using System.Security.Cryptography;
using System.Text;
using System.Text.Json;
using Omika.Core.Contracts.Mobile.Enrollment;
using Omika.Core.Services.Mobile;

namespace Omika.Tests.Mobile.Local;

/// <summary>
/// Tests du codec de QR d'inscription (signature RSA-SHA256 + décodage/vérification
/// par kid). Utilise une paire de clés éphémère : aucun secret serveur embarqué.
/// </summary>
public class EnrollmentQrCodecTests
{
    private const string Kid = "test-kid-1";

    private readonly string _publicKey;
    private readonly string _privateKey;
    private readonly IReadOnlyDictionary<string, string> _registry;

    public EnrollmentQrCodecTests()
    {
        using var rsa = RSA.Create(2048);
        _publicKey = rsa.ToXmlString(false);
        _privateKey = rsa.ToXmlString(true);
        _registry = new Dictionary<string, string> { [Kid] = _publicKey };
    }

    private string Sign(string code, string numero, string url)
        => EnrollmentQrCodec.Sign(
            EnrollmentQrCodec.BuildPayloadJson(Kid, code, numero, url), _privateKey);

    /// <summary>Signe un payload JSON arbitraire (pour forger des cas invalides).</summary>
    private string SignJson(string json)
        => EnrollmentQrCodec.Sign(json, _privateKey);

    private string Envelope(string payloadB64Url, string signatureB64Url)
        => EnrollmentQrCodec.Prefix + payloadB64Url + "." + signatureB64Url;

    private static string B64Url(string raw)
        => Convert.ToBase64String(Encoding.UTF8.GetBytes(raw)).TrimEnd('=').Replace('+', '-').Replace('/', '_');

    // ===== Cas acceptés =====

    [Fact]
    public void QrSigne_Accepte_CodeClient()
    {
        EnrollmentQrPayload? p = EnrollmentQrCodec.Decode(Sign("BATIK.01", "LIC-001", "https://licence.example.com"), _registry);
        Assert.NotNull(p);
        Assert.Equal("BATIK.01", p.CodeClient);
    }

    [Fact]
    public void QrSigne_Accepte_NumeroLicence()
    {
        EnrollmentQrPayload? p = EnrollmentQrCodec.Decode(Sign("BATIK.01", "LIC-001", "https://licence.example.com"), _registry);
        Assert.NotNull(p);
        Assert.Equal("LIC-001", p.NumeroLicence);
    }

    [Fact]
    public void QrSigne_Accepte_UrlLicence()
    {
        EnrollmentQrPayload? p = EnrollmentQrCodec.Decode(Sign("BATIK.01", "LIC-001", "https://licence.example.com"), _registry);
        Assert.NotNull(p);
        Assert.Equal("https://licence.example.com", p.UrlLicence);
    }

    // ===== Cas refusés =====

    [Fact]
    public void PayloadModifie_Refuse()
    {
        string qr = Sign("BATIK.01", "LIC-001", "https://licence.example.com");
        // Altération du contenu signé.
        Assert.Null(EnrollmentQrCodec.Decode(qr + "x", _registry));
    }

    [Fact]
    public void SignatureModifiee_Refuse()
    {
        string qr = Sign("BATIK.01", "LIC-001", "https://licence.example.com");
        int dot = qr.LastIndexOf('.');
        string tampered = qr[..(dot + 1)] + "AAAA"; // signature corrompue
        Assert.Null(EnrollmentQrCodec.Decode(tampered, _registry));
    }

    [Fact]
    public void MauvaiseCle_Refuse()
    {
        using var other = RSA.Create(2048);
        string qr = EnrollmentQrCodec.Sign(
            EnrollmentQrCodec.BuildPayloadJson(Kid, "BATIK.01", "LIC-001", "https://licence.example.com"),
            other.ToXmlString(true));
        Assert.Null(EnrollmentQrCodec.Decode(qr, _registry));
    }

    [Fact]
    public void Base64Invalide_Refuse()
    {
        Assert.Null(EnrollmentQrCodec.Decode(Envelope("!!!", "!!!"), _registry));
    }

    [Fact]
    public void JsonInvalide_Refuse()
    {
        string qr = SignJson("{not-json");
        Assert.Null(EnrollmentQrCodec.Decode(qr, _registry));
    }

    [Fact]
    public void VersionInconnue_Refuse()
    {
        string json = JsonSerializer.Serialize(new
        {
            version = 99,
            keyId = Kid,
            codeClient = "BATIK.01",
            numeroLicence = "LIC-001",
            urlLicence = "https://licence.example.com"
        });
        Assert.Null(EnrollmentQrCodec.Decode(SignJson(json), _registry));
    }

    [Fact]
    public void CodeClientVide_Refuse()
    {
        string json = JsonSerializer.Serialize(new
        {
            version = 1,
            keyId = Kid,
            codeClient = "",
            numeroLicence = "LIC-001",
            urlLicence = "https://licence.example.com"
        });
        Assert.Null(EnrollmentQrCodec.Decode(SignJson(json), _registry));
    }

    [Fact]
    public void NumeroLicenceVide_Refuse()
    {
        string json = JsonSerializer.Serialize(new
        {
            version = 1,
            keyId = Kid,
            codeClient = "BATIK.01",
            numeroLicence = "",
            urlLicence = "https://licence.example.com"
        });
        Assert.Null(EnrollmentQrCodec.Decode(SignJson(json), _registry));
    }

    [Fact]
    public void UrlLicenceVide_Refuse()
    {
        string json = JsonSerializer.Serialize(new
        {
            version = 1,
            keyId = Kid,
            codeClient = "BATIK.01",
            numeroLicence = "LIC-001",
            urlLicence = ""
        });
        Assert.Null(EnrollmentQrCodec.Decode(SignJson(json), _registry));
    }

    [Fact]
    public void KidInconnu_Refuse()
    {
        using var other = RSA.Create(2048);
        string qr = EnrollmentQrCodec.Sign(
            EnrollmentQrCodec.BuildPayloadJson("autre-kid", "BATIK.01", "LIC-001", "https://licence.example.com"),
            other.ToXmlString(true));
        Assert.Null(EnrollmentQrCodec.Decode(qr, _registry));
    }

    [Fact]
    public void RotationKid_DeuxCles_VerifieAvecBonneCle()
    {
        // Simule une rotation : le registre contient l'ancienne ET la nouvelle clé.
        using var oldRsa = RSA.Create(2048);
        using var newRsa = RSA.Create(2048);
        var registry = new Dictionary<string, string>
        {
            ["kid-old"] = oldRsa.ToXmlString(false),
            ["kid-new"] = newRsa.ToXmlString(false)
        };

        string qrNew = EnrollmentQrCodec.Sign(
            EnrollmentQrCodec.BuildPayloadJson("kid-new", "BATIK.01", "LIC-001", "https://licence.example.com"),
            newRsa.ToXmlString(true));

        EnrollmentQrPayload? p = EnrollmentQrCodec.Decode(qrNew, registry);
        Assert.NotNull(p);
        Assert.Equal("BATIK.01", p.CodeClient);
    }
}