using ZB.MOM.WW.OtOpcUa.Core.Abstractions;

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

/// <summary>
///     TwinCAT ADS driver — talks to Beckhoff PLC runtimes (TC2 + TC3) via AMS / ADS. PR 1 ships
///     the <see cref="IDriver"/> skeleton; read / write / discover / subscribe / probe / host-
///     resolver land in PRs 2 and 3.
/// </summary>
public sealed class TwinCATDriver : IDriver, IReadable, IWritable, IDisposable, IAsyncDisposable
{
    private readonly TwinCATDriverOptions _options;
    private readonly string _driverInstanceId;
    private readonly ITwinCATClientFactory _clientFactory;
    private readonly Dictionary<string, DeviceState> _devices = new(StringComparer.OrdinalIgnoreCase);
    private readonly Dictionary<string, TwinCATTagDefinition> _tagsByName = new(StringComparer.OrdinalIgnoreCase);
    private DriverHealth _health = new(DriverState.Unknown, null, null);

    public TwinCATDriver(TwinCATDriverOptions options, string driverInstanceId,
        ITwinCATClientFactory? clientFactory = null)
    {
        ArgumentNullException.ThrowIfNull(options);
        _options = options;
        _driverInstanceId = driverInstanceId;
        _clientFactory = clientFactory ?? new AdsTwinCATClientFactory();
    }

    public string DriverInstanceId => _driverInstanceId;
    public string DriverType => "TwinCAT";

    public Task InitializeAsync(string driverConfigJson, CancellationToken cancellationToken)
    {
        _health = new DriverHealth(DriverState.Initializing, null, null);
        try
        {
            foreach (var device in _options.Devices)
            {
                var addr = TwinCATAmsAddress.TryParse(device.HostAddress)
                    ?? throw new InvalidOperationException(
                        $"TwinCAT device has invalid HostAddress '{device.HostAddress}' — expected 'ads://{{netId}}:{{port}}'.");
                _devices[device.HostAddress] = new DeviceState(addr, device);
            }
            foreach (var tag in _options.Tags) _tagsByName[tag.Name] = tag;
            _health = new DriverHealth(DriverState.Healthy, DateTime.UtcNow, null);
        }
        catch (Exception ex)
        {
            _health = new DriverHealth(DriverState.Faulted, null, ex.Message);
            throw;
        }
        return Task.CompletedTask;
    }

    public async Task ReinitializeAsync(string driverConfigJson, CancellationToken cancellationToken)
    {
        await ShutdownAsync(cancellationToken).ConfigureAwait(false);
        await InitializeAsync(driverConfigJson, cancellationToken).ConfigureAwait(false);
    }

    public Task ShutdownAsync(CancellationToken cancellationToken)
    {
        foreach (var state in _devices.Values) state.DisposeClient();
        _devices.Clear();
        _tagsByName.Clear();
        _health = new DriverHealth(DriverState.Unknown, _health.LastSuccessfulRead, null);
        return Task.CompletedTask;
    }

    public DriverHealth GetHealth() => _health;
    public long GetMemoryFootprint() => 0;
    public Task FlushOptionalCachesAsync(CancellationToken cancellationToken) => Task.CompletedTask;

    internal int DeviceCount => _devices.Count;
    internal DeviceState? GetDeviceState(string hostAddress) =>
        _devices.TryGetValue(hostAddress, out var s) ? s : null;

    // ---- IReadable ----

    public async Task<IReadOnlyList<DataValueSnapshot>> ReadAsync(
        IReadOnlyList<string> fullReferences, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(fullReferences);
        var now = DateTime.UtcNow;
        var results = new DataValueSnapshot[fullReferences.Count];

        for (var i = 0; i < fullReferences.Count; i++)
        {
            var reference = fullReferences[i];
            if (!_tagsByName.TryGetValue(reference, out var def))
            {
                results[i] = new DataValueSnapshot(null, TwinCATStatusMapper.BadNodeIdUnknown, null, now);
                continue;
            }
            if (!_devices.TryGetValue(def.DeviceHostAddress, out var device))
            {
                results[i] = new DataValueSnapshot(null, TwinCATStatusMapper.BadNodeIdUnknown, null, now);
                continue;
            }

            try
            {
                var client = await EnsureConnectedAsync(device, cancellationToken).ConfigureAwait(false);
                var parsed = TwinCATSymbolPath.TryParse(def.SymbolPath);
                var symbolName = parsed?.ToAdsSymbolName() ?? def.SymbolPath;
                var (value, status) = await client.ReadValueAsync(
                    symbolName, def.DataType, parsed?.BitIndex, cancellationToken).ConfigureAwait(false);

                results[i] = new DataValueSnapshot(value, status, now, now);
                if (status == TwinCATStatusMapper.Good)
                    _health = new DriverHealth(DriverState.Healthy, now, null);
                else
                    _health = new DriverHealth(DriverState.Degraded, _health.LastSuccessfulRead,
                        $"ADS status {status:X8} reading {reference}");
            }
            catch (OperationCanceledException) { throw; }
            catch (Exception ex)
            {
                results[i] = new DataValueSnapshot(null, TwinCATStatusMapper.BadCommunicationError, null, now);
                _health = new DriverHealth(DriverState.Degraded, _health.LastSuccessfulRead, ex.Message);
            }
        }

        return results;
    }

    // ---- IWritable ----

    public async Task<IReadOnlyList<WriteResult>> WriteAsync(
        IReadOnlyList<WriteRequest> writes, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(writes);
        var results = new WriteResult[writes.Count];

        for (var i = 0; i < writes.Count; i++)
        {
            var w = writes[i];
            if (!_tagsByName.TryGetValue(w.FullReference, out var def))
            {
                results[i] = new WriteResult(TwinCATStatusMapper.BadNodeIdUnknown);
                continue;
            }
            if (!def.Writable)
            {
                results[i] = new WriteResult(TwinCATStatusMapper.BadNotWritable);
                continue;
            }
            if (!_devices.TryGetValue(def.DeviceHostAddress, out var device))
            {
                results[i] = new WriteResult(TwinCATStatusMapper.BadNodeIdUnknown);
                continue;
            }

            try
            {
                var client = await EnsureConnectedAsync(device, cancellationToken).ConfigureAwait(false);
                var parsed = TwinCATSymbolPath.TryParse(def.SymbolPath);
                var symbolName = parsed?.ToAdsSymbolName() ?? def.SymbolPath;
                var status = await client.WriteValueAsync(
                    symbolName, def.DataType, parsed?.BitIndex, w.Value, cancellationToken).ConfigureAwait(false);
                results[i] = new WriteResult(status);
            }
            catch (OperationCanceledException) { throw; }
            catch (NotSupportedException nse)
            {
                results[i] = new WriteResult(TwinCATStatusMapper.BadNotSupported);
                _health = new DriverHealth(DriverState.Degraded, _health.LastSuccessfulRead, nse.Message);
            }
            catch (Exception ex) when (ex is FormatException or InvalidCastException)
            {
                results[i] = new WriteResult(TwinCATStatusMapper.BadTypeMismatch);
            }
            catch (OverflowException)
            {
                results[i] = new WriteResult(TwinCATStatusMapper.BadOutOfRange);
            }
            catch (Exception ex)
            {
                results[i] = new WriteResult(TwinCATStatusMapper.BadCommunicationError);
                _health = new DriverHealth(DriverState.Degraded, _health.LastSuccessfulRead, ex.Message);
            }
        }

        return results;
    }

    private async Task<ITwinCATClient> EnsureConnectedAsync(DeviceState device, CancellationToken ct)
    {
        if (device.Client is { IsConnected: true } c) return c;
        device.Client ??= _clientFactory.Create();
        try
        {
            await device.Client.ConnectAsync(device.ParsedAddress, _options.Timeout, ct)
                .ConfigureAwait(false);
        }
        catch
        {
            device.Client.Dispose();
            device.Client = null;
            throw;
        }
        return device.Client;
    }

    public void Dispose() => DisposeAsync().AsTask().GetAwaiter().GetResult();
    public async ValueTask DisposeAsync() => await ShutdownAsync(CancellationToken.None).ConfigureAwait(false);

    internal sealed class DeviceState(TwinCATAmsAddress parsedAddress, TwinCATDeviceOptions options)
    {
        public TwinCATAmsAddress ParsedAddress { get; } = parsedAddress;
        public TwinCATDeviceOptions Options { get; } = options;
        public ITwinCATClient? Client { get; set; }

        public void DisposeClient()
        {
            Client?.Dispose();
            Client = null;
        }
    }
}