using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
using Paca.Mobile.Core;
using Xunit;

namespace Paca.Tests.Mobile;

/// <summary>
/// 모바일 미디어 라이브러리 고속 무결성 검증 및 포맷 헤더 분석 게이트 (Gate 191 ~ Gate 194)
/// </summary>
public class MobileMediaIntegrityGateTests
{
    [Fact]
    public void Gate191_ValidateMediaHeader_Mp4_FtypBox_Audit()
    {
        // MP4 컨테이너: 0~3 offset box size, 4~7 offset 'ftyp'
        var mp4ValidHeader = new byte[] { 0x00, 0x00, 0x00, 0x20, 0x66, 0x74, 0x79, 0x70, 0x69, 0x73, 0x6F, 0x6D };
        Assert.True(MediaIntegrityVerifier.ValidateMediaHeader(mp4ValidHeader, ".mp4"));
        Assert.True(MediaIntegrityVerifier.ValidateMediaHeader(mp4ValidHeader, "video.m4a"));

        var invalidHeader = new byte[] { 0x00, 0x00, 0x00, 0x00, 0x41, 0x42, 0x43, 0x44 };
        Assert.False(MediaIntegrityVerifier.ValidateMediaHeader(invalidHeader, ".mp4"));
    }

    [Fact]
    public void Gate192_ValidateMediaHeader_Webm_Ebml_Audit()
    {
        // WebM / MKV EBML Header: 0x1A, 0x45, 0xDF, 0xA3
        var webmHeader = new byte[] { 0x1A, 0x45, 0xDF, 0xA3, 0x9F, 0x42, 0x86, 0x81 };
        Assert.True(MediaIntegrityVerifier.ValidateMediaHeader(webmHeader, ".webm"));
        Assert.True(MediaIntegrityVerifier.ValidateMediaHeader(webmHeader, "sample.mkv"));

        var corruptedHeader = new byte[] { 0x1A, 0x45, 0x00, 0x00 };
        Assert.False(MediaIntegrityVerifier.ValidateMediaHeader(corruptedHeader, ".webm"));
    }

    [Fact]
    public void Gate193_ValidateMediaHeader_Mp3_Id3_And_FrameSync_Audit()
    {
        // MP3 ID3v2: 'ID3' (0x49, 0x44, 0x33)
        var id3Header = new byte[] { 0x49, 0x44, 0x33, 0x04, 0x00, 0x00, 0x00, 0x00 };
        Assert.True(MediaIntegrityVerifier.ValidateMediaHeader(id3Header, ".mp3"));

        // MP3 Sync Word: 0xFF, 0xFB
        var syncHeader = new byte[] { 0xFF, 0xFB, 0x90, 0x64 };
        Assert.True(MediaIntegrityVerifier.ValidateMediaHeader(syncHeader, ".mp3"));

        var badMp3 = new byte[] { 0x00, 0x11, 0x22, 0x33 };
        Assert.False(MediaIntegrityVerifier.ValidateMediaHeader(badMp3, ".mp3"));
    }

    [Fact]
    public void Gate194_InspectIntegrity_FullPayload_Audit()
    {
        // 유효한 mp4 가짜 데이터 생성
        var mp4Data = new byte[64];
        mp4Data[4] = 0x66; mp4Data[5] = 0x74; mp4Data[6] = 0x79; mp4Data[7] = 0x70; // ftyp
        var actualHash = Convert.ToHexString(SHA256.HashData(mp4Data)).ToLowerInvariant();

        // 1. 체크섬 일치 및 헤더 유효
        var okResult = MediaIntegrityVerifier.InspectIntegrity(mp4Data, "sample.mp4", actualHash);
        Assert.True(okResult.IsValid);
        Assert.True(okResult.ChecksumMatch);
        Assert.Equal("mp4", okResult.Format);
        Assert.Null(okResult.ErrorReason);

        // 2. 체크섬 불일치
        var mismatchResult = MediaIntegrityVerifier.InspectIntegrity(mp4Data, "sample.mp4", "0000000000000000000000000000000000000000000000000000000000000000");
        Assert.False(mismatchResult.IsValid);
        Assert.False(mismatchResult.ChecksumMatch);
        Assert.Contains("체크섬", mismatchResult.ErrorReason);

        // 3. 헤더 손상
        var corruptedData = new byte[64]; // all zeros
        var corruptResult = MediaIntegrityVerifier.InspectIntegrity(corruptedData, "sample.mp4");
        Assert.False(corruptResult.IsValid);
        Assert.Contains("헤더", corruptResult.ErrorReason);
    }
}