/*!
 * VisualEditor UserInterface CodeMirrorAction class.
 *
 * @copyright 2011-2017 VisualEditor Team and others; see http://ve.mit-license.org
 */

/**
 * CodeMirror action
 *
 * @class
 * @extends ve.ui.Action
 * @constructor
 * @param {ve.ui.Surface} surface Surface to act on
 */
ve.ui.CodeMirrorAction = function VeUiCodeMirrorAction() {
	// Parent constructor
	ve.ui.CodeMirrorAction.super.apply( this, arguments );
};

/* Inheritance */

OO.inheritClass( ve.ui.CodeMirrorAction, ve.ui.Action );

/* Static Properties */

ve.ui.CodeMirrorAction.static.name = 'codeMirror';

/**
 * @inheritdoc
 */
ve.ui.CodeMirrorAction.static.methods = [ 'toggle' ];

/* Methods */

/**
 * @method
 * @param {boolean} [enable] State to force toggle to, inverts current state if undefined
 * @return {boolean} Action was executed
 */
ve.ui.CodeMirrorAction.prototype.toggle = function ( enable ) {
	var surface = this.surface,
		surfaceView = surface.getView(),
		doc = surface.getModel().getDocument();

	if ( !surface.mirror && enable !== false ) {
		surface.mirror = CodeMirror( surfaceView.$element[ 0 ], {
			value: surface.getDom(),
			mwConfig: mw.config.get( 'extCodeMirrorConfig' ),
			readOnly: 'nocursor',
			lineWrapping: true,
			tabSize: 1,
			scrollbarStyle: 'null',
			specialChars: /^$/,
			viewportMargin: 5,
			// select mediawiki as text input mode
			mode: 'text/mediawiki',
			extraKeys: {
				Tab: false
			}
		} );

		surfaceView.$documentNode.addClass(
			'WebkitTextFillColor' in document.body.style ?
			've-ce-documentNode-codeEditor-webkit-hide' :
			've-ce-documentNode-codeEditor-webkit'
		);

		// As the action is regenerated each time, we need to store the bound listener
		// in the mirror for later disconnection.
		surface.mirror.veTransactionListener = this.onDocumentPrecommit.bind( this );

		doc.on( 'precommit', surface.mirror.veTransactionListener );
	} else if ( surface.mirror && enable !== true ) {
		doc.off( 'precommit', surface.mirror.veTransactionListener );

		surfaceView.$documentNode.removeClass(
			've-ce-documentNode-codeEditor-webkit-hide ve-ce-documentNode-codeEditor-webkit'
		);

		surface.mirror.getWrapperElement().remove();

		surface.mirror = null;
	}

	return true;
};

/**
 * Handle precommit events from the document.
 *
 * The document is still in it's 'old' state before the transaction
 * has been applied at this point.
 *
 * @param {ve.dm.Transaction} tx [description]
 */
ve.ui.CodeMirrorAction.prototype.onDocumentPrecommit = function ( tx ) {
	var i,
		offset = 0,
		replacements = [],
		linearData = this.surface.getModel().getDocument().data,
		store = linearData.getStore(),
		mirror = this.surface.mirror;

	/**
	 * Convert a VE offset to a 2D CodeMirror position
	 *
	 * @private
	 * @param {Number} veOffset VE linear model offset
	 * @return {Object} Code mirror position, containing 'line' and 'ch'
	 */
	function convertOffset( veOffset ) {
		var cmOffset = linearData.getSourceText( new ve.Range( 0, veOffset ) ).length;
		return mirror.posFromIndex( cmOffset );
	}

	tx.operations.forEach( function ( op ) {
		if ( op.type === 'retain' ) {
			offset += op.length;
		} else if ( op.type === 'replace' ) {
			replacements.push( {
				start: convertOffset( offset ),
				// Don't bother recalculating end offset if not a removal, replaceRange works with just one arg
				end: op.remove.length ? convertOffset( offset + op.remove.length ) : undefined,
				data: new ve.dm.ElementLinearData( store, op.insert ).getSourceText()
			} );
			offset += op.remove.length;
		}
	} );

	// Apply replacements in reverse to avoid having to shift offsets
	for ( i = replacements.length - 1; i >= 0; i-- ) {
		mirror.replaceRange(
			replacements[ i ].data,
			replacements[ i ].start,
			replacements[ i ].end
		);
	}
};

/* Registration */

ve.ui.actionFactory.register( ve.ui.CodeMirrorAction );