using System;
using System.Collections.Generic;
using System.Diagnostics.Metrics;
using Microsoft.Extensions.Logging.Abstractions;
using StellaOps.Concelier.WebService.Services;
using StellaOps.Concelier.WebService.Diagnostics;
using Xunit;

namespace StellaOps.Concelier.WebService.Tests;

public sealed class AdvisoryAiTelemetryTests : IDisposable
{
    private readonly MeterListener _listener;
    private readonly List<(long Value, KeyValuePair<string, object?>[] Tags)> _guardrailMeasurements = new();

    public AdvisoryAiTelemetryTests()
    {
        _listener = new MeterListener
        {
            InstrumentPublished = (instrument, listener) =>
            {
                if (instrument.Meter.Name == AdvisoryAiMetrics.MeterName)
                {
                    listener.EnableMeasurementEvents(instrument);
                }
            }
        };
        _listener.SetMeasurementEventCallback<long>((instrument, measurement, tags, state) =>
        {
            if (instrument.Meter.Name == AdvisoryAiMetrics.MeterName &&
                instrument.Name == "advisory_ai_guardrail_blocks_total")
            {
                _guardrailMeasurements.Add((measurement, tags.ToArray()));
            }
        });
        _listener.Start();
    }

    [Fact]
    public void TrackChunkResult_RecordsGuardrailCounts_ForCacheHits()
    {
        var telemetry = new AdvisoryAiTelemetry(NullLogger<AdvisoryAiTelemetry>.Instance);
        var guardrailCounts = new Dictionary<AdvisoryChunkGuardrailReason, int>
        {
            { AdvisoryChunkGuardrailReason.BelowMinimumLength, 2 }
        };

        telemetry.TrackChunkResult(new AdvisoryAiChunkRequestTelemetry(
            Tenant: "tenant-a",
            AdvisoryKey: "CVE-2099-0001",
            Result: "ok",
            Truncated: false,
            CacheHit: true,
            ObservationCount: 1,
            SourceCount: 1,
            ChunkCount: 1,
            Duration: TimeSpan.FromMilliseconds(5),
            GuardrailCounts: guardrailCounts));

        var measurement = Assert.Single(_guardrailMeasurements);
        Assert.Equal(2, measurement.Value);

        var cacheHitTagFound = false;
        foreach (var tag in measurement.Tags)
        {
            if (tag.Key == "cache" && (string?)tag.Value == "hit")
            {
                cacheHitTagFound = true;
                break;
            }
        }

        Assert.True(cacheHitTagFound, "guardrail measurement should be tagged with cache hit outcome.");
    }

    public void Dispose()
    {
        _listener.Dispose();
    }
}