var scenes = [
                 { sceneID: 0, projectID: 1, title: "First scene", sequenceNo: ko.observable(1) },
                 { sceneID: 1, projectID: 1, title: "Second scene", sequenceNo: ko.observable(2) },
                 { sceneID: 2, projectID: 1, title: "Third scene", sequenceNo: ko.observable(3) }
            ];

var texts = [
            { textID: 0, sceneID: ko.observable(0), projectID: 1, title: "Text A", sequenceNo: ko.observable(1) },
            { textID: 1, sceneID: ko.observable(null), projectID: 1, title: "Text B", sequenceNo: ko.observable(2) },
            { textID: 2, sceneID: ko.observable(null), projectID: 1, title: "Text C", sequenceNo: ko.observable(3) },
            { textID: 3, sceneID: ko.observable(2), projectID: 1, title: "Text D", sequenceNo: ko.observable(4) },
            { textID: 4, sceneID: ko.observable(null), projectID: 1, title: "Text E", sequenceNo: ko.observable(5) },
            { textID: 5, sceneID: ko.observable(2), projectID: 1, title: "Text F", sequenceNo: ko.observable(6) },
            { textID: 6, sceneID: ko.observable(1), projectID: 1, title: "Text G", sequenceNo: ko.observable(7) },
            { textID: 7, sceneID: ko.observable(1), projectID: 1, title: "Text H", sequenceNo: ko.observable(8) }
        ];
var u = ko.utils.unwrapObservable;
ko.observableArray.fn.filter = function (predicate) {
    var target = this;
    var computed = ko.computed(function () {
        return ko.utils.arrayFilter(target(), predicate);
    });
    var observableArray = new ko.observableArray(u(computed));
    computed.subscribe(function (newValue) { observableArray(newValue); });
    return observableArray;
};

function ViewModel(scenes, texts) {
        var self = this;
    var projectID = 1;

    this.selectedScene = ko.observable();

    self.allScenes = ko.observableArray(scenes);
    this.scenes = self.allScenes.filter(function (scene) {
            return scene.projectID == projectID;
        });

    self.allTexts = ko.observableArray(texts);
    self.texts = ko.computed(function () {
        return ko.utils.arrayFilter(self.allTexts(), function (text) {
            return text.projectID == projectID;
        });
    });


                this.selectedText = ko.observable();

    // seed the available texts
    //this.availableTexts = ko.observableArray(ko.utils.arrayFilter(this.texts(), function(text) {
    //    return text.sceneID() === null;
    //}));

   //this.availableTexts = ko.computed(function(){
   //       return ko.utils.arrayFilter(self.texts(), function(text) {
   //     return text.sceneID() === null;
   //   })
   //   });

    this.availableTexts = ko.computed({
        read: function(){
           return ko.utils.arrayFilter(self.texts(), function(text) {
           return text.sceneID() === null;
        })
      },
      write: function(value){
        return value;
      },
      owner: self
    });



    this.currentSceneTexts = ko.observableArray();
    this.currentSceneTexts = ko.computed(function(){
            var scene = self.selectedScene();

            if (!scene){
        return [];
        }
        else {
          return ko.utils.arrayFilter(self.texts(), function(text) {
                  return text.sceneID() === scene.sceneID;
          });
        }
    });


    // setup current texts when selected scene changes
    this.selectedScene.subscribe(function(scene) {
        //this.currentSceneTexts(ko.utils.arrayFilter(this.texts(), function(text) {
        //    return text.sceneID() === scene.sceneID;
        // }));
    }, this);

    // handle sequence #s
    function resetSequence(items) {
        var count = 0;
        ko.utils.arrayForEach(items, function(item) {
            item.sequenceNo(++count);
        });
    }

    function recalcSequence() {
        var count = 0;
        ko.utils.arrayForEach(self.scenes(),function(scene){
          var batches;

          if (scene === self.selectedScene()) {
            batches = self.currentSceneTexts();
          } else {
            batches = ko.utils.arrayFilter(self.texts(), function (t) {
                return t.sceneID() === scene.sceneID;
            });
          }

            ko.utils.arrayForEach(batches, function (batch) {
                batch.sequenceNo(count++);
          });
        });

        self.allTexts.sort(function(a,b) {
                return a.sequenceNo() - b.sequenceNo();
        });
     }

    this.scenes.subscribe(resetSequence);
    this.currentSceneTexts.subscribe(recalcSequence);
    this.availableTexts.subscribe(resetSequence);
                this.selectedText.subscribe(recalcSequence);

    // handle updated sceneID on a text (for use in afterMove)
    this.updateSceneID = function(sceneID, arg) {
        arg.item.sceneID(sceneID);
    }


    self.undoTextAllocation = function (field) {
            //alert("remove this!")
        field.sceneID(null);
    };
    self.addTextbatchToScene = function (data) {
        var scene = self.selectedScene();
        if (scene) {
            //alert("add this!")
            data.sceneID(scene.sceneID);
        }
        return false;
    };


}

ko.applyBindings(new ViewModel(scenes, texts));