using System;
using Paca.Mobile.Core;
using Xunit;

namespace Paca.Tests.Core;

public class MediaStreamingTransferGateTests
{
    [Fact]
    public void Gate353_MediaStreamingTransfer_ParsesExplicitRange_Correctly()
    {
        var totalSize = 10_000L;
        var rangeHeader = "bytes=1000-1999";

        var range = MediaStreamingTransferEngine.ParseRangeHeader(rangeHeader, totalSize);

        Assert.True(range.IsPartial);
        Assert.Equal(1000L, range.Start);
        Assert.Equal(1999L, range.End);
        Assert.Equal(1000L, range.ContentLength);
        Assert.Equal("bytes 1000-1999/10000", range.ContentRangeHeader);
    }

    [Fact]
    public void Gate354_MediaStreamingTransfer_ParsesOpenEndedRange_ToEOF()
    {
        var totalSize = 5_000L;
        var rangeHeader = "bytes=2000-";

        var range = MediaStreamingTransferEngine.ParseRangeHeader(rangeHeader, totalSize);

        Assert.True(range.IsPartial);
        Assert.Equal(2000L, range.Start);
        Assert.Equal(4999L, range.End);
        Assert.Equal(3000L, range.ContentLength);
        Assert.Equal("bytes 2000-4999/5000", range.ContentRangeHeader);
    }

    [Fact]
    public void Gate355_MediaStreamingTransfer_ComputesProgressAndSpeed_Accurately()
    {
        // 50 MB transferred out of 100 MB in 5.0 seconds
        var total = 100 * 1024 * 1024L;
        var transferred = 50 * 1024 * 1024L;
        var elapsed = 5.0;

        var progress = MediaStreamingTransferEngine.ComputeProgress("stream-1", transferred, total, elapsed);

        Assert.Equal("stream-1", progress.TransferId);
        Assert.Equal(50.0, progress.ProgressPercent);
        Assert.Equal(10 * 1024 * 1024.0, progress.TransferRateBytesPerSec); // 10 MB/s
        Assert.Equal(10.0, progress.TransferRateMbPerSec);
    }

    [Fact]
    public void Gate356_MediaStreamingTransfer_HandlesInvalidRange_WithFullFallback()
    {
        var totalSize = 2_000L;

        // Invalid range exceeding total size
        var invalidRange = "bytes=5000-6000";
        var result = MediaStreamingTransferEngine.ParseRangeHeader(invalidRange, totalSize);

        Assert.False(result.IsPartial);
        Assert.Equal(0L, result.Start);
        Assert.Equal(1999L, result.End);
        Assert.Equal(2000L, result.ContentLength);

        // Null or empty range
        var nullResult = MediaStreamingTransferEngine.ParseRangeHeader(null, totalSize);
        Assert.False(nullResult.IsPartial);
        Assert.Equal(2000L, nullResult.ContentLength);
    }
}