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

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

/// <summary>
///     <see cref="EffectiveRoles"/> is the single role authority (archreview R3-04, 01/S-12 = 03/C5,
///     01/C-9): one factory, one precedence (<c>Cluster:Roles</c> non-empty wins, else
///     <c>OTOPCUA_ROLES</c>, else empty), two-layer normalization (plain roles lower-cased, a cluster
///     role's ClusterId suffix preserved verbatim), and validation on BOTH sources.
/// </summary>
[Collection(RoleEnvironmentCollection.Name)]
public sealed class EffectiveRolesTests
{
    // ---- Precedence matrix -------------------------------------------------------------------

    [Fact]
    public void Configured_only_resolves_from_Configured_source()
    {
        var roles = EffectiveRoles.Resolve(["admin", "driver"], null);

        roles.Source.ShouldBe(RoleSource.Configured);
        roles.Gossiped.ShouldBe(new[] { "admin", "driver" });
    }

    [Fact]
    public void Environment_only_resolves_from_Environment_source()
    {
        var roles = EffectiveRoles.Resolve(null, "admin,driver");

        roles.Source.ShouldBe(RoleSource.Environment);
        roles.Gossiped.ShouldBe(new[] { "admin", "driver" });
    }

    [Fact]
    public void Both_agree_resolves_from_Configured_source()
    {
        var roles = EffectiveRoles.Resolve(["driver"], "driver");

        roles.Source.ShouldBe(RoleSource.Configured);
        roles.Gossiped.ShouldBe(new[] { "driver" });
    }

    [Fact]
    public void Both_differ_Configured_wins_outright()
    {
        var roles = EffectiveRoles.Resolve(["admin"], "driver,cluster-SITE-A");

        roles.Source.ShouldBe(RoleSource.Configured);
        roles.Gossiped.ShouldBe(new[] { "admin" });
    }

    [Fact]
    public void Neither_source_resolves_empty_with_None_source()
    {
        var roles = EffectiveRoles.Resolve(null, null);

        roles.Source.ShouldBe(RoleSource.None);
        roles.Gossiped.ShouldBeEmpty();
    }

    [Fact]
    public void Empty_configured_array_falls_back_to_the_environment()
    {
        var roles = EffectiveRoles.Resolve([], "driver");

        roles.Source.ShouldBe(RoleSource.Environment);
        roles.Gossiped.ShouldBe(new[] { "driver" });
    }

    // ---- Gossiped normalization: two-layer (choice 2) ----------------------------------------

    [Fact]
    public void Configured_plain_role_is_trimmed_and_lower_cased_in_Gossiped()
    {
        var roles = EffectiveRoles.Resolve([" Driver "], null);

        roles.Gossiped.ShouldBe(new[] { "driver" });
    }

    /// <summary>
    ///     THE falsification control for choice 2: a cluster role's ClusterId suffix must survive
    ///     UNCHANGED — lower-casing it would rename the Akka role of a running deployment
    ///     (<c>cluster-SITE-A</c> vs <c>cluster-site-a</c> are different gossiped roles).
    /// </summary>
    [Fact]
    public void Configured_cluster_role_suffix_case_is_preserved_in_Gossiped()
    {
        var roles = EffectiveRoles.Resolve(["Cluster-SITE-A"], null);

        // The "cluster-" prefix normalizes (it is a plain marker), the "SITE-A" suffix does not.
        roles.Gossiped.ShouldBe(new[] { "cluster-SITE-A" });
    }

    [Fact]
    public void Configured_cluster_role_with_already_lowercase_prefix_keeps_suffix_verbatim()
    {
        var roles = EffectiveRoles.Resolve(["cluster-Site-A"], null);

        roles.Gossiped.ShouldBe(new[] { "cluster-Site-A" });
    }

    [Fact]
    public void Environment_cluster_role_suffix_IS_lowercased_unlike_Configured()
    {
        // Unchanged from RoleParser.Parse's existing (documented) behaviour: the two sources
        // normalize differently on purpose (RoleParser.ClusterIdFromRole's remarks).
        var roles = EffectiveRoles.Resolve(null, "driver,cluster-SITE-A");

        roles.Gossiped.ShouldBe(new[] { "driver", "cluster-site-a" });
    }

    // ---- Has*/HasAdmin/HasDriver case-insensitivity ------------------------------------------

    [Theory]
    [InlineData("driver")]
    [InlineData("Driver")]
    [InlineData("DRIVER")]
    [InlineData(" driver ")]
    public void HasDriver_true_for_every_casing(string configuredRole)
    {
        EffectiveRoles.Resolve([configuredRole], null).HasDriver.ShouldBeTrue();
    }

    [Fact]
    public void HasAdmin_false_when_admin_is_not_present()
    {
        EffectiveRoles.Resolve(["driver"], null).HasAdmin.ShouldBeFalse();
    }

    [Fact]
    public void Has_is_case_insensitive_for_an_arbitrary_role()
    {
        var roles = EffectiveRoles.Resolve(["Admin", "Driver"], null);

        roles.Has("admin").ShouldBeTrue();
        roles.Has("ADMIN").ShouldBeTrue();
        roles.Has("driver").ShouldBeTrue();
        roles.Has("dev").ShouldBeFalse();
    }

    // ---- Unknown / invalid role from EITHER source throws, naming the key --------------------

    [Fact]
    public void Unknown_role_from_the_configured_source_throws_naming_the_key()
    {
        var ex = Should.Throw<ArgumentException>(() => EffectiveRoles.Resolve(["Drivr"], null));

        ex.Message.ShouldContain("Cluster:Roles");
        ex.Message.ShouldContain("Drivr");
    }

    [Fact]
    public void Unknown_role_from_the_environment_source_throws()
    {
        // The env path already validated via RoleParser.Parse — this pins that it still does.
        Should.Throw<ArgumentException>(() => EffectiveRoles.Resolve(null, "admin,master"));
    }

    // ---- ClusterRole / ClusterId ---------------------------------------------------------------

    [Fact]
    public void ClusterRole_and_ClusterId_are_null_for_a_legacy_node()
    {
        var roles = EffectiveRoles.Resolve(["admin", "driver"], null);

        roles.ClusterRole.ShouldBeNull();
        roles.ClusterId.ShouldBeNull();
    }

    [Fact]
    public void ClusterRole_and_ClusterId_resolve_for_a_split_topology_node()
    {
        var roles = EffectiveRoles.Resolve(["driver", "cluster-SITE-A"], null);

        roles.ClusterRole.ShouldBe("cluster-SITE-A");
        roles.ClusterId.ShouldBe("SITE-A");
    }

    // ---- Resolve(IConfiguration) overload ------------------------------------------------------

    [Fact]
    public void Resolve_from_configuration_reads_Cluster_Roles()
    {
        var configuration = new ConfigurationBuilder()
            .AddInMemoryCollection(new Dictionary<string, string?>
            {
                ["Cluster:Roles:0"] = "driver",
                ["Cluster:Roles:1"] = "cluster-SITE-A",
            })
            .Build();

        var roles = EffectiveRoles.Resolve(configuration);

        roles.Source.ShouldBe(RoleSource.Configured);
        roles.Gossiped.ShouldBe(new[] { "driver", "cluster-SITE-A" });
    }

    [Fact]
    public void Resolve_from_configuration_falls_back_to_the_environment()
    {
        using (new EnvVarScope(RoleParser.RolesEnvVar, "admin,driver"))
        {
            var configuration = new ConfigurationBuilder().Build();

            var roles = EffectiveRoles.Resolve(configuration);

            roles.Source.ShouldBe(RoleSource.Environment);
            roles.Gossiped.ShouldBe(new[] { "admin", "driver" });
        }
    }

    // ---- DisagreementWarning (choice 5, T6) ----------------------------------------------------

    [Fact]
    public void Both_sources_set_and_agreeing_has_no_warning()
    {
        var roles = EffectiveRoles.Resolve(["driver"], "driver");

        roles.DisagreementWarning.ShouldBeNull();
    }

    [Fact]
    public void Only_one_source_set_has_no_warning()
    {
        EffectiveRoles.Resolve(["driver"], null).DisagreementWarning.ShouldBeNull();
        EffectiveRoles.Resolve(null, "driver").DisagreementWarning.ShouldBeNull();
        EffectiveRoles.Resolve(null, null).DisagreementWarning.ShouldBeNull();
    }

    [Fact]
    public void Both_sources_set_and_disagreeing_produces_a_warning_naming_both_keys()
    {
        var roles = EffectiveRoles.Resolve(["admin"], "driver,cluster-SITE-A");

        roles.DisagreementWarning.ShouldNotBeNull();
        roles.DisagreementWarning.ShouldContain("Cluster:Roles");
        roles.DisagreementWarning.ShouldContain(RoleParser.RolesEnvVar);
        // Configured still wins outright — the warning is observability, not a behaviour change.
        roles.Gossiped.ShouldBe(new[] { "admin" });
        roles.Source.ShouldBe(RoleSource.Configured);
    }

    [Fact]
    public void Both_sources_set_but_only_differing_by_case_do_not_warn()
    {
        // Same normalized set spelled differently in each source is NOT the "Cluster:Roles wins
        // unintentionally" shape the warning exists for.
        var roles = EffectiveRoles.Resolve(["Driver"], "driver");

        roles.DisagreementWarning.ShouldBeNull();
    }
}