set in the InspectorView.
  UI_SELECT_NODE: "WebAudioEditor:UISelectNode",

  // When the inspector is finished setting a new node.
  UI_INSPECTOR_NODE_SET: "WebAudioEditor:UIInspectorNodeSet",

  // When the inspector is finished rendering in or out of view.
  UI_INSPECTOR_TOGGLED: "WebAudioEditor:UIInspectorToggled",

  // When an audio node is finished loading in the Properties tab.
  UI_PROPERTIES_TAB_RENDERED: "WebAudioEditor:UIPropertiesTabRendered",

  // When the Audio Context graph finishes rendering.
  // Is called with two arguments, first representing number of nodes
  // rendered, second being the number of edge connections rendering (not counting
  // param edges), followed by the count of the param edges rendered.
  UI_GRAPH_RENDERED: "WebAudioEditor:UIGraphRendered"
};

/**
 * The current target and the Web Audio Editor front, set by this tool's host.
 */
let gToolbox, gTarget, gFront;

/**
 * Track an array of audio nodes
 */
let AudioNodes = [];
let AudioNodeConnections = new WeakMap(); // <AudioNodeView, Set<AudioNodeView>>
let AudioParamConnections = new WeakMap(); // <AudioNodeView, Object>

// Light representation wrapping an AudioNode actor with additional properties
function AudioNodeView (actor) {
  this.actor = actor;
  this.id = actor.actorID;
}

// A proxy for the underlying AudioNodeActor to fetch its type
// and subsequently assign the type to the instance.
AudioNodeView.prototype.getType = Task.async(function* () {
  this.type = yield this.actor.getType();
  return this.type;
});

// Helper method to create connections in the AudioNodeConnections
// WeakMap for rendering. Returns a boolean indicating
// if the connection was successfully created. Will return `false`
// when the connection was previously made.
AudioNodeView.prototype.connect = function (destination) {
  let connections = AudioNodeConnections.get(this) || new Set();
  AudioNodeConnections.set(this, connections);

  // Don't duplicate add.
  if (!connections.has(destination)) {
    connections.add(destination);
    return true;
  }
  return false;
};

// Helper method to create connections in the AudioNodeConnections
// WeakMap for rendering. Returns a boolean indicating
// if the connection was successfully created. Will return `false`
// when the connection was previously made.
AudioNodeView.prototype.connectParam = function (destination, param) {
  let connections = AudioParamConnections.get(this) || {};
  AudioParamConnections.set(this, connections);

  let params = connections[destination.id] = connections[destination.id] || [];

  if (!~params.indexOf(param)) {
    params.push(param);
    return true;
  }
  return false;
};

// Helper method to remove audio connections from the current AudioNodeView
AudioNodeView.prototype.disconnect = function () {
  AudioNodeConnections.set(this, new Set());
  AudioParamConnections.set(this, {});
};

// Returns a promise that resolves to an array of objects containing
// both a `param` name property and a `value` property.
AudioNodeView.prototype.getParams = function () {
  return this.actor.getParams();
};


/**
 * Initializes the web audio editor views
 */
function startupWebAudioEditor() {
  return all([
    WebAudioEditorController.initialize(),
    WebAudioGraphView.initialize(),
    WebAudioInspectorView.initialize(),
  ]);
}

/**
 * Destroys the web audio editor controller and views.
 */
function shutdownWebAudioEditor() {
  return all([
    WebAudioEditorController.destroy(),
    WebAudioGraphView.destroy(),
    WebAudioInspectorView.destroy(),
  ]);
}

/**
 * Functions handling target-related lifetime events.
 */
let WebAudioEditorController = {
  /**
   * Listen for events emitted by the current tab target.
   */
  initialize: function() {
    telemetry.toolOpened("webaudioeditor");
    this._onTabNavigated = this._onTabNavigated.bind(this);
    this._onThemeChange = this._onThemeChange.bind(this);
    gTarget.on("will-navigate", this._onTabNavigated);
    gTarget.on("navigate", this._onTabNavigated);
    gFront.on("start-context", this._onStartContext);
    gFront.on("create-node", this._onCreateNode);
    gFront.on("connect-node", this._onConnectNode);
    gFront.on("connect-param", this._onConnectParam);
    gFront.on("disconnect-node", this._onDisconnectNode);
    gFront.on("change-param", this._onChangeParam);
    gFront.on("destroy-node", this._onDestroyNode);

    // Hook into theme change so we can change
    // the graph's marker styling, since we can't do this
    // with CSS
    gDevTools.on("pref-changed", this._onThemeChange);

    // Set up events to refresh the Graph view
    window.on(EVENTS.CREATE_NODE, this._onUpdatedContext);
    window.on(EVENTS.CONNECT_NODE, this._onUpdatedContext);
    window.on(EVENTS.DISCONNECT_NODE, this._onUpdatedContext);
    window.on(EVENTS.DESTROY_NODE, this._onUpdatedContext);
    window.on(EVENTS.CONNECT_PARAM, this._onUpdatedContext);
  },

  /**
   * Remove events emitted by the current tab target.
   */
  destroy: function() {
    telemetry.toolClosed("webaudioeditor");
    gTarget.off("will-navigate", this._onTabNavigated);
    gTarget.off("navigate", this._onTabNavigated);
    gFront.off("start-context", this._onStartContext);
    gFront.off("create-node", this._onCreateNode);
    gFront.off("connect-node", this._onConnectNode);
    gFront.off("connect-param", this._onConnectParam);
    gFront.off("disconnect-node", this._onDisconnectNode);
    gFront.off("change-param", this._onChangeParam);
    gFront.off("destroy-node", this._onDestroyNode);
    window.off(EVENTS.CREATE_NODE, this._onUpdatedContext);
    window.off(EVENTS.CONNECT_NODE, this._onUpdatedContext);
    window.off(EVENTS.DISCONNECT_NODE, this._onUpdatedContext);
    window.off(EVENTS.DESTROY_NODE, this._onUpdatedContext);
    window.off(EVENTS.CONNECT_PARAM, this._onUpdatedContext);
    gDevTools.off("pref-changed", this._onThemeChange);
  },

  /**
   * Called when page is reloaded to show the reload notice and waiting
   * for an audio context notice.
   */
  reset: function () {
    $("#reload-notice").hidden = true;
    $("#waiting-notice").hidden = false;
    $("#content").hidden = true;
    WebAudioGraphView.resetUI();
    WebAudioInspectorView.resetUI();
  },

  /**
   * Called when a new audio node is created, or the audio context
   * routing changes.
   */
  _onUpdatedContext: function () {
    WebAudioGraphView.draw();
  },

  /**
   * Fired when the devtools theme changes (light, dark, etc.)
   * so that the graph can update marker styling, as that
   * cannot currently be done with CSS.
   */
  _onThemeChange: function (event, data) {
    window.emit(EVENTS.THEME_CHANGE, data.newValue);
  },

  /**
   * Called for each location change in the debugged tab.
   */
  _onTabNavigated: Task.async(function* (event) {
    switch (event) {
      case "will-navigate": {
        // Make sure the backend is prepared to handle audio contexts.
        yield gFront.setup({ reload: false });

        // Reset UI to show "Waiting for Audio Context..." and clear out
        // current UI.
        this.reset();

        // Clear out stored audio nodes
        AudioNodes.length = 0;
        AudioNodeConnections.clear();
        window.emit(EVENTS.UI_RESET);
        break;
      }
      case "navigate": {
        // TODO Case of bfcache, needs investigating
        // bug 994250
        break;
      }
    }
  }),

  /**
   * Called after the first audio node is created in an audio context,
   * signaling that the audio context is being used.
   */
  _onStartContext: function() {
    $("#reload-notice").hidden = true;
    $("#waiting-notice").hidden = true;
    $("#content").hidden = false;
    window.emit(EVENTS.START_CONTEXT);
  },

  /**
   * Called when a new node is created. Creates an `AudioNodeView` instance
   * for tracking throughout the editor.
   */
  _onCreateNode: Task.async(function* (nodeActor) {
    let node = new AudioNodeView(nodeActor);
    yield node.getType();
    AudioNodes.push(node);
    window.emit(EVENTS.CREATE_NODE, node.id);
  }),

  /**
   * Called on `destroy-node` when an AudioNode is GC'd. Removes
   * from the AudioNode array and fires an event indicating the removal.
   */
  _onDestroyNode: function (nodeActor) {
    for (let i = 0; i < AudioNodes.length; i++) {
      if (equalActors(AudioNodes[i].actor, nodeActor)) {
        AudioNodes.splice(i, 1);
        window.emit(EVENTS.DESTROY_NODE, nodeActor.actorID);
        break;
      }
    }
  },

  /**
   * Called when a node is connected to another node.
   */
  _onConnectNode: Task.async(function* ({ source: sourceActor, dest: destActor }) {
    let [source, dest] = yield waitForNodeCreation(sourceActor, destActor);

    // Connect nodes, and only emit if it's a new connection.
    if (source.connect(dest)) {
      window.emit(EVENTS.CONNECT_NODE, source.id, dest.id);
    }
  }),

  /**
   * Called when a node is conneceted to another node's AudioParam.
   */
  _onConnectParam: Task.async(function* ({ source: sourceActor, dest: destActor, param }) {
    let [source, dest] = yield waitForNodeCreation(sourceActor, destActor);

    if (source.connectParam(dest, param)) {
      window.emit(EVENTS.CONNECT_PARAM, source.id, dest.id, param);
    }
  }),

  /**
   * Called when a node is disconnected.
   */
  _onDisconnectNode: function(nodeActor) {
    let node = getViewNodeByActor(nodeActor);
    node.disconnect();
    window.emit(EVENTS.DISCONNECT_NODE, node.id);
  },

  /**
   * Called when a node param is changed.
   */
  _onChangeParam: function({ actor, param, value }) {
    window.emit(EVENTS.CHANGE_PARAM, getViewNodeByActor(actor), param, value);
  }
};

/**
 * Convenient way of emitting events from the panel window.
 */
EventEmitter.decorate(this);

/**
 * DOM query helper.
 */
function $(selector, target = document) { return target.querySelector(selector); }
function $$(selector, target = document) { return target.querySelectorAll(selector); }

/**
 * Compare `actorID` between two actors to determine if they're corresponding
 * to the same underlying actor.
 */
function equalActors (actor1, actor2) {
  return actor1.actorID === actor2.actorID;
}

/**
 * Returns the corresponding ViewNode by actor
 */
function getViewNodeByActor (actor) {
  for (let i = 0; i < AudioNodes.length; i++) {
    if (equalActors(AudioNodes[i].actor, actor))
      return AudioNodes[i];
  }
  return null;
}

/**
 * Returns the corresponding ViewNode by actorID
 */
function getViewNodeById (id) {
  return getViewNodeByActor({ actorID: id });
}

// Since node create and connect are probably executed back to back,
// and the controller's `_onCreateNode` needs to look up type,
// the edge creation could be called before the graph node is actually
// created. This way, we can check and listen for the event before
// adding an edge.
function waitForNodeCreation (sourceActor, destActor) {
  let deferred = defer();
  let eventName = EVENTS.CREATE_NODE;
  let source = getViewNodeByActor(sourceActor);
  let dest = getViewNodeByActor(destActor);

  if (!source || !dest)
    window.on(eventName, function createNodeListener (_, id) {
      let createdNode = getViewNodeById(id);
      if (equalActors(sourceActor, createdNode.actor))
        source = createdNode;
      if (equalActors(destActor, createdNode.actor))
        dest = createdNode;
      if (source && dest) {
        window.off(eventName, createNodeListener);
        deferred.resolve([source, dest]);
      }
    });
  else
    deferred.resolve([source, dest]);
  return deferred.promise;
}