lmxopcua/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/DriverSpawnPlannerTests.cs

using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Runtime.Drivers;

namespace ZB.MOM.WW.OtOpcUa.Runtime.Tests.Drivers;

public sealed class DriverSpawnPlannerTests
{
    private static DriverInstanceSpec Spec(string id, string type = "Modbus", string config = "{\"host\":\"127.0.0.1\"}", bool enabled = true, string? resilience = null) =>
        new(Guid.NewGuid(), id, id, type, enabled, config, ClusterId: null, ResilienceConfig: resilience);

    /// <summary>Verifies that all new drivers are placed in ToSpawn when current is empty.</summary>
    [Fact]
    public void All_new_drivers_go_into_ToSpawn_when_current_is_empty()
    {
        var current = new Dictionary<string, DriverChildSnapshot>();
        var target = new[] { Spec("a"), Spec("b") };

        var plan = DriverSpawnPlanner.Compute(current, target);

        plan.ToSpawn.Count.ShouldBe(2);
        plan.ToApplyDelta.ShouldBeEmpty();
        plan.ToStop.ShouldBeEmpty();
    }

    /// <summary>Verifies that the same configuration yields an empty plan.</summary>
    [Fact]
    public void Same_config_yields_empty_plan()
    {
        var current = new Dictionary<string, DriverChildSnapshot>
        {
            ["a"] = new("Modbus", "{\"host\":\"127.0.0.1\"}"),
        };
        var target = new[] { Spec("a") };

        var plan = DriverSpawnPlanner.Compute(current, target);

        plan.ToSpawn.ShouldBeEmpty();
        plan.ToApplyDelta.ShouldBeEmpty();
        plan.ToStop.ShouldBeEmpty();
    }

    /// <summary>Verifies that different configuration is routed to ApplyDelta.</summary>
    [Fact]
    public void Different_config_routes_to_ApplyDelta()
    {
        var current = new Dictionary<string, DriverChildSnapshot>
        {
            ["a"] = new("Modbus", "{\"host\":\"old\"}"),
        };
        var target = new[] { Spec("a", config: "{\"host\":\"new\"}") };

        var plan = DriverSpawnPlanner.Compute(current, target);

        plan.ToApplyDelta.Single().DriverInstanceId.ShouldBe("a");
        plan.ToSpawn.ShouldBeEmpty();
        plan.ToStop.ShouldBeEmpty();
    }

    /// <summary>Verifies that removed drivers are routed to ToStop.</summary>
    [Fact]
    public void Removed_driver_routes_to_ToStop()
    {
        var current = new Dictionary<string, DriverChildSnapshot>
        {
            ["a"] = new("Modbus", "{\"host\":\"127.0.0.1\"}"),
            ["b"] = new("Modbus", "{}"),
        };
        var target = new[] { Spec("a") };

        var plan = DriverSpawnPlanner.Compute(current, target);

        plan.ToStop.ShouldBe(new[] { "b" });
        plan.ToSpawn.ShouldBeEmpty();
        plan.ToApplyDelta.ShouldBeEmpty();
    }

    /// <summary>Verifies that disabled drivers with running children are routed to ToStop.</summary>
    [Fact]
    public void Disabled_driver_with_running_child_routes_to_ToStop()
    {
        var current = new Dictionary<string, DriverChildSnapshot>
        {
            ["a"] = new("Modbus", "{}"),
        };
        var target = new[] { Spec("a", enabled: false) };

        var plan = DriverSpawnPlanner.Compute(current, target);

        plan.ToStop.Single().ShouldBe("a");
        plan.ToSpawn.ShouldBeEmpty();
        plan.ToApplyDelta.ShouldBeEmpty();
    }

    /// <summary>Verifies that disabled new drivers are not spawned.</summary>
    [Fact]
    public void Disabled_new_driver_is_not_spawned()
    {
        var current = new Dictionary<string, DriverChildSnapshot>();
        var target = new[] { Spec("a", enabled: false) };

        var plan = DriverSpawnPlanner.Compute(current, target);

        plan.ToSpawn.ShouldBeEmpty();
        plan.ToApplyDelta.ShouldBeEmpty();
        plan.ToStop.ShouldBeEmpty();
    }

    /// <summary>Verifies that driver type changes trigger stop followed by respawn.</summary>
    [Fact]
    public void Driver_type_change_triggers_stop_plus_respawn()
    {
        var current = new Dictionary<string, DriverChildSnapshot>
        {
            ["a"] = new("Modbus", "{}"),
        };
        var target = new[] { Spec("a", type: "AbCip") };

        var plan = DriverSpawnPlanner.Compute(current, target);

        plan.ToStop.Single().ShouldBe("a");
        plan.ToSpawn.Single().DriverType.ShouldBe("AbCip");
        plan.ToApplyDelta.ShouldBeEmpty();
    }

    /// <summary>
    ///     A ResilienceConfig change forces a stop+respawn (NOT an in-place delta): the CapabilityInvoker
    ///     and its resolved options are bound to the child at spawn, so the only way a changed config takes
    ///     effect is to rebuild the child (the respawn's Create call invalidates the stale cached pipelines).
    /// </summary>
    [Fact]
    public void ResilienceConfig_change_triggers_stop_plus_respawn()
    {
        var current = new Dictionary<string, DriverChildSnapshot>
        {
            // Same DriverType + same DriverConfig; only ResilienceConfig differs.
            ["a"] = new("Modbus", "{\"host\":\"127.0.0.1\"}", ResilienceConfig: "{\"bulkheadMaxConcurrent\":8}"),
        };
        var target = new[] { Spec("a", resilience: "{\"bulkheadMaxConcurrent\":32}") };

        var plan = DriverSpawnPlanner.Compute(current, target);

        plan.ToStop.Single().ShouldBe("a");
        plan.ToSpawn.Single().DriverInstanceId.ShouldBe("a");
        plan.ToApplyDelta.ShouldBeEmpty();
    }

    /// <summary>
    ///     Adding a ResilienceConfig where there was none (null → JSON) is also a respawn — the invoker
    ///     was built with tier defaults and must be rebuilt to pick up the overrides.
    /// </summary>
    [Fact]
    public void Adding_ResilienceConfig_from_null_triggers_respawn()
    {
        var current = new Dictionary<string, DriverChildSnapshot>
        {
            ["a"] = new("Modbus", "{\"host\":\"127.0.0.1\"}", ResilienceConfig: null),
        };
        var target = new[] { Spec("a", resilience: "{\"bulkheadMaxConcurrent\":16}") };

        var plan = DriverSpawnPlanner.Compute(current, target);

        plan.ToStop.Single().ShouldBe("a");
        plan.ToSpawn.Single().DriverInstanceId.ShouldBe("a");
        plan.ToApplyDelta.ShouldBeEmpty();
    }

    /// <summary>
    ///     A pure DriverConfig change with an UNCHANGED ResilienceConfig stays an in-place delta (no
    ///     reconnect) — the resilience pipeline is untouched, so there's no reason to respawn.
    /// </summary>
    [Fact]
    public void DriverConfig_change_with_unchanged_ResilienceConfig_stays_ApplyDelta()
    {
        var current = new Dictionary<string, DriverChildSnapshot>
        {
            ["a"] = new("Modbus", "{\"host\":\"old\"}", ResilienceConfig: "{\"bulkheadMaxConcurrent\":16}"),
        };
        var target = new[] { Spec("a", config: "{\"host\":\"new\"}", resilience: "{\"bulkheadMaxConcurrent\":16}") };

        var plan = DriverSpawnPlanner.Compute(current, target);

        plan.ToApplyDelta.Single().DriverInstanceId.ShouldBe("a");
        plan.ToSpawn.ShouldBeEmpty();
        plan.ToStop.ShouldBeEmpty();
    }
}