using System;

namespace Unity.IO.Compression
{
	internal class OutputWindow
	{
		private const int WindowSize = 32768;

		private const int WindowMask = 32767;

		private byte[] window = new byte[32768];

		private int end;

		private int bytesUsed;

		public int FreeBytes
		{
			get
			{
				return 32768 - bytesUsed;
			}
		}

		public int AvailableBytes
		{
			get
			{
				return bytesUsed;
			}
		}

		public void Write(byte b)
		{
			window[end++] = b;
			end &= 32767;
			bytesUsed++;
		}

		public void WriteLengthDistance(int length, int distance)
		{
			bytesUsed += length;
			int num = (end - distance) & 0x7FFF;
			int num2 = 32768 - length;
			if (num <= num2 && end < num2)
			{
				if (length <= distance)
				{
					Array.Copy(window, num, window, end, length);
					end += length;
				}
				else
				{
					while (length-- > 0)
					{
						window[end++] = window[num++];
					}
				}
			}
			else
			{
				while (length-- > 0)
				{
					window[end++] = window[num++];
					end &= 32767;
					num &= 0x7FFF;
				}
			}
		}

		public int CopyFrom(InputBuffer input, int length)
		{
			length = Math.Min(Math.Min(length, 32768 - bytesUsed), input.AvailableBytes);
			int num = 32768 - end;
			int num2;
			if (length > num)
			{
				num2 = input.CopyTo(window, end, num);
				if (num2 == num)
				{
					num2 += input.CopyTo(window, 0, length - num);
				}
			}
			else
			{
				num2 = input.CopyTo(window, end, length);
			}
			end = (end + num2) & 0x7FFF;
			bytesUsed += num2;
			return num2;
		}

		public int CopyTo(byte[] output, int offset, int length)
		{
			int num;
			if (length > bytesUsed)
			{
				num = end;
				length = bytesUsed;
			}
			else
			{
				num = (end - bytesUsed + length) & 0x7FFF;
			}
			int num2 = length;
			int num3 = length - num;
			if (num3 > 0)
			{
				Array.Copy(window, 32768 - num3, output, offset, num3);
				offset += num3;
				length = num;
			}
			Array.Copy(window, num - length, output, offset, length);
			bytesUsed -= num2;
			return num2;
		}
	}
}