using libplctag;

namespace ZB.MOM.WW.OtOpcUa.Driver.AbCip;

/// <summary>
///     Default libplctag-backed <see cref="IAbCipTagRuntime"/>. Wraps a <see cref="Tag"/>
///     instance + translates our <see cref="AbCipDataType"/> enum into the
///     <c>GetInt32</c> / <c>GetFloat32</c> / <c>GetString</c> / <c>GetBit</c> calls libplctag
///     exposes. One runtime instance per <c>(device, tag path)</c>; lifetime is owned by the
///     driver's per-device state dict.
/// </summary>
internal sealed class LibplctagTagRuntime : IAbCipTagRuntime
{
    private readonly Tag _tag;

    public LibplctagTagRuntime(AbCipTagCreateParams p)
    {
        _tag = new Tag
        {
            Gateway = p.Gateway,
            Path = p.CipPath,
            PlcType = MapPlcType(p.LibplctagPlcAttribute),
            Protocol = Protocol.ab_eip,
            Name = p.TagName,
            Timeout = p.Timeout,
        };
    }

    public Task InitializeAsync(CancellationToken cancellationToken) => _tag.InitializeAsync(cancellationToken);
    public Task ReadAsync(CancellationToken cancellationToken) => _tag.ReadAsync(cancellationToken);
    public Task WriteAsync(CancellationToken cancellationToken) => _tag.WriteAsync(cancellationToken);

    public int GetStatus() => (int)_tag.GetStatus();

    public object? DecodeValue(AbCipDataType type, int? bitIndex) => type switch
    {
        AbCipDataType.Bool => bitIndex is int bit
            ? _tag.GetBit(bit)
            : _tag.GetInt8(0) != 0,
        AbCipDataType.SInt => (int)(sbyte)_tag.GetInt8(0),
        AbCipDataType.USInt => (int)_tag.GetUInt8(0),
        AbCipDataType.Int => (int)_tag.GetInt16(0),
        AbCipDataType.UInt => (int)_tag.GetUInt16(0),
        AbCipDataType.DInt => _tag.GetInt32(0),
        AbCipDataType.UDInt => (int)_tag.GetUInt32(0),
        AbCipDataType.LInt => _tag.GetInt64(0),
        AbCipDataType.ULInt => (long)_tag.GetUInt64(0),
        AbCipDataType.Real => _tag.GetFloat32(0),
        AbCipDataType.LReal => _tag.GetFloat64(0),
        AbCipDataType.String => _tag.GetString(0),
        AbCipDataType.Dt => _tag.GetInt32(0), // seconds-since-epoch DINT; consumer widens as needed
        AbCipDataType.Structure => null,       // UDT whole-tag decode lands in PR 6
        _ => null,
    };

    public void EncodeValue(AbCipDataType type, int? bitIndex, object? value)
    {
        switch (type)
        {
            case AbCipDataType.Bool:
                if (bitIndex is int)
                {
                    // BOOL-within-DINT writes are routed at the driver level (AbCipDriver.
                    // WriteBitInDIntAsync) via a parallel parent-DINT runtime so the RMW stays
                    // serialised. If one reaches here it means the driver dispatch was bypassed —
                    // throw so the error surfaces loudly rather than clobbering the whole DINT.
                    throw new NotSupportedException(
                        "BOOL-with-bitIndex writes must go through AbCipDriver.WriteBitInDIntAsync, not LibplctagTagRuntime.");
                }
                _tag.SetInt8(0, Convert.ToBoolean(value) ? (sbyte)1 : (sbyte)0);
                break;
            case AbCipDataType.SInt:
                _tag.SetInt8(0, Convert.ToSByte(value));
                break;
            case AbCipDataType.USInt:
                _tag.SetUInt8(0, Convert.ToByte(value));
                break;
            case AbCipDataType.Int:
                _tag.SetInt16(0, Convert.ToInt16(value));
                break;
            case AbCipDataType.UInt:
                _tag.SetUInt16(0, Convert.ToUInt16(value));
                break;
            case AbCipDataType.DInt:
                _tag.SetInt32(0, Convert.ToInt32(value));
                break;
            case AbCipDataType.UDInt:
                _tag.SetUInt32(0, Convert.ToUInt32(value));
                break;
            case AbCipDataType.LInt:
                _tag.SetInt64(0, Convert.ToInt64(value));
                break;
            case AbCipDataType.ULInt:
                _tag.SetUInt64(0, Convert.ToUInt64(value));
                break;
            case AbCipDataType.Real:
                _tag.SetFloat32(0, Convert.ToSingle(value));
                break;
            case AbCipDataType.LReal:
                _tag.SetFloat64(0, Convert.ToDouble(value));
                break;
            case AbCipDataType.String:
                _tag.SetString(0, Convert.ToString(value) ?? string.Empty);
                break;
            case AbCipDataType.Dt:
                _tag.SetInt32(0, Convert.ToInt32(value));
                break;
            case AbCipDataType.Structure:
                throw new NotSupportedException("Whole-UDT writes land in PR 6.");
            default:
                throw new NotSupportedException($"AbCipDataType {type} not writable.");
        }
    }

    public void Dispose() => _tag.Dispose();

    private static PlcType MapPlcType(string attribute) => attribute switch
    {
        "controllogix" => PlcType.ControlLogix,
        "compactlogix" => PlcType.ControlLogix, // libplctag treats CompactLogix under ControlLogix family
        "micro800" => PlcType.Micro800,
        "micrologix" => PlcType.MicroLogix,
        "slc500" => PlcType.Slc500,
        "plc5" => PlcType.Plc5,
        "omron-njnx" => PlcType.Omron,
        _ => PlcType.ControlLogix,
    };
}

/// <summary>
///     Default <see cref="IAbCipTagFactory"/> — creates a fresh <see cref="LibplctagTagRuntime"/>
///     per call. Stateless; safe to share across devices.
/// </summary>
internal sealed class LibplctagTagFactory : IAbCipTagFactory
{
    public IAbCipTagRuntime Create(AbCipTagCreateParams createParams) =>
        new LibplctagTagRuntime(createParams);
}