/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import * as strings from './strings';

export function buildReplaceStringWithCasePreserved(matches: string[] | null, pattern: string): string {
	if (matches && (matches[0] !== '')) {
		if (matches[0].toUpperCase() === matches[0]) {
			return pattern.toUpperCase();
		} else if (matches[0].toLowerCase() === matches[0]) {
			return pattern.toLowerCase();
		} else if (strings.containsUppercaseCharacter(matches[0][0])) {
			return pattern[0].toUpperCase() + pattern.substr(1);
		} else {
			// we don't understand its pattern yet.
			return pattern;
		}
	} else {
		return pattern;
	}
}