using System;

namespace ET
{
    public static class IntFlagHelper
    {
        /// <summary>
        /// 获取标志
        /// example : GetFlag(010203,1,2) == 2
        /// </summary>
        /// <param name="value">标志值</param>
        /// <param name="index">第几个标志 (0,1,2,3)</param>
        /// <param name="flagValue">每个标志的大小，10进制移动次数</param>
        /// <returns></returns>
        public static int GetFlag(int value, int index, int flagValue, int flagCount = 0)
        {
            int perFlag = 1;
            while (flagValue-- > 0)
            {
                perFlag *= BIT;
            }

            using ListComponent<int> listComponent = ListComponent<int>.Create();
            int temp = value;
            while (temp != 0)
            {
                listComponent.List.Add(temp % perFlag);
                temp /= perFlag;
            }

            if (flagCount != 0)
            {
                if (flagCount > listComponent.List.Count)
                {
                    for (int i = listComponent.List.Count; i < flagCount; i++)
                    {
                        listComponent.List.Add(0);
                    }
                }

                if (index >= listComponent.List.Count)
                    throw new IndexOutOfRangeException($"index is invalid when index = {index} and list.Count = {listComponent.List.Count}");
            }

            return listComponent.List[^(index+1)];
        }

        public static long GetFlag(long value, int index, int flagValue, int flagCount = 0)
        {
            int perFlag = 1;
            while (flagValue-- > 0)
            {
                perFlag *= BIT;
            }

            using ListComponent<long> listComponent = ListComponent<long>.Create();
            long temp = value;
            while (temp != 0)
            {
                listComponent.List.Add(temp % perFlag);
                temp /= perFlag;
            }

            if (flagCount != 0)
            {
                if (flagCount > listComponent.List.Count)
                {
                    for (int i = listComponent.List.Count; i < flagCount; i++)
                    {
                        listComponent.List.Add(0);
                    }
                }

                if (index >= listComponent.List.Count)
                    throw new IndexOutOfRangeException($"index is invalid when index = {index} and list.Count = {listComponent.List.Count}");
            }

            return listComponent.List[^(index+1)];
        }

        private const int BIT = 10;

        public static void SetFlagValue(ref int oldValue, int index, int setValue, int flagValue, int flagCount = 0)
        {
            int perFlag = 1;
            while (flagValue-- > 0)
            {
                perFlag *= BIT;
            }

            using ListComponent<int> listComponent = ListComponent<int>.Create();
            int temp = oldValue;
            while (temp != 0)
            {
                listComponent.List.Add(temp % perFlag);
                temp /= perFlag;
            }

            if (Math.Pow(perFlag, listComponent.List.Count) > int.MaxValue)
            {
                throw new OverflowException($"the value is too big : {oldValue} > {Math.Pow(perFlag, listComponent.List.Count)}");
            }

            if (flagCount != 0)
            {
                if (flagCount > listComponent.List.Count)
                {
                    for (int i = listComponent.List.Count; i < flagCount; i++)
                    {
                        listComponent.List.Add(0);
                    }
                }

                if (index >= listComponent.List.Count)
                    throw new IndexOutOfRangeException($"index is invalid when index = {index} and list.Count = {listComponent.List.Count}");
            }

            listComponent.List[^(index + 1)] = setValue;
            oldValue = 0;
            checked
            {
                for (int i = 0; i < listComponent.List.Count; i++)
                {
                    int value = listComponent.List[i];
                    for (int j = 0; j < i; j++)
                    {
                        value *= perFlag;
                    }

                    oldValue += value;
                }
            }
        }

        public static void SetFlagValue(ref long oldValue, int index, long setValue, int flagValue, int flagCount = 0)
        {
            int perFlag = 1;
            while (flagValue-- > 0)
            {
                perFlag *= BIT;
            }

            using ListComponent<long> listComponent = ListComponent<long>.Create();
            long temp = oldValue;
            while (temp != 0)
            {
                listComponent.List.Add(temp % perFlag);
                temp /= perFlag;
            }

            if (Math.Pow(perFlag, listComponent.List.Count) > long.MaxValue)
            {
                throw new OverflowException($"the value is too big : {oldValue} > {Math.Pow(perFlag, listComponent.List.Count)}");
            }

            if (flagCount != 0)
            {
                if (flagCount > listComponent.List.Count)
                {
                    for (int i = listComponent.List.Count; i < flagCount; i++)
                    {
                        listComponent.List.Add(0);
                    }
                }

                if (index >= listComponent.List.Count)
                    throw new IndexOutOfRangeException($"index is invalid when index = {index} and list.Count = {listComponent.List.Count}");
            }

            listComponent.List[^(index + 1)] = setValue;
            oldValue = 0;
            checked
            {
                for (int i = 0; i < listComponent.List.Count; i++)
                {
                    long value = listComponent.List[i];
                    for (int j = 0; j < i; j++)
                    {
                        value *= perFlag;
                    }

                    oldValue += value;
                }
            }
        }
    }
}