/**
 * Interface for retrieving webcam photos.
 * Supports HTML5 and Flash.
 */
 var edx = edx || {},
     key = {
         enter: 13
     };

 (function($, _, Backbone, gettext) {
     'use strict';

     edx.verify_student = edx.verify_student || {};

     edx.verify_student.WebcamPhotoView = Backbone.View.extend({

         template: '#webcam_photo-tpl',
         el: '#webcam',

         backends: {
             html5: {
                 name: 'html5',

                 initialize: function(obj) {
                     this.URL = (window.URL || window.webkitURL);
                     this.video = obj.video || '';
                     this.canvas = obj.canvas || '';
                     this.stream = null;

                    // Start the capture
                     var getUserMedia = this.getUserMediaFunc();
                     if (getUserMedia) {
                         getUserMedia(
                             {
                                 video: true,

                                // Specify the `fake` constraint if we detect we are running in a test
                                // environment. In Chrome, this will do nothing, but in Firefox, it will
                                // instruct the browser to use a fake video device.
                                 fake: window.location.hostname === 'localhost'
                             },
                            _.bind(this.getUserMediaCallback, this),
                            _.bind(this.handleVideoFailure, this)
                        );
                     }
                 },

                 isSupported: function() {
                     return this.getUserMediaFunc() !== undefined;
                 },

                 snapshot: function() {
                     var video;

                     if (this.stream) {
                         video = this.getVideo();
                         this.getCanvas().getContext('2d').drawImage(video, 0, 0);
                         video.pause();
                         return true;
                     }

                     return false;
                 },

                 getImageData: function() {
                     return this.getCanvas().toDataURL('image/png');
                 },

                 reset: function() {
                     this.getVideo().play();
                 },

                 getUserMediaFunc: function() {
                     var userMedia = (
                        navigator.getUserMedia || navigator.webkitGetUserMedia ||
                        navigator.mozGetUserMedia || navigator.msGetUserMedia
                    );

                     if (userMedia) {
                         return _.bind(userMedia, navigator);
                     }
                 },

                 getUserMediaCallback: function(stream) {
                     var video = this.getVideo();
                     this.stream = stream;
                     video.src = this.URL.createObjectURL(stream);
                     video.play();
                     this.trigger('webcam-loaded');
                 },

                 getVideo: function() {
                     return $(this.video).first()[0];
                 },

                 getCanvas: function() {
                     return $(this.canvas).first()[0];
                 },

                 handleVideoFailure: function() {
                     this.trigger(
                        'error',
                        gettext('Video Capture Error'),
                        gettext('Please verify that your webcam is connected and that you have allowed your browser to access it.')
                    );
                 }
             },

             flash: {

                 name: 'flash',

                 initialize: function(obj) {
                     this.wrapper = obj.wrapper || '';
                     this.imageData = '';

                    // Wait for the player to load, then verify camera support
                    // Trigger an error if no camera is available.
                     this.checkCameraSupported();
                 },

                 isSupported: function() {
                     try {
                         var flashObj = new ActiveXObject('ShockwaveFlash.ShockwaveFlash');
                         if (flashObj) {
                             return true;
                         }
                     } catch (ex) {
                         if (navigator.mimeTypes['application/x-shockwave-flash'] !== undefined) {
                             return true;
                         }
                     }

                     return false;
                 },

                 snapshot: function() {
                     var flashObj = this.getFlashObject();
                     if (flashObj.cameraAuthorized()) {
                         this.imageData = flashObj.snap();
                         return true;
                     }
                     return false;
                 },

                 reset: function() {
                     this.getFlashObject().reset();
                 },

                 getImageData: function() {
                     return this.imageData;
                 },

                 flashObjectTag: function() {
                     return (
                        '<object type="application/x-shockwave-flash" ' +
                            'id="flash_video" ' +
                            'name="flash_video" ' +
                            'data="/static/js/verify_student/CameraCapture.swf" ' +
                            'width="500" ' +
                            'height="375">' +
                         '<param name="quality" value="high">' +
                         '<param name="allowscriptaccess" value="sameDomain">' +
                         '</object>'
                     );
                 },

                 getFlashObject: function() {
                     return $('#flash_video')[0];
                 },

                 checkCameraSupported: function() {
                     var flashObj = this.getFlashObject(),
                         isLoaded = false,
                         hasCamera = false;

                     isLoaded = (
                        flashObj &&
                        flashObj.hasOwnProperty('percentLoaded') &&
                        flashObj.percentLoaded() === 100
                    );

                    // On some browsers, the flash object will say it has a camera
                    // even "percentLoaded" isn't defined.
                     hasCamera = (
                        flashObj &&
                        flashObj.hasOwnProperty('hasCamera') &&
                        flashObj.hasCamera()
                    );

                    // If we've fully loaded, and no camera is available,
                    // then show an error.
                     if (isLoaded && !hasCamera) {
                         this.trigger(
                            'error',
                            gettext('No Webcam Detected'),
                            gettext("You don't seem to have a webcam connected.") + '  ' +
                            gettext('Double-check that your webcam is connected and working to continue.')
                        );
                     }

                    // If we're still waiting for the player to load, check
                    // back later.
                     else if (!isLoaded && !hasCamera) {
                         setTimeout(_.bind(this.checkCameraSupported, this), 50);
                     }

                    // Otherwise, the flash player says it has a camera,
                    // so we don't need to keep checking.
                 }
             }
         },

         initialize: function(obj) {
             this.submitButton = obj.submitButton || '';
             this.modelAttribute = obj.modelAttribute || '';
             this.errorModel = obj.errorModel || null;
             this.backend = this.backends[obj.backendName] || obj.backend;
             this.captureSoundPath = obj.captureSoundPath || '';

             _.extend(this.backend, Backbone.Events);
             this.backend.initialize({
                 wrapper: '#camera',
                 video: '#photo_id_video',
                 canvas: '#photo_id_canvas'
             });

             this.listenTo(this.backend, 'error', this.handleError);
             this.listenTo(this.backend, 'webcam-loaded', this.handleWebcamLoaded);
         },

         isSupported: function() {
             return this.backend.isSupported();
         },

         render: function() {
             var renderedHtml,
                 $resetBtn,
                 $captureBtn;

            // Set the submit button to disabled by default
             this.setSubmitButtonEnabled(false);

            // Load the template for the webcam into the DOM
             renderedHtml = _.template($(this.template).html())(
                {backendName: this.backend.name}
            );
             $(this.el).html(renderedHtml);

             $resetBtn = this.$el.find('#webcam_reset_button');
             $captureBtn = this.$el.find('#webcam_capture_button');

            // Install event handlers
             $resetBtn.on('click', _.bind(this.reset, this));
             $captureBtn.on('click', _.bind(this.capture, this));

             $resetBtn.on('keyup', _.bind(this.resetByEnter, this));

            // Show the capture button
             $captureBtn.removeClass('is-hidden');
             $('#webcam_capture_button', this.el).removeClass('is-hidden');
             $('#webcam_capture_sound', this.el).attr('src', this.captureSoundPath);

             return this;
         },

         reset: function() {
            // Disable the submit button
             this.setSubmitButtonEnabled(false);

            // Reset the video capture
             this.backend.reset();

            // Reset data on the model
             this.model.set(this.modelAttribute, '');

            // Go back to the initial button state
             $('#webcam_reset_button', this.el).addClass('is-hidden');
             $('#webcam_capture_button', this.el).removeClass('is-hidden');
             $(this.submitButton).attr('title', '');
         },


         resetByEnter: function(event) {
             if (event.keyCode == key.enter) {
                 this.reset();
             }
         },
         capture: function() {
            // Take a snapshot of the video
             var success = this.backend.snapshot();

             if (success) {
                // Trigger an event which parent views can use to fire a
                // business intelligence event
                 this.trigger('imageCaptured');

                // Hide the capture button, and show the reset button
                 $('#webcam_capture_button', this.el).addClass('is-hidden');
                 $('#webcam_reset_button', this.el).removeClass('is-hidden');

                // Save the data to the model
                 this.model.set(this.modelAttribute, this.backend.getImageData());

                // Enable the submit button
                 this.setSubmitButtonEnabled(true);
                 this.setSubmitButtonFocused();
                 this.captureSound();
             }
         },

         handleWebcamLoaded: function(errorTitle, errorMsg) {
            // Hide the text behind camera
             $('#camera .placeholder-art', this.el).hide();
         },

         handleError: function(errorTitle, errorMsg) {
            // Hide the buttons
             $('#webcam_capture_button', this.el).addClass('is-hidden');
             $('#webcam_reset_button', this.el).addClass('is-hidden');

            // Show the error message
             if (this.errorModel) {
                 this.errorModel.set({
                     errorTitle: errorTitle,
                     errorMsg: errorMsg,
                     shown: true
                 });
             }
         },

         setSubmitButtonEnabled: function(isEnabled) {
             $(this.submitButton)
                .toggleClass('is-disabled', !isEnabled)
                .prop('disabled', !isEnabled)
                .attr('aria-disabled', !isEnabled);
         },

         captureSound: function() {
             $('#webcam_capture_sound')[0].play();
         },

         setSubmitButtonFocused: function() {
             $(this.submitButton)
                .trigger('focus')
                .attr('title', gettext('Photo Captured successfully.'));
         },

         isMobileDevice: function() {
            // Check whether user is using mobile device or not
             return (!!navigator.userAgent.match(/(Android|iPad|iPhone|iPod)/g));
         }
     });

    /**
     * Retrieve a supported webcam view implementation.
     *
     * The priority order from most to least preferable is:
     * 1) HTML5
     * 2) Flash
     * 3) File input
     *
     * @param  {Object} obj Parameters to the webcam view.
     * @return {Object}     A Backbone view.
     */
     edx.verify_student.getSupportedWebcamView = function(obj) {
         var view = null;

        // First choice is HTML5, supported by most web browsers
         obj.backendName = 'html5';
         view = new edx.verify_student.WebcamPhotoView(obj);
         if (view.isSupported()) {
             return view;
         }

        // Second choice is Flash, required for older versions of IE
         obj.backendName = 'flash';
         view = new edx.verify_student.WebcamPhotoView(obj);
         if (view.isSupported()) {
             return view;
         }
        // If user is not using mobile device and Flash is not available
        // then show user error message for Flash
         if (!view.isMobileDevice() && !view.isSupported()) {
             view.backend.trigger(
                'error',
                gettext('No Flash Detected'),
                gettext("You don't seem to have Flash installed. Get Flash to continue your verification.")
            );
             return view;
         }

        // Last resort is HTML file input with image capture.
        // This will work everywhere, and on iOS it will
        // allow users to take a photo with the camera.
         return new edx.verify_student.ImageInputView(obj);
     };
 }(jQuery, _, Backbone, gettext));
