using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Reflection.Metadata;
using System.Reflection.Metadata.Ecma335;

namespace Microsoft.CodeAnalysis.Debugging;

internal struct CustomDebugInfoEncoder
{
	private readonly Blob _recordCountFixup;

	private int _recordCount;

	internal const int DynamicAttributeSize = 64;

	internal const int IdentifierSize = 64;

	public BlobBuilder Builder { get; }

	public readonly int RecordCount => _recordCount;

	public CustomDebugInfoEncoder(BlobBuilder builder)
	{
		Builder = builder;
		_recordCount = 0;
		builder.WriteByte(4);
		_recordCountFixup = builder.ReserveBytes(1);
		builder.WriteInt16(0);
	}

	public readonly byte[] ToArray()
	{
		if (_recordCount == 0)
		{
			return null;
		}
		new BlobWriter(_recordCountFixup).WriteByte((byte)_recordCount);
		return Builder.ToArray();
	}

	public void AddStateMachineTypeName(string typeName)
	{
		AddRecord(CustomDebugInfoKind.StateMachineTypeName, typeName, delegate(string name, BlobBuilder builder)
		{
			builder.WriteUTF16(name);
			builder.WriteInt16(0);
		});
	}

	public void AddForwardMethodInfo(MethodDefinitionHandle methodHandle)
	{
		AddRecord(CustomDebugInfoKind.ForwardMethodInfo, methodHandle, delegate(MethodDefinitionHandle mh, BlobBuilder builder)
		{
			builder.WriteInt32(MetadataTokens.GetToken(mh));
		});
	}

	public void AddForwardModuleInfo(MethodDefinitionHandle methodHandle)
	{
		AddRecord(CustomDebugInfoKind.ForwardModuleInfo, methodHandle, delegate(MethodDefinitionHandle mh, BlobBuilder builder)
		{
			builder.WriteInt32(MetadataTokens.GetToken(mh));
		});
	}

	public void AddUsingGroups(IReadOnlyCollection<int> groupSizes)
	{
		if (groupSizes.Count == 0)
		{
			return;
		}
		AddRecord(CustomDebugInfoKind.UsingGroups, groupSizes, delegate(IReadOnlyCollection<int> uc, BlobBuilder builder)
		{
			builder.WriteUInt16((ushort)uc.Count);
			foreach (int item in uc)
			{
				builder.WriteUInt16((ushort)item);
			}
		});
	}

	public void AddStateMachineHoistedLocalScopes(ImmutableArray<StateMachineHoistedLocalScope> scopes)
	{
		if (scopes.IsDefaultOrEmpty)
		{
			return;
		}
		AddRecord(CustomDebugInfoKind.StateMachineHoistedLocalScopes, scopes, delegate(ImmutableArray<StateMachineHoistedLocalScope> s, BlobBuilder builder)
		{
			builder.WriteInt32(s.Length);
			ImmutableArray<StateMachineHoistedLocalScope>.Enumerator enumerator = s.GetEnumerator();
			while (enumerator.MoveNext())
			{
				StateMachineHoistedLocalScope current = enumerator.Current;
				if (current.IsDefault)
				{
					builder.WriteInt32(0);
					builder.WriteInt32(0);
				}
				else
				{
					builder.WriteInt32(current.StartOffset);
					builder.WriteInt32(current.EndOffset - 1);
				}
			}
		});
	}

	public void AddDynamicLocals(IReadOnlyCollection<(string LocalName, byte[] Flags, int Count, int SlotIndex)> dynamicLocals)
	{
		AddRecord(CustomDebugInfoKind.DynamicLocals, dynamicLocals, delegate(IReadOnlyCollection<(string LocalName, byte[] Flags, int Count, int SlotIndex)> infos, BlobBuilder builder)
		{
			builder.WriteInt32(infos.Count);
			foreach (var info in infos)
			{
				builder.WriteBytes(info.Flags);
				builder.WriteBytes(0, 64 - info.Flags.Length);
				builder.WriteInt32(info.Count);
				builder.WriteInt32(info.SlotIndex);
				builder.WriteUTF16(info.LocalName);
				builder.WriteBytes(0, 2 * (64 - info.LocalName.Length));
			}
		});
	}

	public void AddTupleElementNames(IReadOnlyCollection<(string LocalName, int SlotIndex, int ScopeStart, int ScopeEnd, ImmutableArray<string> Names)> tupleLocals)
	{
		AddRecord(CustomDebugInfoKind.TupleElementNames, tupleLocals, delegate(IReadOnlyCollection<(string LocalName, int SlotIndex, int ScopeStart, int ScopeEnd, ImmutableArray<string> Names)> infos, BlobBuilder builder)
		{
			builder.WriteInt32(infos.Count);
			foreach (var info in infos)
			{
				builder.WriteInt32(info.Names.Length);
				ImmutableArray<string>.Enumerator enumerator2 = info.Names.GetEnumerator();
				while (enumerator2.MoveNext())
				{
					string current2 = enumerator2.Current;
					if (current2 != null)
					{
						builder.WriteUTF8(current2);
					}
					builder.WriteByte(0);
				}
				builder.WriteInt32(info.SlotIndex);
				builder.WriteInt32(info.ScopeStart);
				builder.WriteInt32(info.ScopeEnd);
				if (info.LocalName != null)
				{
					builder.WriteUTF8(info.LocalName);
				}
				builder.WriteByte(0);
			}
		});
	}

	public void AddRecord<T>(CustomDebugInfoKind kind, T debugInfo, Action<T, BlobBuilder> recordSerializer)
	{
		int count = Builder.Count;
		Builder.WriteByte(4);
		Builder.WriteByte((byte)kind);
		Builder.WriteByte(0);
		BlobWriter blobWriter = new BlobWriter(Builder.ReserveBytes(5));
		recordSerializer(debugInfo, Builder);
		int num = Builder.Count - count;
		int num2 = 4 * ((num + 3) / 4);
		byte b = (byte)(num2 - num);
		Builder.WriteBytes(0, b);
		blobWriter.WriteByte((byte)(((int)kind > 5) ? b : 0));
		blobWriter.WriteUInt32((uint)num2);
		_recordCount++;
	}
}