using MessagePack;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian;
using ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware.Client.Internal;
using ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware.Client.Ipc;
using ClientHistorianEventDto = ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware.Client.Ipc.HistorianEventDto;

namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware.Client;

/// <summary>
///     .NET 10 client for the Wonderware historian sidecar (PR 3.3 protocol). Implements both
///     <see cref="IHistorianDataSource"/> (read paths consumed by
///     <c>Server.History.IHistoryRouter</c>) and <see cref="IAlarmHistorianWriter"/>
///     (alarm-event drain consumed by <c>Core.AlarmHistorian.SqliteStoreAndForwardSink</c>).
/// </summary>
/// <remarks>
///     The client owns a single <see cref="PipeChannel"/> with one in-flight call at a time;
///     concurrent calls serialize on the channel's gate. Reconnect is handled inside the
///     channel — transient transport failures retry once before propagating.
/// </remarks>
public sealed class WonderwareHistorianClient : IHistorianDataSource, IAlarmHistorianWriter, IAsyncDisposable
{
    private readonly PipeChannel _channel;
    private readonly object _healthLock = new();
    private DateTime? _lastSuccessUtc;
    private DateTime? _lastFailureUtc;
    private string? _lastError;
    private long _totalQueries;
    private long _totalSuccesses;
    private long _totalFailures;
    private int _consecutiveFailures;

    /// <summary>
    ///     Creates a client over a real named-pipe connection. Tests that need an in-process
    ///     duplex pair use the <see cref="ForTests"/> factory.
    /// </summary>
    public WonderwareHistorianClient(WonderwareHistorianClientOptions options, ILogger<WonderwareHistorianClient>? logger = null)
        : this(options, ct => PipeChannel.DefaultNamedPipeConnectFactory(options, ct), logger)
    {
    }

    /// <summary>Test seam — inject an arbitrary connect callback.</summary>
    public static WonderwareHistorianClient ForTests(
        WonderwareHistorianClientOptions options,
        Func<CancellationToken, Task<Stream>> connect,
        ILogger<WonderwareHistorianClient>? logger = null)
        => new(options, connect, logger);

    private WonderwareHistorianClient(
        WonderwareHistorianClientOptions options,
        Func<CancellationToken, Task<Stream>> connect,
        ILogger<WonderwareHistorianClient>? logger)
    {
        ArgumentNullException.ThrowIfNull(options);
        var log = (ILogger?)logger ?? NullLogger.Instance;
        _channel = new PipeChannel(options, connect, log);
    }

    // ===== IHistorianDataSource =====

    public async Task<HistoryReadResult> ReadRawAsync(
        string fullReference, DateTime startUtc, DateTime endUtc, uint maxValuesPerNode,
        CancellationToken cancellationToken)
    {
        var req = new ReadRawRequest
        {
            TagName = fullReference,
            StartUtcTicks = startUtc.Ticks,
            EndUtcTicks = endUtc.Ticks,
            MaxValues = (int)Math.Min(maxValuesPerNode, int.MaxValue),
            CorrelationId = Guid.NewGuid().ToString("N"),
        };
        var reply = await Invoke<ReadRawRequest, ReadRawReply>(MessageKind.ReadRawRequest, MessageKind.ReadRawReply, req, cancellationToken).ConfigureAwait(false);
        ThrowIfFailed(reply.Success, reply.Error, "ReadRaw");
        return new HistoryReadResult(ToSnapshots(reply.Samples), ContinuationPoint: null);
    }

    public async Task<HistoryReadResult> ReadProcessedAsync(
        string fullReference, DateTime startUtc, DateTime endUtc, TimeSpan interval,
        HistoryAggregateType aggregate, CancellationToken cancellationToken)
    {
        var req = new ReadProcessedRequest
        {
            TagName = fullReference,
            StartUtcTicks = startUtc.Ticks,
            EndUtcTicks = endUtc.Ticks,
            IntervalMs = interval.TotalMilliseconds,
            AggregateColumn = MapAggregate(aggregate),
            CorrelationId = Guid.NewGuid().ToString("N"),
        };
        var reply = await Invoke<ReadProcessedRequest, ReadProcessedReply>(MessageKind.ReadProcessedRequest, MessageKind.ReadProcessedReply, req, cancellationToken).ConfigureAwait(false);
        ThrowIfFailed(reply.Success, reply.Error, "ReadProcessed");
        return new HistoryReadResult(ToAggregateSnapshots(reply.Buckets), ContinuationPoint: null);
    }

    public async Task<HistoryReadResult> ReadAtTimeAsync(
        string fullReference, IReadOnlyList<DateTime> timestampsUtc, CancellationToken cancellationToken)
    {
        var ticks = new long[timestampsUtc.Count];
        for (var i = 0; i < timestampsUtc.Count; i++) ticks[i] = timestampsUtc[i].Ticks;

        var req = new ReadAtTimeRequest
        {
            TagName = fullReference,
            TimestampsUtcTicks = ticks,
            CorrelationId = Guid.NewGuid().ToString("N"),
        };
        var reply = await Invoke<ReadAtTimeRequest, ReadAtTimeReply>(MessageKind.ReadAtTimeRequest, MessageKind.ReadAtTimeReply, req, cancellationToken).ConfigureAwait(false);
        ThrowIfFailed(reply.Success, reply.Error, "ReadAtTime");
        return new HistoryReadResult(ToSnapshots(reply.Samples), ContinuationPoint: null);
    }

    public async Task<HistoricalEventsResult> ReadEventsAsync(
        string? sourceName, DateTime startUtc, DateTime endUtc, int maxEvents,
        CancellationToken cancellationToken)
    {
        var req = new ReadEventsRequest
        {
            SourceName = sourceName,
            StartUtcTicks = startUtc.Ticks,
            EndUtcTicks = endUtc.Ticks,
            MaxEvents = maxEvents,
            CorrelationId = Guid.NewGuid().ToString("N"),
        };
        var reply = await Invoke<ReadEventsRequest, ReadEventsReply>(MessageKind.ReadEventsRequest, MessageKind.ReadEventsReply, req, cancellationToken).ConfigureAwait(false);
        ThrowIfFailed(reply.Success, reply.Error, "ReadEvents");
        return new HistoricalEventsResult(ToHistoricalEvents(reply.Events), ContinuationPoint: null);
    }

    public HistorianHealthSnapshot GetHealthSnapshot()
    {
        lock (_healthLock)
        {
            return new HistorianHealthSnapshot(
                TotalQueries: _totalQueries,
                TotalSuccesses: _totalSuccesses,
                TotalFailures: _totalFailures,
                ConsecutiveFailures: _consecutiveFailures,
                LastSuccessTime: _lastSuccessUtc,
                LastFailureTime: _lastFailureUtc,
                LastError: _lastError,
                ProcessConnectionOpen: _channel.IsConnected,
                EventConnectionOpen: _channel.IsConnected,
                ActiveProcessNode: null,
                ActiveEventNode: null,
                Nodes: []);
        }
    }

    // ===== IAlarmHistorianWriter =====

    public async Task<IReadOnlyList<HistorianWriteOutcome>> WriteBatchAsync(
        IReadOnlyList<AlarmHistorianEvent> batch, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(batch);
        if (batch.Count == 0) return [];

        var dtos = new AlarmHistorianEventDto[batch.Count];
        for (var i = 0; i < batch.Count; i++) dtos[i] = ToDto(batch[i]);

        var req = new WriteAlarmEventsRequest
        {
            Events = dtos,
            CorrelationId = Guid.NewGuid().ToString("N"),
        };

        try
        {
            var reply = await Invoke<WriteAlarmEventsRequest, WriteAlarmEventsReply>(
                MessageKind.WriteAlarmEventsRequest, MessageKind.WriteAlarmEventsReply, req, cancellationToken).ConfigureAwait(false);

            // Whole-call failure → transient retry for every event in the batch.
            if (!reply.Success)
            {
                var fail = new HistorianWriteOutcome[batch.Count];
                Array.Fill(fail, HistorianWriteOutcome.RetryPlease);
                return fail;
            }

            // Per-event status: PerEventOk[i] = true → Ack; false → RetryPlease.
            var outcomes = new HistorianWriteOutcome[batch.Count];
            for (var i = 0; i < batch.Count; i++)
            {
                var ok = i < reply.PerEventOk.Length && reply.PerEventOk[i];
                outcomes[i] = ok ? HistorianWriteOutcome.Ack : HistorianWriteOutcome.RetryPlease;
            }
            return outcomes;
        }
        catch
        {
            // Transport / deserialization failure — every event is retry-please. The drain
            // worker's backoff handles recovery.
            var fail = new HistorianWriteOutcome[batch.Count];
            Array.Fill(fail, HistorianWriteOutcome.RetryPlease);
            return fail;
        }
    }

    // ===== Helpers =====

    private async Task<TReply> Invoke<TRequest, TReply>(
        MessageKind requestKind, MessageKind expectedReplyKind, TRequest request, CancellationToken ct)
        where TReply : class
    {
        Interlocked.Increment(ref _totalQueries);
        try
        {
            var reply = await _channel.InvokeAsync<TRequest, TReply>(requestKind, expectedReplyKind, request, ct).ConfigureAwait(false);
            RecordSuccess();
            return reply;
        }
        catch (Exception ex)
        {
            RecordFailure(ex.Message);
            throw;
        }
    }

    private void RecordSuccess()
    {
        lock (_healthLock)
        {
            _totalSuccesses++;
            _consecutiveFailures = 0;
            _lastSuccessUtc = DateTime.UtcNow;
        }
    }

    private void RecordFailure(string message)
    {
        lock (_healthLock)
        {
            _totalFailures++;
            _consecutiveFailures++;
            _lastFailureUtc = DateTime.UtcNow;
            _lastError = message;
        }
    }

    private void ThrowIfFailed(bool success, string? error, string op)
    {
        if (!success)
        {
            // Sidecar-reported failure counts as an operation failure even though the
            // transport delivered a reply. The Invoke wrapper already recorded transport
            // success — undo that and record the failure so the health snapshot reflects
            // operation-level success rates rather than just connectivity.
            ReclassifySuccessAsFailure(error);
            throw new InvalidOperationException(
                $"Sidecar {op} failed: {error ?? "<no message>"}.");
        }
    }

    private void ReclassifySuccessAsFailure(string? message)
    {
        lock (_healthLock)
        {
            // Transport-level RecordSuccess happened a moment ago; reverse it.
            _totalSuccesses--;
            _totalFailures++;
            _consecutiveFailures++;
            _lastFailureUtc = DateTime.UtcNow;
            _lastError = message;
        }
    }

    private static IReadOnlyList<DataValueSnapshot> ToSnapshots(HistorianSampleDto[] dtos)
    {
        if (dtos.Length == 0) return [];
        var snapshots = new DataValueSnapshot[dtos.Length];
        for (var i = 0; i < dtos.Length; i++)
        {
            var dto = dtos[i];
            var value = dto.ValueBytes is null ? null : MessagePackSerializer.Deserialize<object>(dto.ValueBytes);
            snapshots[i] = new DataValueSnapshot(
                Value: value,
                StatusCode: QualityMapper.Map(dto.Quality),
                SourceTimestampUtc: new DateTime(dto.TimestampUtcTicks, DateTimeKind.Utc),
                ServerTimestampUtc: DateTime.UtcNow);
        }
        return snapshots;
    }

    private static IReadOnlyList<DataValueSnapshot> ToAggregateSnapshots(HistorianAggregateSampleDto[] dtos)
    {
        if (dtos.Length == 0) return [];
        var snapshots = new DataValueSnapshot[dtos.Length];
        for (var i = 0; i < dtos.Length; i++)
        {
            var dto = dtos[i];
            // Null aggregate value → BadNoData per Core.Abstractions HistoryReadResult convention.
            snapshots[i] = new DataValueSnapshot(
                Value: dto.Value,
                StatusCode: dto.Value is null ? 0x800E0000u /* BadNoData */ : 0x00000000u /* Good */,
                SourceTimestampUtc: new DateTime(dto.TimestampUtcTicks, DateTimeKind.Utc),
                ServerTimestampUtc: DateTime.UtcNow);
        }
        return snapshots;
    }

    private static IReadOnlyList<HistoricalEvent> ToHistoricalEvents(ClientHistorianEventDto[] dtos)
    {
        if (dtos.Length == 0) return [];
        var events = new HistoricalEvent[dtos.Length];
        for (var i = 0; i < dtos.Length; i++)
        {
            var dto = dtos[i];
            events[i] = new HistoricalEvent(
                EventId: dto.EventId,
                SourceName: dto.Source,
                EventTimeUtc: new DateTime(dto.EventTimeUtcTicks, DateTimeKind.Utc),
                ReceivedTimeUtc: new DateTime(dto.ReceivedTimeUtcTicks, DateTimeKind.Utc),
                Message: dto.DisplayText,
                Severity: dto.Severity);
        }
        return events;
    }

    private static AlarmHistorianEventDto ToDto(AlarmHistorianEvent evt) => new()
    {
        EventId = evt.AlarmId,
        SourceName = evt.EquipmentPath,
        ConditionId = evt.AlarmName,
        AlarmType = evt.AlarmTypeName + ":" + evt.EventKind,
        Message = evt.Message,
        Severity = MapSeverity(evt.Severity),
        EventTimeUtcTicks = evt.TimestampUtc.Ticks,
        AckComment = evt.Comment,
    };

    private static ushort MapSeverity(AlarmSeverity severity) => severity switch
    {
        AlarmSeverity.Low => 250,
        AlarmSeverity.Medium => 500,
        AlarmSeverity.High => 700,
        AlarmSeverity.Critical => 900,
        _ => 500,
    };

    private static string MapAggregate(HistoryAggregateType aggregate) => aggregate switch
    {
        HistoryAggregateType.Average => "Average",
        HistoryAggregateType.Minimum => "Minimum",
        HistoryAggregateType.Maximum => "Maximum",
        HistoryAggregateType.Count => "ValueCount",
        HistoryAggregateType.Total => throw new NotSupportedException(
            "HistoryAggregateType.Total is not supported by the Wonderware AnalogSummary query — use Average/Minimum/Maximum/Count."),
        _ => throw new NotSupportedException($"Unknown HistoryAggregateType {aggregate}"),
    };

    public ValueTask DisposeAsync() => _channel.DisposeAsync();

    /// <summary>
    ///     Synchronous dispose required by <see cref="IDisposable"/> on
    ///     <see cref="IHistorianDataSource"/>. The underlying channel's async cleanup is
    ///     non-blocking (just resets transport state + disposes streams), so the
    ///     GetAwaiter()/GetResult() bridge is safe.
    /// </summary>
    public void Dispose() => _channel.DisposeAsync().AsTask().GetAwaiter().GetResult();
}