// ***********************************************************************
// Assembly         : Construction
// Author           : zjx
// Created          : 09-16-2020
//
// Last Modified By : zjx
// Last Modified On : 09-16-2020
// ***********************************************************************
// <copyright file="EnumerableExtensions.cs" company="jindongfang">
// Copyright (c) jindongfang. All rights reserved.
// </copyright>
// <summary></summary>
// ***********************************************************************
using System;
using System.Collections.Generic;
using System.Linq;

namespace WellWorkDataUI
{
    /// <summary>
    /// Class EnumerableExtensions.
    /// </summary>
    public static class EnumerableExtensions
    {
        /// <summary>
        /// Orders the by list.
        /// </summary>
        /// <typeparam name="TSource">The type of the t source.</typeparam>
        /// <typeparam name="TOrder">The type of the t order.</typeparam>
        /// <param name="source">The source.</param>
        /// <param name="order">The order.</param>
        /// <param name="equal">The equal.</param>
        /// <returns>IEnumerable&lt;TSource&gt;.</returns>
        public static IEnumerable<TSource> OrderByList<TSource, TOrder>(this IEnumerable<TSource> source, IEnumerable<TOrder> order, Func<TSource, TOrder, bool> equal)
        {
            IEnumerable<TSource> result = from s in source
                                          from o in order.Select((v, i) => new { obj = v, index = i })
                                          where equal(s, o.obj)
                                          orderby o.index
                                          select s;

            return result.Union(source.Where(r => !order.Any(k => equal(r, k))));
        }

        /// <summary>
        /// MinOrDefault
        /// </summary>
        /// <typeparam name="T">t</typeparam>
        /// <param name="sequence">sequence</param>
        /// <returns>T</returns>
        public static T MinOrDefault<T>(this IEnumerable<T> sequence)
        {
            if (sequence.Any())
            {
                return sequence.Min();
            }
            else
            {
                return default(T);
            }
        }

        /// <summary>
        /// MaxOrDefault
        /// </summary>
        /// <typeparam name="T">t</typeparam>
        /// <param name="sequence">sequence</param>
        /// <returns>T</returns>
        public static T MaxOrDefault<T>(this IEnumerable<T> sequence)
        {
            if (sequence.Any())
            {
                return sequence.Max();
            }
            else
            {
                return default(T);
            }
        }

        /// <summary>
        /// SumOrDefault
        /// </summary>
        /// <typeparam name="T">t</typeparam>
        /// <param name="sequence">sequence</param>
        /// <returns>T</returns>
        public static double? SumOrDefault(this IEnumerable<double?> sequence)
        {
            if (sequence.Any())
            {
                return sequence.Sum();
            }
            else
            {
                return default(double?);
            }
        }
    }
}