using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Options;
using Shouldly;
using Xunit;

namespace ZB.MOM.WW.OtOpcUa.Cluster.Tests;

/// <summary>
///     Every failure this validator catches otherwise surfaces as an <i>absence</i> — a deployment
///     that never arrives, an alarm ack that does nothing, a node whose ack is dropped without a
///     trace. Absences are the hardest class of fault to attribute in the field, so the whole point
///     of these tests is that the host refuses to start instead.
/// </summary>
/// <remarks>
///     Role-dependent facts run in <see cref="RoleEnvironmentCollection"/> because the validator
///     resolves roles through <c>RoleParser.ResolveEffectiveRoles</c>, which reads
///     <c>OTOPCUA_ROLES</c> when <c>Cluster:Roles</c> is empty — a process-wide env var, so the
///     whole class is serialized against the other role-reading suites.
/// </remarks>
[Collection(RoleEnvironmentCollection.Name)]
public class MeshTransportOptionsValidatorTests
{
    private static ValidateOptionsResult Validate(MeshTransportOptions o, params string[] roles) =>
        Validate(o, new Dictionary<string, string?>(), roles);

    /// <summary>
    ///     As <see cref="Validate(MeshTransportOptions, string[])"/>, plus arbitrary configuration
    ///     keys — the admin-side rule cross-reads <c>ConfigServe:GrpcListenPort</c>, which lives
    ///     outside this options class entirely.
    /// </summary>
    private static ValidateOptionsResult Validate(
        MeshTransportOptions o, Dictionary<string, string?> extra, params string[] roles)
    {
        var pairs = new Dictionary<string, string?>(extra);
        for (var i = 0; i < roles.Length; i++)
        {
            pairs[$"Cluster:Roles:{i}"] = roles[i];
        }

        var configuration = new ConfigurationBuilder().AddInMemoryCollection(pairs).Build();

        return new MeshTransportOptionsValidator(configuration, EffectiveRoles.Resolve(configuration))
            .Validate(MeshTransportOptions.SectionName, o);
    }

    private static Dictionary<string, string?> ConfigServePort(string? value) =>
        new() { ["ConfigServe:GrpcListenPort"] = value };

    private static MeshTransportOptions WellFormedGrpc() => new()
    {
        Mode = MeshTransportOptions.ModeGrpc,
        GrpcPsk = "not-a-real-key",
        CentralGrpcEndpoints = ["http://central-1:4055", "https://central-2:4055"],
    };

    [Fact]
    public void Default_options_are_valid()
    {
        // The default is Dps — the pre-Phase-2 transport. A node that never sets this section must
        // behave exactly as it did before, which is the whole premise of the dark switch.
        Validate(new MeshTransportOptions()).Succeeded.ShouldBeTrue();
    }

    [Fact]
    public void Unknown_mode_fails()
    {
        var result = Validate(new MeshTransportOptions { Mode = "not-a-transport" });

        result.Failed.ShouldBeTrue();
        result.FailureMessage.ShouldContain("not-a-transport");
    }

    [Fact]
    public void Unknown_mode_message_names_both_accepted_values()
    {
        // An operator who mistypes the mode gets the full menu, not a partial one.
        var result = Validate(new MeshTransportOptions { Mode = "not-a-mode" });

        result.Failed.ShouldBeTrue();
        result.FailureMessage.ShouldContain(MeshTransportOptions.ModeDps);
        result.FailureMessage.ShouldContain(MeshTransportOptions.ModeGrpc);
    }

    [Fact]
    public void The_retired_ClusterClient_mode_fails_rather_than_falling_back_to_Dps()
    {
        // A node left carrying the deleted transport's mode value must be refused at boot. Silently
        // treating it as Dps would leave a split-topology node running, listening, and delivering
        // nothing across its mesh boundary — the exact absence this validator exists to prevent.
        var result = Validate(new MeshTransportOptions { Mode = "ClusterClient" });

        result.Failed.ShouldBeTrue();
        result.FailureMessage.ShouldContain("MeshTransport:Mode");
        result.FailureMessage.ShouldContain(MeshTransportOptions.ModeGrpc);
    }

    [Fact]
    public void Mode_matching_is_case_insensitive()
    {
        Validate(new MeshTransportOptions { Mode = "dps" }).Succeeded.ShouldBeTrue();
    }

    [Fact]
    public void Non_positive_contact_refresh_fails()
    {
        var result = Validate(new MeshTransportOptions { ContactRefreshSeconds = 0 });

        result.Failed.ShouldBeTrue();
        result.FailureMessage.ShouldContain(nameof(MeshTransportOptions.ContactRefreshSeconds));
    }

    // ---- Grpc mode (the cross-mesh command plane) -----------------------------------------------

    [Fact]
    public void Grpc_is_an_accepted_mode()
    {
        Validate(WellFormedGrpc(), "driver", "cluster-SITE-A").Succeeded.ShouldBeTrue();
    }

    [Fact]
    public void Grpc_mode_matching_is_case_insensitive()
    {
        var options = WellFormedGrpc();
        options.Mode = "grpc";

        Validate(options, "driver", "cluster-SITE-A").Succeeded.ShouldBeTrue();
    }

    [Fact]
    public void Grpc_driver_node_without_a_psk_fails()
    {
        var options = WellFormedGrpc();
        options.GrpcPsk = null;

        var result = Validate(options, "driver", "cluster-SITE-A");

        result.Failed.ShouldBeTrue();
        result.FailureMessage.ShouldContain("MeshTransport:GrpcPsk");
        result.FailureMessage.ShouldContain("MeshTransport__GrpcPsk");
    }

    [Fact]
    public void Grpc_driver_node_with_an_empty_psk_fails()
    {
        // Empty is the shape an unset environment variable actually produces, and it is exactly as
        // fatal as null — a blank bearer authenticates nothing.
        var options = WellFormedGrpc();
        options.GrpcPsk = "   ";

        Validate(options, "driver", "cluster-SITE-A").Failed.ShouldBeTrue();
    }

    [Fact]
    public void The_psk_value_is_never_echoed_in_a_failure_message()
    {
        // The whole point of a validator that reads a secret is that its diagnostics are safe to
        // paste into a ticket. Naming the key is the contract; printing it is a leak.
        var options = WellFormedGrpc();
        options.GrpcPsk = "super-secret-mesh-psk";
        options.CentralGrpcEndpoints = ["central-1:4055"];

        var result = Validate(options, "driver", "cluster-SITE-A");

        result.Failed.ShouldBeTrue();
        result.FailureMessage.ShouldNotContain("super-secret-mesh-psk");
    }

    [Fact]
    public void Grpc_driver_node_without_central_endpoints_fails()
    {
        var options = WellFormedGrpc();
        options.CentralGrpcEndpoints = [];

        var result = Validate(options, "driver", "cluster-SITE-A");

        result.Failed.ShouldBeTrue();
        result.FailureMessage.ShouldContain("MeshTransport:CentralGrpcEndpoints");
    }

    [Fact]
    public void A_central_endpoint_that_is_not_an_http_url_fails()
    {
        var options = WellFormedGrpc();
        options.CentralGrpcEndpoints = ["central-1:4055"];

        var result = Validate(options, "driver", "cluster-SITE-A");

        result.Failed.ShouldBeTrue();
        result.FailureMessage.ShouldContain("central-1:4055");
        result.FailureMessage.ShouldContain("http://");
    }

    [Fact]
    public void One_bad_central_endpoint_among_good_ones_still_fails()
    {
        var options = WellFormedGrpc();
        options.CentralGrpcEndpoints = ["http://central-1:4055", "akka.tcp://otopcua@central-2:4053"];

        var result = Validate(options, "driver", "cluster-SITE-A");

        result.Failed.ShouldBeTrue();
        result.FailureMessage.ShouldContain("akka.tcp://otopcua@central-2:4053");
    }

    [Fact]
    public void Grpc_driver_node_with_a_non_positive_dispatch_timeout_fails()
    {
        var options = WellFormedGrpc();
        options.DispatchTimeoutSeconds = 0;

        var result = Validate(options, "driver", "cluster-SITE-A");

        result.Failed.ShouldBeTrue();
        result.FailureMessage.ShouldContain("MeshTransport:DispatchTimeoutSeconds");
    }

    [Fact]
    public void Grpc_driver_node_with_a_non_positive_ack_timeout_fails()
    {
        var options = WellFormedGrpc();
        options.AckTimeoutSeconds = -1;

        var result = Validate(options, "driver", "cluster-SITE-A");

        result.Failed.ShouldBeTrue();
        result.FailureMessage.ShouldContain("MeshTransport:AckTimeoutSeconds");
    }

    [Fact]
    public void Grpc_admin_only_node_needs_none_of_the_node_side_keys()
    {
        // The node-side surface is what a DRIVER uses to dial central and post its ack. An admin-only
        // central node dials nodes instead and resolves per-cluster keys at runtime, so requiring
        // these here would make an admin node carry a PSK and an endpoint list it never reads.
        // (The ConfigServe port IS required of an admin node under Grpc — supplied here so this test
        // stays about the node-side keys and nothing else.)
        Validate(
            new MeshTransportOptions { Mode = MeshTransportOptions.ModeGrpc },
            ConfigServePort("4055"),
            "admin", "cluster-MAIN").Succeeded.ShouldBeTrue();
    }

    [Fact]
    public void Grpc_admin_node_without_a_config_serve_listener_fails()
    {
        // Central hosts CentralCommandService on the ConfigServe h2c listener, so an unset port means
        // the service is never mapped and every node's ack has nowhere to land. Nothing errors at
        // runtime — the deployment simply times out naming nodes that applied perfectly, which is the
        // exact absence this validator exists to convert into a refusal to start.
        var result = Validate(
            new MeshTransportOptions { Mode = MeshTransportOptions.ModeGrpc },
            "admin", "cluster-MAIN");

        result.Failed.ShouldBeTrue();
        result.FailureMessage.ShouldContain("ConfigServe:GrpcListenPort");
        result.FailureMessage.ShouldContain("ConfigServe__GrpcListenPort");
    }

    [Fact]
    public void Grpc_admin_node_with_a_zero_config_serve_port_fails()
    {
        // 0 is the documented "disabled" value, not merely a missing key — it must fail exactly as an
        // absent one does, because it binds nothing just as surely.
        Validate(
            new MeshTransportOptions { Mode = MeshTransportOptions.ModeGrpc },
            ConfigServePort("0"),
            "admin", "cluster-MAIN").Failed.ShouldBeTrue();
    }

    [Fact]
    public void Grpc_admin_node_with_an_unparseable_config_serve_port_fails()
    {
        // A typo'd port binds nothing, so it belongs on the same side of the line as an absent one.
        Validate(
            new MeshTransportOptions { Mode = MeshTransportOptions.ModeGrpc },
            ConfigServePort("40o55"),
            "admin", "cluster-MAIN").Failed.ShouldBeTrue();
    }

    [Fact]
    public void Grpc_admin_node_with_a_config_serve_listener_passes()
    {
        Validate(
            new MeshTransportOptions { Mode = MeshTransportOptions.ModeGrpc },
            ConfigServePort("4055"),
            "admin", "cluster-MAIN").Succeeded.ShouldBeTrue();
    }

    [Fact]
    public void Grpc_driver_only_node_needs_no_config_serve_listener()
    {
        // A driver node dials central; it serves no central command endpoint at all, and requiring an
        // admin-side listener port of it would demand configuration it never reads.
        Validate(WellFormedGrpc(), "driver", "cluster-SITE-A").Succeeded.ShouldBeTrue();
    }

    [Fact]
    public void Dps_admin_node_needs_no_config_serve_listener()
    {
        // The no-new-obligations invariant, admin side: a central node still on the default transport
        // publishes on DistributedPubSub and hosts no command endpoint.
        Validate(
            new MeshTransportOptions { Mode = MeshTransportOptions.ModeDps },
            "admin", "cluster-MAIN").Succeeded.ShouldBeTrue();
    }

    [Fact]
    public void The_admin_role_is_also_read_from_OTOPCUA_ROLES()
    {
        // Same roles-source divergence as the driver case (Gitea #532), on the side that hosts the
        // endpoint: a central node configured only through the env var is still the node whose
        // listener every ack depends on.
        using (new EnvVarScope("OTOPCUA_ROLES", "admin,cluster-MAIN"))
        {
            Validate(new MeshTransportOptions { Mode = MeshTransportOptions.ModeGrpc })
                .Failed.ShouldBeTrue();
        }
    }

    [Fact]
    public void Grpc_role_less_node_needs_none_of_the_node_side_keys()
    {
        // Every in-process test host and every single-mesh node has no declared role. Requiring the
        // Grpc surface of them would turn a dark-switch value into a tree-wide config obligation.
        Validate(new MeshTransportOptions { Mode = MeshTransportOptions.ModeGrpc }).Succeeded.ShouldBeTrue();
    }

    [Fact]
    public void Roles_come_from_OTOPCUA_ROLES_when_Cluster_Roles_is_empty()
    {
        // Roles-source divergence (Gitea #532): a node configured only through the env var is still a
        // driver node in Akka. A validator reading Cluster:Roles alone would exempt the exact node
        // that has to dial central, and its acks would be rejected unauthenticated at runtime.
        using (new EnvVarScope("OTOPCUA_ROLES", "driver,cluster-SITE-A"))
        {
            var options = WellFormedGrpc();
            options.GrpcPsk = null;

            Validate(options).Failed.ShouldBeTrue();
        }
    }

    [Fact]
    public void Dps_mode_requires_none_of_the_new_Grpc_keys()
    {
        // The no-new-obligations invariant: adding a third mode must not make any existing
        // deployment's configuration invalid. A Dps driver node that sets nothing new still passes.
        Validate(
            new MeshTransportOptions { Mode = MeshTransportOptions.ModeDps },
            "driver", "cluster-SITE-A").Succeeded.ShouldBeTrue();
    }

    [Fact]
    public void Grpc_fused_admin_and_driver_node_must_satisfy_BOTH_surfaces()
    {
        // The central pair is fused (admin,driver,cluster-MAIN), so it is the one node shape that owes
        // both halves at once — and the two blocks are independent `if`s, not an `if`/`else if`. Were
        // they chained, a fused node would be graded on the driver surface only and its missing
        // ConfigServe listener would pass validation, leaving central with no place for any node's ack
        // to land. Asserted from BOTH sides so a future chaining in either order is caught.
        var missingNodeSide = new MeshTransportOptions { Mode = MeshTransportOptions.ModeGrpc };
        var withPort = Validate(missingNodeSide, ConfigServePort("4055"), "driver", "admin", "cluster-MAIN");
        withPort.Failed.ShouldBeTrue();
        withPort.FailureMessage.ShouldContain("MeshTransport:GrpcPsk");
        withPort.FailureMessage.ShouldContain("MeshTransport:CentralGrpcEndpoints");

        var missingAdminSide = Validate(WellFormedGrpc(), "driver", "admin", "cluster-MAIN");
        missingAdminSide.Failed.ShouldBeTrue();
        missingAdminSide.FailureMessage.ShouldContain("ConfigServe:GrpcListenPort");

        // And the fully-configured fused node passes — the rule is "both", not "neither".
        Validate(WellFormedGrpc(), ConfigServePort("4055"), "driver", "admin", "cluster-MAIN")
            .Succeeded.ShouldBeTrue();
    }

    [Fact]
    public void ClusterPsks_defaults_to_an_empty_case_insensitive_map()
    {
        // Production leaves the map empty and the runtime provider falls back to the Secrets store;
        // the rig populates it. Case-insensitivity matters because a ClusterId reaches this lookup
        // from three sources — a role suffix, a DB column and an env key — that do not agree on case.
        var options = new MeshTransportOptions();

        options.ClusterPsks.ShouldBeEmpty();
        options.ClusterPsks["MAIN"] = "rig-key";
        options.ClusterPsks.ContainsKey("main").ShouldBeTrue();
    }

    [Fact]
    public void ClusterPsks_stays_case_insensitive_after_binding_configuration()
    {
        // Asserting the comparer on a fresh instance proves nothing about the shape that reaches
        // production: the options binder could construct its own Dictionary and drop the comparer
        // silently, and the symptom would be a rig lookup that misses on a ClusterId spelled the way
        // the DB spells it. Bind for real and check the comparer survived.
        var configuration = new ConfigurationBuilder()
            .AddInMemoryCollection(new Dictionary<string, string?>
            {
                ["MeshTransport:ClusterPsks:SITE-A"] = "rig-key",
            })
            .Build();

        var options = new MeshTransportOptions();
        configuration.GetSection(MeshTransportOptions.SectionName).Bind(options);

        options.ClusterPsks["site-a"].ShouldBe("rig-key");
    }
}