using Shouldly;
using Xunit;

namespace ZB.MOM.WW.OtOpcUa.Driver.Modbus.Tests;

/// <summary>
///     CONV-4 (Modbus leg) — Modbus keys per-host resilience per SLAVE UNIT
///     (<c>host:port/unitN</c>). An equipment tag must carry its own <c>unitId</c> so multi-unit
///     equipment tags key their own breaker; <see cref="ModbusDriver.ResolveHost"/> must resolve
///     the equipment ref through the resolver rather than only matching authored names. Scope:
///     <c>unitId</c> ONLY — the parser's other strictness gaps are R2-11's.
/// </summary>
[Trait("Category", "Unit")]
public sealed class ModbusUnitIdResolveHostTests
{
    private sealed class NoopTransport : IModbusTransport
    {
        public Task ConnectAsync(CancellationToken ct) => Task.CompletedTask;
        public Task<byte[]> SendAsync(byte unitId, byte[] pdu, CancellationToken ct)
            => Task.FromResult(new byte[] { 0x03, 0x00 });
        public ValueTask DisposeAsync() => ValueTask.CompletedTask;
    }

    private static ModbusDriver NewDriver() => new(
        new ModbusDriverOptions { Host = "10.0.0.1", Port = 502, UnitId = 1, Probe = new ModbusProbeOptions { Enabled = false } },
        "modbus-1", _ => new NoopTransport());

    /// <summary>The parser reads an optional unitId into the transient definition.</summary>
    [Fact]
    public void Parser_reads_optional_unitId()
    {
        var json = """{"region":"HoldingRegisters","address":0,"dataType":"Int16","unitId":7}""";
        ModbusEquipmentTagParser.TryParse(json, out var def).ShouldBeTrue();
        def.UnitId.ShouldBe((byte)7);
    }

    /// <summary>An absent unitId leaves the definition on the driver-level default (null override).</summary>
    [Fact]
    public void Parser_absent_unitId_is_null()
    {
        var json = """{"region":"HoldingRegisters","address":0,"dataType":"Int16"}""";
        ModbusEquipmentTagParser.TryParse(json, out var def).ShouldBeTrue();
        def.UnitId.ShouldBeNull();
    }

    /// <summary>An equipment ref carrying a unitId keys its own per-unit host name.</summary>
    [Fact]
    public void EquipmentTag_WithUnitId_ResolvesPerUnitHostName()
    {
        var drv = NewDriver();
        var json = """{"region":"HoldingRegisters","address":0,"dataType":"Int16","unitId":7}""";
        drv.ResolveHost(json).ShouldBe("10.0.0.1:502/unit7");
    }

    /// <summary>An equipment ref without a unitId keys the driver-level unit host name.</summary>
    [Fact]
    public void EquipmentTag_WithoutUnitId_KeysDriverDefaultUnit()
    {
        var drv = NewDriver();
        var json = """{"region":"HoldingRegisters","address":0,"dataType":"Int16"}""";
        drv.ResolveHost(json).ShouldBe("10.0.0.1:502/unit1");
    }
}