using System;
using System.Collections.Generic;
using System.IO;
using Hjg.Pngcs.Chunks;
using Hjg.Pngcs.Zlib;

namespace Hjg.Pngcs
{
	// Token: 0x02000035 RID: 53
	internal class PngIDatChunkInputStream : Stream
	{
		// Token: 0x060001DD RID: 477 RVA: 0x00007CE5 File Offset: 0x00005EE5
		public override void Write(byte[] buffer, int offset, int count)
		{
		}

		// Token: 0x060001DE RID: 478 RVA: 0x00007CE7 File Offset: 0x00005EE7
		public override void SetLength(long value)
		{
		}

		// Token: 0x060001DF RID: 479 RVA: 0x00007CE9 File Offset: 0x00005EE9
		public override long Seek(long offset, SeekOrigin origin)
		{
			return -1L;
		}

		// Token: 0x060001E0 RID: 480 RVA: 0x00007CED File Offset: 0x00005EED
		public override void Flush()
		{
		}

		// Token: 0x1700002A RID: 42
		// (get) Token: 0x060001E1 RID: 481 RVA: 0x00007CEF File Offset: 0x00005EEF
		// (set) Token: 0x060001E2 RID: 482 RVA: 0x00007CF7 File Offset: 0x00005EF7
		public override long Position { get; set; }

		// Token: 0x1700002B RID: 43
		// (get) Token: 0x060001E3 RID: 483 RVA: 0x00007D00 File Offset: 0x00005F00
		public override long Length
		{
			get
			{
				return 0L;
			}
		}

		// Token: 0x1700002C RID: 44
		// (get) Token: 0x060001E4 RID: 484 RVA: 0x00007D04 File Offset: 0x00005F04
		public override bool CanWrite
		{
			get
			{
				return false;
			}
		}

		// Token: 0x1700002D RID: 45
		// (get) Token: 0x060001E5 RID: 485 RVA: 0x00007D07 File Offset: 0x00005F07
		public override bool CanRead
		{
			get
			{
				return true;
			}
		}

		// Token: 0x1700002E RID: 46
		// (get) Token: 0x060001E6 RID: 486 RVA: 0x00007D0A File Offset: 0x00005F0A
		public override bool CanSeek
		{
			get
			{
				return false;
			}
		}

		// Token: 0x060001E7 RID: 487 RVA: 0x00007D10 File Offset: 0x00005F10
		public PngIDatChunkInputStream(Stream iStream, int lenFirstChunk, long offset_0)
		{
			this.idLastChunk = new byte[4];
			this.toReadThisChunk = 0;
			this.ended = false;
			this.foundChunksInfo = new List<PngIDatChunkInputStream.IdatChunkInfo>();
			this.offset = offset_0;
			this.checkCrc = true;
			this.inputStream = iStream;
			this.crcEngine = new CRC32();
			this.lenLastChunk = lenFirstChunk;
			this.toReadThisChunk = lenFirstChunk;
			Array.Copy(ChunkHelper.b_IDAT, 0, this.idLastChunk, 0, 4);
			this.crcEngine.Update(this.idLastChunk, 0, 4);
			this.foundChunksInfo.Add(new PngIDatChunkInputStream.IdatChunkInfo(this.lenLastChunk, offset_0 - 8L));
			if (this.lenLastChunk == 0)
			{
				this.EndChunkGoForNext();
			}
		}

		// Token: 0x060001E8 RID: 488 RVA: 0x00007DC4 File Offset: 0x00005FC4
		public override void Close()
		{
			base.Close();
		}

		// Token: 0x060001E9 RID: 489 RVA: 0x00007DCC File Offset: 0x00005FCC
		private void EndChunkGoForNext()
		{
			for (;;)
			{
				int num = PngHelperInternal.ReadInt4(this.inputStream);
				this.offset += 4L;
				if (this.checkCrc)
				{
					int value = (int)this.crcEngine.GetValue();
					if (this.lenLastChunk > 0 && num != value)
					{
						break;
					}
					this.crcEngine.Reset();
				}
				this.lenLastChunk = PngHelperInternal.ReadInt4(this.inputStream);
				if (this.lenLastChunk < 0)
				{
					goto Block_3;
				}
				this.toReadThisChunk = this.lenLastChunk;
				PngHelperInternal.ReadBytes(this.inputStream, this.idLastChunk, 0, 4);
				this.offset += 8L;
				this.ended = !PngCsUtils.arraysEqual4(this.idLastChunk, ChunkHelper.b_IDAT);
				if (!this.ended)
				{
					this.foundChunksInfo.Add(new PngIDatChunkInputStream.IdatChunkInfo(this.lenLastChunk, this.offset - 8L));
					if (this.checkCrc)
					{
						this.crcEngine.Update(this.idLastChunk, 0, 4);
					}
				}
				if (this.lenLastChunk != 0 || this.ended)
				{
					return;
				}
			}
			throw new PngjBadCrcException("error reading idat; offset: " + this.offset);
			Block_3:
			throw new PngjInputException("invalid len for chunk: " + this.lenLastChunk);
		}

		// Token: 0x060001EA RID: 490 RVA: 0x00007F0C File Offset: 0x0000610C
		public void ForceChunkEnd()
		{
			if (!this.ended)
			{
				byte[] array = new byte[this.toReadThisChunk];
				PngHelperInternal.ReadBytes(this.inputStream, array, 0, this.toReadThisChunk);
				if (this.checkCrc)
				{
					this.crcEngine.Update(array, 0, this.toReadThisChunk);
				}
				this.EndChunkGoForNext();
			}
		}

		// Token: 0x060001EB RID: 491 RVA: 0x00007F64 File Offset: 0x00006164
		public override int Read(byte[] b, int off, int len_0)
		{
			if (this.ended)
			{
				return -1;
			}
			if (this.toReadThisChunk == 0)
			{
				throw new Exception("this should not happen");
			}
			int num = this.inputStream.Read(b, off, (len_0 >= this.toReadThisChunk) ? this.toReadThisChunk : len_0);
			if (num == -1)
			{
				num = -2;
			}
			if (num > 0)
			{
				if (this.checkCrc)
				{
					this.crcEngine.Update(b, off, num);
				}
				this.offset += (long)num;
				this.toReadThisChunk -= num;
			}
			if (num >= 0 && this.toReadThisChunk == 0)
			{
				this.EndChunkGoForNext();
			}
			return num;
		}

		// Token: 0x060001EC RID: 492 RVA: 0x00007FFF File Offset: 0x000061FF
		public int Read(byte[] b)
		{
			return this.Read(b, 0, b.Length);
		}

		// Token: 0x060001ED RID: 493 RVA: 0x0000800C File Offset: 0x0000620C
		public override int ReadByte()
		{
			byte[] array = new byte[1];
			int num = this.Read(array, 0, 1);
			if (num >= 0)
			{
				return (int)array[0];
			}
			return -1;
		}

		// Token: 0x060001EE RID: 494 RVA: 0x00008033 File Offset: 0x00006233
		public int GetLenLastChunk()
		{
			return this.lenLastChunk;
		}

		// Token: 0x060001EF RID: 495 RVA: 0x0000803B File Offset: 0x0000623B
		public byte[] GetIdLastChunk()
		{
			return this.idLastChunk;
		}

		// Token: 0x060001F0 RID: 496 RVA: 0x00008043 File Offset: 0x00006243
		public long GetOffset()
		{
			return this.offset;
		}

		// Token: 0x060001F1 RID: 497 RVA: 0x0000804B File Offset: 0x0000624B
		public bool IsEnded()
		{
			return this.ended;
		}

		// Token: 0x060001F2 RID: 498 RVA: 0x00008053 File Offset: 0x00006253
		internal void DisableCrcCheck()
		{
			this.checkCrc = false;
		}

		// Token: 0x04000103 RID: 259
		private readonly Stream inputStream;

		// Token: 0x04000104 RID: 260
		private readonly CRC32 crcEngine;

		// Token: 0x04000105 RID: 261
		private bool checkCrc;

		// Token: 0x04000106 RID: 262
		private int lenLastChunk;

		// Token: 0x04000107 RID: 263
		private byte[] idLastChunk;

		// Token: 0x04000108 RID: 264
		private int toReadThisChunk;

		// Token: 0x04000109 RID: 265
		private bool ended;

		// Token: 0x0400010A RID: 266
		private long offset;

		// Token: 0x0400010B RID: 267
		public IList<PngIDatChunkInputStream.IdatChunkInfo> foundChunksInfo;

		// Token: 0x02000036 RID: 54
		public class IdatChunkInfo
		{
			// Token: 0x060001F3 RID: 499 RVA: 0x0000805C File Offset: 0x0000625C
			public IdatChunkInfo(int len_0, long offset_1)
			{
				this.len = len_0;
				this.offset = offset_1;
			}

			// Token: 0x0400010D RID: 269
			public readonly int len;

			// Token: 0x0400010E RID: 270
			public readonly long offset;
		}
	}
}