using System;
using System.Security.Cryptography;
using System.Text;
using Paca.Core;
using Xunit;

namespace Paca.Tests.Core;

/// <summary>
/// 적응형 청크 크기 조절, 체크섬 무결성, 발열 스로틀링, 트랜스코딩 프로파일 및 스트리밍 프록시 게이트 (Gate 131 ~ Gate 135)
/// </summary>
public class AdaptiveStreamingAndIntegrityGateTests
{
    [Fact]
    public void Gate131_AdaptiveChunkSizingEngine_Audit()
    {
        var engine = new AdaptiveChunkSizingEngine();

        // 60 Mbps (초고속망) -> 8MB 청크
        Assert.Equal(8 * 1024 * 1024, engine.CalculateOptimalChunkSize(measuredSpeedKbps: 60 * 1024));

        // 20 Mbps (표준망) -> 4MB 청크
        Assert.Equal(4 * 1024 * 1024, engine.CalculateOptimalChunkSize(measuredSpeedKbps: 20 * 1024));

        // 5 Mbps (저속망) -> 1MB 청크
        Assert.Equal(1 * 1024 * 1024, engine.CalculateOptimalChunkSize(measuredSpeedKbps: 5 * 1024));

        // 500 Kbps (극저속망) -> 512KB 청크
        Assert.Equal(512 * 1024, engine.CalculateOptimalChunkSize(measuredSpeedKbps: 500));
    }

    [Fact]
    public void Gate132_MediaChecksumValidator_Sha256_Audit()
    {
        var validator = new MediaChecksumValidator();
        var sampleBytes = Encoding.UTF8.GetBytes("Paca Secure Media Download Engine 2026");

        // 기대되는 SHA-256 해시 계산
        using var sha = SHA256.Create();
        var expectedHash = Convert.ToHexString(sha.ComputeHash(sampleBytes)).ToLowerInvariant();

        Assert.True(validator.VerifySha256(sampleBytes, expectedHash));
        Assert.False(validator.VerifySha256(sampleBytes, "invalid_hash_string"));
    }

    [Fact]
    public void Gate133_ThermalThrottlingGuard_Audit()
    {
        var guard = new ThermalThrottlingGuard();
        Assert.Equal(42.0, guard.OverheatThresholdCelsius);
        Assert.Equal(38.0, guard.NormalRecoveryThresholdCelsius);

        // 35°C 정상 -> 스로틀링 비활성, 6세그먼트
        Assert.False(guard.IsThrottled(currentTemperatureCelsius: 35.0));
        Assert.Equal(6, guard.GetAdjustedSegments(requestedSegments: 6, currentTemperatureCelsius: 35.0));

        // 43°C 과열 -> 스로틀링 활성, 1세그먼트로 강제 감속
        Assert.True(guard.IsThrottled(currentTemperatureCelsius: 43.0));
        Assert.Equal(1, guard.GetAdjustedSegments(requestedSegments: 6, currentTemperatureCelsius: 43.0));
    }

    [Fact]
    public void Gate134_TranscodeProfileManager_Profiles_Audit()
    {
        var manager = new TranscodeProfileManager();

        var mp4Args = manager.GetFfmpegProfileArgs("mp4_universal");
        Assert.Contains("-c:v libx264", mp4Args);
        Assert.Contains("-c:a aac", mp4Args);

        var webmArgs = manager.GetFfmpegProfileArgs("webm_modern");
        Assert.Contains("-c:v libvpx-vp9", webmArgs);
        Assert.Contains("-c:a libopus", webmArgs);

        var mp3Args = manager.GetFfmpegProfileArgs("audio_mp3_hq");
        Assert.Contains("-vn", mp3Args);
        Assert.Contains("-b:a 320k", mp3Args);
    }

    [Fact]
    public void Gate135_RemoteStreamProxyBuffer_RingBuffer_Audit()
    {
        var buffer = new RemoteStreamProxyBuffer(capacityBytes: 1024);
        Assert.Equal(0, buffer.BufferedBytes);

        var chunk1 = new byte[256];
        Array.Fill(chunk1, (byte)0xAA);
        buffer.Write(chunk1);
        Assert.Equal(256, buffer.BufferedBytes);

        var readTarget = new byte[128];
        var readCount = buffer.Read(readTarget, 0, 128);
        Assert.Equal(128, readCount);
        Assert.Equal(128, buffer.BufferedBytes);
        Assert.Equal(0xAA, readTarget[0]);
    }
}