/**
 * VisualEditor data model Converter class.
 *
 * @copyright 2011-2012 VisualEditor Team and others; see AUTHORS.txt
 * @license The MIT License (MIT); see LICENSE.txt
 */

/**
 * Converter between HTML DOM and VisualEditor linear data.
 *
 * @class
 * @constructor
 * @param {Object} options Conversion options
 */
ve.dm.Converter = function ( nodeFactory, annotationFactory ) {
	// Properties
	this.nodeFactory = nodeFactory;
	this.annotationFactory = annotationFactory;
	this.elements = { 'toDomElement': {}, 'toDataElement': {}, 'dataElementTypes': {} };
	this.annotations = { 'toDomElement': {}, 'toDataAnnotation': {} };

	// Events
	this.nodeFactory.addListenerMethod( this, 'register', 'onNodeRegister' );
	this.annotationFactory.addListenerMethod( this, 'register', 'onAnnotationRegister' );
};

/* Static Methods */

/**
 * Get linear model data from a string optionally applying annotations
 *
 * @param {String} text Plain text to convert
 * @param {Array} [annotations] Array of annotation objects to apply
 * @returns {Array} Linear model data, one element per character
 */
ve.dm.Converter.getDataContentFromText = function ( text, annotations ) {
	var characters = text.split( '' ),
		annotationMap = {},
		i;
	if ( !annotations || annotations.length === 0 ) {
		return characters;
	}
	// Build annotation map
	for ( i = 0; i < annotations.length; i++ ) {
		if ( annotations[i].data && ve.isEmptyObject( annotations[i].data ) ) {
			// Cleanup empty data property
			delete annotations[i].data;
		}
		annotationMap[ve.getHash( annotations[i] )] = annotations[i];
	}
	// Apply annotations to characters
	for ( i = 0; i < characters.length; i++ ) {
		// Make a shallow copy of the annotationMap object, otherwise adding an annotation to one
		// character automatically adds it to all of others as well, annotations should be treated
		// as immutable, so it's OK to share references, but annotation maps are not immutable, so
		// its not safe to share references - each annotated character needs its own map
		characters[i] = [characters[i], ve.extendObject( {}, annotationMap )];
	}
	return characters;
};

/* Methods */

/**
 * Responds to register events from the node factory.
 *
 * If a node is special; such as document, alienInline, alienBlock and text; its {converters}
 * property should be set to null, as to distinguish it from a new node type that someone has simply
 * forgotten to implement converters for.
 *
 * @method
 * @param {String} type Node type
 * @param {Function} constructor Node constructor
 * @throws 'Missing conversion data in node implementation of {type}'
 */
ve.dm.Converter.prototype.onNodeRegister = function ( dataElementType, constructor ) {
	if ( constructor.converters === undefined ) {
		throw new Error( 'Missing conversion data in node implementation of ' + dataElementType );
	} else if ( constructor.converters !== null ) {
		var i,
			domElementTypes = constructor.converters.domElementTypes,
			toDomElement = constructor.converters.toDomElement,
			toDataElement = constructor.converters.toDataElement;
		// Registration
		this.elements.toDomElement[dataElementType] = toDomElement;
		for ( i = 0; i < domElementTypes.length; i++ ) {
			this.elements.toDataElement[domElementTypes[i]] = toDataElement;
			this.elements.dataElementTypes[domElementTypes[i]] = dataElementType;
		}
	}
};

/**
 * Responds to register events from the annotation factory.
 *
 * @method
 * @param {String} type Base annotation type
 * @param {Function} constructor Annotation constructor
 * @throws 'Missing conversion data in annotation implementation of {type}'
 */
ve.dm.Converter.prototype.onAnnotationRegister = function ( dataElementType, constructor ) {
	if ( constructor.converters === undefined ) {
		throw new Error( 'Missing conversion data in annotation implementation of ' + dataElementType );
	} else if ( constructor.converters !== null ) {
		var i,
			domElementTypes = constructor.converters.domElementTypes,
			toDomElement = constructor.converters.toDomElement,
			toDataAnnotation = constructor.converters.toDataAnnotation;
		// Registration
		this.annotations.toDomElement[dataElementType] = toDomElement;
		for ( i = 0; i < domElementTypes.length; i++ ) {
			this.annotations.toDataAnnotation[domElementTypes[i]] = toDataAnnotation;
		}
	}
};

/**
 * Get the DOM element for a given linear model element.
 *
 * This invokes the toDomElement function registered for the element type.
 * NOTE: alienBlock and alienInline elements are not supported, if you pass them this function
 * will return false. (Opposite of District 9: no aliens allowed.)
 *
 * @method
 * @param {Object} dataElement Linear model element
 * @returns {HTMLElement|false} DOM element, or false if this element cannot be converted
 */
ve.dm.Converter.prototype.getDomElementFromDataElement = function ( dataElement ) {
	var key, domElement, dataElementAttributes,
		dataElementType = dataElement.type;
	if (
		// Aliens
		dataElementType === 'alienInline' || dataElementType === 'alienBlock' ||
		// Unsupported elements
		!( dataElementType in this.elements.toDomElement)
	) {
		return false;
	}
	domElement = this.elements.toDomElement[dataElementType]( dataElementType, dataElement );
	dataElementAttributes = dataElement.attributes;
	if ( dataElementAttributes ) {
		for ( key in dataElementAttributes ) {
			// Only include 'html/*' attributes and strip the 'html/' from the beginning of the name
			if ( key.indexOf( 'html/' ) === 0 ) {
				domElement.setAttribute( key.substr( 5 ), dataElementAttributes[key] );
			}
		}
	}
	return domElement;
};

/**
 * Get the linear model data element for a given DOM element.
 *
 * This invokes the toDataElement function registered for the element type
 *
 * @method
 * @param {HTMLElement} domElement DOM element
 * @returns {Object|false} Linear model element, or false if this node cannot be converted
 */
ve.dm.Converter.prototype.getDataElementFromDomElement = function ( domElement ) {
	var dataElement, domElementAttributes, dataElementAttributes, domElementAttribute, i,
		domElementType = domElement.nodeName.toLowerCase();
	if (
		// Unsupported elements
		!( domElementType in this.elements.toDataElement )
		// TODO check for generated elements
	) {
		return false;
	}
	dataElement = this.elements.toDataElement[domElementType]( domElementType, domElement );
	domElementAttributes = domElement.attributes;
	if ( domElementAttributes.length ) {
		dataElementAttributes = dataElement.attributes = dataElement.attributes || {};
		// Inlcude all attributes and prepend 'html/' to each attribute name
		for ( i = 0; i < domElementAttributes.length; i++ ) {
			domElementAttribute = domElementAttributes[i];
			dataElementAttributes['html/' + domElementAttribute.name] = domElementAttribute.value;
		}
	}
	return dataElement;
};

/**
 * Check if an HTML DOM node represents an annotation, and if so, build an annotation object for it.
 *
 * @example Annotation Object
 *    { 'type': 'type', data: { 'key': 'value', ... } }
 *
 * @param {HTMLElement} domElement HTML DOM node
 * @returns {Object|false} Annotation object, or false if this node is not an annotation
 */
ve.dm.Converter.prototype.getDataAnnotationFromDomElement = function ( domElement ) {
	var domElementType = domElement.nodeName.toLowerCase(),
		toDataAnnotation = this.annotations.toDataAnnotation[domElementType];
	if ( typeof toDataAnnotation === 'function' ) {
		return toDataAnnotation( domElementType, domElement );
	}
	return false;
};

/**
 * Build an HTML DOM node for a linear model annotation.
 *
 * @method
 * @param {Object} dataAnnotation Annotation object
 * @returns {HTMLElement|false} HTML DOM node, or false if this annotation is not known
 */
ve.dm.Converter.prototype.getDomElementFromDataAnnotation = function ( dataAnnotation ) {
	var split = dataAnnotation.type.split( '/' ),
		baseType = split[0],
		subType = split.slice( 1 ).join( '/' ),
		toDomElement = this.annotations.toDomElement[baseType];
	if ( typeof toDomElement === 'function' ) {
		return toDomElement( subType, dataAnnotation );
	}
	return false;
};

/**
 * Convert an HTML DOM tree to a linear model.
 *
 * Do not use the annotations, dataElement and path parameters, they're used for internal
 * recursion only.
 *
 * @method
 * @param {HTMLElement} domElement Wrapper div containing the HTML to convert
 * @param {Array} [annotations] Array of annotations (objects) to apply to the generated data
 * @param {Object} [dataElement] Data element to wrap the returned data in
 * @param {Array} [path] Array of linear model element types
 * @returns {Array} Linear model data
 */
ve.dm.Converter.prototype.getDataFromDom = function ( domElement, annotations, dataElement, path, alreadyWrapped ) {
	function createAlien( domElement, isInline ) {
		var type = isInline ? 'alienInline' : 'alienBlock';
		return [
			{
				'type': type,
				'attributes': {
					'html': $( '<div>' ).append( $( domElement ).clone() ).html()
				}
			},
			{ 'type': '/' + type }
		];
	}

	// Fallback to defaults
	annotations = annotations || [];
	path = path || ['document'];
	var i, childDomElement, annotation, childDataElement, text, childTypes, matches, paragraph,
		wrapperElement = dataElement,
		data = [],
		branchType = path[path.length - 1],
		branchIsContent = ve.dm.nodeFactory.canNodeContainContent( branchType ),
		wrapping = false;
	// Open element
	if ( dataElement ) {
		data.push( dataElement );
	}
	// Add contents
	for ( i = 0; i < domElement.childNodes.length; i++ ) {
		childDomElement = domElement.childNodes[i];
		switch ( childDomElement.nodeType ) {
			case Node.ELEMENT_NODE:
				// Detect and handle annotated content
				annotation = this.getDataAnnotationFromDomElement( childDomElement );
				if ( annotation ) {
					// Start auto-wrapping of bare content
					if ( !wrapping && !alreadyWrapped && !branchIsContent ) {
						// Mark this paragraph as having been generated by
						// us, so we can strip it on the way out
						data.push( {
							'type': 'paragraph',
							'internal': { 'generated': 'wrapper' }
						} );
						wrapping = true;
					}
					// Append child element data
					data = data.concat(
						this.getDataFromDom(
							childDomElement, annotations.concat( annotation ), undefined, path, wrapping || alreadyWrapped
						)
					);
					break;
				}
				// End auto-wrapping of bare content
				if ( wrapping ) {
					data.push( { 'type': '/paragraph' } );
					wrapping = false;
				}
				// Append child element data
				childDataElement = this.getDataElementFromDomElement( childDomElement );
				if ( childDataElement ) {
					data = data.concat(
						this.getDataFromDom(
							childDomElement,
							[],
							childDataElement,
							path.concat( childDataElement.type ),
							wrapping || alreadyWrapped
						)
					);
					break;
				}
				// We don't know what this is, fall back to alien
				data = data.concat( createAlien( childDomElement, branchIsContent ) );
				break;
			case Node.TEXT_NODE:
				// HACK: strip trailing newline in <li> tags. Workaround for a Parsoid bug
				// TODO kill this in favor of the fringe whitespace preservation
				// code below
				text = childDomElement.data;
				if ( domElement.nodeName.toLowerCase() === 'li' ) {
					text = text.replace( /\n$/, '' );
				}
				if ( !branchIsContent ) {
					// If it's bare content, strip leading and trailing newlines
					// FIXME these newlines should be preserved somehow
					text = text.replace( /^\n+/, '' ).replace( /\n+$/, '' );
				}
				if ( text === '' ) {
					// Don't produce an empty text node or an empty paragraph
					break;
				}

				// Start auto-wrapping of bare content
				if ( !wrapping && !alreadyWrapped && !branchIsContent ) {
					// Mark this paragraph as having been generated by
					// us, so we can strip it on the way out
					paragraph = {
						'type': 'paragraph',
						'internal': { 'generated': 'wrapper' }
					};
					data.push( paragraph );
					wrapping = true;
					wrapperElement = paragraph;
				}

				// Strip leading and trailing whitespace
				// (but only in non-annotation nodes)
				// and store it so it can be restored later.
				// whitespace = [ outerPre, innerPre, innerPost, outerPost ]
				//           <tag>         text           </tag>          <nextTag>
				// ^^^^^^^^^^     ^^^^^^^^^    ^^^^^^^^^^^      ^^^^^^^^^^
				//  outerPre      innerPre      innerPost        outerPost
				if ( annotations.length === 0 && i === 0 && wrapperElement ) {
					// Strip leading whitespace from the first child
					matches = text.match( /^\s+/ );
					if ( matches && matches[0] !== '' ) {
						if ( !wrapperElement.internal ) {
							wrapperElement.internal = {};
						}
						if ( !wrapperElement.internal.whitespace ) {
							wrapperElement.internal.whitespace = [];
						}
						wrapperElement.internal.whitespace[1] = matches[0];
						text = text.substring( matches[0].length );
					}
				}
				if (
					annotations.length === 0 &&
					i === domElement.childNodes.length - 1 &&
					wrapperElement
				) {
					// Strip trailing whitespace from the last child
					matches = text.match( /\s+$/ );
					if ( matches && matches[0] !== '' ) {
						if ( !wrapperElement.internal ) {
							wrapperElement.internal = {};
						}
						if ( !wrapperElement.internal.whitespace ) {
							wrapperElement.internal.whitespace = [];
						}
						wrapperElement.internal.whitespace[2] = matches[0];
						text = text.substring( 0,
							text.length - matches[0].length );
					}
				}

				// Annotate the text and output it
				data = data.concat(
					ve.dm.Converter.getDataContentFromText( text, annotations )
				);
				break;
			case Node.COMMENT_NODE:
				// TODO: Preserve comments by inserting them into the linear model too
				// Could use placeholders for this too, although they'd need to be
				// inline in certain cases
				break;
		}
	}
	// End auto-wrapping of bare content
	if ( wrapping ) {
		data.push( { 'type': '/paragraph' } );
	}

	// If we're closing a node that doesn't have any children, but could contain a paragraph,
	// add a paragraph. This prevents things like empty list items
	childTypes = ve.dm.nodeFactory.getChildNodeTypes( branchType );
	if ( branchType !== 'paragraph' && dataElement && data[data.length - 1] === dataElement &&
		!wrapping && !ve.dm.nodeFactory.canNodeContainContent( branchType ) &&
		!ve.dm.nodeFactory.isNodeContent( branchType ) &&
		( childTypes === null || ve.indexOf( 'paragraph', childTypes ) !== -1 )
	) {
		data.push( { 'type': 'paragraph', 'internal': { 'generated': 'wrapper' } } );
		data.push( { 'type': '/paragraph' } );
	}

	// Close element
	if ( dataElement ) {
		data.push( { 'type': '/' + dataElement.type } );
	}
	// Don't return an empty document
	if ( branchType === 'document' && data.length === 0 ) {
		return [
			{ 'type': 'paragraph', 'internal': { 'generated': 'wrapper' } },
			{ 'type': '/paragraph' }
		];
	}
	return data;
};

/**
 * Convert linear model data to an HTML DOM
 *
 * @method
 * @param {Array} data Linear model data
 * @returns {HTMLElement} Wrapper div containing the resulting HTML
 */
ve.dm.Converter.prototype.getDomFromData = function ( data ) {
	var text, i, j, annotations, hash, annotationElement, done, dataElement, wrapper,
		childDomElement, pre, post, parentDomElement,
		container = document.createElement( 'div' ),
		domElement = container,
		annotationStack = {}; // { hash: DOMnode }
	for ( i = 0; i < data.length; i++ ) {
		if ( typeof data[i] === 'string' ) {
			// Text
			text = '';
			// Continue forward as far as the plain text goes
			while ( typeof data[i] === 'string' ) {
				text += data[i];
				i++;
			}
			// i points to the first non-text thing, go back one so we don't skip this later
			i--;
			// Add text
			domElement.appendChild( document.createTextNode( text ) );
		} else if (
			ve.isArray( data[i] ) ||
			(
				data[i].annotations !== undefined &&
				ve.dm.nodeFactory.isNodeContent( data[i].type )
			)
		) {
			// Annotated text
			text = '';
			while (
				ve.isArray( data[i] ) ||
				(
					data[i].annotations !== undefined &&
					ve.dm.nodeFactory.isNodeContent( data[i].type )
				)
			) {
				annotations = data[i].annotations || data[i][1];
				// Check for closed annotations
				for ( hash in annotationStack ) {
					if ( !( hash in annotations ) ) {
						// It's closed
						// Traverse up until we hit the node we need to close, and then
						// traverse up one more time to close that node
						done = false;
						while ( !done ) {
							done = domElement === annotationStack[hash];
							// Remove the annotation from the stack
							delete annotationStack[domElement.veAnnotationHash];
							// Remove the temporary veAnnotationHash property
							delete domElement.veAnnotationHash;
							// Add text if needed
							if ( text.length > 0 ) {
								domElement.appendChild( document.createTextNode( text ) );
								text = '';
							}
							// Traverse up
							domElement = domElement.parentNode;
						}
					}
				}
				// Check for opened annotations
				for ( hash in annotations ) {
					if ( !( hash in annotationStack ) ) {
						// It's opened
						annotationElement = this.getDomElementFromDataAnnotation( annotations[hash] );
						// Temporary property, will remove this when closing the annotation
						annotationElement.veAnnotationHash = hash;
						// Add to the annotation stack
						annotationStack[hash] = annotationElement;
						// Add text if needed
						if ( text.length > 0 ) {
							domElement.appendChild( document.createTextNode( text ) );
							text = '';
						}
						// Attach new node and descend into it
						domElement.appendChild( annotationElement );
						domElement = annotationElement;
					}
				}
				if ( data[i].annotations === undefined ) {
					text += data[i][0];
				} else {
					// Add text if needed
					if ( text.length > 0 ) {
						domElement.appendChild( document.createTextNode( text ) );
						text = '';
					}
					// Insert the element
					domElement.appendChild( this.getDomElementFromDataElement( data[i] ) );
					// Increment i once more so we skip over the closing as well
					i++;
				}
				i++;
			}
			// We're now at the first non-annotated thing, go back one so we don't skip this later
			i--;

			// Add any gathered text
			if ( text.length > 0 ) {
				domElement.appendChild( document.createTextNode( text ) );
				text = '';
			}
			// Close any remaining annotation nodes
			while ( domElement.veAnnotationHash !== undefined ) {
				delete annotationStack[domElement.veAnnotationHash];
				delete domElement.veAnnotationHash;
				domElement = domElement.parentNode;
			}
		} else if ( data[i].type !== undefined ) {
			dataElement = data[i];
			// Element
			if ( dataElement.type === 'alienBlock' || dataElement.type === 'alienInline' ) {
				// Create nodes from source
				wrapper = document.createElement( 'div' );
				wrapper.innerHTML = dataElement.attributes.html;
				// Add element - adds all child elements, but there really should only be 1
				while ( wrapper.firstChild ) {
					domElement.appendChild( wrapper.firstChild );
				}
				// Make sure the alien closing is skipped
				i++;
			} else if ( dataElement.type.charAt( 0 ) === '/' ) {
				// Process inner whitespace
				// whitespace = [ outerPre, innerPre, innerPost, outerPost ]
				if ( domElement.veInternal && domElement.veInternal.whitespace ) {
					pre = domElement.veInternal.whitespace[1];
					if ( pre ) {
						if ( domElement.firstChild.nodeType === 3 ) {
							// First child is a TextNode, prepend to it
							domElement.firstChild.insertData( 0, pre );
						} else {
							// Prepend a TextNode
							domElement.insertBefore(
								document.createTextNode( pre ),
								domElement.firstChild
							);
						}
					}
					post = domElement.veInternal.whitespace[2];
					if ( post ) {
						if ( domElement.lastChild.nodeType === 3 ) {
							// Last child is a TextNode, append to it
							domElement.lastChild.appendData( post );
						} else {
							// Append a TextNode
							domElement.appendChild(
								document.createTextNode( post )
							);
						}
					}
				}

				// If closing a generated wrapper node, unwrap it
				// It would be nicer if we could avoid generating in the first
				// place, but then remembering where we have to skip ascending
				// to the parent would be tricky.
				parentDomElement = domElement.parentNode;
				if ( domElement.veInternal && domElement.veInternal.generated === 'wrapper' ) {
					while ( domElement.firstChild ) {
						parentDomElement.insertBefore(
							domElement.firstChild,
							domElement
						);
					}
					parentDomElement.removeChild( domElement );
				}

				// Clean up the internal data
				delete domElement.veInternal;
				// Ascend to parent node
				domElement = parentDomElement;
			} else {
				// Create node from data
				childDomElement = this.getDomElementFromDataElement( dataElement );
				// Add reference to internal data
				if ( dataElement.internal ) {
					childDomElement.veInternal = dataElement.internal;
				}
				// Add element
				domElement.appendChild( childDomElement );
				// Descend into child node
				domElement = childDomElement;
			}
		}
	}
	return container;
};

/* Initialization */

ve.dm.converter = new ve.dm.Converter( ve.dm.nodeFactory, ve.dm.annotationFactory );