firebase-as-array.js

/*! Firebase.getAsArray - v0.1.0 - 2014-04-21
* Copyright (c) 2014 Kato
* MIT LICENSE */

(function(exports) {

  exports.getAsArray = function(ref, eventCallback) {
    return new ReadOnlySynchronizedArray(ref, eventCallback).getList();
  };

  function ReadOnlySynchronizedArray(ref, eventCallback) {
    this.list = [];
    this.subs = []; // used to track event listeners for dispose()
    this.ref = ref;
    this.eventCallback = eventCallback;
    this._wrapList();
    this._initListeners();
  }

  ReadOnlySynchronizedArray.prototype = {
    getList: function() {
      return this.list;
    },

    add: function(data) {
      var key = this.ref.push().key();
      var ref = this.ref.child(key);
      if( arguments.length > 0 ) { ref.set(parseForJson(data), this._handleErrors.bind(this, key)); }
      return ref;
    },

    set: function(key, newValue) {
      this.ref.child(key).set(parseForJson(newValue), this._handleErrors.bind(this, key));
    },

    update: function(key, newValue) {
      this.ref.child(key).update(parseForJson(newValue), this._handleErrors.bind(this, key));
    },

    setPriority: function(key, newPriority) {
      this.ref.child(key).setPriority(newPriority);
    },

    remove: function(key) {
      this.ref.child(key).remove(this._handleErrors.bind(null, key));
    },

    posByKey: function(key) {
      return findKeyPos(this.list, key);
    },

    placeRecord: function(key, prevId) {
      if( prevId === null ) {
        return 0;
      }
      else {
        var i = this.posByKey(prevId);
        if( i === -1 ) {
          return this.list.length;
        }
        else {
          return i+1;
        }
      }
    },

    getRecord: function(key) {
      var i = this.posByKey(key);
      if( i === -1 ) return null;
      return this.list[i];
    },

    dispose: function() {
      var ref = this.ref;
      this.subs.forEach(function(s) {
        ref.off(s[0], s[1]);
      });
      this.subs = [];
    },

    _serverAdd: function(snap, prevId) {
      var data = parseVal(snap.key(), snap.val());
      this._moveTo(snap.key(), data, prevId);
      this._handleEvent('child_added', snap.key(), data);
    },

    _serverRemove: function(snap) {
      var pos = this.posByKey(snap.key());
      if( pos !== -1 ) {
        this.list.splice(pos, 1);
        this._handleEvent('child_removed', snap.key(), this.list[pos]);
      }
    },

    _serverChange: function(snap) {
      var pos = this.posByKey(snap.key());
      if( pos !== -1 ) {
        this.list[pos] = applyToBase(this.list[pos], parseVal(snap.key(), snap.val()));
        this._handleEvent('child_changed', snap.key(), this.list[pos]);
      }
    },

    _serverMove: function(snap, prevId) {
      var id = snap.key();
      var oldPos = this.posByKey(id);
      if( oldPos !== -1 ) {
        var data = this.list[oldPos];
        this.list.splice(oldPos, 1);
        this._moveTo(id, data, prevId);
        this._handleEvent('child_moved', snap.key(), data);
      }
    },

    _moveTo: function(id, data, prevId) {
      var pos = this.placeRecord(id, prevId);
      this.list.splice(pos, 0, data);
    },

    _handleErrors: function(key, err) {
      if( err ) {
        this._handleEvent('error', null, key);
        console.error(err);
      }
    },

    _handleEvent: function(eventType, recordId, data) {
      // console.log(eventType, recordId);
      this.eventCallback && this.eventCallback(eventType, recordId, data);
    },

    _wrapList: function() {
      this.list.$indexOf = this.posByKey.bind(this);
      this.list.$add = this.add.bind(this);
      this.list.$remove = this.remove.bind(this);
      this.list.$set = this.set.bind(this);
      this.list.$update = this.update.bind(this);
      this.list.$move = this.setPriority.bind(this);
      this.list.$rawData = function(key) { return parseForJson(this.getRecord(key)) }.bind(this);
      this.list.$off = this.dispose.bind(this);
    },

    _initListeners: function() {
      this._monit('child_added', this._serverAdd);
      this._monit('child_removed', this._serverRemove);
      this._monit('child_changed', this._serverChange);
      this._monit('child_moved', this._serverMove);
    },

    _monit: function(event, method) {
      this.subs.push([event, this.ref.on(event, method.bind(this))]);
    }
  };

  function applyToBase(base, data) {
    // do not replace the reference to objects contained in the data
    // instead, just update their child values
    if( isObject(base) && isObject(data) ) {
      var key;
      for(key in base) {
        if( key !== '$id' && base.hasOwnProperty(key) && !data.hasOwnProperty(key) ) {
          delete base[key];
        }
      }
      for(key in data) {
        if( data.hasOwnProperty(key) ) {
          base[key] = data[key];
        }
      }
      return base;
    }
    else {
      return data;
    }
  }

  function isObject(x) {
    return typeof(x) === 'object' && x !== null;
  }

  function findKeyPos(list, key) {
    for(var i = 0, len = list.length; i < len; i++) {
      if( list[i].$id === key ) {
        return i;
      }
    }
    return -1;
  }

  function parseForJson(data) {
    if( data && typeof(data) === 'object' ) {
      delete data['$id'];
      if( data.hasOwnProperty('.value') ) {
        data = data['.value'];
      }
    }
    if( data === undefined ) {
      data = null;
    }
    return data;
  }

  function parseVal(id, data) {
    if( typeof(data) !== 'object' || !data ) {
      data = { '.value': data };
    }
    data['$id'] = id;
    return data;
  }
})(typeof(window)==='undefined'? exports : window.Firebase);