//----------------------------------------------------------------------------
//  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
 */

(function () {
    "use strict";

    // Use require.js 'define' method so that require.js is intelligent enough to
    // syncronously load everything within this file when it is being 'required' 
    // elsewhere.
    define(["underscore",
             "backbone",
            ], function (underscore, backbone) {
            
        // Backbone.sync method must be in widgetmanager.js file instead of 
        // widget.js so it can be overwritten for different contexts.
        Backbone.sync = function (method, model, options) {
            var result = model._handle_sync(method, options);
            if (options.success) {
                options.success(result);
            }
        }; 

        //--------------------------------------------------------------------
        // WidgetManager class
        //--------------------------------------------------------------------
        var WidgetManager = function () {
            this.comm_manager = null;
            this._model_types = {}; /* Dictionary of model type names 
                                      (target_name) and model types. */
            this._view_types = {}; /* Dictionary of view names and view types. */
            this._models = {}; /* Dictionary of model ids and model instances */
        };


        WidgetManager.prototype.attach_comm_manager = function (comm_manager) {
            this.comm_manager = comm_manager;

            // Register already-registered widget model types with the comm manager.
            for (var widget_model_name in this._model_types) {
                // TODO: Should not be a for.
                this.comm_manager.register_target(widget_model_name, $.proxy(this._handle_comm_open, this));
            }
        };


        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.
            if (this.comm_manager !== null) {
                this.comm_manager.register_target(widget_model_name, $.proxy(this._handle_comm_open, this));
            }
            this._model_types[widget_model_name] = widget_model_type;
        };


        WidgetManager.prototype.register_widget_view = function (widget_view_name, widget_view_type) {
            this._view_types[widget_view_name] = widget_view_type;
        };


        WidgetManager.prototype.display_view = function(msg_id, model) {
            var cell = this.get_msg_cell(msg_id);
            if (cell === null) {
                console.log("Could not determine where the display" + 
                    " message was from.  Widget will not be displayed");
            } else {
                var view = this.create_view(model);
                if (view !== undefined 
                    && cell.widget_subarea !== undefined 
                    && cell.widget_subarea !== null) {
                    
                    view.cell = cell;
                    cell.widget_area.show();
                    cell.widget_subarea.append(view.$el);
                }
            }
        },


        WidgetManager.prototype.create_view = function(model, options) {
            var view_name = model.get('view_name');
            var ViewType = this._view_types[view_name];
            if (ViewType !== undefined && ViewType !== null) {
                var parameters = {model: model, options: options};
                var view = new ViewType(parameters);
                view.render();
                IPython.keyboard_manager.register_events(view.$el);
                model.views.push(view);
                model.on('destroy', view.remove, view);
                return view;
            }
        },


        WidgetManager.prototype.get_msg_cell = function (msg_id) {
            var cell = null;
            // First, check to see if the msg was triggered by cell execution.
            if (IPython.notebook !== undefined && IPython.notebook !== null) {
                cell = IPython.notebook.get_msg_cell(msg_id);
            }
            if (cell !== null) {
                return cell
            }
            // Second, check to see if a get_cell callback was defined
            // for the message.  get_cell callbacks are registered for
            // widget messages, so this block is actually checking to see if the
            // message was triggered by a widget.
            var kernel = null;
            if (this.comm_manager !== null) {
                kernel = this.comm_manager.kernel;
            }
            if (kernel !== undefined && kernel !== null) {
                var callbacks = kernel.get_callbacks_for_msg(msg_id);
                if (callbacks !== undefined && 
                    callbacks.iopub !== undefined && 
                    callbacks.iopub.get_cell !== undefined) {

                    return callbacks.iopub.get_cell();
                }    
            }
            
            // Not triggered by a cell or widget (no get_cell callback 
            // exists).
            return null;
        };

        WidgetManager.prototype.callbacks = function (view) {
            // callback handlers specific a view
            var callbacks = {};
            var cell = view.cell;
            if (cell !== null) {
                // Try to get output handlers
                var handle_output = null;
                var handle_clear_output = null;
                if (cell.output_area !== undefined && cell.output_area !== null) {
                    handle_output = $.proxy(cell.output_area.handle_output, cell.output_area);
                    handle_clear_output = $.proxy(cell.output_area.handle_clear_output, cell.output_area);
                }

                // Create callback dict using what is known
                var that = this;
                callbacks = {
                    iopub : {
                        output : handle_output,
                        clear_output : handle_clear_output,

                        status : function (msg) {
                            view.model._handle_status(msg, that.callbacks(view));
                        },

                        // Special function only registered by widget messages.
                        // Allows us to get the cell for a message so we know
                        // where to add widgets if the code requires it.
                        get_cell : function () {
                            return cell;
                        },
                    },
                };
            }
            return callbacks;
        };


        WidgetManager.prototype.get_model = function (model_id) {
            var model = this._models[model_id];
            if (model !== undefined && model.id == model_id) {
                return model;
            }
            return null;
        };


        WidgetManager.prototype._handle_comm_open = function (comm, msg) {
            var widget_type_name = msg.content.target_name;
            var widget_model = new this._model_types[widget_type_name](this, comm.comm_id, comm);
            this._models[comm.comm_id] = widget_model; // comm_id == model_id
        };
        
        //--------------------------------------------------------------------
        // Init code
        //--------------------------------------------------------------------
        IPython.WidgetManager = WidgetManager;
        if (IPython.widget_manager === undefined || IPython.widget_manager === null) {
            IPython.widget_manager = new WidgetManager();    
        }

        return IPython.widget_manager;
    });
}());