namespace GFGGame
{
    //两边扩散结构
    //初始化时从最大值，最小值之间随机一个值
    //每次取值从两边随机一边取值
    public struct BilateralDiffusionStruct
    {
        private readonly int minValue;
        private readonly int maxValue;
        public int leftPosition;
        public int rightPosition;

        public BilateralDiffusionStruct(int minValue, int maxValue)
        {
            this.minValue = minValue;
            this.maxValue = maxValue;
            var currenValue = RandomUtil.RandomInt(minValue, maxValue);
            if (currenValue == maxValue)
            {
                leftPosition = currenValue;
                rightPosition = currenValue;
            }
            else
            {
                leftPosition = currenValue;
                rightPosition = currenValue + 1;
            }
        }

        public BilateralDiffusionStruct(int minValue, int maxValue, int leftPosition, int rightPosition)
        {
            this.minValue = minValue;
            this.maxValue = maxValue;
            this.leftPosition = leftPosition;
            this.rightPosition = rightPosition;
        }

        public int NextValue()
        {
            int nextValue;
            if (leftPosition > minValue && rightPosition < maxValue)
            {
                nextValue = RandomUtil.RandomNext(2) == 0 ? leftPosition-- : rightPosition++;
            }
            else if (leftPosition <= minValue && rightPosition >= maxValue)
            {
                return -1;
            }
            else if (leftPosition < minValue)
            {
                nextValue = rightPosition++;
            }
            else
            {
                nextValue = leftPosition--;
            }

            return nextValue;
        }

        public bool IsFull()
        {
            return leftPosition < minValue && rightPosition > maxValue;
        }
    }
}