// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System;
using System.Collections.Generic;
using System.IO;
using System.Runtime.CompilerServices;

namespace Microsoft.Build.Framework;

internal static class BinaryWriterExtensions
{
#if !NET
    [ThreadStatic]
    private static byte[]? s_guidBuffer;
#endif

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void WriteOptionalString(this BinaryWriter writer, string? value)
    {
        if (value == null)
        {
            writer.Write((byte)0);
        }
        else
        {
            writer.Write((byte)1);
            writer.Write(value);
        }
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void WriteOptionalInt32(this BinaryWriter writer, int? value)
    {
        if (value == null)
        {
            writer.Write((byte)0);
        }
        else
        {
            writer.Write((byte)1);
            writer.Write(value.Value);
        }
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void WriteTimestamp(this BinaryWriter writer, DateTime timestamp)
    {
        writer.Write(timestamp.Ticks);
        writer.Write((Int32)timestamp.Kind);
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void Write7BitEncodedInt(this BinaryWriter writer, int value)
    {
        // Write out an int 7 bits at a time.  The high bit of the byte,
        // when on, tells reader to continue reading more bytes.
        uint v = (uint)value;   // support negative numbers
        while (v >= 0x80)
        {
            writer.Write((byte)(v | 0x80));
            v >>= 7;
        }

        writer.Write((byte)v);
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void WriteOptionalBuildEventContext(this BinaryWriter writer, BuildEventContext? context)
    {
        if (context == null)
        {
            writer.Write((byte)0);
        }
        else
        {
            writer.Write((byte)1);
            writer.WriteBuildEventContext(context);
        }
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void WriteBuildEventContext(this BinaryWriter writer, BuildEventContext context)
    {
        writer.Write(context.NodeId);
        writer.Write(context.ProjectContextId);
        writer.Write(context.TargetId);
        writer.Write(context.TaskId);
        writer.Write(context.SubmissionId);
        writer.Write(context.ProjectInstanceId);
        writer.Write(context.EvaluationId);
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void WriteGuid(this BinaryWriter writer, Guid value)
    {
        const int GuidSize = 16;

#if NET
        Span<byte> bytes = stackalloc byte[GuidSize];
        value.TryWriteBytes(bytes);
#else
        byte[] bytes = s_guidBuffer ??= new byte[GuidSize];

        unsafe
        {
            fixed (byte* ptr = bytes)
            {
                *(Guid*)ptr = value;
            }
        }
#endif

        writer.Write(bytes);
    }

    public static void WriteExtendedBuildEventData(this BinaryWriter writer, IExtendedBuildEventArgs data)
    {
        writer.Write(data.ExtendedType);
        writer.WriteOptionalString(data.ExtendedData);

        writer.Write(data.ExtendedMetadata != null);
        if (data.ExtendedMetadata != null)
        {
            writer.Write7BitEncodedInt(data.ExtendedMetadata.Count);
            foreach (KeyValuePair<string, string?> kvp in data.ExtendedMetadata)
            {
                writer.Write(kvp.Key);
                writer.WriteOptionalString(kvp.Value);
            }
        }
    }

    public static void WriteDurationsDictionary(this BinaryWriter writer, Dictionary<string, TimeSpan> durations)
    {
        writer.Write7BitEncodedInt(durations.Count);
        foreach (KeyValuePair<string, TimeSpan> kvp in durations)
        {
            writer.Write(kvp.Key);
            writer.Write(kvp.Value.Ticks);
        }
    }
}