/*!
 * VisualEditor UserInterface Context class.
 *
 * @copyright 2011-2013 VisualEditor Team and others; see AUTHORS.txt
 * @license The MIT License (MIT); see LICENSE.txt
 */

/**
 * UserInterface context.
 *
 * @class
 *
 * @constructor
 * @param {ve.Surface} surface
 */
ve.ui.Context = function VeUiContext( surface ) {
	// Properties
	this.surface = surface;
	this.inspectors = {};
	this.visible = false;
	this.showing = false;
	this.selecting = false;
	this.selection = null;
	this.toolbar = null;
	this.inspectors = new ve.ui.WindowSet( surface, ve.ui.inspectorFactory );
	this.$ = $( '<div>' );
	this.$callout = $( '<div>' );
	this.$body = $( '<div>' );
	this.$menu = $( '<div>' );

	// Initialization
	this.inspectors.$.addClass( 've-ui-context-inspectors' );
	this.$
		.addClass( 've-ui-context' )
		.append(
			this.$callout.addClass( 've-ui-context-callout' ),
			this.$body.addClass( 've-ui-context-body' )
		);
	this.$body.append(
		this.$menu.addClass( 've-ui-context-menu' ),
		this.inspectors.$.addClass( 've-ui-context-inspectors' )
	);

	// Events
	this.surface.getModel().addListenerMethods( this, {
		'change': 'onChange'
	} );
	this.surface.getView().addListenerMethods( this, {
		'selectionStart': 'onSelectionStart',
		'selectionEnd': 'onSelectionEnd'
	} );
	this.inspectors.addListenerMethods( this, {
		'setup': 'onInspectorSetup',
		'open': 'onInspectorOpen',
		'close': 'onInspectorClose'
	} );
	$( window ).on( {
		'resize': ve.bind( this.update, this ),
		'focus': ve.bind( this.onWindowFocus, this )
	} );
};

/* Methods */

/**
 * Handle change events on the model.
 *
 * Changes are ignored while the user is selecting text.
 *
 * @method
 * @param {ve.dm.Transaction} tx Change transaction
 * @param {ve.Range} selection Change selection
 */
ve.ui.Context.prototype.onChange = function ( tx, selection ) {
	if ( selection && selection.start === 0 ) {
		return;
	}
	if ( selection && !this.selecting ) {
		this.update();
	}
};

/**
 * Handle selection start events on the view.
 *
 * @method
 */
ve.ui.Context.prototype.onSelectionStart = function () {
	this.selecting = true;
	this.hide();
};

/**
 * Handle selection end events on the view.
 *
 * @method
 */
ve.ui.Context.prototype.onSelectionEnd = function () {
	this.selecting = false;
	this.update();
};

/**
 * Handle window focus events on the view.
 *
 * @method
 */
ve.ui.Context.prototype.onWindowFocus = function () {
	this.hide();
};

/**
 * Handle an inspector being setup.
 *
 * @method
 * @param {ve.ui.Inspector} inspector Inspector that's been setup
 */
ve.ui.Context.prototype.onInspectorSetup = function () {
	this.selection = this.surface.getModel().getSelection();
};

/**
 * Handle an inspector being opened.
 *
 * @method
 * @param {ve.ui.Inspector} inspector Inspector that's been opened
 */
ve.ui.Context.prototype.onInspectorOpen = function () {
	this.show();
};

/**
 * Handle an inspector being closed.
 *
 * @method
 * @param {ve.ui.Inspector} inspector Inspector that's been opened
 * @param {boolean} accept Changes have been accepted
 */
ve.ui.Context.prototype.onInspectorClose = function () {
	this.update();
};

/**
 * Gets the surface the context is being used in.
 *
 * @method
 * @returns {ve.Surface} Surface of context
 */
ve.ui.Context.prototype.getSurface = function () {
	return this.surface;
};

/**
 * Destroy the context, removing all DOM elements.
 *
 * @method
 * @returns {ve.ui.Context} Context UserInterface
 * @chainable
 */
ve.ui.Context.prototype.destroy = function () {
	this.$.remove();
	return this;
};

/**
 * Updates the context menu.
 *
 * @method
 * @chainable
 */
ve.ui.Context.prototype.update = function () {
	var items,
		fragment = this.surface.getModel().getFragment(),
		selection = fragment.getRange(),
		inspector = this.inspectors.getCurrent();

	if ( inspector && selection.equals( this.selection ) ) {
		// There's an inspector, and the selection hasn't changed, update the position
		this.show();
	} else {
		// No inspector is open, or the selection has changed, show a menu of available inspectors
		items = ve.ui.inspectorFactory.getInspectorsForAnnotations( fragment.getAnnotations() );
		if ( items.length ) {
			// There's at least one inspectable annotation, build a menu and show it
			this.$menu.empty();
			this.toolbar = new ve.ui.Toolbar(
				$( '<div class="ve-ui-context-toolbar"></div>' ),
				this.surface,
				[{ 'name': 'inspectors', 'items' : items }]
			);
			this.$menu.append( this.toolbar.$ );
			this.show();
		} else if ( this.visible ) {
			// Nothing to inspect
			this.hide();
		}
	}

	// Remember selection for next time
	this.selection = selection.clone();

	return this;
};

/**
 * Shows the context menu.
 *
 * @method
 * @chainable
 */
ve.ui.Context.prototype.show = function () {
	var position, $container, width, height, bodyWidth, buffer, center, overlapRight, overlapLeft,
		inspector = this.inspectors.getCurrent();

	if ( !this.showing ) {
		this.showing = true;

		this.$.show();

		// Show either inspector or menu
		if ( inspector ) {
			this.inspectors.$.show();
			this.$menu.hide();
			inspector.fitHeightToContents();
		} else {
			this.inspectors.$.hide();
			this.$menu.show();
		}

		// Get dimensions
		position = this.surface.getView().getSelectionRect().end;
		$container = inspector ? this.inspectors.$ : this.$menu;
		width = $container.outerWidth( true );
		height = $container.outerHeight( true );
		bodyWidth = $( 'body' ).width();
		buffer = ( width / 2 ) + 20;
		overlapRight = bodyWidth - ( position.x + buffer );
		overlapLeft = position.x - buffer;
		center = -( width / 2 );

		// Prevent body from displaying off-screen
		if ( overlapRight < 0 ) {
			center += overlapRight;
		} else if ( overlapLeft < 0 ) {
			center -= overlapLeft;
		}

		// Move to just below the cursor
		this.$.css( { 'left': position.x, 'width': width, 'top': position.y } );

		if ( !this.visible ) {
			this.$body
				.css( { 'width': 0, 'height': 0, 'left': 0 } )
				.addClass( 've-ui-context-body-transition' );
		}

		this.$body.css( { 'left': center, 'width': width, 'height': height } );

		this.visible = true;
		this.showing = false;
	}

	return this;
};

/**
 * Hides the context menu.
 *
 * @method
 * @chainable
 */
ve.ui.Context.prototype.hide = function () {
	var inspector = this.inspectors.getCurrent();

	if ( inspector ) {
		// This will recurse, but inspector will be undefined next time
		inspector.close();
		return this;
	}

	this.$body
		.removeClass( 've-ui-context-body-transition' )
		.css( { 'width': 0, 'height': 0, 'left': 0 } );
	this.inspectors.$.hide();
	this.$menu.hide();
	this.$.hide();
	this.visible = false;

	return this;
};

/**
 * Opens a given inspector.
 *
 * @method
 * @param {string} name Symbolic name of inspector
 * @chainable
 */
ve.ui.Context.prototype.openInspector = function ( name ) {
	this.inspectors.open( name );
	return this;
};

/**
 * Closes currently open inspector.
 *
 * @method
 * @param {boolean} remove Remove annotation while closing
 * @chainable
 */
ve.ui.Context.prototype.closeInspector = function ( remove ) {
	this.inspectors.close( remove );
	return this;
};