/* SPDX-License-Identifier: Apache-2.0
*
* The OpenSearch Contributors require contributions made to
* this file be licensed under the Apache-2.0 license or a
* compatible open source license.
*/
/*
* Modifications Copyright OpenSearch Contributors. See
* GitHub history for details.
*
*  Licensed to Elasticsearch B.V. under one or more contributor
*  license agreements. See the NOTICE file distributed with
*  this work for additional information regarding copyright
*  ownership. Elasticsearch B.V. licenses this file to you under
*  the Apache License, Version 2.0 (the "License"); you may
*  not use this file except in compliance with the License.
*  You may obtain a copy of the License at
*
*   http://www.apache.org/licenses/LICENSE-2.0
*
*  Unless required by applicable law or agreed to in writing,
*  software distributed under the License is distributed on an
*  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
*  KIND, either express or implied.  See the License for the
*  specific language governing permissions and limitations
*  under the License.
*/

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text.RegularExpressions;

namespace ApiGenerator
{
    public static class Extensions
    {
        /// <summary>
        /// Removes _ . but not an underscore at the start of the string, unless the string is _all or removeLeadingUnderscore == true.
        /// </summary>
        private static readonly Regex RemovePunctuationExceptFirstUnderScore = new Regex(@"(?!^_(?!All$))[_\.]");

        public static IEnumerable<T> DistinctBy<T, TKey>(this IEnumerable<T> items, Func<T, TKey> property) =>
            items.GroupBy(property).Select(x => x.First());

        public static string ToPascalCase(this string s, bool removeLeadingUnderscore = false)
        {
            if (string.IsNullOrEmpty(s)) return s;

            var textInfo = new CultureInfo("en-US").TextInfo;
            var titleCased = textInfo.ToTitleCase(s.ToLowerInvariant());
            var result = RemovePunctuationExceptFirstUnderScore.Replace(titleCased, "");
            if (removeLeadingUnderscore)
                result = result.TrimStart('_');
            return result;
        }

        public static string ToCamelCase(this string s)
        {
            if (string.IsNullOrEmpty(s)) return s;

            var pascal = s.ToPascalCase(true);
            if (pascal.Length <= 1) return pascal;

            return char.ToLower(pascal[0]) + pascal.Substring(1);
        }

        public static string SplitPascalCase(this string s) =>
            Regex.Replace(s, "([A-Z]+[a-z]*)", " $1").Trim();

		public static bool IsNullOrEmpty(this string s) =>
			string.IsNullOrEmpty(s);
	}
}