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 InvokeAndClassifyAsync<ReadRawRequest, ReadRawReply>(
            MessageKind.ReadRawRequest, MessageKind.ReadRawReply, req,
            r => (r.Success, r.Error), "ReadRaw", cancellationToken).ConfigureAwait(false);
        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 InvokeAndClassifyAsync<ReadProcessedRequest, ReadProcessedReply>(
            MessageKind.ReadProcessedRequest, MessageKind.ReadProcessedReply, req,
            r => (r.Success, r.Error), "ReadProcessed", cancellationToken).ConfigureAwait(false);
        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 InvokeAndClassifyAsync<ReadAtTimeRequest, ReadAtTimeReply>(
            MessageKind.ReadAtTimeRequest, MessageKind.ReadAtTimeReply, req,
            r => (r.Success, r.Error), "ReadAtTime", cancellationToken).ConfigureAwait(false);
        return new HistoryReadResult(AlignAtTimeSnapshots(timestampsUtc, reply.Samples), ContinuationPoint: null);
    }

    /// <summary>
    ///     Reconciles a <c>ReadAtTime</c> sidecar reply against the requested timestamps to
    ///     honour the <see cref="IHistorianDataSource.ReadAtTimeAsync"/> contract: the result
    ///     MUST have exactly one snapshot per requested timestamp, in request order. The sidecar
    ///     is not required to return a sample for every timestamp (e.g. it may drop
    ///     boundary-less timestamps) nor to preserve order, so each requested timestamp is
    ///     matched by ticks; any timestamp the sidecar did not return is filled with a
    ///     Bad-quality (<c>0x80000000</c>) snapshot rather than positionally misaligning values.
    /// </summary>
    private static IReadOnlyList<DataValueSnapshot> AlignAtTimeSnapshots(
        IReadOnlyList<DateTime> timestampsUtc, HistorianSampleDto[] samples)
    {
        // Index returned samples by timestamp ticks. Duplicate timestamps keep the first.
        var byTicks = new Dictionary<long, HistorianSampleDto>(samples.Length);
        foreach (var sample in samples)
            byTicks.TryAdd(sample.TimestampUtcTicks, sample);

        var result = new DataValueSnapshot[timestampsUtc.Count];
        for (var i = 0; i < timestampsUtc.Count; i++)
        {
            var requested = DateTime.SpecifyKind(timestampsUtc[i], DateTimeKind.Utc);
            if (byTicks.TryGetValue(requested.Ticks, out var dto))
            {
                result[i] = new DataValueSnapshot(
                    Value: DeserializeSampleValue(dto.ValueBytes),
                    StatusCode: QualityMapper.Map(dto.Quality),
                    SourceTimestampUtc: requested,
                    ServerTimestampUtc: DateTime.UtcNow);
            }
            else
            {
                // Gap — sidecar returned no sample for this timestamp. Per the contract this
                // is a Bad-quality snapshot stamped at the requested time, not a dropped row.
                result[i] = new DataValueSnapshot(
                    Value: null,
                    StatusCode: 0x80000000u, // Bad
                    SourceTimestampUtc: requested,
                    ServerTimestampUtc: DateTime.UtcNow);
            }
        }
        return result;
    }

    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 InvokeAndClassifyAsync<ReadEventsRequest, ReadEventsReply>(
            MessageKind.ReadEventsRequest, MessageKind.ReadEventsReply, req,
            r => (r.Success, r.Error), "ReadEvents", cancellationToken).ConfigureAwait(false);
        return new HistoricalEventsResult(ToHistoricalEvents(reply.Events), ContinuationPoint: null);
    }

    /// <summary>
    ///     Returns a snapshot of operation counters and the single pipe channel's connection
    ///     state.
    /// </summary>
    /// <remarks>
    ///     This client owns one duplex named-pipe channel to the sidecar — it has no notion of
    ///     separate process / event connections and no per-node telemetry. The single channel's
    ///     connected state is reported for both <see cref="HistorianHealthSnapshot.ProcessConnectionOpen"/>
    ///     and <see cref="HistorianHealthSnapshot.EventConnectionOpen"/>, and
    ///     <see cref="HistorianHealthSnapshot.ActiveProcessNode"/> /
    ///     <see cref="HistorianHealthSnapshot.ActiveEventNode"/> /
    ///     <see cref="HistorianHealthSnapshot.Nodes"/> are intentionally null/empty. Consumers
    ///     that need to distinguish two connections should read another driver. (Finding 010.)
    ///     <para>
    ///         All six counter fields (TotalQueries, TotalSuccesses, TotalFailures,
    ///         ConsecutiveFailures, LastSuccessTime, LastFailureTime, LastError) are mutated
    ///         exclusively under <c>_healthLock</c>, so the snapshot is internally consistent —
    ///         in particular <c>TotalSuccesses + TotalFailures == TotalQueries</c> at every
    ///         observed snapshot (a call that has started but not yet completed has not
    ///         incremented any counter). (Finding 003 / 004.)
    ///     </para>
    /// </remarks>
    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 =====

    /// <summary>
    ///     Writes a batch of alarm events to the Wonderware historian via the sidecar.
    /// </summary>
    /// <remarks>
    ///     <para>
    ///         <b>PermanentFail limitation (finding 002):</b> this writer never returns
    ///         <see cref="HistorianWriteOutcome.PermanentFail"/>. The sidecar wire contract
    ///         (<see cref="WriteAlarmEventsReply.PerEventOk"/>) carries only a per-event
    ///         boolean (succeeded / did-not-succeed) and provides no unrecoverable vs.
    ///         transient distinction. A poison event that the historian SDK can never persist
    ///         (e.g. a permanently malformed row) will therefore retry indefinitely inside the
    ///         store-and-forward drain worker rather than being moved to the dead-letter table.
    ///         Extending the protocol to add a per-event status enum (Ack / Retry / Permanent)
    ///         requires a coordinated additive change to the .NET 4.8 sidecar and is tracked as
    ///         a follow-up. Until then, the drain worker's own retry-count limit is the
    ///         backstop against an infinite loop.
    ///     </para>
    ///     <para>
    ///         Transport or deserialization failures return <see cref="HistorianWriteOutcome.RetryPlease"/>
    ///         for every event in the batch; the drain worker's backoff controls recovery.
    ///     </para>
    /// </remarks>
    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 InvokeAsync<WriteAlarmEventsRequest, WriteAlarmEventsReply>(
                MessageKind.WriteAlarmEventsRequest, MessageKind.WriteAlarmEventsReply, req,
                r => (r.Success, r.Error), 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.
            // NOTE: PermanentFail is never emitted — see <remarks> for the wire-contract
            // limitation and why poison events currently retry rather than dead-letter.
            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. PermanentFail is never emitted (see <remarks>).
            var fail = new HistorianWriteOutcome[batch.Count];
            Array.Fill(fail, HistorianWriteOutcome.RetryPlease);
            return fail;
        }
    }

    // ===== Constants =====

    /// <summary>
    ///     Per-sample ValueBytes size cap. MessagePack with the default
    ///     <see cref="MessagePack.Resolvers.StandardResolver"/> (primitive-only — no typeless
    ///     or dynamic-type resolution) is not susceptible to type-confusion gadget chains, but
    ///     we still cap the per-sample byte budget to guard against a buggy or unexpectedly
    ///     large peer payload. 64 KiB is well above any primitive historian value.
    ///     (Finding 007 — NuGetAuditSuppress GHSA-37gx-xxp4-5rgx / GHSA-w3x6-4m5h-cxqf.)
    /// </summary>
    private const int MaxValueBytesPerSample = 64 * 1024;

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

    /// <summary>
    ///     Sends one request through the channel and records the outcome (transport success or
    ///     transport failure) under a single <c>_healthLock</c> acquisition that also bumps
    ///     <c>_totalQueries</c>. Sidecar-level success / failure is NOT classified here — the
    ///     caller passes that through <see cref="InvokeAndClassifyAsync"/> instead. (Finding
    ///     003 / 004: all six counter fields share one synchronization mechanism so a snapshot
    ///     can never observe a torn state.)
    /// </summary>
    private async Task<TReply> InvokeAsync<TRequest, TReply>(
        MessageKind requestKind, MessageKind expectedReplyKind, TRequest request,
        Func<TReply, (bool ok, string? error)> evaluate, CancellationToken ct)
        where TReply : class
    {
        try
        {
            var reply = await _channel.InvokeAsync<TRequest, TReply>(requestKind, expectedReplyKind, request, ct).ConfigureAwait(false);
            // Classify transport+sidecar in one lock so TotalQueries/TotalSuccesses/
            // TotalFailures move together and no intermediate "success-then-undo" state is
            // visible to a concurrent GetHealthSnapshot.
            var (ok, error) = evaluate(reply);
            RecordOutcome(ok, error);
            return reply;
        }
        catch (Exception ex)
        {
            RecordOutcome(success: false, ex.Message);
            throw;
        }
    }

    /// <summary>
    ///     Convenience wrapper around <see cref="InvokeAsync"/> that throws
    ///     <see cref="InvalidOperationException"/> on a sidecar-reported failure. Used by the
    ///     <see cref="IHistorianDataSource"/> read methods.
    /// </summary>
    private async Task<TReply> InvokeAndClassifyAsync<TRequest, TReply>(
        MessageKind requestKind, MessageKind expectedReplyKind, TRequest request,
        Func<TReply, (bool ok, string? error)> evaluate, string op, CancellationToken ct)
        where TReply : class
    {
        var reply = await InvokeAsync<TRequest, TReply>(requestKind, expectedReplyKind, request, evaluate, ct).ConfigureAwait(false);
        var (ok, error) = evaluate(reply);
        if (!ok)
        {
            throw new InvalidOperationException(
                $"Sidecar {op} failed: {error ?? "<no message>"}.");
        }
        return reply;
    }

    /// <summary>
    ///     Records the outcome of a single call — increments <c>_totalQueries</c> and exactly
    ///     one of <c>_totalSuccesses</c> / <c>_totalFailures</c> under a single
    ///     <c>_healthLock</c> acquisition. (Findings 003 + 004.)
    /// </summary>
    private void RecordOutcome(bool success, string? error)
    {
        lock (_healthLock)
        {
            _totalQueries++;
            if (success)
            {
                _totalSuccesses++;
                _consecutiveFailures = 0;
                _lastSuccessUtc = DateTime.UtcNow;
            }
            else
            {
                _totalFailures++;
                _consecutiveFailures++;
                _lastFailureUtc = DateTime.UtcNow;
                _lastError = error;
            }
        }
    }

    /// <summary>
    ///     Deserializes a sample's value bytes using the MessagePack default
    ///     <see cref="MessagePack.Resolvers.StandardResolver"/> (primitive types only — no
    ///     typeless or dynamic-type resolution). A per-sample size cap guards against a
    ///     hostile or buggy peer sending an unexpectedly large payload before deserialization
    ///     allocates memory for it. (Finding 007.)
    /// </summary>
    private static object? DeserializeSampleValue(byte[]? valueBytes)
    {
        if (valueBytes is null) return null;
        if (valueBytes.Length > MaxValueBytesPerSample)
            throw new InvalidDataException(
                $"Sidecar sample ValueBytes length {valueBytes.Length} exceeds the {MaxValueBytesPerSample}-byte cap.");
        // Deserializes using the default resolver which only handles primitive types
        // (bool, int, long, float, double, string, byte[], DateTime, etc.). The resolver
        // does NOT support TypelessContractlessStandardResolver so no type-confusion gadget
        // chains are reachable from this call site.
        return MessagePackSerializer.Deserialize<object>(valueBytes);
    }

    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];
            snapshots[i] = new DataValueSnapshot(
                Value: DeserializeSampleValue(dto.ValueBytes),
                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 runs
    ///     <see cref="System.IO.Pipes.NamedPipeClientStream"/> teardown, which can block briefly
    ///     on OS handle release — strictly speaking it is not non-blocking — but the
    ///     <c>GetAwaiter()/GetResult()</c> bridge is deadlock-safe because the cleanup never
    ///     awaits a captured <see cref="System.Threading.SynchronizationContext"/> nor takes any
    ///     lock that the caller could hold. (Finding 010.)
    /// </summary>
    public void Dispose() => _channel.DisposeAsync().AsTask().GetAwaiter().GetResult();
}