using System;

namespace Unity.IO.Compression
{
	internal class FastEncoder
	{
		private FastEncoderWindow inputWindow;

		private Match currentMatch;

		private double lastCompressionRatio;

		internal int BytesInHistory
		{
			get
			{
				return inputWindow.BytesAvailable;
			}
		}

		internal DeflateInput UnprocessedInput
		{
			get
			{
				return inputWindow.UnprocessedInput;
			}
		}

		internal double LastCompressionRatio
		{
			get
			{
				return lastCompressionRatio;
			}
		}

		public FastEncoder()
		{
			inputWindow = new FastEncoderWindow();
			currentMatch = new Match();
		}

		internal void FlushInput()
		{
			inputWindow.FlushWindow();
		}

		internal void GetBlock(DeflateInput input, OutputBuffer output, int maxBytesToCopy)
		{
			WriteDeflatePreamble(output);
			GetCompressedOutput(input, output, maxBytesToCopy);
			WriteEndOfBlock(output);
		}

		internal void GetCompressedData(DeflateInput input, OutputBuffer output)
		{
			GetCompressedOutput(input, output, -1);
		}

		internal void GetBlockHeader(OutputBuffer output)
		{
			WriteDeflatePreamble(output);
		}

		internal void GetBlockFooter(OutputBuffer output)
		{
			WriteEndOfBlock(output);
		}

		private void GetCompressedOutput(DeflateInput input, OutputBuffer output, int maxBytesToCopy)
		{
			int bytesWritten = output.BytesWritten;
			int num = 0;
			int num2 = BytesInHistory + input.Count;
			do
			{
				int num3 = ((input.Count >= inputWindow.FreeWindowSpace) ? inputWindow.FreeWindowSpace : input.Count);
				if (maxBytesToCopy >= 1)
				{
					num3 = Math.Min(num3, maxBytesToCopy - num);
				}
				if (num3 > 0)
				{
					inputWindow.CopyBytes(input.Buffer, input.StartIndex, num3);
					input.ConsumeBytes(num3);
					num += num3;
				}
				GetCompressedOutput(output);
			}
			while (SafeToWriteTo(output) && InputAvailable(input) && (maxBytesToCopy < 1 || num < maxBytesToCopy));
			int bytesWritten2 = output.BytesWritten;
			int num4 = bytesWritten2 - bytesWritten;
			int num5 = BytesInHistory + input.Count;
			int num6 = num2 - num5;
			if (num4 != 0)
			{
				lastCompressionRatio = (double)num4 / (double)num6;
			}
		}

		private void GetCompressedOutput(OutputBuffer output)
		{
			while (inputWindow.BytesAvailable > 0 && SafeToWriteTo(output))
			{
				inputWindow.GetNextSymbolOrMatch(currentMatch);
				if (currentMatch.State == MatchState.HasSymbol)
				{
					WriteChar(currentMatch.Symbol, output);
					continue;
				}
				if (currentMatch.State == MatchState.HasMatch)
				{
					WriteMatch(currentMatch.Length, currentMatch.Position, output);
					continue;
				}
				WriteChar(currentMatch.Symbol, output);
				WriteMatch(currentMatch.Length, currentMatch.Position, output);
			}
		}

		private bool InputAvailable(DeflateInput input)
		{
			return input.Count > 0 || BytesInHistory > 0;
		}

		private bool SafeToWriteTo(OutputBuffer output)
		{
			return output.FreeBytes > 16;
		}

		private void WriteEndOfBlock(OutputBuffer output)
		{
			uint num = FastEncoderStatics.FastEncoderLiteralCodeInfo[256];
			int n = (int)(num & 0x1F);
			output.WriteBits(n, num >> 5);
		}

		internal static void WriteMatch(int matchLen, int matchPos, OutputBuffer output)
		{
			uint num = FastEncoderStatics.FastEncoderLiteralCodeInfo[254 + matchLen];
			int num2 = (int)(num & 0x1F);
			if (num2 <= 16)
			{
				output.WriteBits(num2, num >> 5);
			}
			else
			{
				output.WriteBits(16, (num >> 5) & 0xFFFF);
				output.WriteBits(num2 - 16, num >> 21);
			}
			num = FastEncoderStatics.FastEncoderDistanceCodeInfo[FastEncoderStatics.GetSlot(matchPos)];
			output.WriteBits((int)(num & 0xF), num >> 8);
			int num3 = (int)((num >> 4) & 0xF);
			if (num3 != 0)
			{
				output.WriteBits(num3, (uint)matchPos & FastEncoderStatics.BitMask[num3]);
			}
		}

		internal static void WriteChar(byte b, OutputBuffer output)
		{
			uint num = FastEncoderStatics.FastEncoderLiteralCodeInfo[b];
			output.WriteBits((int)(num & 0x1F), num >> 5);
		}

		internal static void WriteDeflatePreamble(OutputBuffer output)
		{
			output.WriteBytes(FastEncoderStatics.FastEncoderTreeStructureData, 0, FastEncoderStatics.FastEncoderTreeStructureData.Length);
			output.WriteBits(9, 34u);
		}
	}
}