using ScadaLink.AuditLog.Site.Telemetry;
using ScadaLink.AuditLog.Telemetry;
using ScadaLink.Commons.Interfaces.Services;
using ScadaLink.Commons.Messages.Integration;
using ScadaLink.Commons.Types;
using ScadaLink.Communication.Grpc;
using Google.Protobuf.WellKnownTypes;
using Timestamp = Google.Protobuf.WellKnownTypes.Timestamp;

namespace ScadaLink.AuditLog.Tests.Integration.Infrastructure;

/// <summary>
/// Test-side combined-telemetry dispatcher: wraps a production
/// <see cref="ICachedCallTelemetryForwarder"/> so the local audit + tracking
/// stores still get written, then projects the same packet onto the wire as a
/// <see cref="CachedTelemetryBatch"/> and pushes it through the supplied
/// <see cref="ISiteStreamAuditClient"/>. The bridge can be composed into the
/// existing <see cref="CachedCallLifecycleBridge"/> chain as the
/// <see cref="ICachedCallTelemetryForwarder"/> implementation so a single
/// observer callback fans out to both halves.
/// </summary>
/// <remarks>
/// <para>
/// Production wiring keeps the wire push deferred to M6 — the site SQLite hot
/// path is the source of truth and a future M6 drain will push the rows
/// through the gRPC client. For end-to-end testing today we need a way to
/// exercise the central dual-write transaction immediately, so this
/// dispatcher synthesises the wire packet inline and round-trips it through
/// the stub client. The shape mirrors what the M6 drain will eventually emit.
/// </para>
/// <para>
/// <b>Best-effort:</b> both the inner forwarder call and the wire push are
/// wrapped in independent try/catch blocks. A thrown wire client doesn't
/// abort the local writes (the audit row is already in SQLite); a thrown
/// local forwarder doesn't abort the wire push (central still gets the
/// dual-write attempt).
/// </para>
/// </remarks>
public sealed class CombinedTelemetryDispatcher : ICachedCallTelemetryForwarder
{
    private readonly ICachedCallTelemetryForwarder _inner;
    private readonly ISiteStreamAuditClient _wireClient;

    public CombinedTelemetryDispatcher(
        ICachedCallTelemetryForwarder inner,
        ISiteStreamAuditClient wireClient)
    {
        _inner = inner ?? throw new ArgumentNullException(nameof(inner));
        _wireClient = wireClient ?? throw new ArgumentNullException(nameof(wireClient));
    }

    /// <inheritdoc/>
    public async Task ForwardAsync(CachedCallTelemetry telemetry, CancellationToken ct = default)
    {
        ArgumentNullException.ThrowIfNull(telemetry);

        // Inner forwarder writes the audit row to SQLite + updates the
        // tracking store. Best-effort — exceptions are already swallowed
        // inside the production forwarder, but wrap defensively here too in
        // case a test substitutes a stricter inner.
        try
        {
            await _inner.ForwardAsync(telemetry, ct).ConfigureAwait(false);
        }
        catch
        {
            // Swallow — alog.md §7 best-effort contract.
        }

        // Project the same packet onto the wire and push it through the stub
        // client. This is the bit a future M6 drain will subsume — until
        // then the test wraps the two halves into one observer-driven step.
        try
        {
            var batch = new CachedTelemetryBatch();
            batch.Packets.Add(BuildPacket(telemetry));
            await _wireClient.IngestCachedTelemetryAsync(batch, ct).ConfigureAwait(false);
        }
        catch
        {
            // Swallow — the audit row is still in SQLite for a future drain;
            // the central row will materialise the next time the wire path
            // is exercised (or via the M6 reconciliation pull).
        }
    }

    private static CachedTelemetryPacket BuildPacket(CachedCallTelemetry telemetry)
    {
        return new CachedTelemetryPacket
        {
            AuditEvent = AuditEventMapper.ToDto(telemetry.Audit),
            Operational = ToOperationalDto(telemetry.Operational),
        };
    }

    private static SiteCallOperationalDto ToOperationalDto(SiteCallOperational op)
    {
        var dto = new SiteCallOperationalDto
        {
            TrackedOperationId = op.TrackedOperationId.Value.ToString("D"),
            Channel = op.Channel,
            Target = op.Target,
            SourceSite = op.SourceSite,
            Status = op.Status,
            RetryCount = op.RetryCount,
            LastError = op.LastError ?? string.Empty,
            CreatedAtUtc = Timestamp.FromDateTime(EnsureUtc(op.CreatedAtUtc)),
            UpdatedAtUtc = Timestamp.FromDateTime(EnsureUtc(op.UpdatedAtUtc)),
        };
        if (op.HttpStatus.HasValue)
        {
            dto.HttpStatus = op.HttpStatus.Value;
        }
        if (op.TerminalAtUtc.HasValue)
        {
            dto.TerminalAtUtc = Timestamp.FromDateTime(EnsureUtc(op.TerminalAtUtc.Value));
        }
        return dto;
    }

    private static DateTime EnsureUtc(DateTime value) =>
        value.Kind == DateTimeKind.Utc
            ? value
            : DateTime.SpecifyKind(value.ToUniversalTime(), DateTimeKind.Utc);
}