using Omika.Core.Observability;
using Omika.Core.Observability.Outbox;

namespace Omika.Tests.Observability.Outbox;

/// <summary>Tests du DiagnosticOutbox : filtrage P0..P3, saturation, éviction, rétention, fail-open.</summary>
public class DiagnosticOutboxTests
{
    private static (DiagnosticOutbox Outbox, InMemoryDiagnosticOutboxStore Store, DiagnosticCounters Counters) Create(
        DiagnosticOutboxOptions? options = null)
    {
        var store = new InMemoryDiagnosticOutboxStore();
        var counters = new DiagnosticCounters();
        var outbox = new DiagnosticOutbox(store, options ?? new DiagnosticOutboxOptions(), counters);
        return (outbox, store, counters);
    }

    [Fact]
    public async Task Store_StoresP0ThroughP3_ByDefault()
    {
        (DiagnosticOutbox outbox, _, DiagnosticCounters counters) = Create();

        int stored = await outbox.StoreAsync(
        [
            OutboxTestHarness.NewEvent(TelemetryPriority.P0),
            OutboxTestHarness.NewEvent(TelemetryPriority.P1),
            OutboxTestHarness.NewEvent(TelemetryPriority.P2),
            OutboxTestHarness.NewEvent(TelemetryPriority.P3)
        ]);

        Assert.Equal(4, stored);
        Assert.Equal(4, counters.OutboxStored);
        Assert.Equal(0, counters.OutboxDropped);
    }

    [Fact]
    public async Task Store_DropsP4_ByDefault()
    {
        (DiagnosticOutbox outbox, _, DiagnosticCounters counters) = Create();

        int stored = await outbox.StoreAsync([OutboxTestHarness.NewEvent(TelemetryPriority.P4)]);

        Assert.Equal(0, stored);
        Assert.Equal(1, counters.OutboxDropped);
    }

    [Fact]
    public async Task Store_IncludeP4Option_StoresP4()
    {
        var options = new DiagnosticOutboxOptions { IncludeP4 = true };
        (DiagnosticOutbox outbox, _, DiagnosticCounters counters) = Create(options);

        int stored = await outbox.StoreAsync([OutboxTestHarness.NewEvent(TelemetryPriority.P4)]);

        Assert.Equal(1, stored);
        Assert.Equal(1, counters.OutboxStored);
    }

    [Fact]
    public async Task Store_EvictsP3_BeforeP0_WhenSaturated()
    {
        var options = new DiagnosticOutboxOptions { MaxRows = 10 };
        (DiagnosticOutbox outbox, InMemoryDiagnosticOutboxStore store, DiagnosticCounters counters) = Create(options);

        // Remplit l'outbox avec 10 P3.
        List<OmikaEvent> p3s = Enumerable.Range(0, 10)
            .Select(_ => (OmikaEvent)OutboxTestHarness.NewEvent(TelemetryPriority.P3))
            .ToList();
        await outbox.StoreAsync(p3s);
        Assert.Equal(10, await store.CountAsync());

        // Un nouveau P0 doit évincer un P3 (pas un P0).
        await outbox.StoreAsync([OutboxTestHarness.NewEvent(TelemetryPriority.P0)]);

        Assert.Equal(10, await store.CountAsync());
        Assert.Contains(store.Snapshot(), r => r.Priority == TelemetryPriority.P0);
        Assert.Equal(1, counters.OutboxEvictedP3);
        Assert.Equal(0, counters.OutboxEvictedP0);
    }

    [Fact]
    public async Task Store_FullOfP0_DropsNewP0_WithCounter()
    {
        var options = new DiagnosticOutboxOptions { MaxRows = 5 };
        (DiagnosticOutbox outbox, InMemoryDiagnosticOutboxStore store, DiagnosticCounters counters) = Create(options);

        await outbox.StoreAsync(Enumerable.Range(0, 5)
            .Select(_ => OutboxTestHarness.NewEvent(TelemetryPriority.P0))
            .ToList());
        Assert.Equal(5, await store.CountAsync());

        int stored = await outbox.StoreAsync([OutboxTestHarness.NewEvent(TelemetryPriority.P0)]);

        Assert.Equal(0, stored);
        Assert.Equal(5, await store.CountAsync());
        Assert.Equal(1, counters.OutboxDroppedFull);
    }

    [Fact]
    public async Task Store_Disabled_StoresNothing()
    {
        var options = new DiagnosticOutboxOptions { Enabled = false };
        (DiagnosticOutbox outbox, InMemoryDiagnosticOutboxStore store, _) = Create(options);

        int stored = await outbox.StoreAsync([OutboxTestHarness.NewEvent(TelemetryPriority.P0)]);

        Assert.Equal(0, stored);
        Assert.Equal(0, await store.CountAsync());
    }

    [Fact]
    public async Task CleanupExpired_RemovesExpiredOnly()
    {
        (DiagnosticOutbox outbox, InMemoryDiagnosticOutboxStore store, DiagnosticCounters counters) = Create();

        // Utilise une rétention courte pour forcer l'expiration.
        var options = new DiagnosticOutboxOptions { Retention = TimeSpan.FromMilliseconds(1) };
        (outbox, store, counters) = Create(options);
        await outbox.StoreAsync([OutboxTestHarness.NewEvent(TelemetryPriority.P3)]);

        await Task.Delay(20);
        int removed = await outbox.CleanupExpiredAsync();

        Assert.Equal(1, removed);
        Assert.Equal(1, counters.OutboxExpired);
        Assert.Equal(0, await store.CountAsync());
    }

    [Fact]
    public async Task Store_ThrowingStore_FailOpen_DegradesAndCounts()
    {
        var store = new InMemoryDiagnosticOutboxStore { ThrowOnStore = true };
        var counters = new DiagnosticCounters();
        var outbox = new DiagnosticOutbox(store, new DiagnosticOutboxOptions(), counters);

        int stored = await outbox.StoreAsync([OutboxTestHarness.NewEvent(TelemetryPriority.P0)]);

        Assert.Equal(0, stored);
        Assert.Equal(1, counters.OutboxDegraded);
        Assert.True(outbox.IsDegraded);
    }
}