"use strict";

var {classes: Cc, interfaces: Ci, utils: Cu} = Components;

Cu.import("resource://gre/modules/ExtensionUtils.jsm");
var {
  EventManager,
} = ExtensionUtils;

// WeakMap[Extension -> Map[name -> Alarm]]
var alarmsMap = new WeakMap();

// WeakMap[Extension -> Set[callback]]
var alarmCallbacksMap = new WeakMap();

// Manages an alarm created by the extension (alarms API).
function Alarm(extension, name, alarmInfo) {
  this.extension = extension;
  this.name = name;
  this.when = alarmInfo.when;
  this.delayInMinutes = alarmInfo.delayInMinutes;
  this.periodInMinutes = alarmInfo.periodInMinutes;
  this.canceled = false;

  let delay, scheduledTime;
  if (this.when) {
    scheduledTime = this.when;
    delay = this.when - Date.now();
  } else {
    if (!this.delayInMinutes) {
      this.delayInMinutes = this.periodInMinutes;
    }
    delay = this.delayInMinutes * 60 * 1000;
    scheduledTime = Date.now() + delay;
  }

  this.scheduledTime = scheduledTime;

  let timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
  timer.init(this, delay, Ci.nsITimer.TYPE_ONE_SHOT);
  this.timer = timer;
}

Alarm.prototype = {
  clear() {
    this.timer.cancel();
    alarmsMap.get(this.extension).delete(this.name);
    this.canceled = true;
  },

  observe(subject, topic, data) {
    if (this.canceled) {
      return;
    }

    for (let callback of alarmCallbacksMap.get(this.extension)) {
      callback(this);
    }

    if (!this.periodInMinutes) {
      this.clear();
      return;
    }

    let delay = this.periodInMinutes * 60 * 1000;
    this.scheduledTime = Date.now() + delay;
    this.timer.init(this, delay, Ci.nsITimer.TYPE_ONE_SHOT);
  },

  get data() {
    return {
      name: this.name,
      scheduledTime: this.scheduledTime,
      periodInMinutes: this.periodInMinutes,
    };
  },
};

/* eslint-disable mozilla/balanced-listeners */
extensions.on("startup", (type, extension) => {
  alarmsMap.set(extension, new Map());
  alarmCallbacksMap.set(extension, new Set());
});

extensions.on("shutdown", (type, extension) => {
  for (let alarm of alarmsMap.get(extension).values()) {
    alarm.clear();
  }
  alarmsMap.delete(extension);
  alarmCallbacksMap.delete(extension);
});
/* eslint-enable mozilla/balanced-listeners */

extensions.registerSchemaAPI("alarms", "alarms", (extension, context) => {
  return {
    alarms: {
      create: function(name, alarmInfo) {
        name = name || "";
        let alarms = alarmsMap.get(extension);
        if (alarms.has(name)) {
          alarms.get(name).clear();
        }
        let alarm = new Alarm(extension, name, alarmInfo);
        alarms.set(alarm.name, alarm);
      },

      get: function(name) {
        name = name || "";
        let alarms = alarmsMap.get(extension);
        if (alarms.has(name)) {
          return Promise.resolve(alarms.get(name).data);
        }
        return Promise.resolve();
      },

      getAll: function() {
        let result = Array.from(alarmsMap.get(extension).values(), alarm => alarm.data);
        return Promise.resolve(result);
      },

      clear: function(name) {
        name = name || "";
        let alarms = alarmsMap.get(extension);
        if (alarms.has(name)) {
          alarms.get(name).clear();
          return Promise.resolve(true);
        }
        return Promise.resolve(false);
      },

      clearAll: function() {
        let cleared = false;
        for (let alarm of alarmsMap.get(extension).values()) {
          alarm.clear();
          cleared = true;
        }
        return Promise.resolve(cleared);
      },

      onAlarm: new EventManager(context, "alarms.onAlarm", fire => {
        let callback = alarm => {
          fire(alarm.data);
        };

        alarmCallbacksMap.get(extension).add(callback);
        return () => {
          alarmCallbacksMap.get(extension).delete(callback);
        };
      }).api(),
    },
  };
});
