//----------------------------------------------------------------------------
//  Copyright (C) 2013  The IPython Development Team
//
//  Distributed under the terms of the BSD License.  The full license is in
//  the file COPYING, distributed as part of this software.
//----------------------------------------------------------------------------

//============================================================================
// WidgetModel, WidgetView, and WidgetManager
//============================================================================
/**
 * Base Widget classes
 * @module IPython
 * @namespace IPython
 * @submodule widget
 */


// require(['components/underscore/underscore-min.js',
//          'components/backbone/backbone-min.js'],

var IPython = (function (IPython) {
    "use strict";

    //-----------------------------------------------------------------------
    // WidgetModel class
    //-----------------------------------------------------------------------
    var WidgetModel = Backbone.Model.extend({});


    //-----------------------------------------------------------------------
    // WidgetView class
    //-----------------------------------------------------------------------
    var WidgetView = Backbone.View.extend({
        
        initialize: function() {
            this.model.on('change',this.refresh,this);
        },
        
        refresh: function() {
            this.update();
            
            if (this.model.css != undefined) {
                for (var selector in this.model.css) {
                    if (this.model.css.hasOwnProperty(selector)) {
                        
                        // Get the elements via the css selector.  If the selector is
                        // blank, assume the current element is the target.
                        var elements = this.$el.find(selector);
                        if (selector=='') {
                            elements = this.$el;
                        }
                        
                        // Apply the css traits to all elements that match the selector.
                        if (elements.length>0){
                            var css_traits = this.model.css[selector];    
                            for (var css_key in css_traits) {
                                if (css_traits.hasOwnProperty(css_key)) {
                                    elements.css(css_key, css_traits[css_key]);
                                }
                            }
                        }
                    }
                }
            }
        },
    });


    //-----------------------------------------------------------------------
    // WidgetManager class
    //-----------------------------------------------------------------------
    // Public constructor
    var WidgetManager = function(comm_manager){
        this.comm_manager = comm_manager;
        this.widget_model_types = {};
        this.widget_view_types = {};
        this.model_widget_views = {};
        
        var that = this;
        Backbone.sync = function(method, model, options, error) {
            var result = that.send_sync(method, model);
            if (options.success) {
              options.success(result);
            }
        }; 
    }

    // Register a widget model type.
    WidgetManager.prototype.register_widget_model = function (widget_model_name, widget_model_type) {
        
        // Register the widget with the comm manager.  Make sure to pass this object's context
        // in so `this` works in the call back.
        this.comm_manager.register_target(widget_model_name, $.proxy(this.handle_com_open, this));
        
        // Register the types of the model and view correspong to this widget type.  Later
        // the widget manager will initialize these when the comm is opened.
        this.widget_model_types[widget_model_name] = widget_model_type;
    }

    // Register a widget view type.
    WidgetManager.prototype.register_widget_view = function (widget_view_name, widget_view_type) {
        this.widget_view_types[widget_view_name] = widget_view_type;
    }

    // Handle when a comm is opened.
    WidgetManager.prototype.handle_com_open = function (comm, msg) {
        var widget_type_name = msg.content.target_name;
        
        // Create the corresponding widget model.
        var widget_model = new this.widget_model_types[widget_type_name];
        
        // Remember comm associated with the model.
        widget_model.comm = comm;
        comm.model = widget_model;
        
        // Create an array to remember the views associated with the model.
        widget_model.views = [];
        
        // Add a handle to delete the control when the comm is closed.
        var that = this;
        var handle_close = function(msg) {
            that.handle_comm_closed(comm, msg);
        }
        comm.on_close(handle_close);
        
        // Handle incomming messages.
        var handle_msg = function(msg) {
            that.handle_comm_msg(comm, msg);
        }
        comm.on_msg(handle_msg);
    }

    // Create view that represents the model.
    WidgetManager.prototype.show_view = function (widget_area, widget_model, widget_view_name) {
        var widget_view = new this.widget_view_types[widget_view_name]({model: widget_model});
        widget_view.render();
        widget_model.views.push(widget_view);
        
        // Add the view's element to cell's widget div.
        widget_area
            .append($("<div />").append(widget_view.$el));   
        
        // Update the view based on the model contents.
        widget_view.refresh();
    }

    // Handle incomming comm msg.
    WidgetManager.prototype.handle_comm_msg = function (comm, msg) {
        // Different logic for different methods.
        var method = msg.content.data.method;
        switch (method){
            case 'show':
                
                // TODO: Get cell from registered output handler.
                var cell = IPython.notebook.get_cell(IPython.notebook.get_selected_index()-1);
                var widget_subarea = cell.element.find('.widget_area').find('.widget_subarea');
                
                if (msg.content.data.parent != undefined) {
                    var find_results = widget_subarea.find("." + msg.content.data.parent);
                    if (find_results.length > 0) {
                        widget_subarea = find_results;
                    }
                }
                
                this.show_view(widget_subarea, comm.model, msg.content.data.view_name);
                break;
            case 'update':
                this.handle_update(comm, msg.content.data.state);
                break;
        }
    }

    // Handle when a widget is updated via the python side.
    WidgetManager.prototype.handle_update = function (comm, state) {
        for (var key in state) {
            if (state.hasOwnProperty(key)) {
                if (key=="_css"){
                    comm.model.css = state[key];
                } else {
                    comm.model.set(key, state[key]); 
                }
            }
        }
        comm.model.save();
    }

    // Handle when a widget is closed.
    WidgetManager.prototype.handle_comm_closed = function (comm, msg) {
        for (var view_index in comm.model.views) {
            var view = comm.model.views[view_index];
            view.remove();
        }
    }

    // Get the cell output area corresponding to the comm.
    WidgetManager.prototype._get_comm_outputarea = function (comm) {
        // TODO: get element from comm instead of guessing
        var cell = IPython.notebook.get_cell(IPython.notebook.get_selected_index())
        return cell.output_area;
    }

    // Send widget state to python backend.
    WidgetManager.prototype.send_sync = function (method, model) {
        
        // Create a callback for the output if the widget has an output area associate with it.
        var callbacks = {};
        var comm = model.comm;
        var outputarea = this._get_comm_outputarea(comm);
        if (outputarea != null) {
            callbacks = {
                iopub : {
                output : $.proxy(outputarea.handle_output, outputarea),
                clear_output : $.proxy(outputarea.handle_clear_output, outputarea)}
            };
        };
        
        var data = {sync_method: method, sync_data: model.toJSON()};
        comm.send(data, callbacks);
        return data;
    }

    IPython.WidgetManager = WidgetManager;
    IPython.WidgetModel = WidgetModel;
    IPython.WidgetView = WidgetView;

  
    return IPython;

}(IPython));