using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Diagnostics.HealthChecks;
using Microsoft.Extensions.Options;
using Shouldly;
using Xunit;
using ZB.MOM.WW.Health;
using ZB.MOM.WW.Health.Akka;
using ZB.MOM.WW.OtOpcUa.Host.Health;

namespace ZB.MOM.WW.OtOpcUa.Host.Tests.Health;

/// <summary>
/// Pins OtOpcUa's active-tier wiring. The <i>rule</i> (oldest Up member of a role) now lives in the
/// shared <c>ClusterActiveNode</c> and is tested there against a real two-node cluster; what stays
/// OtOpcUa's own decision — and what regressed in <c>lmxopcua#494</c> — is <b>which check is
/// registered on the active tag, and with which roles</b>.
/// </summary>
public sealed class ActiveTierRegistrationTests
{
    private static HealthCheckRegistration ClusterPrimaryRegistration(bool hasAdmin) =>
        new ServiceCollection()
            .AddOtOpcUaHealth(hasAdmin)
            .BuildServiceProvider()
            .GetRequiredService<IOptions<HealthCheckServiceOptions>>()
            .Value.Registrations
            .Where(r => r.Name == "cluster-primary")
            .ShouldHaveSingleItem();

    [Fact]
    public void Active_tier_uses_the_shared_ActiveNodeHealthCheck()
    {
        // Not a bespoke copy. Two apps in the family independently hand-rolled this check because the
        // shared one selected by RoleLeader; since Health 0.3.0 the shared one is the correct rule, so
        // a private reimplementation reappearing here would be the regression.
        var registration = ClusterPrimaryRegistration(hasAdmin: true);

        registration.Factory(new ServiceCollection().BuildServiceProvider())
            .ShouldBeOfType<ActiveNodeHealthCheck>();
    }

    [Theory]
    [InlineData(true)]
    [InlineData(false)]
    public void Active_tier_check_is_registered_on_every_node_role(bool hasAdmin)
    {
        // Registered on driver-only nodes too, unlike the admin-only configdb probe. A site pair needs
        // an active tier just as much as the central pair does — under the old admin-scoped check all
        // four driver-only site nodes answered 200 and no consumer could find a site's Primary.
        ClusterPrimaryRegistration(hasAdmin).Tags.ShouldContain(ZbHealthTags.Active);
    }

    /// <summary>
    ///     R03:2.1 + fix round 1 / I6 (coordinator ruling) — the OPC UA endpoint probe's tiers by role:
    ///     <list type="bullet">
    ///         <item>driver-only: Ready + Active (it cannot serve and must not be routed to);</item>
    ///         <item>fused admin+driver: Ready ONLY, until the ServiceLevel calculator consumes the fact
    ///         (F-C1) — Traefik routes the AdminUI on <c>/health/active</c>, so a failed SDK on the active
    ///         central node must not take the AdminUI out of rotation;</item>
    ///         <item>admin-only: absent (it starts no endpoint to be degraded by).</item>
    ///     </list>
    /// </summary>
    [Theory]
    [InlineData(false, true, true, true)]
    [InlineData(true, true, true, false)]
    [InlineData(true, false, false, false)]
    public void Opcua_endpoint_probe_tiers_follow_the_node_roles(bool hasAdmin, bool hasDriver, bool ready, bool active)
    {
        var registrations = new ServiceCollection()
            .AddOtOpcUaHealth(hasAdmin: hasAdmin, hasDriver: hasDriver)
            .BuildServiceProvider()
            .GetRequiredService<IOptions<HealthCheckServiceOptions>>()
            .Value.Registrations
            .Where(r => r.Name == OpcUaEndpointHealthCheck.Name)
            .ToList();

        if (!ready && !active)
        {
            registrations.ShouldBeEmpty();
            return;
        }

        var registration = registrations.ShouldHaveSingleItem();
        registration.Tags.Contains(ZbHealthTags.Ready).ShouldBe(ready);
        registration.Tags.Contains(ZbHealthTags.Active).ShouldBe(active);
    }

    [Fact]
    public void Active_tier_check_is_not_on_the_ready_tier()
    {
        // Readiness must not depend on being the active node: a healthy standby is ready to serve, and
        // tagging it ready would take the whole pair out of rotation whenever one node is standby.
        ClusterPrimaryRegistration(hasAdmin: true).Tags.ShouldNotContain(ZbHealthTags.Ready);
    }
}