/* 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";

/**
 * A base class from which all detail views inherit.
 */
let DetailsSubview = {
  /**
   * Sets up the view with event binding.
   */
  initialize: function () {
    this._onRecordingStoppedOrSelected = this._onRecordingStoppedOrSelected.bind(this);
    this._onOverviewRangeChange = this._onOverviewRangeChange.bind(this);
    this._onDetailsViewSelected = this._onDetailsViewSelected.bind(this);
    this._onPrefChanged = this._onPrefChanged.bind(this);

    PerformanceController.on(EVENTS.RECORDING_STOPPED, this._onRecordingStoppedOrSelected);
    PerformanceController.on(EVENTS.RECORDING_SELECTED, this._onRecordingStoppedOrSelected);
    PerformanceController.on(EVENTS.PREF_CHANGED, this._onPrefChanged);
    OverviewView.on(EVENTS.OVERVIEW_RANGE_SELECTED, this._onOverviewRangeChange);
    OverviewView.on(EVENTS.OVERVIEW_RANGE_CLEARED, this._onOverviewRangeChange);
    DetailsView.on(EVENTS.DETAILS_VIEW_SELECTED, this._onDetailsViewSelected);
  },

  /**
   * Unbinds events.
   */
  destroy: function () {
    clearNamedTimeout("range-change-debounce");

    PerformanceController.off(EVENTS.RECORDING_STOPPED, this._onRecordingStoppedOrSelected);
    PerformanceController.off(EVENTS.RECORDING_SELECTED, this._onRecordingStoppedOrSelected);
    PerformanceController.off(EVENTS.PREF_CHANGED, this._onPrefChanged);
    OverviewView.off(EVENTS.OVERVIEW_RANGE_SELECTED, this._onOverviewRangeChange);
    OverviewView.off(EVENTS.OVERVIEW_RANGE_CLEARED, this._onOverviewRangeChange);
    DetailsView.off(EVENTS.DETAILS_VIEW_SELECTED, this._onDetailsViewSelected);
  },

  /**
   * Amount of time (in milliseconds) to wait until this view gets updated,
   * when the range is changed in the overview.
   */
  rangeChangeDebounceTime: 0,

  /**
   * Flag specifying if this view should be updated when selected. This will
   * be set to true, for example, when the range changes in the overview and
   * this view is not currently visible.
   */
  shouldUpdateWhenShown: false,

  /**
   * Flag specifying if this view may get updated even when it's not selected.
   * Should only be used in tests.
   */
  canUpdateWhileHidden: false,

  /**
   * An array of preferences under `devtools.performance.ui.` that the view should
   * rerender and callback `this._onRerenderPrefChanged` upon change.
   */
  rerenderPrefs: [],

  /**
   * An array of preferences under `devtools.performance.` that the view should
   * observe and callback `this._onObservedPrefChange` upon change.
   */
  observedPrefs: [],

  /**
   * Called when recording stops or is selected.
   */
  _onRecordingStoppedOrSelected: function(_, recording) {
    if (!recording || recording.isRecording()) {
      return;
    }
    if (DetailsView.isViewSelected(this) || this.canUpdateWhileHidden) {
      this.render();
    } else {
      this.shouldUpdateWhenShown = true;
    }
  },

  /**
   * Fired when a range is selected or cleared in the OverviewView.
   */
  _onOverviewRangeChange: function (_, interval) {
    if (DetailsView.isViewSelected(this)) {
      let debounced = () => this.render(interval);
      setNamedTimeout("range-change-debounce", this.rangeChangeDebounceTime, debounced);
    } else {
      this.shouldUpdateWhenShown = true;
    }
  },

  /**
   * Fired when a view is selected in the DetailsView.
   */
  _onDetailsViewSelected: function() {
    if (DetailsView.isViewSelected(this) && this.shouldUpdateWhenShown) {
      this.render(OverviewView.getTimeInterval());
      this.shouldUpdateWhenShown = false;
    }
  },

  /**
   * Fired when a preference in `devtools.performance.ui.` is changed.
   */
  _onPrefChanged: function (_, prefName) {
    if (~this.observedPrefs.indexOf(prefName) && this._onObservedPrefChange) {
      this._onObservedPrefChange(_, prefName);
    }

    // All detail views require a recording to be complete, so do not
    // attempt to render if recording is in progress or does not exist.
    let recording = PerformanceController.getCurrentRecording();
    if (!recording || recording.isRecording()) {
      return;
    }

    if (!~this.rerenderPrefs.indexOf(prefName)) {
      return;
    }

    if (this._onRerenderPrefChanged) {
      this._onRerenderPrefChanged(_, prefName);
    }

    if (DetailsView.isViewSelected(this) || this.canUpdateWhileHidden) {
      this.render(OverviewView.getTimeInterval());
    } else {
      this.shouldUpdateWhenShown = true;
    }
  }
};

/**
 * Convenient way of emitting events from the view.
 */
EventEmitter.decorate(DetailsSubview);