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

/**
 * DataModel document.
 *
 * WARNING: The data parameter is passed by reference. Do not modify a data array after passing
 * it to this constructor, and do not construct multiple Documents with the same data array. If you
 * need to do these things, make a deep copy (ve.copyArray()) of the data array and operate on the
 * copy.
 *
 * @class
 * @extends ve.Document
 * @constructor
 * @param {HTMLDocument|Array|ve.dm.LinearData} documentOrData HTML document, raw linear model data or LinearData to start with
 * @param {ve.dm.Document} [parentDocument] Document to use as root for created nodes
 */
ve.dm.Document = function VeDmDocument( documentOrData, parentDocument ) {
	// Parent constructor
	ve.Document.call( this, new ve.dm.DocumentNode() );

	// Initialization
	/*
	 * Build a tree of nodes and nodes that will be added to them after a full scan is complete,
	 * then from the bottom up add nodes to their potential parents. This avoids massive length
	 * updates being broadcast upstream constantly while building is underway.
	 */
	var i, node, children, meta,
		doc = parentDocument || this,
		root = doc.getDocumentNode(),
		textLength = 0,
		inTextNode = false,
		// Stack of stacks, each containing a
		stack = [[this.documentNode], []],
		currentStack = stack[1],
		parentStack = stack[0],
		currentNode = this.documentNode;
	this.documentNode.setDocument( doc );
	this.documentNode.setRoot( root );

	// Properties
	this.parentDocument = parentDocument;

	if ( documentOrData instanceof ve.dm.LinearData ) {
		this.data = documentOrData;
	} else if ( !ve.isArray( documentOrData ) && typeof documentOrData === 'object' ) {
		this.data = ve.dm.converter.getDataFromDom( new ve.dm.IndexValueStore(), documentOrData );
	} else {
		this.data = new ve.dm.ElementLinearData(
			new ve.dm.IndexValueStore(),
			ve.isArray( documentOrData ) ? documentOrData : []
		);
	}
	this.store = this.data.getStore();

	// Sparse array containing the metadata for each offset
	// Each element is either undefined, or an array of metadata elements
	// Because the indexes in the metadata array represent offsets in the data array, the
	// metadata array has one element more than the data array.
	this.metadata = new ve.dm.MetaLinearData( this.getStore(), [] );

	// extract metadata and build node tree
	// NB: this.data.getLength() will change as data is spliced out
	for ( i = 0; i < this.data.getLength(); i++ ) {
		// Infer that if an item in the linear model has a type attribute than it must be an element
		if ( !this.data.isElementData( i ) ) {
			// Text node opening
			if ( !inTextNode ) {
				// Create a lengthless text node
				node = new ve.dm.TextNode();
				// Set the root pointer now, to prevent cascading updates
				node.setRoot( root );
				// Put the node on the current inner stack
				currentStack.push( node );
				currentNode = node;
				// Set a flag saying we're inside a text node
				inTextNode = true;
			}
			// Track the length
			textLength++;
		} else {
			// Element data
			if ( !this.data.isCloseElementData( i ) &&
				ve.dm.metaItemFactory.lookup( this.data.getData( i ).type )
			) {
				// Metadata
				// Splice the meta element and its closing out of the linmod
				meta = this.data.getData( i );
				this.data.splice( i, 2 );
				// Put the metadata in the meta-linmod
				if ( !this.metadata.getData( i ) ) {
					this.metadata.setData( i, [] );
				}
				this.metadata.getData( i ).push( meta );
				// Make sure the loop doesn't skip the next element
				i--;
				continue;
			}

			// Text node closing
			if ( inTextNode ) {
				// Finish the text node by setting the length
				currentNode.setLength( textLength );
				// Put the state variables back as they were
				currentNode = parentStack[parentStack.length - 1];
				inTextNode = false;
				textLength = 0;
			}
			// Element open/close
			if ( !this.data.isCloseElementData( i ) ) {
				// Branch or leaf node opening
				// Create a childless node
				node = ve.dm.nodeFactory.create(
					this.data.getData( i ).type, [], this.data.getData( i )
				);
				// Set the root pointer now, to prevent cascading updates
				node.setRoot( root );
				// Put the childless node on the current inner stack
				currentStack.push( node );
				if ( ve.dm.nodeFactory.canNodeHaveChildren( node.getType() ) ) {
					// Create a new inner stack for this node
					parentStack = currentStack;
					currentStack = [];
					stack.push( currentStack );
				}
				currentNode = node;
			} else {
				// Branch or leaf node closing
				if ( ve.dm.nodeFactory.canNodeHaveChildren( currentNode.getType() ) ) {
					// Pop this node's inner stack from the outer stack. It'll have all of the
					// node's child nodes fully constructed
					children = stack.pop();
					currentStack = parentStack;
					parentStack = stack[stack.length - 2];
					if ( !parentStack ) {
						// This can only happen if we got unbalanced data
						throw new Error( 'Unbalanced input passed to document' );
					}
					// Attach the children to the node
					ve.batchSplice( currentNode, 0, 0, children );
				}
				currentNode = parentStack[parentStack.length - 1];
			}
		}
	}
	// pad out the metadata array
	if ( this.metadata.getLength() < this.data.getLength() + 1 ) {
		this.metadata.data = this.metadata.data.concat(
			new Array( 1 + this.data.getLength() - this.metadata.getLength() )
		);
	}

	if ( inTextNode ) {
		// Text node ended by end-of-input rather than by an element
		currentNode.setLength( textLength );
		// Don't bother updating currentNode et al, we don't use them below
	}
	// The end state is stack = [ [this.documentNode] [ array, of, its, children ] ]
	// so attach all nodes in stack[1] to the root node
	ve.batchSplice( this.documentNode, 0, 0, stack[1] );
};

/* Inheritance */

ve.inheritClass( ve.dm.Document, ve.Document );

/* Events */

/**
 * @event transact
 * @param {ve.dm.Transaction} tx Transaction that was just processed
 * @param {boolean} reversed Whether the transaction was processed in reverse
 */

/* Static methods */

/**
 * Apply annotations to content data.
 *
 * This method modifies data in place.
 *
 * @method
 * @param {Array} data Data to apply annotations to
 * @param {ve.dm.AnnotationSet} annotationSet Annotations to apply
 */
ve.dm.Document.addAnnotationsToData = function ( data, annotationSet ) {
	var i, length, newAnnotationSet, store = annotationSet.getStore();
	if ( annotationSet.isEmpty() ) {
		// Nothing to do
		return;
	}
	// Apply annotations to data
	for ( i = 0, length = data.length; i < length; i++ ) {
		if ( !ve.isArray( data[i] ) ) {
			data[i] = [data[i]];
			newAnnotationSet = annotationSet.clone();
		} else {
			newAnnotationSet = new ve.dm.AnnotationSet( store, store.values( data[i][1] ) );
			newAnnotationSet.addSet( annotationSet.clone() );
		}
		data[i][1] = newAnnotationSet.getIndexes();
	}
};

/* Methods */

/**
 * Reverse a transaction's effects on the content data.
 *
 * @method
 * @param {ve.dm.Transaction} transaction Transaction to roll back
 * @emits transact
 * @throws {Error} Cannot roll back a transaction that has not been committed
 */
ve.dm.Document.prototype.rollback = function ( transaction ) {
	if ( !transaction.hasBeenApplied() ) {
		throw new Error( 'Cannot roll back a transaction that has not been committed' );
	}
	new ve.dm.TransactionProcessor( this, transaction, true ).process();
	this.emit( 'transact', transaction, true );
};

/**
 * Apply a transaction's effects on the content data.
 *
 * @method
 * @param {ve.dm.Transaction} transaction Transaction to apply
 * @emits transact
 * @throws {Error} Cannot commit a transaction that has already been committed
 */
ve.dm.Document.prototype.commit = function ( transaction ) {
	if ( transaction.hasBeenApplied() ) {
		throw new Error( 'Cannot commit a transaction that has already been committed' );
	}
	new ve.dm.TransactionProcessor( this, transaction, false ).process();
	this.emit( 'transact', transaction, false );
};

/**
 * Get a slice or copy of the document data.
 *
 * @method
 * @param {ve.Range} [range] Range of data to get, all data will be given by default
 * @param {boolean} [deep=false] Whether to return a deep copy (WARNING! This may be very slow)
 * @returns {Array} Slice or copy of document data
 */
ve.dm.Document.prototype.getData = function ( range, deep ) {
	return this.data.getDataSlice( range, deep );
};

/**
 * Get a slice or copy of the document metadata.
 *
 * @method
 * @param {ve.Range} [range] Range of metadata to get, all metadata will be given by default
 * @param {boolean} [deep=false] Whether to return a deep copy (WARNING! This may be very slow)
 * @returns {Array} Slice or copy of document metadata
 */
ve.dm.Document.prototype.getMetadata = function ( range, deep ) {
	return this.metadata.getDataSlice( range, deep );
};

/**
 * Get the document's index-value store
 *
 * @method
 * @returns {ve.dm.IndexValueStore} The document's index-value store
 */
ve.dm.Document.prototype.getStore = function () {
	return this.store;
};

/**
 * Get the metadata replace operation required to keep data & metadata in sync after a splice
 *
 * @method
 * @param {number} offset Data offset to start at
 * @param {number} remove Number of elements being removed
 * @param {Array} insert Element data being inserted
 * @returns {Object} Metadata replace operation to keep data & metadata in sync
 */
ve.dm.Document.prototype.getMetadataReplace = function( offset, remove, insert ) {
	var removeMetadata, insertMetadata, replace = {};
	if ( remove > insert.length ) {
		// if we are removing more than we are inserting we need to collapse the excess metadata
		removeMetadata = this.getMetadata( new ve.Range( offset + insert.length, offset + remove + 1 ) );
		// check removeMetadata is non-empty
		if ( !ve.compareArrays( removeMetadata, new Array( removeMetadata.length ) ) ) {
			insertMetadata = ve.dm.MetaLinearData.static.merge( removeMetadata );
			replace.retain = insert.length;
			replace.remove = removeMetadata;
			replace.insert = insertMetadata;
		}
	}
	// if insert.length === remove metadata can just stay where it is
	if ( insert.length > remove ) {
		// if we are inserting more than we are removing then we need to pad out with undefineds
		replace.retain = remove;
		replace.insert = new Array( insert.length - remove );
	}
	return replace;
};

/**
 * Splice metadata into and/or out of the linear model.
 *
 * `this.metadata` will be updated accordingly.
 *
 * @method
 * @see ve#batchSplice
 * @param offset
 * @param index
 * @param remove
 * @param insert
 * @returns {Array}
 */
ve.dm.Document.prototype.spliceMetadata = function ( offset, index, remove, insert ) {
	var elements = this.metadata.getData( offset );
	if ( !elements ) {
		elements = [];
		this.metadata.setData( offset, elements );
	}
	insert = insert || [];
	return ve.batchSplice( elements, index, remove, insert );
};

/**
 * Get the full document data including metadata.
 *
 * Metadata will be into the document data to produce the "full data" result.
 *
 * @returns {Array} Data with metadata interleaved
 */
ve.dm.Document.prototype.getFullData = function () {
	var result = [], i, j, jLen, iLen = this.data.getLength();
	for ( i = 0; i <= iLen; i++ ) {
		if ( this.metadata.getData( i ) ) {
			for ( j = 0, jLen = this.metadata.getData( i ).length; j < jLen; j++ ) {
				result.push( this.metadata.getData( i )[j] );
				result.push( { 'type': '/' + this.metadata.getData( i )[j].type } );
			}
		}
		if ( i < iLen ) {
			result.push( this.data.getData( i ) );
		}
	}
	return result;
};

/**
 * Get a node from an offset.
 *
 * @method
 * @param offset
 */
ve.dm.Document.prototype.getNodeFromOffset = function ( offset ) {
	// FIXME duplicated from ve.ce.Document
	if ( offset < 0 || offset > this.data.getLength() ) {
		throw new Error( 've.dm.Document.getNodeFromOffset(): offset ' + offset + ' is out of bounds' );
	}
	var node = this.documentNode.getNodeFromOffset( offset );
	if ( !node.canHaveChildren() ) {
		node = node.getParent();
	}
	return node;
};

/**
 * Get the content data of a node.
 *
 * @method
 * @param {ve.dm.Node} node Node to get content data for
 * @returns {Array|null} List of content and elements inside node or null if node is not found
 */
ve.dm.Document.prototype.getDataFromNode = function ( node ) {
	var length = node.getLength(),
		offset = this.documentNode.getOffsetFromNode( node );
	if ( offset >= 0 ) {
		// XXX: If the node is wrapped in an element than we should increment the offset by one so
		// we only return the content inside the element.
		if ( node.isWrapped() ) {
			offset++;
		}
		return this.data.slice( offset, offset + length );
	}
	return null;
};

/**
 * Get plain text of a range.
 *
 * @method
 * @param {ve.Range} [range] Range of data to get the text of
 * @returns {string|''} Selected text or an empty string
 */
ve.dm.Document.prototype.getText = function ( range ) {
	var data = this.getData( range ),
		str = '',
		i;
	for ( i = 0; i < data.length; i++ ) {
		if ( typeof data[i] === 'string' ) {
			str += data[i];
		} else if ( ve.isArray( data[i] ) ) {
			str += data[i][0];
		}
	}
	return str;
};

/**
 * Rebuild one or more nodes following a change in document data.
 *
 * The data provided to this method may contain either one node or multiple sibling nodes, but it
 * must be balanced and valid. Data provided to this method also may not contain any content at the
 * top level. The tree is updated during this operation.
 *
 * Process:
 *  1. Nodes between {index} and {index} + {numNodes} in {parent} will be removed
 *  2. Data will be retrieved from this.data using {offset} and {newLength}
 *  3. A document fragment will be generated from the retrieved data
 *  4. The document fragment's nodes will be inserted into {parent} at {index}
 *
 * Use cases:
 *  1. Rebuild old nodes and offset data after a change to the linear model.
 *  2. Insert new nodes and offset data after a insertion in the linear model.
 *
 * @param {ve.dm.Node} parent Parent of the node(s) being rebuilt
 * @param {number} index Index within parent to rebuild or insert nodes
 *  - If {numNodes} == 0: Index to insert nodes at
 *  - If {numNodes} >= 1: Index of first node to rebuild
 * @param {number} numNodes Total number of nodes to rebuild
 *  - If {numNodes} == 0: Nothing will be rebuilt, but the node(s) built from data will be
 *    inserted before {index}. To insert nodes at the end, use number of children in 'parent'
 *  - If {numNodes} == 1: Only the node at {index} will be rebuilt
 *  - If {numNodes} > 1: The node at {index} and the next {numNodes-1} nodes will be rebuilt
 * @param {number} offset Linear model offset to rebuild from
 * @param {number} newLength Length of data in linear model to rebuild or insert nodes for
 * @returns {ve.dm.Node[]} Array containing the rebuilt/inserted nodes
 */
ve.dm.Document.prototype.rebuildNodes = function ( parent, index, numNodes, offset, newLength ) {
	var // Get a slice of the document where it's been changed
		data = this.data.sliceObject( offset, offset + newLength ),
		// Build document fragment from data
		fragment = new ve.dm.Document( data, this ),
		// Get generated child nodes from the document fragment
		nodes = fragment.getDocumentNode().getChildren();
	// Replace nodes in the model tree
	ve.batchSplice( parent, index, numNodes, nodes );
	// Return inserted nodes
	return nodes;
};

/**
 * Fix up data so it can safely be inserted into the document data at an offset.
 *
 * TODO: this function needs more work but it seems to work, mostly
 *
 * @method
 * @param {Array} data Snippet of linear model data to insert
 * @param {number} offset Offset in the linear model where the caller wants to insert data
 * @returns {Array} A (possibly modified) copy of data
 */
ve.dm.Document.prototype.fixupInsertion = function ( data, offset ) {
	var
		// Array where we build the return value
		newData = [],

		// *** Stacks ***
		// Array of element openings (object). Openings in data are pushed onto this stack
		// when they are encountered and popped off when they are closed
		openingStack = [],
		// Array of node objects. Closings in data that close nodes that were
		// not opened in data (i.e. were already in the document) are pushed onto this stack
		// and popped off when balanced out by an opening in data
		closingStack = [],
		// Array of objects describing wrappers that need to be fixed up when a given
		// element is closed.
		//     'expectedType': closing type that triggers this fixup. Includes initial '/'
		//     'openings': array of opening elements that should be closed (in reverse order)
		//     'reopenElements': array of opening elements to insert (in reverse order)
		fixupStack = [],

		// *** State persisting across iterations of the outer loop ***
		// The node (from the document) we're currently in. When in a node that was opened
		// in data, this is set to its first ancestor that is already in the document
		parentNode,
		// The type of the node we're currently in, even if that node was opened within data
		parentType,
		// Whether we are currently in a text node
		inTextNode,

		// *** Temporary variables that do not persist across iterations ***
		// The type of the node we're currently inserting. When the to-be-inserted node
		// is wrapped, this is set to the type of the outer wrapper.
		childType,
		// Stores the return value of getParentNodeTypes( childType )
		allowedParents,
		// Stores the return value of getChildNodeTypes( parentType )
		allowedChildren,
		// Whether parentType matches allowedParents
		parentsOK,
		// Whether childType matches allowedChildren
		childrenOK,
		// Array of opening elements to insert (for wrapping the to-be-inserted element)
		openings,
		// Array of closing elements to insert (for splitting nodes)
		closings,
		// Array of opening elements matching the elements in closings (in the same order)
		reopenElements,

		// *** Other variables ***
		// Used to store values popped from various stacks
		popped,
		// Loop variables
		i, j;

	/**
	 * Append a linear model element to newData and update the state.
	 *
	 * This function updates parentNode, parentType, openingStack and closingStack.
	 *
	 * @private
	 * @method
	 * @param {Object|Array|string} element Linear model element
	 * @param {number} index Index in data that the element came from (for error reporting only)
	 */
	function writeElement( element, index ) {
		var expectedType;

		if ( element.type !== undefined ) {
			// Content, do nothing
			if ( element.type.charAt( 0 ) !== '/' ) {
				// Opening
				// Check if this opening balances an earlier closing of a node that was already in
				// the document. This is only the case if openingStack is empty (otherwise we still
				// have unclosed nodes from within data) and if this opening matches the top of
				// closingStack
				if ( openingStack.length === 0 && closingStack.length > 0 &&
					closingStack[closingStack.length - 1].getType() === element.type
				) {
					// The top of closingStack is now balanced out, so remove it
					// Also restore parentNode from closingStack. While this is technically not
					// entirely accurate (the current node is a new node that's a sibling of this
					// node), it's good enough for the purposes of this algorithm
					parentNode = closingStack.pop();
				} else {
					// This opens something new, put it on openingStack
					openingStack.push( element );
				}
				parentType = element.type;
			} else {
				// Closing
				// Make sure that this closing matches the currently opened node
				if ( openingStack.length > 0 ) {
					// The opening was on openingStack, so we're closing a node that was opened
					// within data. Don't track that on closingStack
					expectedType = openingStack.pop().type;
				} else {
					// openingStack is empty, so we're closing a node that was already in the
					// document. This means we have to reopen it later, so track this on
					// closingStack
					expectedType = parentNode.getType();
					closingStack.push( parentNode );
					parentNode = parentNode.getParent();
					if ( !parentNode ) {
						throw new Error( 'Inserted data is trying to close the root node ' +
							'(at index ' + index + ')' );
					}
					parentType = expectedType;

					// Validate
					// FIXME this breaks certain input, should fix it up, not scream and die
					// For now we fall back to inserting balanced data, but then we miss out on
					// a lot of the nice content adoption abilities of just fixing up the data in
					// the context of the insertion point - an example of how this will fail is if
					// you try to insert "b</p></li></ul><p>c" into "<p>a[cursor]d</p>"
					if (
						element.type !== '/' + expectedType &&
						(
							// Only throw an error if the content can't be adopted from one content
							// branch to another
							!ve.dm.nodeFactory.canNodeContainContent( element.type.substr( 1 ) ) ||
							!ve.dm.nodeFactory.canNodeContainContent( expectedType )
						)
					) {
						throw new Error( 'Cannot adopt content from ' + element.type +
							' nodes into ' + expectedType + ' nodes (at index ' + index + ')' );
					}
				}
			}
		}
		newData.push( element );
	}

	parentNode = this.getNodeFromOffset( offset );
	parentType = parentNode.getType();
	inTextNode = false;
	for ( i = 0; i < data.length; i++ ) {
		if ( inTextNode && data[i].type !== undefined ) {
			// We're leaving a text node, process fixupStack if needed
			// TODO duplicated code
			if (
				fixupStack.length > 0 &&
				fixupStack[fixupStack.length - 1].expectedType === '/text'
			) {
				popped = fixupStack.pop();
				// Go through these in reverse!
				for ( j = popped.openings.length - 1; j >= 0; j-- ) {
					writeElement( { 'type': '/' + popped.openings[j].type }, i );
				}
				for ( j = popped.reopenElements.length - 1; j >= 0; j-- ) {
					writeElement( popped.reopenElements[j], i );
				}
			}
			parentType = openingStack.length > 0 ?
				openingStack[openingStack.length - 1].type : parentNode.getType();
		}
		if ( data[i].type === undefined || data[i].type.charAt( 0 ) !== '/' ) {
			childType = data[i].type || 'text';
			openings = [];
			closings = [];
			reopenElements = [];
			// Opening or content
			// Make sure that opening this element here does not violate the parent/children/content
			// rules. If it does, insert stuff to fix it

			// If this node is content, check that the containing node can contain content. If not,
			// wrap in a paragraph
			if ( ve.dm.nodeFactory.isNodeContent( childType ) &&
				!ve.dm.nodeFactory.canNodeContainContent( parentType )
			) {
				childType = 'paragraph';
				openings.unshift( ve.dm.nodeFactory.getDataElement( childType ) );
			}

			// Check that this node is allowed to have the containing node as its parent. If not,
			// wrap it until it's fixed
			do {
				allowedParents = ve.dm.nodeFactory.getParentNodeTypes( childType );
				parentsOK = allowedParents === null ||
					ve.indexOf( parentType, allowedParents ) !== -1;
				if ( !parentsOK ) {
					// We can't have this as the parent
					if ( allowedParents.length === 0 ) {
						throw new Error( 'Cannot insert ' + childType + ' because it ' +
							' cannot have a parent (at index ' + i + ')' );
					}
					// Open an allowed node around this node
					childType = allowedParents[0];
					openings.unshift( ve.dm.nodeFactory.getDataElement( childType ) );
				}
			} while ( !parentsOK );

			// Check that the containing node can have this node as its child. If not, close nodes
			// until it's fixed
			do {
				allowedChildren = ve.dm.nodeFactory.getChildNodeTypes( parentType );
				childrenOK = allowedChildren === null ||
					ve.indexOf( childType, allowedChildren ) !== -1;
				// Also check if we're trying to insert structure into a node that has to contain
				// content
				childrenOK = childrenOK && !(
					!ve.dm.nodeFactory.isNodeContent( childType ) &&
					ve.dm.nodeFactory.canNodeContainContent( parentType )
				);
				if ( !childrenOK ) {
					// We can't insert this into this parent
					// Close the parent and try one level up
					closings.push( { 'type': '/' + parentType } );
					if ( openingStack.length > 0 ) {
						popped = openingStack.pop();
						parentType = popped.type;
						reopenElements.push( ve.copyObject( popped ) );
						// The opening was on openingStack, so we're closing a node that was opened
						// within data. Don't track that on closingStack
					} else {
						// openingStack is empty, so we're closing a node that was already in the
						// document. This means we have to reopen it later, so track this on
						// closingStack
						closingStack.push( parentNode );
						reopenElements.push( parentNode.getClonedElement() );
						parentNode = parentNode.getParent();
						if ( !parentNode ) {
							throw new Error( 'Cannot insert ' + childType + ' even ' +
								' after closing all containing nodes ' +
								'(at index ' + i + ')' );
						}
						parentType = parentNode.getType();
					}
				}
			} while ( !childrenOK );

			for ( j = 0; j < closings.length; j++ ) {
				// writeElement() would update openingStack/closingStack, but we've already done
				// that for closings
				newData.push( closings[j] );
			}
			for ( j = 0; j < openings.length; j++ ) {
				writeElement( openings[j], i );
			}
			writeElement( data[i], i );
			if ( data[i].type === undefined ) {
				// Special treatment for text nodes
				inTextNode = true;
				if ( openings.length > 0 ) {
					// We wrapped the text node, update parentType
					parentType = childType;
					fixupStack.push( {
						'expectedType': '/text',
						'openings': openings,
						'reopenElements': reopenElements
					} );
				}
				// If we didn't wrap the text node, then the node we're inserting into can have
				// content, so we couldn't have closed anything
			} else {
				fixupStack.push( {
					'expectedType': '/' + data[i].type,
					'openings': openings,
					'reopenElements': reopenElements
				} );
				parentType = data[i].type;
			}
		} else {
			// Closing
			writeElement( data[i], i );
			// TODO don't close fixup stuff if the next thing immediately needs to be fixed up as
			// well; instead, merge the two wrappers
			if (
				fixupStack.length > 0 &&
				fixupStack[fixupStack.length - 1].expectedType === data[i].type
			) {
				popped = fixupStack.pop();
				// Go through these in reverse!
				for ( j = popped.openings.length - 1; j >= 0; j-- ) {
					writeElement( { 'type': '/' + popped.openings[j].type }, i );
				}
				for ( j = popped.reopenElements.length - 1; j >= 0; j-- ) {
					writeElement( popped.reopenElements[j], i );
				}
			}
			parentType = openingStack.length > 0 ?
				openingStack[openingStack.length - 1].type : parentNode.getType();
		}
	}

	if ( inTextNode ) {
		// We're leaving a text node, process fixupStack if needed
		// TODO duplicated code
		if (
			fixupStack.length > 0 &&
			fixupStack[fixupStack.length - 1].expectedType === '/text'
		) {
			popped = fixupStack.pop();
			// Go through these in reverse!
			for ( j = popped.openings.length - 1; j >= 0; j-- ) {
				writeElement( { 'type': '/' + popped.openings[j].type }, i );
			}
			for ( j = popped.reopenElements.length - 1; j >= 0; j-- ) {
				writeElement( popped.reopenElements[j], i );
			}
		}
		parentType = openingStack.length > 0 ?
			openingStack[openingStack.length - 1].type : parentNode.getType();
	}

	// Close unclosed openings
	while ( openingStack.length > 0 ) {
		popped = openingStack[openingStack.length - 1];
		// writeElement() will perform the actual pop() that removes
		// popped from openingStack
		writeElement( { 'type': '/' + popped.type }, i );
	}
	// Re-open closed nodes
	while ( closingStack.length > 0 ) {
		popped = closingStack[closingStack.length - 1];
		// writeElement() will perform the actual pop() that removes
		// popped from closingStack
		writeElement( popped.getClonedElement(), i );
	}

	return newData;
};

/**
 * Get the document data for a range.
 *
 * Data will be fixed up so that unopened closings and unclosed openings in the document data slice
 * are balanced.
 *
 * @returns {ve.dm.DocumentSlice} Balanced slice of linear model data
 */
ve.dm.Document.prototype.getSlice = function ( range ) {
	var first, last, firstNode, lastNode,
		node = this.getNodeFromOffset( range.start ),
		selection = this.selectNodes( range, 'siblings' ),
		addOpenings = [],
		addClosings = [];
	if ( selection.length === 0 ) {
		return new ve.dm.DocumentSlice( [] );
	}
	if ( selection.length === 1 && selection[0].range.equals( range ) ) {
		// Nothing to fix up
		return new ve.dm.DocumentSlice( this.data.slice( range.start, range.end ) );
	}

	first = selection[0];
	last = selection[selection.length - 1];
	firstNode = first.node;
	lastNode = last.node;
	while ( !firstNode.isWrapped() ) {
		firstNode = firstNode.getParent();
	}
	while ( !lastNode.isWrapped() ) {
		lastNode = lastNode.getParent();
	}

	if ( first.range ) {
		while ( true ) {
			while ( !node.isWrapped() ) {
				node = node.getParent();
			}
			addOpenings.push( node.getClonedElement() );
			if ( node === firstNode ) {
				break;
			}
			node = node.getParent();
		}
	}

	node = this.getNodeFromOffset( range.end );
	if ( last !== first && last.range ) {
		while ( true ) {
			while ( !node.isWrapped() ) {
				node = node.getParent();
			}
			addClosings.push( { 'type': '/' + node.getType() } );
			if ( node === lastNode ) {
				break;
			}
			node = node.getParent();
		}
	}

	return new ve.dm.DocumentSlice(
		addOpenings.reverse()
			.concat( this.data.slice( range.start, range.end ) )
			.concat( addClosings ),
		new ve.Range( addOpenings.length, addOpenings.length + range.getLength() )
	);
};