var View = wp.media.View,
	UploaderStatus;

/**
 * wp.media.view.UploaderStatus
 *
 * An uploader status for on-going uploads.
 *
 * @memberOf wp.media.view
 *
 * @class
 * @augments wp.media.View
 * @augments wp.Backbone.View
 * @augments Backbone.View
 */
UploaderStatus = View.extend(/** @lends wp.media.view.UploaderStatus.prototype */{
	className: 'media-uploader-status',
	template:  wp.template('uploader-status'),

	events: {
		'click .upload-dismiss-errors': 'dismiss'
	},

	initialize: function() {
		this.queue = wp.Uploader.queue;
		this.queue.on( 'add remove reset', this.visibility, this );
		this.queue.on( 'add remove reset change:percent', this.progress, this );
		this.queue.on( 'add remove reset change:uploading', this.info, this );

		this.errors = wp.Uploader.errors;
		this.errors.reset();
		this.errors.on( 'add remove reset', this.visibility, this );
		this.errors.on( 'add', this.error, this );
	},
	/**
	 * @return {wp.media.view.UploaderStatus}
	 */
	dispose: function() {
		wp.Uploader.queue.off( null, null, this );
		/**
		 * call 'dispose' directly on the parent class
		 */
		View.prototype.dispose.apply( this, arguments );
		return this;
	},

	visibility: function() {
		this.$el.toggleClass( 'uploading', !! this.queue.length );
		this.$el.toggleClass( 'errors', !! this.errors.length );
		this.$el.toggle( !! this.queue.length || !! this.errors.length );
	},

	ready: function() {
		_.each({
			'$bar':      '.media-progress-bar div',
			'$index':    '.upload-index',
			'$total':    '.upload-total',
			'$filename': '.upload-filename'
		}, function( selector, key ) {
			this[ key ] = this.$( selector );
		}, this );

		this.visibility();
		this.progress();
		this.info();
	},

	progress: function() {
		var queue = this.queue,
			$bar = this.$bar;

		if ( ! $bar || ! queue.length ) {
			return;
		}

		$bar.width( ( queue.reduce( function( memo, attachment ) {
			if ( ! attachment.get('uploading') ) {
				return memo + 100;
			}

			var percent = attachment.get('percent');
			return memo + ( _.isNumber( percent ) ? percent : 100 );
		}, 0 ) / queue.length ) + '%' );
	},

	info: function() {
		var queue = this.queue,
			index = 0, active;

		if ( ! queue.length ) {
			return;
		}

		active = this.queue.find( function( attachment, i ) {
			index = i;
			return attachment.get('uploading');
		});

		this.$index.text( index + 1 );
		this.$total.text( queue.length );
		this.$filename.html( active ? this.filename( active.get('filename') ) : '' );
	},
	/**
	 * @param {string} filename
	 * @return {string}
	 */
	filename: function( filename ) {
		return _.escape( filename );
	},
	/**
	 * @param {Backbone.Model} error
	 */
	error: function( error ) {
		var statusError = new wp.media.view.UploaderStatusError( {
			filename: this.filename( error.get( 'file' ).name ),
			message:  error.get( 'message' )
		} );

		// Can show additional info here while retrying to create image sub-sizes.
		this.views.add( '.upload-errors', statusError, { at: 0 } );
	},

	dismiss: function() {
		var errors = this.views.get('.upload-errors');

		if ( errors ) {
			_.invoke( errors, 'remove' );
		}
		wp.Uploader.errors.reset();
		// Move focus to the modal after the dismiss button gets removed from the DOM.
		if ( this.controller.modal ) {
			this.controller.modal.focusManager.focus();
		}
	}
});

module.exports = UploaderStatus;
