TypeScript/src/services/pullLanguageService.ts

/// <reference path='typescriptServices.ts' />

/// <reference path="..\compiler\types.ts"/>
/// <reference path="..\compiler\core.ts"/>
/// <reference path="..\compiler\scanner.ts"/>
/// <reference path="..\compiler\parser.ts"/>
/// <reference path="..\compiler\checker.ts"/>

module TypeScript.Services {
    interface CompletionSession {
        filename: string;           // the file where the completion was requested
        position: number;           // position in the file where the completion was requested
        entries: CompletionEntry[]; // entries for this completion
        symbols: ts.Map<ts.Symbol>; // symbols by entry name map
        location: ts.Node;          // the node where the completion was requested
        typeChecker: ts.TypeChecker;// the typeChecker used to generate this completion
    }

    // Information about a specific host file.
    interface HostFileInformation {
        filename: string;
        version: number;
        isOpen: boolean;
        byteOrderMark: TypeScript.ByteOrderMark;
        _sourceText?: TypeScript.IScriptSnapshot;
    }

    export function getDefaultCompilerOptions(): ts.CompilerOptions {
        // Set "ES5" target by default for language service
        return {
            target: ts.ScriptTarget.ES5,
            module: ts.ModuleKind.None,
        };
    }

    // Cache host information about scripts. Should be refreshed 
    // at each language service public entry point, since we don't know when 
    // set of scripts handled by the host changes.
    class HostCache {
        private _filenameToEntry: ts.Map<HostFileInformation>;
        private _compilationSettings: ts.CompilerOptions;

        constructor(private host: ILanguageServiceHost) {
            // script id => script index
            this._filenameToEntry = {};

            var filenames = host.getScriptFileNames();
            for (var i = 0, n = filenames.length; i < n; i++) {
                var filename = filenames[i];
                this._filenameToEntry[TypeScript.switchToForwardSlashes(filename)] = {
                    filename: filename,
                    version: host.getScriptVersion(filename),
                    isOpen: host.getScriptIsOpen(filename),
                    byteOrderMark: host.getScriptByteOrderMark(filename)
                };
            }

            this._compilationSettings = host.getCompilationSettings() || getDefaultCompilerOptions();
        }

        public compilationSettings() {
            return this._compilationSettings;
        }

        public contains(filename: string): boolean {
            return !!this._filenameToEntry[TypeScript.switchToForwardSlashes(filename)];
        }

        public getHostfilename(filename: string) {
            var hostCacheEntry = this._filenameToEntry[TypeScript.switchToForwardSlashes(filename)];
            if (hostCacheEntry) {
                return hostCacheEntry.filename;
            }
            return filename;
        }

        public getfilenames(): string[] {
            var fileNames: string[] = [];
            for (var id in this._filenameToEntry) {
                fileNames.push(id);
            }
            return fileNames;
        }

        public getVersion(filename: string): number {
            return this._filenameToEntry[TypeScript.switchToForwardSlashes(filename)].version;
        }

        public isOpen(filename: string): boolean {
            return this._filenameToEntry[TypeScript.switchToForwardSlashes(filename)].isOpen;
        }

        public getByteOrderMark(filename: string): TypeScript.ByteOrderMark {
            return this._filenameToEntry[TypeScript.switchToForwardSlashes(filename)].byteOrderMark;
        }

        public getScriptSnapshot(filename: string): TypeScript.IScriptSnapshot {
            var file = this._filenameToEntry[TypeScript.switchToForwardSlashes(filename)];
            if (!file._sourceText) {
                file._sourceText = this.host.getScriptSnapshot(file.filename);
            }
            return file._sourceText;
        }

        public getScriptTextChangeRangeSinceVersion(filename: string, lastKnownVersion: number): TypeScript.TextChangeRange {
            var currentVersion = this.getVersion(filename);
            if (lastKnownVersion === currentVersion) {
                return TypeScript.TextChangeRange.unchanged; // "No changes"
            }

            var scriptSnapshot = this.getScriptSnapshot(filename);
            return scriptSnapshot.getTextChangeRangeSinceVersion(lastKnownVersion);
        }
    }

    export class SyntaxTreeCache {
        private _hostCache: HostCache;

        // For our syntactic only features, we also keep a cache of the syntax tree for the 
        // currently edited file.  
        private _currentfilename: string = "";
        private _currentFileVersion: number = -1;
        private _currentFileSyntaxTree: TypeScript.SyntaxTree = null;
        private _currentFileScriptSnapshot: TypeScript.IScriptSnapshot = null;

        constructor(private _host: ILanguageServiceHost) {
            this._hostCache = new HostCache(_host);
        }

        public getCurrentFileSyntaxTree(filename: string): TypeScript.SyntaxTree {
            this._hostCache = new HostCache(this._host);

            var version = this._hostCache.getVersion(filename);
            var syntaxTree: TypeScript.SyntaxTree = null;

            if (this._currentFileSyntaxTree === null || this._currentfilename !== filename) {
                var scriptSnapshot = this._hostCache.getScriptSnapshot(filename);
                syntaxTree = this.createSyntaxTree(filename, scriptSnapshot);
            }
            else if (this._currentFileVersion !== version) {
                var scriptSnapshot = this._hostCache.getScriptSnapshot(filename);
                syntaxTree = this.updateSyntaxTree(filename, scriptSnapshot, this._currentFileSyntaxTree, this._currentFileVersion);
            }

            if (syntaxTree !== null) {
                // All done, ensure state is up to date
                this._currentFileScriptSnapshot = scriptSnapshot;
                this._currentFileVersion = version;
                this._currentfilename = filename;
                this._currentFileSyntaxTree = syntaxTree;
            }

            return this._currentFileSyntaxTree;
        }

        public getCurrentScriptSnapshot(filename: string): IScriptSnapshot {
            // update _currentFileScriptSnapshot as a part of 'getCurrentFileSyntaxTree' call
            this.getCurrentFileSyntaxTree(filename);
            return this._currentFileScriptSnapshot;
        }

        private createSyntaxTree(filename: string, scriptSnapshot: TypeScript.IScriptSnapshot): TypeScript.SyntaxTree {
            var text = TypeScript.SimpleText.fromScriptSnapshot(scriptSnapshot);

            // For the purposes of features that use this syntax tree, we can just use the default
            // compilation settings.  The features only use the syntax (and not the diagnostics),
            // and the syntax isn't affected by the compilation settings.
            var syntaxTree = TypeScript.Parser.parse(filename, text, getDefaultCompilerOptions().target, TypeScript.isDTSFile(filename));

            return syntaxTree;
        }

        private updateSyntaxTree(filename: string, scriptSnapshot: TypeScript.IScriptSnapshot, previousSyntaxTree: TypeScript.SyntaxTree, previousFileVersion: number): TypeScript.SyntaxTree {
            var editRange = this._hostCache.getScriptTextChangeRangeSinceVersion(filename, previousFileVersion);

            // Debug.assert(newLength >= 0);

            // The host considers the entire buffer changed.  So parse a completely new tree.
            if (editRange === null) {
                return this.createSyntaxTree(filename, scriptSnapshot);
            }

            var nextSyntaxTree = IncrementalParser.parse(
                previousSyntaxTree, editRange, SimpleText.fromScriptSnapshot(scriptSnapshot));

            this.ensureInvariants(filename, editRange, nextSyntaxTree, this._currentFileScriptSnapshot, scriptSnapshot);

            return nextSyntaxTree;
        }

        private ensureInvariants(filename: string, editRange: TypeScript.TextChangeRange, incrementalTree: TypeScript.SyntaxTree, oldScriptSnapshot: TypeScript.IScriptSnapshot, newScriptSnapshot: TypeScript.IScriptSnapshot) {
            // First, verify that the edit range and the script snapshots make sense.

            // If this fires, then the edit range is completely bogus.  Somehow the lengths of the
            // old snapshot, the change range and the new snapshot aren't in sync.  This is very
            // bad.
            var expectedNewLength = oldScriptSnapshot.getLength() - editRange.span().length() + editRange.newLength();
            var actualNewLength = newScriptSnapshot.getLength();

            function provideMoreDebugInfo() {

                var debugInformation = ["expected length:", expectedNewLength, "and actual length:", actualNewLength, "are not equal\r\n"];

                var oldSpan = editRange.span();

                function prettyPrintString(s: string): string {
                    return '"' + s.replace(/\r/g, '\\r').replace(/\n/g, '\\n') + '"';
                }

                debugInformation.push('Edit range (old text) (start: ' + oldSpan.start() + ', end: ' + oldSpan.end() + ') \r\n');
                debugInformation.push('Old text edit range contents: ' + prettyPrintString(oldScriptSnapshot.getText(oldSpan.start(), oldSpan.end())));

                var newSpan = editRange.newSpan();

                debugInformation.push('Edit range (new text) (start: ' + newSpan.start() + ', end: ' + newSpan.end() + ') \r\n');
                debugInformation.push('New text edit range contents: ' + prettyPrintString(newScriptSnapshot.getText(newSpan.start(), newSpan.end())));

                return debugInformation.join(' ');
            }

            Debug.assert(
                expectedNewLength === actualNewLength,
                "Expected length is different from actual!",
                provideMoreDebugInfo);

            if (Debug.shouldAssert(AssertionLevel.VeryAggressive)) {
                // If this fires, the text change range is bogus.  It says the change starts at point 
                // 'X', but we can see a text difference *before* that point.
                var oldPrefixText = oldScriptSnapshot.getText(0, editRange.span().start());
                var newPrefixText = newScriptSnapshot.getText(0, editRange.span().start());
                Debug.assert(oldPrefixText === newPrefixText, 'Expected equal prefix texts!');

                // If this fires, the text change range is bogus.  It says the change goes only up to
                // point 'X', but we can see a text difference *after* that point.
                var oldSuffixText = oldScriptSnapshot.getText(editRange.span().end(), oldScriptSnapshot.getLength());
                var newSuffixText = newScriptSnapshot.getText(editRange.newSpan().end(), newScriptSnapshot.getLength());
                Debug.assert(oldSuffixText === newSuffixText, 'Expected equal suffix texts!');

                // Ok, text change range and script snapshots look ok.  Let's verify that our 
                // incremental parsing worked properly.
                //var normalTree = this.createSyntaxTree(filename, newScriptSnapshot);
                //Debug.assert(normalTree.structuralEquals(incrementalTree), 'Expected equal incremental and normal trees');

                // Ok, the trees looked good.  So at least our incremental parser agrees with the 
                // normal parser.  Now, verify that the incremental tree matches the contents of the 
                // script snapshot.
                var incrementalTreeText = fullText(incrementalTree.sourceUnit());
                var actualSnapshotText = newScriptSnapshot.getText(0, newScriptSnapshot.getLength());
                Debug.assert(incrementalTreeText === actualSnapshotText, 'Expected full texts to be equal');
            }
        }
    }

    interface FormattingOptions {
        useTabs: boolean;
        spacesPerTab: number;
        indentSpaces: number;
        newLineCharacter: string;
    }

    class DocumentRegistryEntry {
        public refCount: number = 0;
        public owners: string[] = [];
        constructor(public document: Document) {
        }
    }

    export interface IDocumentRegistry {
        acquireDocument(
            filename: string,
            compilationSettings: ts.CompilerOptions,
            scriptSnapshot: IScriptSnapshot,
            byteOrderMark: ByteOrderMark,
            version: number,
            isOpen: boolean,
            referencedFiles: string[]): TypeScript.Document;

        updateDocument(
            document: Document,
            filename: string,
            compilationSettings: ts.CompilerOptions,
            scriptSnapshot: IScriptSnapshot,
            version: number,
            isOpen: boolean,
            textChangeRange: TextChangeRange
            ): TypeScript.Document;

        releaseDocument(filename: string, compilationSettings: ts.CompilerOptions): void
    }

    export class NonCachingDocumentRegistry implements IDocumentRegistry {

        public static Instance: IDocumentRegistry = new NonCachingDocumentRegistry();

        public acquireDocument(
            filename: string,
            compilationSettings: ts.CompilerOptions,
            scriptSnapshot: IScriptSnapshot,
            byteOrderMark: ByteOrderMark,
            version: number,
            isOpen: boolean,
            referencedFiles: string[]= []): TypeScript.Document {
            return Document.create(compilationSettings, filename, scriptSnapshot, byteOrderMark, version, isOpen, referencedFiles);
        }

        public updateDocument(
            document: Document,
            filename: string,
            compilationSettings: ts.CompilerOptions,
            scriptSnapshot: IScriptSnapshot,
            version: number,
            isOpen: boolean,
            textChangeRange: TextChangeRange
            ): TypeScript.Document {
            return document.update(scriptSnapshot, version, isOpen, textChangeRange);
        }

        public releaseDocument(filename: string, compilationSettings: ts.CompilerOptions): void {
            // no op since this class doesn't cache anything
        }
    }

    export class DocumentRegistry implements IDocumentRegistry {
        private buckets: ts.Map<ts.Map<DocumentRegistryEntry>> = {};

        private getKeyFromCompilationSettings(settings: ts.CompilerOptions): string {
            return "_" + ts.ScriptTarget[settings.target]; //  + "|" + settings.propagateEnumConstants.toString()
        }

        private getBucketForCompilationSettings(settings: ts.CompilerOptions, createIfMissing: boolean): ts.Map<DocumentRegistryEntry> {
            var key = this.getKeyFromCompilationSettings(settings);
            var bucket = this.buckets[key];
            if (!bucket && createIfMissing) {
                this.buckets[key] = bucket = {};
            }
            return bucket;
        }

        public reportStats() {
            var bucketInfoArray = Object.keys(this.buckets).filter(name => name && name.charAt(0) === '_').map(name => {
                var entries = this.buckets[name];
                var documents = [];
                for (var i in entries) {
                    var entry = entries[i];
                    documents.push({
                        name: i,
                        refCount: entry.refCount,
                        references: entry.owners.slice(0)
                    });
                }
                documents.sort((x, y) => y.refCount - x.refCount);
                return { bucket: name, documents: documents }
            });
            return JSON.stringify(bucketInfoArray, null, 2);
        }

        public acquireDocument(
            filename: string,
            compilationSettings: ts.CompilerOptions,
            scriptSnapshot: IScriptSnapshot,
            byteOrderMark: ByteOrderMark,
            version: number,
            isOpen: boolean,
            referencedFiles: string[]= []): TypeScript.Document {

            var bucket = this.getBucketForCompilationSettings(compilationSettings, /*createIfMissing*/ true);
            var entry = bucket[filename];
            if (!entry) {
                var document = Document.create(compilationSettings, filename, scriptSnapshot, byteOrderMark, version, isOpen, referencedFiles);

                entry = new DocumentRegistryEntry(document);
                bucket[filename] = entry;
            }
            entry.refCount++;

            return entry.document;
        }

        public updateDocument(
            document: Document,
            filename: string,
            compilationSettings: ts.CompilerOptions,
            scriptSnapshot: IScriptSnapshot,
            version: number,
            isOpen: boolean,
            textChangeRange: TextChangeRange
            ): TypeScript.Document {

            var bucket = this.getBucketForCompilationSettings(compilationSettings, /*createIfMissing*/ false);
            Debug.assert(bucket);
            var entry = bucket[filename];
            Debug.assert(entry);

            if (entry.document.isOpen === isOpen && entry.document.version === version) {
                return entry.document;
            }

            entry.document = entry.document.update(scriptSnapshot, version, isOpen, textChangeRange);
            return entry.document;
        }

        public releaseDocument(filename: string, compilationSettings: ts.CompilerOptions): void {
            var bucket = this.getBucketForCompilationSettings(compilationSettings, false);
            Debug.assert(bucket);

            var entry = bucket[filename];
            entry.refCount--;

            Debug.assert(entry.refCount >= 0);
            if (entry.refCount === 0) {
                delete bucket[filename];
            }
        }
    }

    export class LanguageService implements ILanguageService {
        private logger: TypeScript.ILogger;
        private _syntaxTreeCache: SyntaxTreeCache;
        private formattingRulesProvider: Formatting.RulesProvider;

        // A cache of all the information about the files on the host side.
        private hostCache: HostCache = null;
        private program: ts.Program;
        private typeChecker: ts.TypeChecker;
        private useCaseSensitivefilenames = false;
        private documentsByName: ts.Map<Document> = {};
        private documentRegistry: IDocumentRegistry
        private cancellationToken: CancellationToken;
        private activeCompletionSession: CompletionSession;

        constructor(public host: ILanguageServiceHost, documentRegistry: IDocumentRegistry) {
            this.logger = this.host;
            this.cancellationToken = new CancellationToken(this.host.getCancellationToken());
            this.documentRegistry = documentRegistry;
            this._syntaxTreeCache = new SyntaxTreeCache(this.host);

            // Check if the localized messages json is set, otherwise query the host for it
            if (!TypeScript.LocalizedDiagnosticMessages) {
                TypeScript.LocalizedDiagnosticMessages = this.host.getLocalizedDiagnosticMessages();
            }
        }

        private createCompilerHost(): ts.CompilerHost {
            return {
                getSourceFile: (filename, languageVersion) => {
                    var document = this.documentsByName[filename];

                    Debug.assert(!!document, "document can not be undefined");

                    return document.sourceFile();
                },
                getCancellationToken: () => this.cancellationToken,
                getCanonicalFileName: (filename) => this.useCaseSensitivefilenames ? filename : filename.toLowerCase(),
                useCaseSensitiveFileNames: () => this.useCaseSensitivefilenames,
                getNewLine: ()=> "\n",
                // Need something that doesn't depend on sys.ts here
                getDefaultLibFilename: (): string => {
                    throw Error("TOD:: getDefaultLibfilename");
                },
                writeFile: (filename, data) => {
                    throw Error("TODO: write file");
                },
                getCurrentDirectory: (): string => {
                    throw Error("TODO: getCurrentDirectory");
                }
            };
        }

        private synchronizeHostData(): void {
            // Reset the cache at start of every refresh
            this.hostCache = new HostCache(this.host);

            var compilationSettings = this.hostCache.compilationSettings();

            // TODO: check if we need to create a new compiler to start with
            //       1. files are identical
            //       2. compilation settings are identical

            // Now, remove any files from the compiler that are no longer in the host.
            var oldProgram = this.program;
            if (oldProgram) {
                var oldSettings = this.program.getCompilerOptions();

                // If the language version changed, then that affects what types of things we parse. So
                // we have to dump all syntax trees.
                // TODO: handle propagateEnumConstants
                var settingsChangeAffectsSyntax = oldSettings.target !== compilationSettings.target;

                var changesInCompilationSettingsAffectSyntax =
                    oldSettings && compilationSettings && !compareDataObjects(oldSettings, compilationSettings) && settingsChangeAffectsSyntax;
                var oldSourceFiles = this.program.getSourceFiles();

                for (var i = 0, n = oldSourceFiles.length; i < n; i++) {
                    this.cancellationToken.throwIfCancellationRequested();
                    var filename = oldSourceFiles[i].filename;
                    if (!this.hostCache.contains(filename) || changesInCompilationSettingsAffectSyntax) {
                        this.documentRegistry.releaseDocument(filename, oldSettings);
                        delete this.documentsByName[filename];
                    }
                }
            }

            // Now, for every file the host knows about, either add the file (if the compiler
            // doesn't know about it.).  Or notify the compiler about any changes (if it does
            // know about it.)
            var hostfilenames = this.hostCache.getfilenames();

            for (var i = 0, n = hostfilenames.length; i < n; i++) {
                var filename = hostfilenames[i];

                var version = this.hostCache.getVersion(filename);
                var isOpen = this.hostCache.isOpen(filename);
                var scriptSnapshot = this.hostCache.getScriptSnapshot(filename);

                var document: Document = this.documentsByName[filename];
                if (document) {
                    //
                    // If the document is the same, assume no update
                    //
                    if (document.version === version && document.isOpen === isOpen) {
                        continue;
                    }

                    // Only perform incremental parsing on open files that are being edited.  If a file was
                    // open, but is now closed, we want to reparse entirely so we don't have any tokens that
                    // are holding onto expensive script snapshot instances on the host.  Similarly, if a 
                    // file was closed, then we always want to reparse.  This is so our tree doesn't keep 
                    // the old buffer alive that represented the file on disk (as the host has moved to a 
                    // new text buffer).
                    var textChangeRange: TextChangeRange = null;
                    if (document.isOpen && isOpen) {
                        textChangeRange = this.hostCache.getScriptTextChangeRangeSinceVersion(filename, document.version);
                    }

                    document = this.documentRegistry.updateDocument(document, filename, compilationSettings, scriptSnapshot, version, isOpen, textChangeRange);
                }
                else {
                    document = this.documentRegistry.acquireDocument(filename, compilationSettings, scriptSnapshot, this.hostCache.getByteOrderMark(filename), version, isOpen, []);
                }

                // Remeber the new document
                this.documentsByName[filename] = document;
            }

            // Now create a new compiler
            this.program = ts.createProgram(hostfilenames, compilationSettings, this.createCompilerHost());
            this.typeChecker = this.program.getTypeChecker();
        }

        dispose(): void {
            if (this.program) {
                ts.forEach(this.program.getSourceFiles(),
                    (f) => this.documentRegistry.releaseDocument(f.filename, this.program.getCompilerOptions()));
            }
        }

        refresh() {
            // No-op.  Only kept around for compatability with the interface we shipped.
        }
        cleanupSemanticCache() { }

        getSyntacticDiagnostics(filename: string) {
            this.synchronizeHostData();
            return this.program.getDiagnostics(this.program.getSourceFile(filename));
        }
        getSemanticDiagnostics(filename: string) {
            this.synchronizeHostData();
            return this.typeChecker.getDiagnostics(this.program.getSourceFile(filename));
        }
        getCompilerOptionsDiagnostics() {
            this.synchronizeHostData();
            return this.program.getGlobalDiagnostics();
        }

        private getCompletionEntriesFromSymbols(symbols: ts.Symbol[], session:CompletionSession): void {
            ts.forEach(symbols, (symbol) => {
                var entry = this.createCompletionEntry(symbol);
                if (entry) {
                    session.entries.push(entry);
                    session.symbols[entry.name] = symbol;
                }
            });
        }

        private createCompletionEntry(symbol: ts.Symbol): CompletionEntry {
            // Try to get a valid display name for this symbol, if we could not find one, then ignore it. 
            // We would like to only show things that can be added after a dot, so for instance numeric properties can
            // not be accessed with a dot (a.1 <- invalid)
            var displayName = CompletionHelpers.getValidCompletionEntryDisplayName(symbol.getName(), this.program.getCompilerOptions().target);
            if (!displayName) {
                return undefined;
            }

            var declarations = symbol.getDeclarations();
            var firstDeclaration = [0];
            return {
                name: displayName,
                kind: this.getSymbolKind(symbol),
                kindModifiers: declarations ? this.getNodeModifiers(declarations[0]) : ScriptElementKindModifier.none
            };
        }

        getCompletionsAtPosition(filename: string, position: number, isMemberCompletion: boolean) {
            this.synchronizeHostData();

            filename = TypeScript.switchToForwardSlashes(filename);

            var document = this.documentsByName[filename];
            var sourceUnit = document.sourceUnit();

            if (CompletionHelpers.isCompletionListBlocker(document.syntaxTree().sourceUnit(), position)) {
                this.logger.log("Returning an empty list because completion was blocked.");
                return null;
            }

            var node = TypeScript.ASTHelpers.getAstAtPosition(sourceUnit, position, /*useTrailingTriviaAsLimChar*/ true, /*forceInclusive*/ true);

            if (node && node.kind() === TypeScript.SyntaxKind.IdentifierName &&
                start(node) === end(node)) {
                // Ignore missing name nodes
                node = node.parent;
            }

            var isRightOfDot = false;
            if (node &&
                node.kind() === TypeScript.SyntaxKind.MemberAccessExpression &&
                end((<TypeScript.MemberAccessExpressionSyntax>node).expression) < position) {

                isRightOfDot = true;
                node = (<TypeScript.MemberAccessExpressionSyntax>node).expression;
            }
            else if (node &&
                node.kind() === TypeScript.SyntaxKind.QualifiedName &&
                end((<TypeScript.QualifiedNameSyntax>node).left) < position) {

                isRightOfDot = true;
                node = (<TypeScript.QualifiedNameSyntax>node).left;
            }
            else if (node && node.parent &&
                node.kind() === TypeScript.SyntaxKind.IdentifierName &&
                node.parent.kind() === TypeScript.SyntaxKind.MemberAccessExpression &&
                (<TypeScript.MemberAccessExpressionSyntax>node.parent).name === node) {

                isRightOfDot = true;
                node = (<TypeScript.MemberAccessExpressionSyntax>node.parent).expression;
            }
            else if (node && node.parent &&
                node.kind() === TypeScript.SyntaxKind.IdentifierName &&
                node.parent.kind() === TypeScript.SyntaxKind.QualifiedName &&
                (<TypeScript.QualifiedNameSyntax>node.parent).right === node) {

                isRightOfDot = true;
                node = (<TypeScript.QualifiedNameSyntax>node.parent).left;
            }

            // TODO: this is a hack for now, we need a proper walking mechanism to verify that we have the correct node
            var mappedNode = this.getNodeAtPosition(document.sourceFile(), end(node) - 1);

            Debug.assert(mappedNode, "Could not map a Fidelity node to an AST node");

            // Get the completions
            this.activeCompletionSession = {
                filename: filename,
                position: position,
                entries: [],
                symbols: {},
                location: mappedNode,
                typeChecker: this.typeChecker
            };

            // Right of dot member completion list
            if (isRightOfDot) {
                var type: ts.Type = this.typeChecker.getTypeOfExpression(mappedNode);
                if (!type) {
                    return undefined;
                }

                var symbols = type.getApparentProperties();
                isMemberCompletion = true;
                this.getCompletionEntriesFromSymbols(symbols, this.activeCompletionSession);
            }
            else {
                var containingObjectLiteral = CompletionHelpers.getContainingObjectLiteralApplicableForCompletion(document.syntaxTree().sourceUnit(), position);

                // Object literal expression, look up possible property names from contextual type
                if (containingObjectLiteral) {
                    var searchPosition = Math.min(position, end(containingObjectLiteral));
                    var path = TypeScript.ASTHelpers.getAstAtPosition(sourceUnit, searchPosition);
                    // Get the object literal node

                    while (node && node.kind() !== TypeScript.SyntaxKind.ObjectLiteralExpression) {
                        node = node.parent;
                    }

                    if (!node || node.kind() !== TypeScript.SyntaxKind.ObjectLiteralExpression) {
                        // AST Path look up did not result in the same node as Fidelity Syntax Tree look up.
                        // Once we remove AST this will no longer be a problem.
                        return null;
                    }

                    isMemberCompletion = true;

                    //// Try to get the object members form contextual typing
                    //var contextualMembers = this.compiler.getContextualMembersFromAST(node, document);
                    //if (contextualMembers && contextualMembers.symbols && contextualMembers.symbols.length > 0) {
                    //    // get existing members
                    //    var existingMembers = this.compiler.getVisibleMemberSymbolsFromAST(node, document);

                    //    // Add filtterd items to the completion list
                    //    this.getCompletionEntriesFromSymbols({
                    //        symbols: CompletionHelpers.filterContextualMembersList(contextualMembers.symbols, existingMembers, filename, position),
                    //        enclosingScopeSymbol: contextualMembers.enclosingScopeSymbol
                    //    }, entries);
                    //}
                }
                // Get scope memebers
                else {
                    isMemberCompletion = false;
                    /// TODO filter meaning based on the current context
                    var symbolMeanings = ts.SymbolFlags.Type | ts.SymbolFlags.Value | ts.SymbolFlags.Namespace;
                    var symbols = this.typeChecker.getSymbolsInScope(mappedNode, symbolMeanings);

                    this.getCompletionEntriesFromSymbols(symbols, this.activeCompletionSession);
                }
            }

            // Add keywords if this is not a member completion list
            if (!isMemberCompletion) {
                Array.prototype.push.apply(this.activeCompletionSession.entries, KeywordCompletions.getKeywordCompltions());
            }

            return {
                isMemberCompletion: isMemberCompletion,
                entries: this.activeCompletionSession.entries
            };
        }
        getCompletionEntryDetails(filename: string, position: number, entryName: string) {
            // Note: No need to call synchronizeHostData, as we have captured all the data we need
            //       in the getCompletionsAtPosition erlier
            filename = TypeScript.switchToForwardSlashes(filename);

            var session = this.activeCompletionSession;

            // Ensure that the current active completion session is still valid for this request
            if (!session || session.filename !== filename || session.position !== position) {
                return undefined;
            }

            var symbol = this.activeCompletionSession.symbols[entryName];
            if (symbol) {
                var type = session.typeChecker.getTypeOfSymbol(symbol);
                Debug.assert(type, "Could not find type for symbol");
                var completionEntry = this.createCompletionEntry(symbol);
                return {
                    name: entryName,
                    kind: completionEntry.kind,
                    kindModifiers: completionEntry.kindModifiers,
                    type: session.typeChecker.typeToString(type, session.location),
                    fullSymbolName: this.typeChecker.symbolToString(symbol, session.location),
                    docComment: ""
                };
            }
            else {
                // No symbol, it is a keyword
                return {
                    name: entryName,
                    kind: ScriptElementKind.keyword,
                    kindModifiers: ScriptElementKindModifier.none,
                    type: undefined,
                    fullSymbolName: entryName,
                    docComment: undefined
                };
            }
        }

        private getNodeAtPosition(sourceFile: ts.SourceFile, position: number) {
            var current: ts.Node = sourceFile;
            outer: while (true) {
                // find the child that has this
                for (var i = 0, n = current.getChildCount(); i < n; i++) {
                    var child = current.getChildAt(i);
                    if (ts.getTokenPosOfNode(child) <= position && position < child.end) {
                        current = child;
                        continue outer;
                    }
                    if (child.end > position) break;
                }
                return current;
            }
        }

        private getEnclosingDeclaration(node: ts.Node): ts.Node {
            while (true) {
                node = node.parent;
                if (!node) {
                    return node;
                }
                switch (node.kind) {
                    case ts.SyntaxKind.Method:
                    case ts.SyntaxKind.FunctionDeclaration:
                    case ts.SyntaxKind.FunctionExpression:
                    case ts.SyntaxKind.GetAccessor:
                    case ts.SyntaxKind.SetAccessor:
                    case ts.SyntaxKind.ClassDeclaration:
                    case ts.SyntaxKind.InterfaceDeclaration:
                    case ts.SyntaxKind.EnumDeclaration:
                    case ts.SyntaxKind.ModuleDeclaration:
                        return node;
                }
            }
        }

        getSymbolKind(symbol: ts.Symbol): string {
            var flags = symbol.getFlags();

            if (flags & ts.SymbolFlags.Module) return ScriptElementKind.moduleElement;
            if (flags & ts.SymbolFlags.Class) return ScriptElementKind.classElement;
            if (flags & ts.SymbolFlags.Interface) return ScriptElementKind.interfaceElement;
            if (flags & ts.SymbolFlags.Enum) return ScriptElementKind.enumElement;
            if (flags & ts.SymbolFlags.Variable) return ScriptElementKind.variableElement;
            if (flags & ts.SymbolFlags.Function) return ScriptElementKind.functionElement;
            if (flags & ts.SymbolFlags.GetAccessor) return ScriptElementKind.memberGetAccessorElement;
            if (flags & ts.SymbolFlags.SetAccessor) return ScriptElementKind.memberSetAccessorElement;
            if (flags & ts.SymbolFlags.Method) return ScriptElementKind.memberFunctionElement;
            if (flags & ts.SymbolFlags.Property) return ScriptElementKind.memberVariableElement;
            if (flags & ts.SymbolFlags.IndexSignature) return ScriptElementKind.indexSignatureElement;
            if (flags & ts.SymbolFlags.ConstructSignature) return ScriptElementKind.constructSignatureElement;
            if (flags & ts.SymbolFlags.CallSignature) return ScriptElementKind.callSignatureElement;
            if (flags & ts.SymbolFlags.Constructor) return ScriptElementKind.constructorImplementationElement;
            if (flags & ts.SymbolFlags.TypeParameter) return ScriptElementKind.typeParameterElement;
            if (flags & ts.SymbolFlags.EnumMember) return ScriptElementKind.variableElement;

            return ScriptElementKind.unknown;
        }

        getTypeKind(type: ts.Type): string {
            var flags = type.getFlags();

            if (flags & ts.TypeFlags.Enum) return ScriptElementKind.enumElement;
            if (flags & ts.TypeFlags.Class) return ScriptElementKind.classElement;
            if (flags & ts.TypeFlags.Interface) return ScriptElementKind.interfaceElement;
            if (flags & ts.TypeFlags.TypeParameter) return ScriptElementKind.typeParameterElement;
            if (flags & ts.TypeFlags.Intrinsic) return ScriptElementKind.primitiveType;
            if (flags & ts.TypeFlags.StringLiteral) return ScriptElementKind.primitiveType;

            return ScriptElementKind.unknown;
        }

        getNodeModifiers(node: ts.Node): string {
            var flags = node.flags;
            var result: string[] = [];

            if (flags & ts.NodeFlags.Private) result.push(ScriptElementKindModifier.privateMemberModifier);
            if (flags & ts.NodeFlags.Public) result.push(ScriptElementKindModifier.publicMemberModifier);
            if (flags & ts.NodeFlags.Static) result.push(ScriptElementKindModifier.staticModifier);
            if (flags & ts.NodeFlags.Export) result.push(ScriptElementKindModifier.exportedModifier);
            if (ts.isInAmbientContext(node)) result.push(ScriptElementKindModifier.ambientModifier);

            return result.length > 0 ? result.join(',') : ScriptElementKindModifier.none;
        }

        getTypeAtPosition(filename: string, position: number): TypeInfo {
            this.synchronizeHostData();

            filename = TypeScript.switchToForwardSlashes(filename);
            var document = this.documentsByName[filename];
            var node = this.getNodeAtPosition(document.sourceFile(), position);
            if (!node) return undefined;
            
            switch (node.kind) {
                // A declaration
                case ts.SyntaxKind.Identifier:
                    if (node.parent.kind === ts.SyntaxKind.CallExpression || node.parent.kind === ts.SyntaxKind.NewExpression) {
                        // TODO: handle new and call expressions
                    }

                    var symbol = this.typeChecker. getSymbolOfIdentifier(<ts.Identifier>node);
                    Debug.assert(symbol, "getTypeAtPosition: Could not find symbol for node");
                    var type = this.typeChecker.getTypeOfSymbol(symbol);

                    return {
                        memberName: new MemberNameString(this.typeChecker.typeToString(type)),
                        docComment: "",
                        fullSymbolName: this.typeChecker.symbolToString(symbol, this.getEnclosingDeclaration(node)),
                        kind: this.getSymbolKind(symbol),
                        minChar: node.pos,
                        limChar: node.end
                    };

                // An Expression
                case ts.SyntaxKind.ThisKeyword:
                case ts.SyntaxKind.QualifiedName:
                case ts.SyntaxKind.SuperKeyword:
                case ts.SyntaxKind.StringLiteral:
                    var type = this.typeChecker.getTypeOfExpression(node);
                    Debug.assert(type, "getTypeAtPosition: Could not find type for node");
                    return {
                        memberName: new MemberNameString(""),
                        docComment: "",
                        fullSymbolName: this.typeChecker.typeToString(type, this.getEnclosingDeclaration(node)),
                        kind: this.getTypeKind(type),
                        minChar: node.pos,
                        limChar: node.end
                    };
                    break;
            }
        }
        getSignatureAtPosition(filename: string, position: number) {
            return undefined;
        }
        getDefinitionAtPosition(filename: string, position: number) {
            return [];
        }
        getReferencesAtPosition(filename: string, position: number) {
            return [];
        }
        getOccurrencesAtPosition(filename: string, position: number) {
            return [];
        }
        getImplementorsAtPosition(filename: string, position: number) {
            return [];
        }
        getNavigateToItems(searchValue: string) {
            return [];
        }
        getEmitOutput(filename: string) {
            return undefined;
        }

        private getTypeInfoEligiblePath(filename: string, position: number, isConstructorValidPosition: boolean) {
            var sourceUnit = this._syntaxTreeCache.getCurrentFileSyntaxTree(filename).sourceUnit();

            var ast = TypeScript.ASTHelpers.getAstAtPosition(sourceUnit, position, /*useTrailingTriviaAsLimChar*/ false, /*forceInclusive*/ true);
            if (ast === null) {
                return null;
            }

            if (ast.kind() === SyntaxKind.ParameterList && ast.parent.kind() === SyntaxKind.CallSignature && ast.parent.parent.kind() === SyntaxKind.ConstructorDeclaration) {
                ast = ast.parent.parent;
            }

            switch (ast.kind()) {
                default:
                    return null;
                case TypeScript.SyntaxKind.ConstructorDeclaration:
                    var constructorAST = <TypeScript.ConstructorDeclarationSyntax>ast;
                    if (!isConstructorValidPosition || !(position >= start(constructorAST) && position <= start(constructorAST) + "constructor".length)) {
                        return null;
                    }
                    else {
                        return ast;
                    }
                case TypeScript.SyntaxKind.FunctionDeclaration:
                    return null;
                case TypeScript.SyntaxKind.MemberAccessExpression:
                case TypeScript.SyntaxKind.QualifiedName:
                case TypeScript.SyntaxKind.SuperKeyword:
                case TypeScript.SyntaxKind.StringLiteral:
                case TypeScript.SyntaxKind.ThisKeyword:
                case TypeScript.SyntaxKind.IdentifierName:
                    return ast;
            }
        }
        getNameOrDottedNameSpan(filename: string, startPos: number, endPos: number): SpanInfo {
            filename = TypeScript.switchToForwardSlashes(filename);

            var node = this.getTypeInfoEligiblePath(filename, startPos, false);
            if (!node)  return null;

            while (node) {
                if (TypeScript.ASTHelpers.isNameOfMemberAccessExpression(node) ||
                    TypeScript.ASTHelpers.isRightSideOfQualifiedName(node)) {
                    node = node.parent;
                }
                else {
                    break;
                }
            }

            return {
                minChar: start(node),
                limChar: end(node)
            };
        }
        getBreakpointStatementAtPosition(filename: string, position: number) {
            // doesn't use compiler - no need to synchronize with host
            filename = TypeScript.switchToForwardSlashes(filename);

            var syntaxtree = this.getSyntaxTree(filename);
            return TypeScript.Services.Breakpoints.getBreakpointLocation(syntaxtree, position);
        }
        getScriptLexicalStructure(filename: string) {
            filename = TypeScript.switchToForwardSlashes(filename);
            var syntaxTree = this.getSyntaxTree(filename);
            var items: NavigateToItem[] = [];
            GetScriptLexicalStructureWalker.getListsOfAllScriptLexicalStructure(items, filename, syntaxTree.sourceUnit());
            return items;
        }
        getOutliningRegions(filename: string) {
            // doesn't use compiler - no need to synchronize with host
            filename = TypeScript.switchToForwardSlashes(filename);
            var syntaxTree = this.getSyntaxTree(filename);
            return OutliningElementsCollector.collectElements(syntaxTree.sourceUnit());
        }
        getBraceMatchingAtPosition(filename: string, position: number) {
            filename = TypeScript.switchToForwardSlashes(filename);
            var syntaxTree = this.getSyntaxTree(filename);
            return BraceMatcher.getMatchSpans(syntaxTree, position);
        }
        getIndentationAtPosition(filename: string, position: number, editorOptions: EditorOptions) {
            filename = TypeScript.switchToForwardSlashes(filename);

            var syntaxTree = this.getSyntaxTree(filename);

            var scriptSnapshot = this._syntaxTreeCache.getCurrentScriptSnapshot(filename);
            var scriptText = TypeScript.SimpleText.fromScriptSnapshot(scriptSnapshot);
            var textSnapshot = new TypeScript.Services.Formatting.TextSnapshot(scriptText);
            var options = new FormattingOptions(!editorOptions.ConvertTabsToSpaces, editorOptions.TabSize, editorOptions.IndentSize, editorOptions.NewLineCharacter)

            return TypeScript.Services.Formatting.SingleTokenIndenter.getIndentationAmount(position, syntaxTree.sourceUnit(), textSnapshot, options);
        }
        getFormattingEditsForRange(filename: string, minChar: number, limChar: number, options: FormatCodeOptions): TextEdit[] {
            filename = TypeScript.switchToForwardSlashes(filename);

            var manager = this.getFormattingManager(filename, options);
            return manager.formatSelection(minChar, limChar);
        }
        getFormattingEditsForDocument(filename: string, minChar: number, limChar: number, options: FormatCodeOptions): TextEdit[] {
            filename = TypeScript.switchToForwardSlashes(filename);

            var manager = this.getFormattingManager(filename, options);
            return manager.formatDocument(minChar, limChar);
        }
        getFormattingEditsOnPaste(filename: string, minChar: number, limChar: number, options: FormatCodeOptions): TextEdit[] {
            filename = TypeScript.switchToForwardSlashes(filename);

            var manager = this.getFormattingManager(filename, options);
            return manager.formatOnPaste(minChar, limChar);
        }
        getFormattingEditsAfterKeystroke(filename: string, position: number, key: string, options: FormatCodeOptions): TextEdit[] {
            filename = TypeScript.switchToForwardSlashes(filename);

            var manager = this.getFormattingManager(filename, options);
            if (key === "}")  return manager.formatOnClosingCurlyBrace(position);
            else if (key === ";")  return manager.formatOnSemicolon(position);
            else if (key === "\n") return manager.formatOnEnter(position);
            else return [];
        }
        private getFormattingManager(filename: string, options: FormatCodeOptions) {
            // Ensure rules are initialized and up to date wrt to formatting options
            if (this.formattingRulesProvider == null) {
                this.formattingRulesProvider = new TypeScript.Services.Formatting.RulesProvider(this.logger);
            }

            this.formattingRulesProvider.ensureUpToDate(options);

            // Get the Syntax Tree
            var syntaxTree = this.getSyntaxTree(filename);

            // Convert IScriptSnapshot to ITextSnapshot
            var scriptSnapshot = this._syntaxTreeCache.getCurrentScriptSnapshot(filename);
            var scriptText = TypeScript.SimpleText.fromScriptSnapshot(scriptSnapshot);
            var textSnapshot = new TypeScript.Services.Formatting.TextSnapshot(scriptText);

            var manager = new TypeScript.Services.Formatting.FormattingManager(syntaxTree, textSnapshot, this.formattingRulesProvider, options);

            return manager;
        }
        getSyntaxTree(filename: string): TypeScript.SyntaxTree {
            filename = TypeScript.switchToForwardSlashes(filename);
            return this._syntaxTreeCache.getCurrentFileSyntaxTree(filename);
        }
    }
}