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 = NewIngestion(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 = NewIngestion(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 = NewIngestion(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 = NewIngestion(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 brokerId = await CreateBrokerAsync(db);
        var (meterId, _) = await SetupAsync(
            db, MeterMode.CumulativeCounter, topic: "tele/plug7/SENSOR", endpointId: brokerId);
        var router = new MqttMessageRouter(db, NewIngestion(db), NullLogger<MqttMessageRouter>.Instance);

        var routed = await router.RouteAsync(
            brokerId,
            "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);
    }

    [Fact]
    public async Task Mqtt_router_ignores_a_source_bound_to_another_broker()
    {
        await using var db = fx.CreateContext();
        var brokerA = await CreateBrokerAsync(db);
        var brokerB = await CreateBrokerAsync(db);

        // Topic filter that both brokers' traffic would match — the binding is the only thing
        // separating them.
        var (meterId, _) = await SetupAsync(
            db, MeterMode.CumulativeCounter, topic: "tele/+/SENSOR", endpointId: brokerB);
        var router = new MqttMessageRouter(db, NewIngestion(db), NullLogger<MqttMessageRouter>.Instance);

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

        Assert.Equal(0, routed);
        Assert.False(await db.Readings.AnyAsync(r => r.MeterId == meterId));

        // Same message on the broker it is actually bound to does land.
        Assert.Equal(1, await router.RouteAsync(
            brokerB,
            "tele/plug7/SENSOR",
            """{"Time":"2024-03-01T10:00:00","ENERGY":{"Total":8421.0}}"""));

        await CleanupAsync(db, meterId);
    }

    [Fact]
    public async Task Ingesting_a_reading_derives_consumption_without_a_separate_recompute()
    {
        // Regression: live ingestion used to write only the raw reading, so consumption/generation
        // stayed frozen at the last import until something else recomputed the meter.
        await using var db = fx.CreateContext();
        var (meterId, sourceId) = await SetupAsync(db, MeterMode.CumulativeCounter);
        var service = NewIngestion(db);

        await service.IngestAsync(sourceId, T0, 1000);
        await service.IngestAsync(sourceId, T0.AddHours(1), 1250);

        var consumption = await db.Consumption.AsNoTracking()
            .Where(c => c.MeterId == meterId)
            .OrderBy(c => c.Time)
            .ToListAsync();

        // The first reading is anchored against the meter's baseline (0), so it contributes 1000;
        // what proves the fix is the second reading's 250 delta being there at all.
        Assert.Equal(2, consumption.Count);
        Assert.Equal(250d, consumption.Single(c => c.Time == T0.AddHours(1)).Amount, 3);
        Assert.Equal(1250d, consumption.Sum(c => c.Amount), 3);

        await CleanupAsync(db, meterId);
    }

    [Fact]
    public async Task A_batch_can_defer_normalization_and_derive_the_same_series_once_at_the_end()
    {
        // Recomputing rewrites a meter's whole consumption series, so the batch endpoint skips it
        // per reading and does it once. The result must be identical to normalizing as it goes.
        await using var db = fx.CreateContext();
        var (meterId, _) = await SetupAsync(db, MeterMode.CumulativeCounter);
        var service = NewIngestion(db);

        for (var hour = 0; hour < 5; hour++)
        {
            await service.IngestByMeterAsync(meterId, T0.AddHours(hour), 1000 + (hour * 10), renormalize: false);
        }

        Assert.False(await db.Consumption.AnyAsync(c => c.MeterId == meterId));

        await service.RenormalizeMeterAsync(meterId);

        var consumption = await db.Consumption.AsNoTracking().Where(c => c.MeterId == meterId).ToListAsync();
        Assert.Equal(5, consumption.Count);
        Assert.Equal(1040d, consumption.Sum(c => c.Amount), 3); // baseline 0 → 1000, then 4 × 10

        await CleanupAsync(db, meterId);
    }

    [Fact]
    public async Task A_hand_entered_reading_is_stamped_manual_and_normalizes_immediately()
    {
        // The meter-detail "Add reading" path: provenance has to survive, otherwise a value somebody
        // walked to the meter to read is indistinguishable from one a sensor reported.
        await using var db = fx.CreateContext();
        var (meterId, _) = await SetupAsync(db, MeterMode.CumulativeCounter);
        var service = NewIngestion(db);

        var written = await service.IngestByMeterAsync(meterId, T0, 1000, quality: ReadingQuality.Manual);

        Assert.Equal(IngestionOutcome.Written, written);
        var reading = await db.Readings.AsNoTracking().SingleAsync(r => r.MeterId == meterId && r.Time == T0);
        Assert.Equal(ReadingQuality.Manual, reading.Quality);
        Assert.True(await db.Consumption.AnyAsync(c => c.MeterId == meterId));

        // Correcting a typo re-enters the same timestamp: value replaced, still manual.
        var updated = await service.IngestByMeterAsync(meterId, T0, 1100, quality: ReadingQuality.Manual);

        Assert.Equal(IngestionOutcome.Updated, updated);
        var corrected = await db.Readings.AsNoTracking().SingleAsync(r => r.MeterId == meterId && r.Time == T0);
        Assert.Equal(1100d, corrected.Value, 6);
        Assert.Equal(ReadingQuality.Manual, corrected.Quality);

        await CleanupAsync(db, meterId);
    }

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

        await service.IngestByMeterAsync(meterId, T0, 1000, quality: ReadingQuality.Manual);
        await service.IngestAsync(sourceId, T0, 1200); // same instant, this time from the broker

        var reading = await db.Readings.AsNoTracking().SingleAsync(r => r.MeterId == meterId && r.Time == T0);
        Assert.Equal(1200d, reading.Value, 6); // the newer value still wins...
        Assert.Equal(ReadingQuality.Manual, reading.Quality); // ...but provenance is not silently rewritten

        await CleanupAsync(db, meterId);
    }

    [Fact]
    public async Task A_hand_entered_decrease_on_a_counter_is_rejected_like_any_other()
    {
        // The dialog warns before saving, but the guard is what actually protects the series: a
        // mistyped register must not silently wipe out a month of consumption.
        await using var db = fx.CreateContext();
        var (meterId, _) = await SetupAsync(db, MeterMode.CumulativeCounter);
        var service = NewIngestion(db);

        await service.IngestByMeterAsync(meterId, T0, 1000, quality: ReadingQuality.Manual);
        var outcome = await service.IngestByMeterAsync(
            meterId, T0.AddDays(30), 100, quality: ReadingQuality.Manual);

        Assert.Equal(IngestionOutcome.RejectedDecrease, outcome);
        Assert.False(await db.Readings.AnyAsync(r => r.MeterId == meterId && r.Time == T0.AddDays(30)));

        await CleanupAsync(db, meterId);
    }

    private static IngestionService NewIngestion(MeterVaultDbContext db) =>
        new(db, new MeterVault.Infrastructure.Normalization.NormalizationService(
            db, MeterVault.Core.Normalization.NormalizationEngine.CreateDefault()));

    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", int? endpointId = null)
    {
        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,
            EndpointId = endpointId ?? await CreateBrokerAsync(db),
            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<int> CreateBrokerAsync(MeterVaultDbContext db)
    {
        var endpoint = new IngestionEndpoint
        {
            Type = EndpointType.MqttBroker,
            Name = $"broker-{Guid.NewGuid():N}",
            Config = """{"host":"localhost","port":1883}""",
        };
        db.IngestionEndpoints.Add(endpoint);
        await db.SaveChangesAsync();
        return endpoint.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.Consumption.Where(c => c.MeterId == meterId).ExecuteDeleteAsync();
        await db.Meters.Where(m => m.Id == meterId).ExecuteDeleteAsync();
        await db.IngestionEndpoints.Where(e => e.Name.StartsWith("broker-")).ExecuteDeleteAsync();
    }
}