using System;

namespace Unity.IO.Compression
{
	internal class DeflaterManaged : IDeflater, IDisposable
	{
		private enum DeflaterState
		{
			NotStarted = 0,
			SlowDownForIncompressible1 = 1,
			SlowDownForIncompressible2 = 2,
			StartingSmallData = 3,
			CompressThenCheck = 4,
			CheckingForIncompressible = 5,
			HandlingSmallData = 6
		}

		private const int MinBlockSize = 256;

		private const int MaxHeaderFooterGoo = 120;

		private const int CleanCopySize = 8072;

		private const double BadCompressionThreshold = 1.0;

		private FastEncoder deflateEncoder;

		private CopyEncoder copyEncoder;

		private DeflateInput input;

		private OutputBuffer output;

		private DeflaterState processingState;

		private DeflateInput inputFromHistory;

		internal DeflaterManaged()
		{
			deflateEncoder = new FastEncoder();
			copyEncoder = new CopyEncoder();
			input = new DeflateInput();
			output = new OutputBuffer();
			processingState = DeflaterState.NotStarted;
		}

		private bool NeedsInput()
		{
			return ((IDeflater)this).NeedsInput();
		}

		bool IDeflater.NeedsInput()
		{
			return input.Count == 0 && deflateEncoder.BytesInHistory == 0;
		}

		void IDeflater.SetInput(byte[] inputBuffer, int startIndex, int count)
		{
			input.Buffer = inputBuffer;
			input.Count = count;
			input.StartIndex = startIndex;
			if (count > 0 && count < 256)
			{
				switch (processingState)
				{
				case DeflaterState.NotStarted:
				case DeflaterState.CheckingForIncompressible:
					processingState = DeflaterState.StartingSmallData;
					break;
				case DeflaterState.CompressThenCheck:
					processingState = DeflaterState.HandlingSmallData;
					break;
				}
			}
		}

		int IDeflater.GetDeflateOutput(byte[] outputBuffer)
		{
			output.UpdateBuffer(outputBuffer);
			switch (processingState)
			{
			case DeflaterState.NotStarted:
			{
				DeflateInput.InputState state3 = input.DumpState();
				OutputBuffer.BufferState state4 = output.DumpState();
				deflateEncoder.GetBlockHeader(output);
				deflateEncoder.GetCompressedData(input, output);
				if (!UseCompressed(deflateEncoder.LastCompressionRatio))
				{
					input.RestoreState(state3);
					output.RestoreState(state4);
					copyEncoder.GetBlock(input, output, false);
					FlushInputWindows();
					processingState = DeflaterState.CheckingForIncompressible;
				}
				else
				{
					processingState = DeflaterState.CompressThenCheck;
				}
				break;
			}
			case DeflaterState.CompressThenCheck:
				deflateEncoder.GetCompressedData(input, output);
				if (!UseCompressed(deflateEncoder.LastCompressionRatio))
				{
					processingState = DeflaterState.SlowDownForIncompressible1;
					inputFromHistory = deflateEncoder.UnprocessedInput;
				}
				break;
			case DeflaterState.SlowDownForIncompressible1:
				deflateEncoder.GetBlockFooter(output);
				processingState = DeflaterState.SlowDownForIncompressible2;
				goto case DeflaterState.SlowDownForIncompressible2;
			case DeflaterState.SlowDownForIncompressible2:
				if (inputFromHistory.Count > 0)
				{
					copyEncoder.GetBlock(inputFromHistory, output, false);
				}
				if (inputFromHistory.Count == 0)
				{
					deflateEncoder.FlushInput();
					processingState = DeflaterState.CheckingForIncompressible;
				}
				break;
			case DeflaterState.CheckingForIncompressible:
			{
				DeflateInput.InputState state = input.DumpState();
				OutputBuffer.BufferState state2 = output.DumpState();
				deflateEncoder.GetBlock(input, output, 8072);
				if (!UseCompressed(deflateEncoder.LastCompressionRatio))
				{
					input.RestoreState(state);
					output.RestoreState(state2);
					copyEncoder.GetBlock(input, output, false);
					FlushInputWindows();
				}
				break;
			}
			case DeflaterState.StartingSmallData:
				deflateEncoder.GetBlockHeader(output);
				processingState = DeflaterState.HandlingSmallData;
				goto case DeflaterState.HandlingSmallData;
			case DeflaterState.HandlingSmallData:
				deflateEncoder.GetCompressedData(input, output);
				break;
			}
			return output.BytesWritten;
		}

		bool IDeflater.Finish(byte[] outputBuffer, out int bytesRead)
		{
			if (processingState == DeflaterState.NotStarted)
			{
				bytesRead = 0;
				return true;
			}
			output.UpdateBuffer(outputBuffer);
			if (processingState == DeflaterState.CompressThenCheck || processingState == DeflaterState.HandlingSmallData || processingState == DeflaterState.SlowDownForIncompressible1)
			{
				deflateEncoder.GetBlockFooter(output);
			}
			WriteFinal();
			bytesRead = output.BytesWritten;
			return true;
		}

		void IDisposable.Dispose()
		{
		}

		protected void Dispose(bool disposing)
		{
		}

		private bool UseCompressed(double ratio)
		{
			return ratio <= 1.0;
		}

		private void FlushInputWindows()
		{
			deflateEncoder.FlushInput();
		}

		private void WriteFinal()
		{
			copyEncoder.GetBlock(null, output, true);
		}
	}
}