using System;
using System.Collections.Generic;
using System.Linq;

namespace AsbCloudInfrastructure
{
    public static class Helper
    {
        public static T Max<T>(params T[] items)
            where T : IComparable
        {
            var count = items.Length;
            if (count < 1)
                throw new ArgumentException("Count of params must be greater than 1");

            var max = items[0];
            for (var i = 1; i < count; i++)
                if (max.CompareTo(items[i]) < 0)
                    max = items[i];

            return max;
        }

        public static T Min<T>(params T[] items)
            where T : IComparable
        {
            var count = items.Length;
            if (count < 1)
                throw new ArgumentException("Count of params must be greater than 1");

            var min = items[0];
            for (var i = 1; i < count; i++)
                if (min.CompareTo(items[i]) > 0)
                    min = items[i];

            return min;
        }

        public static (T min, T max) MinMax<T>(params T[] items)
            where T : IComparable
        {
            var count = items.Length;
            if (count < 1)
                throw new ArgumentException("Count of params must be greater than 1");

            var min = items[0];
            var max = items[0];
            for (var i = 1; i < count; i++)
                if (max.CompareTo(items[i]) < 0)
                    max = items[i];
                else if (min.CompareTo(items[i]) > 0)
                    min = items[i];

            return (min, max);
        }

        public static List<Tuple<T, T>> MergeArrays<T, Tid>(IEnumerable<T> array1, IEnumerable<T> array2, Func<T, Tid> getId)
            where Tid : IComparable
            where T : class
        {
            var a1 = array1.ToArray();
            var a2 = array2.ToArray();

            var m = new List<Tuple<T, T>>((a1.Length + a2.Length)/3);
            void Add(T item1, T item2) =>
                 m.Add(new Tuple<T, T>(item1, item2));

            int i1 = 0;
            int i2 = 0;
            while (true)
            {
                var is1 = a1.Length > i1;
                var is2 = a2.Length > i2;
                if (!(is1 || is2))
                    break;

                if (is1 && is2)
                {
                    if (getId(a1[i1]).CompareTo(getId(a2[i2])) == 0)
                        Add(a1[i1++], a2[i2++]);
                    else
                    {
                        int nextI1 = Array.IndexOf(a1, a2[i2], i1);
                        int nextI2 = Array.IndexOf(a2, a1[i1], i2);

                        if ((nextI1 > -1) && ((nextI2 == -1) || ((nextI1 - i1) < (nextI2 - i2))))
                        {
                            for (; i1 < nextI1; i1++)
                                Add(a1[i1], null);
                        }

                        if ((nextI2 > -1) && ((nextI1 == -1) || ((nextI1 - i1) > (nextI2 - i2))))
                        {
                            for (; i2 < nextI2; i2++)
                                Add(null, a2[i2]);
                        }

                        if ((nextI1 == -1) && (nextI2 == -1))
                        {
                            for (; i2 < a2.Length; i2++)
                                Add(null, a2[i2]);

                            for (; i1 < a1.Length; i1++)
                                Add(a1[i1], null);
                        }
                    }
                }
                else if (is1)
                {
                    Add(a1[i1++], null);
                }
                else if (is2)
                {
                    Add(null, a2[i2++]);
                }
            }

            return m;
        }
    }
}