using System.Text.Json;
using App.Core.Interfaces.Licensing;
using App.Core.Services.Licensing;

namespace App.Core.Tests.Licensing;

/// <summary>
/// Couvre uniquement le flux "essai" de LicenseService (pas de licence installée) : c'est la
/// partie testable sans dépendre de la vraie clé publique Ed25519, qui n'est pas encore générée
/// (voir Ed25519PublicKeyProvider). Le flux "licence installée" (ActivateLicense / licence déjà
/// présente) sera couvert une fois LicenseGenerator exécuté pour de vrai et la clé embarquée.
/// </summary>
public class LicenseServiceTests
{
    private sealed class FakeHardwareIdProvider(HardwareId hardwareId) : IHardwareIdProvider
    {
        public HardwareId GetCurrent() => hardwareId;
    }

    private sealed class FakeTrialStateStore : ITrialStateStore
    {
        public TrialState? Stored { get; private set; }

        public TrialState? Load() => Stored;

        public void Save(TrialState state) => Stored = state;
    }

    private sealed class FakeLicenseFileRepository : ILicenseFileRepository
    {
        public LicenseFile? Installed { get; set; }

        public LicenseFile? LoadInstalled() => Installed;

        public void Install(LicenseFile license) => Installed = license;
    }

    private sealed class CorruptedLicenseFileRepository : ILicenseFileRepository
    {
        public LicenseFile? LoadInstalled() => throw new JsonException("fichier .lic corrompu (test)");

        public void Install(LicenseFile license) => throw new NotSupportedException();
    }

    private static readonly HardwareId TestHardware = new("MB-TEST", "DISK-TEST");

    private static LicenseService CreateService(FakeTrialStateStore trialStore, ILicenseFileRepository? licenseRepo = null) =>
        new(new FakeHardwareIdProvider(TestHardware), trialStore, licenseRepo ?? new FakeLicenseFileRepository());

    [Fact]
    public void CheckLicenseStatus_FirstLaunch_CreatesTrialAndReturnsFullDuration()
    {
        var trialStore = new FakeTrialStateStore();
        var service = CreateService(trialStore);
        var now = new DateTime(2026, 1, 1, 9, 0, 0, DateTimeKind.Utc);

        var result = service.CheckLicenseStatus(now);

        Assert.Equal(LicenseStatus.TrialActive, result.Status);
        Assert.Equal(TrialState.TrialDurationDays, result.TrialDaysRemaining);
        Assert.NotNull(trialStore.Stored);
        Assert.Equal(now, trialStore.Stored!.InstallDateUtc);
        Assert.Equal(TestHardware.ComputeHash(), trialStore.Stored.HardwareIdHash);
    }

    [Fact]
    public void CheckLicenseStatus_SubsequentLaunch_ReturnsRemainingDaysAndUpdatesLastRun()
    {
        var trialStore = new FakeTrialStateStore();
        var service = CreateService(trialStore);
        var installDate = new DateTime(2026, 1, 1, 9, 0, 0, DateTimeKind.Utc);
        service.CheckLicenseStatus(installDate);

        var result = service.CheckLicenseStatus(installDate.AddDays(10));

        Assert.Equal(LicenseStatus.TrialActive, result.Status);
        Assert.Equal(20, result.TrialDaysRemaining);
        Assert.Equal(installDate.AddDays(10), trialStore.Stored!.LastRunTimestampUtc);
        Assert.Equal(installDate, trialStore.Stored.InstallDateUtc); // date d'installation jamais modifiée
    }

    [Fact]
    public void CheckLicenseStatus_After30Days_ReturnsTrialExpired()
    {
        var trialStore = new FakeTrialStateStore();
        var service = CreateService(trialStore);
        var installDate = new DateTime(2026, 1, 1, 9, 0, 0, DateTimeKind.Utc);
        service.CheckLicenseStatus(installDate);

        var result = service.CheckLicenseStatus(installDate.AddDays(31));

        Assert.Equal(LicenseStatus.TrialExpired, result.Status);
        Assert.Equal(0, result.TrialDaysRemaining);
    }

    [Fact]
    public void CheckLicenseStatus_ClockRolledBack_ReturnsClockTamperDetected()
    {
        var trialStore = new FakeTrialStateStore();
        var service = CreateService(trialStore);
        var installDate = new DateTime(2026, 1, 15, 9, 0, 0, DateTimeKind.Utc);
        service.CheckLicenseStatus(installDate);

        // L'utilisateur recule l'horloge système de 5 jours pour tenter de prolonger l'essai.
        var result = service.CheckLicenseStatus(installDate.AddDays(-5));

        Assert.Equal(LicenseStatus.ClockTamperDetected, result.Status);
    }

    [Fact]
    public void GetCurrentHardwareId_DelegatesToHardwareIdProvider()
    {
        var service = CreateService(new FakeTrialStateStore());

        Assert.Equal(TestHardware, service.GetCurrentHardwareId());
    }

    [Fact]
    public void CheckLicenseStatus_CorruptedLicenseFile_ReturnsInvalidRatherThanFallingBackToTrial()
    {
        var trialStore = new FakeTrialStateStore();
        var service = CreateService(trialStore, new CorruptedLicenseFileRepository());

        var result = service.CheckLicenseStatus(DateTime.UtcNow);

        Assert.Equal(LicenseStatus.InvalidSignature, result.Status);
        // Ne doit surtout pas avoir créé un nouvel essai : corrompre le fichier ne doit jamais
        // redonner 30 jours gratuits.
        Assert.Null(trialStore.Stored);
    }
}