export function provideSignatureHelp(model: ITextModel, position: Position, token: CancellationToken): Promise<SignatureHelp> {

	const supports = SignatureHelpProviderRegistry.ordered(model);

	return first2(supports.map(support => () => {
		return Promise.resolve(support.provideSignatureHelp(model, position, token)).catch(onUnexpectedExternalError);
	}));
}

export function provideSignatureHelp(model: ITextModel, position: Position, context: modes.SignatureHelpContext, token: CancellationToken): Promise<modes.SignatureHelp | null | undefined> {

	const supports = modes.SignatureHelpProviderRegistry.ordered(model);

	return first(supports.map(support => () => {
		return Promise.resolve(support.provideSignatureHelp(model, position, token, context)).catch(onUnexpectedExternalError);
	}));
}

export function provideSignatureHelp(model:IModel, position:IEditorPosition, cancellationToken = CancellationToken.None): Thenable<SignatureHelp> {

	let support = SignatureHelpProviderRegistry.ordered(model)[0];
	if (!support) {
		return TPromise.as(undefined);
	}

	return toThenable(support.provideSignatureHelp(model, position, cancellationToken));
}

export function provideSignatureHelp(model:IReadOnlyModel, position:Position): TPromise<SignatureHelp> {
	const support = SignatureHelpProviderRegistry.ordered(model)[0];

	if (!support) {
		return TPromise.as(undefined);
	}

	return asWinJsPromise(token => support.provideSignatureHelp(model, position, token));
}

export function provideSignatureHelp(model: ITextModel, position: Position): TPromise<SignatureHelp> {

	const supports = SignatureHelpProviderRegistry.ordered(model);

	return first(supports.map(support => () => {
		return asWinJsPromise(token => support.provideSignatureHelp(model, position, token))
			.then(undefined, onUnexpectedExternalError);
	}));
}

	constructor(
		editor: ICommonCodeEditor,
		contextKeyService: IContextKeyService
	) {
		super();
		this._editor = editor;

		this._langId = EditorContextKeys.languageId.bindTo(contextKeyService);
		this._hasCompletionItemProvider = EditorContextKeys.hasCompletionItemProvider.bindTo(contextKeyService);
		this._hasCodeActionsProvider = EditorContextKeys.hasCodeActionsProvider.bindTo(contextKeyService);
		this._hasCodeLensProvider = EditorContextKeys.hasCodeLensProvider.bindTo(contextKeyService);
		this._hasDefinitionProvider = EditorContextKeys.hasDefinitionProvider.bindTo(contextKeyService);
		this._hasImplementationProvider = EditorContextKeys.hasImplementationProvider.bindTo(contextKeyService);
		this._hasTypeDefinitionProvider = EditorContextKeys.hasTypeDefinitionProvider.bindTo(contextKeyService);
		this._hasHoverProvider = EditorContextKeys.hasHoverProvider.bindTo(contextKeyService);
		this._hasDocumentHighlightProvider = EditorContextKeys.hasDocumentHighlightProvider.bindTo(contextKeyService);
		this._hasDocumentSymbolProvider = EditorContextKeys.hasDocumentSymbolProvider.bindTo(contextKeyService);
		this._hasReferenceProvider = EditorContextKeys.hasReferenceProvider.bindTo(contextKeyService);
		this._hasRenameProvider = EditorContextKeys.hasRenameProvider.bindTo(contextKeyService);
		this._hasDocumentFormattingProvider = EditorContextKeys.hasDocumentFormattingProvider.bindTo(contextKeyService);
		this._hasDocumentSelectionFormattingProvider = EditorContextKeys.hasDocumentSelectionFormattingProvider.bindTo(contextKeyService);
		this._hasSignatureHelpProvider = EditorContextKeys.hasSignatureHelpProvider.bindTo(contextKeyService);
		this._isInWalkThrough = EditorContextKeys.isInEmbeddedEditor.bindTo(contextKeyService);

		const update = () => this._update();

		// update when model/mode changes
		this._register(editor.onDidChangeModel(update));
		this._register(editor.onDidChangeModelLanguage(update));

		// update when registries change
		this._register(modes.SuggestRegistry.onDidChange(update));
		this._register(modes.CodeActionProviderRegistry.onDidChange(update));
		this._register(modes.CodeLensProviderRegistry.onDidChange(update));
		this._register(modes.DefinitionProviderRegistry.onDidChange(update));
		this._register(modes.ImplementationProviderRegistry.onDidChange(update));
		this._register(modes.TypeDefinitionProviderRegistry.onDidChange(update));
		this._register(modes.HoverProviderRegistry.onDidChange(update));
		this._register(modes.DocumentHighlightProviderRegistry.onDidChange(update));
		this._register(modes.DocumentSymbolProviderRegistry.onDidChange(update));
		this._register(modes.ReferenceProviderRegistry.onDidChange(update));
		this._register(modes.RenameProviderRegistry.onDidChange(update));
		this._register(modes.DocumentFormattingEditProviderRegistry.onDidChange(update));
		this._register(modes.DocumentRangeFormattingEditProviderRegistry.onDidChange(update));
		this._register(modes.SignatureHelpProviderRegistry.onDidChange(update));

		update();
	}

export function provideSignatureHelp(model: ITextModel, position: Position): TPromise<SignatureHelp> {

	const supports = SignatureHelpProviderRegistry.ordered(model);
	let result: SignatureHelp;

	return sequence(supports.map(support => () => {

		if (result) {
			// stop when there is a result
			return undefined;
		}

		return asWinJsPromise(token => support.provideSignatureHelp(model, position, token)).then(thisResult => {
			result = thisResult;
		}, onUnexpectedExternalError);

	})).then(() => result);
}

	private _update() {
		const model = this._editor.getModel();
		if (!model) {
			this.reset();
			return;
		}
		this._langId.set(model.getLanguageIdentifier().language);
		this._hasCompletionItemProvider.set(modes.SuggestRegistry.has(model));
		this._hasCodeActionsProvider.set(modes.CodeActionProviderRegistry.has(model));
		this._hasCodeLensProvider.set(modes.CodeLensProviderRegistry.has(model));
		this._hasDefinitionProvider.set(modes.DefinitionProviderRegistry.has(model));
		this._hasImplementationProvider.set(modes.ImplementationProviderRegistry.has(model));
		this._hasTypeDefinitionProvider.set(modes.TypeDefinitionProviderRegistry.has(model));
		this._hasHoverProvider.set(modes.HoverProviderRegistry.has(model));
		this._hasDocumentHighlightProvider.set(modes.DocumentHighlightProviderRegistry.has(model));
		this._hasDocumentSymbolProvider.set(modes.DocumentSymbolProviderRegistry.has(model));
		this._hasReferenceProvider.set(modes.ReferenceProviderRegistry.has(model));
		this._hasRenameProvider.set(modes.RenameProviderRegistry.has(model));
		this._hasSignatureHelpProvider.set(modes.SignatureHelpProviderRegistry.has(model));
		this._hasDocumentFormattingProvider.set(modes.DocumentFormattingEditProviderRegistry.has(model) || modes.DocumentRangeFormattingEditProviderRegistry.has(model));
		this._hasDocumentSelectionFormattingProvider.set(modes.DocumentRangeFormattingEditProviderRegistry.has(model));
		this._isInWalkThrough.set(model.uri.scheme === Schemas.walkThroughSnippet);
	}

export function registerSignatureHelpProvider(languageId: string, provider: modes.SignatureHelpProvider): IDisposable {
	return modes.SignatureHelpProviderRegistry.register(languageId, provider);
}