using System.Text.Json;
using MeterVault.Core.Domain;
using MeterVault.Infrastructure.Ingestion;
using MeterVault.Infrastructure.Persistence;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging.Abstractions;

namespace MeterVault.Integration.Tests.Ingestion;

[Collection("Timescale")]
public sealed class IngestionServiceTests(TimescaleFixture fx)
{
    private static readonly DateTimeOffset T0 = new(2024, 1, 1, 0, 0, 0, TimeSpan.Zero);

    [Fact]
    public async Task Writes_and_updates_idempotently_with_scale_and_offset()
    {
        await using var db = fx.CreateContext();
        var (meterId, sourceId) = await SetupAsync(db, MeterMode.CumulativeCounter, scale: 0.001, offset: 0);
        var service = new IngestionService(db);

        // 1000 raw × 0.001 = 1.0.
        Assert.Equal(IngestionOutcome.Written, await service.IngestAsync(sourceId, T0, 1000));
        Assert.Equal(IngestionOutcome.Updated, await service.IngestAsync(sourceId, T0, 2000)); // same time → update

        var reading = await db.Readings.SingleAsync(r => r.MeterId == meterId && r.Time == T0);
        Assert.Equal(2.0, reading.Value, 6);

        var source = await db.MeterSources.SingleAsync(s => s.Id == sourceId);
        Assert.Equal("ok", source.LastStatus);
        Assert.Equal(2.0, source.LastValue!.Value, 6);

        await CleanupAsync(db, meterId);
    }

    [Fact]
    public async Task Rejects_spurious_decrease_on_a_cumulative_register()
    {
        await using var db = fx.CreateContext();
        var (meterId, sourceId) = await SetupAsync(db, MeterMode.CumulativeCounter);
        var service = new IngestionService(db);

        await service.IngestAsync(sourceId, T0, 500);
        var outcome = await service.IngestAsync(sourceId, T0.AddHours(1), 400); // decrease, no event

        Assert.Equal(IngestionOutcome.RejectedDecrease, outcome);
        Assert.False(await db.Readings.AnyAsync(r => r.MeterId == meterId && r.Time == T0.AddHours(1)));

        await CleanupAsync(db, meterId);
    }

    [Fact]
    public async Task Old_reset_does_not_permanently_disable_the_decrease_guard()
    {
        await using var db = fx.CreateContext();
        var (meterId, sourceId) = await SetupAsync(db, MeterMode.CumulativeCounter);
        var service = new IngestionService(db);

        // A reset early on explains an early decrease...
        await service.IngestAsync(sourceId, T0, 100);
        db.MeterEvents.Add(new MeterEvent { MeterId = meterId, Time = T0.AddMinutes(10), EventType = MeterEventType.CounterReset, NewValue = 0 });
        await db.SaveChangesAsync();
        Assert.Equal(IngestionOutcome.Written, await service.IngestAsync(sourceId, T0.AddMinutes(20), 30));
        await service.IngestAsync(sourceId, T0.AddHours(1), 200);

        // ...but a later spurious decrease with NO event in its window must still be rejected.
        var outcome = await service.IngestAsync(sourceId, T0.AddHours(2), 150);

        Assert.Equal(IngestionOutcome.RejectedDecrease, outcome);

        await CleanupAsync(db, meterId);
    }

    [Fact]
    public async Task Allows_decrease_when_a_swap_event_explains_it()
    {
        await using var db = fx.CreateContext();
        var (meterId, sourceId) = await SetupAsync(db, MeterMode.CumulativeCounter);
        var service = new IngestionService(db);

        await service.IngestAsync(sourceId, T0, 500);
        db.MeterEvents.Add(new MeterEvent
        {
            MeterId = meterId,
            Time = T0.AddMinutes(30),
            EventType = MeterEventType.MeterSwap,
            PrevValue = 500,
            NewValue = 0,
        });
        await db.SaveChangesAsync();

        var outcome = await service.IngestAsync(sourceId, T0.AddHours(1), 20); // new meter reads low

        Assert.Equal(IngestionOutcome.Written, outcome);

        await CleanupAsync(db, meterId);
    }

    [Fact]
    public async Task Mqtt_router_ingests_a_tasmota_payload()
    {
        await using var db = fx.CreateContext();
        var (meterId, _) = await SetupAsync(db, MeterMode.CumulativeCounter, topic: "tele/plug7/SENSOR");
        var router = new MqttMessageRouter(db, new IngestionService(db), NullLogger<MqttMessageRouter>.Instance);

        var routed = await router.RouteAsync(
            "tele/plug7/SENSOR",
            """{"Time":"2024-03-01T10:00:00","ENERGY":{"Total":8421.0}}""");

        Assert.Equal(1, routed);
        var reading = await db.Readings.SingleAsync(r => r.MeterId == meterId);
        Assert.Equal(8421.0, reading.Value, 3);
        Assert.Equal(new DateTimeOffset(2024, 3, 1, 10, 0, 0, TimeSpan.Zero), reading.Time);

        await CleanupAsync(db, meterId);
    }

    private static async Task<(int MeterId, int SourceId)> SetupAsync(
        MeterVaultDbContext db, MeterMode mode, double scale = 1, double offset = 0,
        string topic = "tele/x/SENSOR", string? path = "ENERGY.Total")
    {
        await DatabaseSeeder.SeedAsync(db);
        var type = await db.EnergyTypes.FirstAsync(t => t.Key == "electricity");

        var meter = new Meter
        {
            Name = $"ingest-{Guid.NewGuid():N}",
            EnergyTypeId = type.Id,
            Mode = mode,
            Unit = "kWh",
        };
        db.Meters.Add(meter);
        await db.SaveChangesAsync();

        var source = new MeterSource
        {
            MeterId = meter.Id,
            SourceType = SourceType.Tasmota,
            ValueKind = SourceValueKind.Register,
            Scale = scale,
            Offset = offset,
            Config = JsonSerializer.Serialize(new { topic, path }),
        };
        db.MeterSources.Add(source);
        await db.SaveChangesAsync();

        return (meter.Id, source.Id);
    }

    private static async Task CleanupAsync(MeterVaultDbContext db, int meterId)
    {
        await db.Readings.Where(r => r.MeterId == meterId).ExecuteDeleteAsync();
        await db.MeterEvents.Where(e => e.MeterId == meterId).ExecuteDeleteAsync();
        await db.Meters.Where(m => m.Id == meterId).ExecuteDeleteAsync();
    }
}