using System.Text.Json;
using System.Text.Json.Serialization;
using Shouldly;
using Xunit;

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

/// <summary>
///     Regression guard for the 2026-06-19 enum-serialization bug (the FB-9 Modbus-Int64 authoring
///     case). The AdminUI Modbus page now serialises tag enums (<see cref="ModbusRegion"/>,
///     <see cref="ModbusDataType"/>, byte-order) as STRINGS. This proves the factory parses that
///     AdminUI-shaped Int64-tag blob, and documents that the pre-fix NUMERIC form threw because the
///     <c>ModbusTagDto</c> enum fields are <c>string?</c>.
/// </summary>
public sealed class ModbusDriverConfigEnumSerializationTests
{
    // Mirrors the (now fixed) AdminUI ModbusDriverPage._jsonOpts: camelCase + string enums.
    private static readonly JsonSerializerOptions _adminPageOpts = new()
    {
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
        Converters = { new JsonStringEnumConverter() },
    };

    /// <summary>Verifies the factory parses an AdminUI-authored Modbus config carrying an Int64
    /// holding-register tag (string enums) without throwing.</summary>
    [Fact]
    public void Factory_parses_admin_authored_int64_string_enum_config()
    {
        var tag = new ModbusTagDefinition("Int64Tag", ModbusRegion.HoldingRegisters, (ushort)100, ModbusDataType.Int64);
        var opts = new ModbusDriverOptions { Host = "10.0.0.5", Port = 502, UnitId = 1, Tags = new[] { tag } };
        var blob = JsonSerializer.Serialize(opts, _adminPageOpts);
        // The fixed AdminUI page must emit tag enums as strings, not numbers.
        blob.ShouldContain("\"dataType\":\"Int64\"");

        using var driver = ModbusDriverFactoryExtensions.CreateInstance("mb-test", blob);
        driver.DriverType.ShouldBe("Modbus");
    }

    /// <summary>Documents the original bug: the pre-fix AdminUI page emitted numeric tag enums
    /// (<c>"dataType":5,"region":3</c>) which the string-typed tag DTO cannot bind, so the factory throws.</summary>
    [Fact]
    public void Factory_throws_on_the_numeric_enum_form_the_pre_fix_page_emitted()
    {
        const string numericBlob =
            "{\"host\":\"10.0.0.5\",\"port\":502,\"unitId\":1,\"tags\":[" +
            "{\"name\":\"Int64Tag\",\"region\":3,\"address\":100,\"dataType\":5}]}";
        Should.Throw<Exception>(() => ModbusDriverFactoryExtensions.CreateInstance("mb-test", numericBlob));
    }
}