using System;
using System.IO;
using System.Linq;
using Paca.Avalonia;
using Paca.Mobile.Core;
using Xunit;

namespace Paca.Tests.Platform;

/// <summary>
/// Phase 5: 크로스플랫폼 패리티 및 모바일/데스크톱 견고성 헌법 게이트 (Gate 501 ~ 503).
/// - Gate 501: Paca.Avalonia MainViewModel 일시정지/재개(Pause/Resume) 및 IDisposable 생명주기
/// - Gate 502: Paca.Mobile.Core LanDiscoveryProber 널 안전성, IPv6 및 P2P QR TTL 만료 검증
/// - Gate 503: Paca.Mobile.Core SmartCollectionEngine 널 타이틀 방어 및 M3U8 개행문자 살균
/// </summary>
public class CrossPlatformParityHardeningPhase5Tests
{
    [Fact]
    public void Gate501_Avalonia_MainViewModel_Pause_Resume_And_Disposable_Lifecycle_Audit()
    {
        using var vm = new MainViewModel();

        // 1. IDisposable 구현 검증
        Assert.IsAssignableFrom<IDisposable>(vm);

        // 2. PauseCommand & ResumeCommand 배선 확인
        Assert.NotNull(vm.PauseCommand);
        Assert.NotNull(vm.ResumeCommand);
        Assert.NotNull(vm.DownloadCommand);
        Assert.NotNull(vm.CancelCommand);

        // 3. 초기 상태: IsBusy=false, IsPaused=false, CanExecute 검증
        Assert.False(vm.IsBusy);
        Assert.False(vm.IsPaused);
        Assert.False(vm.PauseCommand.CanExecute(null));
        Assert.False(vm.ResumeCommand.CanExecute(null));

        // 4. IsBusy 상태 시뮬레이션
        vm.IsBusy = true;
        Assert.True(vm.PauseCommand.CanExecute(null));
        Assert.False(vm.ResumeCommand.CanExecute(null));

        // 5. 일시정지(Pause) 실행
        vm.Pause();
        Assert.True(vm.IsPaused);
        Assert.Equal("일시정지됨", vm.Status);
        Assert.False(vm.PauseCommand.CanExecute(null));
        Assert.True(vm.ResumeCommand.CanExecute(null));

        // 6. 재개(Resume) 실행
        vm.Resume();
        Assert.False(vm.IsPaused);
        Assert.Equal("다운로드 재개 중...", vm.Status);
        Assert.True(vm.PauseCommand.CanExecute(null));
        Assert.False(vm.ResumeCommand.CanExecute(null));

        // 7. 다운로드 완료(IsBusy=false) 시 IsPaused 자동 초기화
        vm.Pause();
        Assert.True(vm.IsPaused);
        vm.IsBusy = false;
        Assert.False(vm.IsPaused);
        Assert.False(vm.PauseCommand.CanExecute(null));
        Assert.False(vm.ResumeCommand.CanExecute(null));
    }

    [Fact]
    public void Gate502_LanDiscoveryProber_Robust_Address_And_NullSafe_Packet_Handling_Audit()
    {
        var prober = new LanDiscoveryProber();

        // 1. Null/Whitespace 페이로드 안전성 (예외 미발생)
        prober.HandleReceivedPayload(null!, null!);
        prober.HandleReceivedPayload("", "192.168.1.50");
        prober.HandleReceivedPayload("   ", "");

        // 2. RemoteIp가 null/빈값인 경우 127.0.0.1 기본 폴백
        var pong = LanDiscoveryMessage.CreatePong("PC-NullIp", ":5000", true, "FP-001");
        prober.HandleReceivedPayload(pong.ToPayload(), null!);
        var devices = prober.GetActiveDevices();
        var devNullIp = devices.FirstOrDefault(d => d.DeviceName == "PC-NullIp");
        Assert.NotNull(devNullIp);
        Assert.Equal("127.0.0.1:5000", devNullIp.Endpoint);

        // 3. IPv6 remoteIp의 브래킷([]) 포맷팅 검증
        var pongIpv6 = LanDiscoveryMessage.CreatePong("PC-IPv6", ":52100", true, "FP-IPV6");
        prober.HandleReceivedPayload(pongIpv6.ToPayload(), "fe80::1");
        devices = prober.GetActiveDevices();
        var devIpv6 = devices.FirstOrDefault(d => d.DeviceName == "PC-IPv6");
        Assert.NotNull(devIpv6);
        Assert.Equal("[fe80::1]:52100", devIpv6.Endpoint);
        Assert.Equal("http://[fe80::1]:52100", devIpv6.HttpBaseUrl);

        // 4. P2pQrPayloadCodec TTL 만료 검증
        var now = DateTimeOffset.UtcNow;
        var freshPayload = new P2pQrPayload
        {
            Host = "192.168.1.10",
            Port = 5000,
            Token = "token-fresh",
            CreatedAtUnix = now.ToUnixTimeSeconds()
        };
        var encodedFresh = P2pQrPayloadCodec.Encode(freshPayload);
        Assert.Contains("&ts=", encodedFresh);
        var decodedFresh = P2pQrPayloadCodec.Decode(encodedFresh);
        Assert.Equal(freshPayload.CreatedAtUnix, decodedFresh.CreatedAtUnix);
        Assert.False(P2pQrPayloadCodec.IsExpired(decodedFresh, TimeSpan.FromMinutes(5), now));

        var expiredPayload = new P2pQrPayload
        {
            Host = "192.168.1.10",
            Port = 5000,
            Token = "token-expired",
            CreatedAtUnix = now.AddMinutes(-10).ToUnixTimeSeconds()
        };
        var encodedExpired = P2pQrPayloadCodec.Encode(expiredPayload);
        var decodedExpired = P2pQrPayloadCodec.Decode(encodedExpired);
        Assert.True(P2pQrPayloadCodec.IsExpired(decodedExpired, TimeSpan.FromMinutes(5), now));
    }

    [Fact]
    public void Gate503_SmartCollectionEngine_NullSafe_Title_And_M3u8_Sanitization_Audit()
    {
        // 1. Title이 null이거나 빈 문자열인 경우 NRE 없이 정상 분류
        var itemNullTitle = new MediaItemMetadata(
            Id: "item-1",
            Title: null!,
            Url: "https://youtube.com/shorts/test1234",
            DurationSeconds: 45,
            SizeBytes: 1024 * 1024,
            Format: "mp4"
        );

        var itemAudio = new MediaItemMetadata(
            Id: "item-2",
            Title: "Podcast Episode 1",
            Url: "https://example.com/audio.mp3",
            DurationSeconds: 1200,
            SizeBytes: 20 * 1024 * 1024,
            Format: "mp3"
        );

        var itemWithNewlines = new MediaItemMetadata(
            Id: "item-3",
            Title: "Title With\r\nDangerous\nNewlines",
            Url: "https://example.com/video.mp4",
            DurationSeconds: 300,
            SizeBytes: 50 * 1024 * 1024,
            Format: "mp4"
        );

        var collections = SmartCollectionEngine.GroupIntoCollections(new[] { itemNullTitle, itemAudio, itemWithNewlines });
        Assert.Contains(itemNullTitle, collections[SmartCollectionEngine.CollectionShorts]);
        Assert.Contains(itemAudio, collections[SmartCollectionEngine.CollectionMusic]);
        Assert.Contains(itemWithNewlines, collections[SmartCollectionEngine.CollectionGeneral]);

        // 2. M3U8 플레이리스트 생성 시 개행 문자 살균 검증
        var m3u8 = SmartCollectionEngine.GenerateM3u8Playlist("Playlist\r\nName", new[] { itemWithNewlines });
        Assert.DoesNotContain("\r\nDangerous", m3u8);
        Assert.Contains("#PLAYLIST:Playlist Name", m3u8);
        Assert.Contains("#EXTINF:300,Title With Dangerous Newlines", m3u8);
    }
}