// 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 BinaryReaderExtensions
{
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static string? ReadOptionalString(this BinaryReader reader)
    {
        return reader.ReadByte() == 0 ? null : reader.ReadString();
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static int? ReadOptionalInt32(this BinaryReader reader)
    {
        return reader.ReadByte() == 0 ? null : reader.ReadInt32();
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static int Read7BitEncodedInt(this BinaryReader reader)
    {
        // Read out an Int32 7 bits at a time.  The high bit
        // of the byte when on means to continue reading more bytes.
        int count = 0;
        int shift = 0;
        byte b;
        do
        {
            // Check for a corrupted stream.  Read a max of 5 bytes.
            // In a future version, add a DataFormatException.
            if (shift == 5 * 7)  // 5 bytes max per Int32, shift += 7
            {
                throw new FormatException();
            }

            // ReadByte handles end of stream cases for us.
            b = reader.ReadByte();
            count |= (b & 0x7F) << shift;
            shift += 7;
        } while ((b & 0x80) != 0);
        return count;
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static DateTime ReadTimestamp(this BinaryReader reader)
    {
        long timestampTicks = reader.ReadInt64();
        DateTimeKind kind = (DateTimeKind)reader.ReadInt32();
        var timestamp = new DateTime(timestampTicks, kind);
        return timestamp;
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static BuildEventContext? ReadOptionalBuildEventContext(this BinaryReader reader)
    {
        if (reader.ReadByte() == 0)
        {
            return null;
        }

        return reader.ReadBuildEventContext();
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static BuildEventContext ReadBuildEventContext(this BinaryReader reader)
    {
        int nodeId = reader.ReadInt32();
        int projectContextId = reader.ReadInt32();
        int targetId = reader.ReadInt32();
        int taskId = reader.ReadInt32();
        int submissionId = reader.ReadInt32();
        int projectInstanceId = reader.ReadInt32();
        int evaluationId = reader.ReadInt32();

        var buildEventContext = new BuildEventContext(submissionId, nodeId, evaluationId, projectInstanceId, projectContextId, targetId, taskId);
        return buildEventContext;
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static Guid ReadGuid(this BinaryReader reader)
    {
        const int GuidSize = 16;

#if NET
        Span<byte> bytes = stackalloc byte[GuidSize];
        reader.Read(bytes);
#else
        byte[] bytes = reader.ReadBytes(GuidSize);
#endif

        return new Guid(bytes);
    }

    public static void ReadExtendedBuildEventData(this BinaryReader reader, IExtendedBuildEventArgs data)
    {
        data.ExtendedType = reader.ReadString();
        data.ExtendedData = reader.ReadOptionalString();

        bool haveMetadata = reader.ReadBoolean();
        if (haveMetadata)
        {
            data.ExtendedMetadata = new Dictionary<string, string?>();

            int count = reader.Read7BitEncodedInt();
            for (int i = 0; i < count; i++)
            {
                string key = reader.ReadString();
                string? value = reader.ReadOptionalString();

                data.ExtendedMetadata.Add(key, value);
            }
        }
        else
        {
            data.ExtendedMetadata = null;
        }
    }

    public static Dictionary<string, TimeSpan> ReadDurationDictionary(this BinaryReader reader)
    {
        int count = reader.Read7BitEncodedInt();
        var durations = new Dictionary<string, TimeSpan>(count);
        for (int i = 0; i < count; i++)
        {
            string key = reader.ReadString();
            TimeSpan value = TimeSpan.FromTicks(reader.ReadInt64());

            durations.Add(key, value);
        }

        return durations;
    }
}