export function provideSuggestionItems(model: IReadOnlyModel, position: Position, options: ISuggestOptions = {}): TPromise<ISuggestionItem[]> {

	const result: ISuggestionItem[] = [];
	const suggestFilter = createSuggesionFilter(options);
	const suggestCompare = createSuggesionComparator(options);

	// add suggestions from snippet registry
	const snippets = SnippetsRegistry.getSnippets(model, position);
	fillInSuggestResult(result, snippets, undefined, suggestFilter);


	// add suggestions from contributed providers - providers are ordered in groups of
	// equal score and once a group produces a result the process stops
	let hasResult = false;
	const factory = (options.groups || SuggestRegistry.orderedGroups(model)).map(supports => {
		return () => {
			// stop when we have a result
			if (hasResult) {
				return;
			}
			// for each support in the group ask for suggestions
			return TPromise.join(supports.map(support => asWinJsPromise(token => support.provideCompletionItems(model, position, token)).then(values => {
				if (!isFalsyOrEmpty(values)) {
					for (let suggestResult of values) {
						hasResult = fillInSuggestResult(result, suggestResult, support, suggestFilter) || hasResult;
					}
				}
			}, onUnexpectedError)));
		};
	});

	return sequence(factory).then(() => result.sort(suggestCompare));
}

	return sequence(factory).then(() => {
		// add snippets to the first group
		const snippets = SnippetsRegistry.getSnippets(model, position);
		if (suggestions.length === 0) {
			suggestions.push([snippets]);
		} else {
			suggestions[0].push(snippets);
		}
		return suggestions;
	});

	return sequence(factory).then(() => {
		// add snippets to the first group
		const snippets = SnippetsRegistry.getSnippets(model, position);
		result.push(snippets);
		return result;
	});