using FinalFactory.Rendezvous.Contracts;
using FinalFactory.Rendezvous.Server.Provisioning;

namespace FinalFactory.Rendezvous.Tests.Provisioning;

public sealed class PrincipalCredentialTests
{
    [Fact]
    public void Base64UrlDecoderRejectsNonCanonicalTrailingBits()
    {
        Assert.True(Base64Url.TryDecode("AA", out byte[] canonical));
        Assert.Equal(new byte[] { 0 }, canonical);
        Assert.False(Base64Url.TryDecode("AB", out byte[] nonCanonical));
        Assert.Empty(nonCanonical);
    }

    [Fact]
    public void DedicatedAndPlayerGrantCredentialsRoundtripToDistinctPrincipals()
    {
        using DictionarySecretProvider secrets = ProvisioningTestData.CreateSecrets("secret-1");
        using SigningKeyRing keys = SigningKeyRing.Create(
            [ProvisioningTestData.CreateKey()],
            secrets);
        PrincipalCredentialService service = CreateService(keys);
        DedicatedPublisherPrincipal dedicated = ProvisioningTestData.CreateDedicatedPublisher();
        PlayerHostGrantPrincipal playerGrant = new(
            "host-grant-7",
            ProvisioningTestData.Now.AddMinutes(5),
            dedicated.GameId,
            dedicated.EnvironmentId,
            dedicated.AllowedRegions);

        CredentialValidationResult dedicatedResult = service.Validate(
            service.Issue(dedicated, ProvisioningTestData.Now),
            ProvisioningTestData.Now);
        CredentialValidationResult grantResult = service.Validate(
            service.Issue(playerGrant, ProvisioningTestData.Now),
            ProvisioningTestData.Now);

        Assert.IsType<DedicatedPublisherPrincipal>(dedicatedResult.Principal);
        Assert.IsType<PlayerHostGrantPrincipal>(grantResult.Principal);
    }

    [Fact]
    public void WrongIssuerAndAudienceAreRejectedAfterSignatureValidation()
    {
        using DictionarySecretProvider secrets = ProvisioningTestData.CreateSecrets("secret-1");
        using SigningKeyRing keys = SigningKeyRing.Create(
            [ProvisioningTestData.CreateKey()],
            secrets);
        PrincipalCredentialService issuer = CreateService(keys);
        string token = issuer.Issue(
            ProvisioningTestData.CreateDedicatedPublisher(),
            ProvisioningTestData.Now);

        PrincipalCredentialService wrongIssuer = new(
            "other-issuer",
            "rendezvous-service",
            TimeSpan.FromSeconds(30),
            keys);
        PrincipalCredentialService wrongAudience = new(
            "final-factory-rendezvous",
            "other-audience",
            TimeSpan.FromSeconds(30),
            keys);

        Assert.Equal(
            CredentialValidationError.IssuerMismatch,
            wrongIssuer.Validate(token, ProvisioningTestData.Now).Error);
        Assert.Equal(
            CredentialValidationError.AudienceMismatch,
            wrongAudience.Validate(token, ProvisioningTestData.Now).Error);
    }

    [Fact]
    public void ExpiryTamperingAndRevocationAreRejected()
    {
        using DictionarySecretProvider secrets = ProvisioningTestData.CreateSecrets("secret-1");
        using SigningKeyRing keys = SigningKeyRing.Create(
            [ProvisioningTestData.CreateKey()],
            secrets);
        PrincipalCredentialService service = CreateService(keys);
        string token = service.Issue(
            ProvisioningTestData.CreateDedicatedPublisher(
                ProvisioningTestData.Now.AddMinutes(1)),
            ProvisioningTestData.Now);
        char replacement = token[^1] == 'A' ? 'B' : 'A';
        string tampered = token[..^1] + replacement;

        Assert.Equal(
            CredentialValidationError.Expired,
            service.Validate(token, ProvisioningTestData.Now.AddSeconds(91)).Error);
        Assert.Equal(
            CredentialValidationError.SignatureInvalid,
            service.Validate(tampered, ProvisioningTestData.Now).Error);
        Assert.True(keys.Revoke("key-1"));
        Assert.Equal(
            CredentialValidationError.KeyRevoked,
            service.Validate(token, ProvisioningTestData.Now).Error);
    }

    [Fact]
    public void KeyRotationHonorsOverlapAndRejectsRetiredKeys()
    {
        SigningKeyOptions oldKey = ProvisioningTestData.CreateKey(
            "old-key",
            "old-secret",
            ProvisioningTestData.Now.AddHours(-1),
            ProvisioningTestData.Now.AddMinutes(10),
            ProvisioningTestData.Now.AddMinutes(60));
        SigningKeyOptions newKey = ProvisioningTestData.CreateKey(
            "new-key",
            "new-secret",
            ProvisioningTestData.Now.AddMinutes(10),
            ProvisioningTestData.Now.AddHours(2),
            ProvisioningTestData.Now.AddHours(3));
        using DictionarySecretProvider secrets = ProvisioningTestData.CreateSecrets(
            "old-secret",
            "new-secret");
        using SigningKeyRing keys = SigningKeyRing.Create([oldKey, newKey], secrets);
        PrincipalCredentialService service = CreateService(keys);
        string oldToken = service.Issue(
            ProvisioningTestData.CreateDedicatedPublisher(
                ProvisioningTestData.Now.AddMinutes(50)),
            ProvisioningTestData.Now);

        Assert.True(service.Validate(oldToken, ProvisioningTestData.Now.AddMinutes(20)).IsValid);
        Assert.Equal(
            CredentialValidationError.KeyRetired,
            service.Validate(oldToken, ProvisioningTestData.Now.AddMinutes(61)).Error);

        string newToken = service.Issue(
            ProvisioningTestData.CreateDedicatedPublisher(
                ProvisioningTestData.Now.AddMinutes(90)),
            ProvisioningTestData.Now.AddMinutes(20));
        Assert.True(service.Validate(newToken, ProvisioningTestData.Now.AddMinutes(20)).IsValid);
    }

    [Fact]
    public void OperatorCredentialNeverBecomesAPublisherPrincipal()
    {
        SigningKeyOptions operatorKey = ProvisioningTestData.CreateKey(
            credentialKinds: [PrincipalCredentialKind.Operator],
            gameId: null,
            environmentId: null);
        using DictionarySecretProvider secrets = ProvisioningTestData.CreateSecrets("secret-1");
        using SigningKeyRing keys = SigningKeyRing.Create(
            [operatorKey],
            secrets);
        PrincipalCredentialService service = CreateService(keys);
        OperatorPrincipal operatorPrincipal = new(
            "operator-1",
            ProvisioningTestData.Now.AddMinutes(5),
            new HashSet<OperatorPermission> { OperatorPermission.RotateKeys });

        CredentialValidationResult result = service.Validate(
            service.Issue(operatorPrincipal, ProvisioningTestData.Now),
            ProvisioningTestData.Now);

        Assert.IsType<OperatorPrincipal>(result.Principal);
        Assert.IsNotAssignableFrom<IPublisherPrincipal>(result.Principal);
    }

    [Fact]
    public void ConfiguredRevocationDoesNotRequireRetiredSecretMaterial()
    {
        SigningKeyOptions revoked = ProvisioningTestData.CreateKey(
            "revoked-key",
            "removed-secret",
            revoked: true);
        SigningKeyOptions active = ProvisioningTestData.CreateKey(
            "active-key",
            "active-secret");
        using DictionarySecretProvider secrets = ProvisioningTestData.CreateSecrets("active-secret");
        using SigningKeyRing keys = SigningKeyRing.Create([revoked, active], secrets);

        Assert.Equal(
            VerificationKeyLookup.Revoked,
            keys.FindVerificationKey("revoked-key", ProvisioningTestData.Now, out _));
        Assert.True(keys.TryGetSigningKey(
            ProvisioningTestData.Now,
            PrincipalCredentialKind.DedicatedPublisher,
            "space-game",
            "production",
            out SigningKey? signingKey));
        Assert.Equal("active-key", signingKey?.KeyId);
    }

    [Fact]
    public void SigningKeyAuthorityRejectsCrossGameClaimsEvenWithAValidSignature()
    {
        using DictionarySecretProvider secrets = ProvisioningTestData.CreateSecrets("secret-1");
        using SigningKeyRing keys = SigningKeyRing.Create(
            [ProvisioningTestData.CreateKey()],
            secrets);
        Assert.Equal(
            VerificationKeyLookup.Available,
            keys.FindVerificationKey("key-1", ProvisioningTestData.Now, out SigningKey? signingKey));
        Assert.NotNull(signingKey);

        CredentialPayload payload = new()
        {
            Version = ContractLimits.ContractVersion,
            Issuer = "final-factory-rendezvous",
            Audience = "rendezvous-service",
            Subject = "malicious-grant-issuer",
            Kind = PrincipalCredentialKind.PlayerHostGrant,
            GameId = "unscouted",
            EnvironmentId = "production",
            Regions = ["eu-central"],
            IssuedAtUnixSeconds = ProvisioningTestData.Now.ToUnixTimeSeconds(),
            NotBeforeUnixSeconds = ProvisioningTestData.Now.ToUnixTimeSeconds(),
            ExpiresAtUnixSeconds = ProvisioningTestData.Now.AddMinutes(5).ToUnixTimeSeconds(),
            Nonce = Guid.NewGuid().ToString("N"),
        };
        string encodedPayload = Base64Url.Encode(
            System.Text.Json.JsonSerializer.SerializeToUtf8Bytes(payload, ContractJson.Options));
        string signedContent = $"rv1.key-1.{encodedPayload}";
        string token = $"{signedContent}.{Base64Url.Encode(signingKey.Sign(signedContent))}";

        CredentialValidationResult result = CreateService(keys).Validate(
            token,
            ProvisioningTestData.Now);

        Assert.Equal(CredentialValidationError.KeyScopeMismatch, result.Error);
        Assert.Null(result.Principal);
    }

    private static PrincipalCredentialService CreateService(SigningKeyRing keys) => new(
        "final-factory-rendezvous",
        "rendezvous-service",
        TimeSpan.FromSeconds(30),
        keys);
}