/* 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/. */

const {interfaces: Ci, utils: Cu} = Components;
Cu.import("resource://gre/modules/Services.jsm");
Cu.import("resource://gre/modules/XPCOMUtils.jsm");
Cu.importGlobalProperties(["fetch"]);

XPCOMUtils.defineLazyModuleGetter(this, "AppConstants",
  "resource://gre/modules/AppConstants.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "ClientID",
  "resource://gre/modules/ClientID.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "TelemetryEnvironment",
  "resource://gre/modules/TelemetryEnvironment.jsm");

const PREF_BRANCH = "browser.ping-centre.";

const TELEMETRY_PREF = `${PREF_BRANCH}telemetry`;
const LOGGING_PREF = `${PREF_BRANCH}log`;
const PRODUCTION_ENDPOINT_PREF = `${PREF_BRANCH}production.endpoint`;

const FHR_UPLOAD_ENABLED_PREF = "datareporting.healthreport.uploadEnabled";

/**
 * Observe various notifications and send them to a telemetry endpoint.
 *
 * @param {Object} options
 * @param {string} options.topic - a unique ID for users of PingCentre to distinguish
 *                  their data on the server side.
 * @param {string} options.overrideEndpointPref - optional pref for URL where the POST is sent.
 */
class PingCentre {
  constructor(options) {
    if (!options.topic) {
      throw new Error("Must specify topic.");
    }

    this._topic = options.topic;
    this._prefs = Services.prefs.getBranch("");

    this._setPingEndpoint(options.topic, options.overrideEndpointPref);

    this._enabled = this._prefs.getBoolPref(TELEMETRY_PREF);
    this._onTelemetryPrefChange = this._onTelemetryPrefChange.bind(this);
    this._prefs.addObserver(TELEMETRY_PREF, this._onTelemetryPrefChange);

    this._fhrEnabled = this._prefs.getBoolPref(FHR_UPLOAD_ENABLED_PREF);
    this._onFhrPrefChange = this._onFhrPrefChange.bind(this);
    this._prefs.addObserver(FHR_UPLOAD_ENABLED_PREF, this._onFhrPrefChange);

    this.logging = this._prefs.getBoolPref(LOGGING_PREF);
    this._onLoggingPrefChange = this._onLoggingPrefChange.bind(this);
    this._prefs.addObserver(LOGGING_PREF, this._onLoggingPrefChange);
  }

  /**
   * Lazily get the Telemetry id promise
   */
  get telemetryClientId() {
    Object.defineProperty(this, "telemetryClientId", {value: ClientID.getClientID()});
    return this.telemetryClientId;
  }

  get enabled() {
    return this._enabled && this._fhrEnabled;
  }

  _setPingEndpoint(topic, overrideEndpointPref) {
    const overrideValue = overrideEndpointPref &&
      this._prefs.getStringPref(overrideEndpointPref);
    if (overrideValue) {
      this._pingEndpoint = overrideValue;
    } else {
      this._pingEndpoint = this._prefs.getStringPref(PRODUCTION_ENDPOINT_PREF);
    }
  }

  _onLoggingPrefChange(aSubject, aTopic, prefKey) {
    this.logging = this._prefs.getBoolPref(prefKey);
  }

  _onTelemetryPrefChange(aSubject, aTopic, prefKey) {
    this._enabled = this._prefs.getBoolPref(prefKey);
  }

  _onFhrPrefChange(aSubject, aTopic, prefKey) {
    this._fhrEnabled = this._prefs.getBoolPref(prefKey);
  }

  _createExperimentsString(activeExperiments, filter) {
    let experimentsString = "";
    for (let experimentID in activeExperiments) {
      if (!activeExperiments[experimentID] ||
          !activeExperiments[experimentID].branch ||
          (filter && !experimentID.includes(filter))) {
        continue;
      }
      let expString = `${experimentID}:${activeExperiments[experimentID].branch}`;
      experimentsString = experimentsString.concat(`${expString};`);
    }
    return experimentsString;
  }

  async sendPing(data, options) {
    let filter = options && options.filter;
    let experiments = TelemetryEnvironment.getActiveExperiments();
    let experimentsString = this._createExperimentsString(experiments, filter);
    if (!this.enabled) {
      return Promise.resolve();
    }

    let clientID = data.client_id || await this.telemetryClientId;
    let locale = data.locale || Services.locale.getAppLocalesAsLangTags().pop();
    const payload = Object.assign({
      locale,
      topic: this._topic,
      client_id: clientID,
      version: AppConstants.MOZ_APP_VERSION,
      release_channel: AppConstants.MOZ_UPDATE_CHANNEL
    }, data);
    if (experimentsString) {
      payload.shield_id = experimentsString;
    }

    if (this.logging) {
      // performance related pings cause a lot of logging, so we mute them
      if (data.action !== "activity_stream_performance") {
        Services.console.logStringMessage(`TELEMETRY PING: ${JSON.stringify(payload)}\n`);
      }
    }

    return fetch(this._pingEndpoint, {method: "POST", body: JSON.stringify(payload)}).then(response => {
      if (!response.ok) {
        Cu.reportError(`Ping failure with HTTP response code: ${response.status}`);
      }
    }).catch(e => {
      Cu.reportError(`Ping failure with error: ${e}`);
    });
  }

  uninit() {
    try {
      this._prefs.removeObserver(TELEMETRY_PREF, this._onTelemetryPrefChange);
      this._prefs.removeObserver(LOGGING_PREF, this._onLoggingPrefChange);
      this._prefs.removeObserver(FHR_UPLOAD_ENABLED_PREF, this._onFhrPrefChange);
    } catch (e) {
      Cu.reportError(e);
    }
  }
}

this.PingCentre = PingCentre;
this.PingCentreConstants = {
  PRODUCTION_ENDPOINT_PREF,
  FHR_UPLOAD_ENABLED_PREF,
  TELEMETRY_PREF,
  LOGGING_PREF
};
this.EXPORTED_SYMBOLS = ["PingCentre", "PingCentreConstants"];