using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using Paca.Core;
using Paca.Core.Utils;
using Xunit;

namespace Paca.Tests.Core;

public class StreamingAndResourceGuardianExtremeRedTests
{
    // ==========================================
    // 1. TranscodeProfileManager & ThermalGuard
    // ==========================================

    [Theory]
    [InlineData(null)]
    [InlineData("")]
    [InlineData("   ")]
    public void TranscodeProfileManager_GetFfmpegProfileArgs_NullOrWhitespace_ReturnsCopySafeFallback(string? badProfile)
    {
        var manager = new TranscodeProfileManager();
        var args = manager.GetFfmpegProfileArgs(badProfile!);
        Assert.NotNull(args);
        Assert.Equal("-c copy", args);
    }

    [Theory]
    [InlineData(0)]
    [InlineData(-5)]
    public void ThermalThrottlingGuard_AdjustedSegments_ZeroOrNegativeRequested_ReturnsAtLeastOne(int badSegments)
    {
        var guard = new ThermalThrottlingGuard();
        int adjusted = guard.GetAdjustedSegments(badSegments, 25.0); // Normal temp
        Assert.True(adjusted >= 1, "Segments must be at least 1 even if requested was <= 0");
    }

    // ==========================================
    // 2. RemoteStreamProxyBuffer Bound & Safety
    // ==========================================

    [Fact]
    public void RemoteStreamProxyBuffer_NullData_DoesNotThrowNullReference()
    {
        var buffer = new RemoteStreamProxyBuffer(1024);
        var ex = Record.Exception(() => buffer.Write(null!));
        Assert.Null(ex);
        Assert.Equal(0, buffer.BufferedBytes);
    }

    [Fact]
    public void RemoteStreamProxyBuffer_ExceedingCapacity_EvictsOldestBytesToRespectCapacity()
    {
        const int capacity = 100;
        var buffer = new RemoteStreamProxyBuffer(capacity);

        // Write 60 bytes of 0x01
        byte[] chunk1 = new byte[60];
        Array.Fill(chunk1, (byte)1);
        buffer.Write(chunk1);
        Assert.Equal(60, buffer.BufferedBytes);

        // Write 60 bytes of 0x02 (Total would be 120, exceeding capacity 100)
        byte[] chunk2 = new byte[60];
        Array.Fill(chunk2, (byte)2);
        buffer.Write(chunk2);

        // Capacity must NOT be exceeded
        Assert.True(buffer.BufferedBytes <= capacity, $"Buffered bytes ({buffer.BufferedBytes}) must not exceed capacity ({capacity})");

        // Reading remaining bytes should contain the newer bytes (0x02)
        byte[] readTarget = new byte[capacity];
        int readCount = buffer.Read(readTarget, 0, capacity);
        Assert.Equal(buffer.CapacityBytes, readCount);
        Assert.Equal(2, readTarget[readCount - 1]); // Last byte must be from chunk2
    }

    // ==========================================
    // 3. DiskSpaceGuardian OS HResult & Unnesting
    // ==========================================

    [Fact]
    public void DiskSpaceGuardian_IsDiskFullException_HResultCheck_ReturnsTrueEvenWithUnknownLanguageMessage()
    {
        // 0x80070070 = HRESULT for ERROR_DISK_FULL (112)
        var foreignEx = new IOException("Espace disque insuffisant sur le lecteur C:", unchecked((int)0x80070070));
        bool isFull = DiskSpaceGuardian.IsDiskFullException(foreignEx);
        Assert.True(isFull, "Must detect disk full via HResult 0x80070070 regardless of OS language");
    }

    [Fact]
    public void DiskSpaceGuardian_IsDiskFullException_WrappedInAggregateException_DetectsInnerDiskFull()
    {
        var inner = new IOException("There is not enough space on the disk.");
        var aggregate = new AggregateException("Task failed", inner);
        bool isFull = DiskSpaceGuardian.IsDiskFullException(aggregate);
        Assert.True(isFull, "Must unnest AggregateException to find inner disk full exception");
    }

    [Theory]
    [InlineData(0)]
    [InlineData(-100)]
    public void DiskSpaceGuardian_HasSufficientSpace_ZeroOrNegativeBytes_ReturnsTrue(long bytes)
    {
        bool result = DiskSpaceGuardian.HasSufficientSpace("C:\\fake\\path.mp4", bytes);
        Assert.True(result);
    }

    [Theory]
    [InlineData(null)]
    [InlineData("")]
    [InlineData("   ")]
    public void DiskSpaceGuardian_HasSufficientSpace_NullOrWhitespacePath_ReturnsTrue(string? badPath)
    {
        bool result = DiskSpaceGuardian.HasSufficientSpace(badPath!, 1024);
        Assert.True(result);
    }

    // ==========================================
    // 4. ThrottledStream & BufferPool Safety
    // ==========================================

    [Fact]
    public void ThrottledStream_NullBaseStream_ThrowsArgumentNullException()
    {
        Assert.Throws<ArgumentNullException>(() => new ThrottledStream(null!, 1024));
    }

    [Fact]
    public void ThrottledStream_ZeroOrNegativeMaxBytes_DoesNotThrowAndReadsNormally()
    {
        byte[] source = new byte[] { 1, 2, 3, 4, 5 };
        using var ms = new MemoryStream(source);
        using var throttled = new ThrottledStream(ms, maxBytesPerSecond: 0); // Unthrottled

        byte[] dest = new byte[5];
        int read = throttled.Read(dest, 0, 5);
        Assert.Equal(5, read);
        Assert.Equal(source, dest);
    }

    [Fact]
    public void BufferPoolManager_Return_NullArray_DoesNotThrow()
    {
        var ex = Record.Exception(() => BufferPoolManager.Return(null!));
        Assert.Null(ex);
    }

    [Theory]
    [InlineData(0)]
    [InlineData(-100)]
    public void AdaptiveChunkSizingEngine_NegativeOrZeroSpeed_ReturnsMinimum512KB(int speed)
    {
        var engine = new AdaptiveChunkSizingEngine();
        int size = engine.CalculateOptimalChunkSize(speed);
        Assert.Equal(512 * 1024, size);
    }
}