using Dapper;
using MeterVault.Core.Domain;
using MeterVault.Core.Normalization;
using MeterVault.Infrastructure.Costing;
using MeterVault.Infrastructure.Ingestion;
using MeterVault.Infrastructure.Normalization;
using MeterVault.Infrastructure.Options;
using MeterVault.Infrastructure.Persistence;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging.Abstractions;

namespace MeterVault.Integration.Tests.Ingestion;

/// <summary>
/// Consumption between two readings shows up in the months it accrued in — checked the way the charts
/// see it, bucketed by the database in the instance timezone — and stored data built under the old rule
/// is rebuilt once instead of waiting for each meter's next reading.
/// </summary>
[Collection("Timescale")]
public sealed class MonthAttributionTests(TimescaleFixture fx)
{
    private static readonly TimeZoneInfo Berlin = TimeZoneInfo.FindSystemTimeZoneById("Europe/Berlin");

    /// <summary>A Berlin wall-clock time as the UTC instant the database stores.</summary>
    private static DateTimeOffset BerlinTime(int year, int month, int day, int hour) =>
        new DateTimeOffset(new DateTime(year, month, day, hour, 0, 0), Berlin.GetUtcOffset(new DateTime(year, month, day, hour, 0, 0)))
            .ToUniversalTime();

    [Fact]
    public async Task A_reading_six_weeks_after_the_last_fills_both_months_it_covers()
    {
        await using var db = fx.CreateContext();
        var meterId = await CreateMeterAsync(db);
        var ingestion = new IngestionService(db, BerlinNormalization(db));
        var august1 = BerlinTime(2026, 8, 1, 9);
        var september16 = BerlinTime(2026, 9, 16, 18);

        await ingestion.IngestByMeterAsync(meterId, august1, 700, quality: ReadingQuality.Manual);
        await ingestion.IngestByMeterAsync(meterId, september16, 746, quality: ReadingQuality.Manual);

        var months = await MonthlyAsync(db, meterId);
        var expectedAugust = 46 * ((BerlinTime(2026, 9, 1, 0) - august1) / (september16 - august1));

        // August also holds the first reading's 700, counted from the meter's zero baseline.
        Assert.Equal(700 + expectedAugust, months[new DateOnly(2026, 8, 1)], 6);
        Assert.Equal(46 - expectedAugust, months[new DateOnly(2026, 9, 1)], 6);

        await CleanupAsync(db, meterId);
    }

    [Fact]
    public async Task Stored_consumption_from_an_older_revision_is_rebuilt_once()
    {
        await using var db = fx.CreateContext();
        var meterId = await CreateMeterAsync(db);
        db.Readings.AddRange(
            new Reading { MeterId = meterId, Time = BerlinTime(2026, 8, 1, 9), Value = 700, Quality = ReadingQuality.Manual },
            new Reading { MeterId = meterId, Time = BerlinTime(2026, 9, 16, 18), Value = 746, Quality = ReadingQuality.Manual });
        // What the previous rule stored: the whole six weeks on the September reading.
        db.Consumption.AddRange(
            new Consumption { MeterId = meterId, Time = BerlinTime(2026, 8, 1, 9), Amount = 700, Quality = ReadingQuality.Manual },
            new Consumption { MeterId = meterId, Time = BerlinTime(2026, 9, 16, 18), Amount = 46, Quality = ReadingQuality.Manual });
        await SetRevisionAsync(db, "1");

        var upgrade = new NormalizationUpgrade(db, BerlinNormalization(db), NullLogger<NormalizationUpgrade>.Instance);
        var rebuilt = await upgrade.RunAsync();

        Assert.True(rebuilt >= 1);
        var months = await MonthlyAsync(db, meterId);
        Assert.True(months[new DateOnly(2026, 8, 1)] > 700 + 30, "August did not get its share back.");
        var stored = await db.AppSettings.AsNoTracking().SingleAsync(s => s.Key == NormalizationUpgrade.SettingKey);
        Assert.Equal(NormalizationUpgrade.CurrentRevision.ToString(System.Globalization.CultureInfo.InvariantCulture), stored.Value);

        // Up to date now: the next start does nothing.
        Assert.Equal(0, await new NormalizationUpgrade(db, BerlinNormalization(db), NullLogger<NormalizationUpgrade>.Instance).RunAsync());

        await CleanupAsync(db, meterId);
    }

    [Fact]
    public async Task A_meter_that_cannot_be_rebuilt_neither_stops_startup_nor_the_other_meters()
    {
        await using var db = fx.CreateContext();
        var good = await CreateMeterAsync(db);
        var broken = await CreateMeterAsync(db);
        db.Readings.AddRange(
            new Reading { MeterId = good, Time = BerlinTime(2026, 8, 1, 9), Value = 700, Quality = ReadingQuality.Manual },
            new Reading { MeterId = good, Time = BerlinTime(2026, 9, 16, 18), Value = 746, Quality = ReadingQuality.Manual });
        await db.SaveChangesAsync();
        // A mode this build cannot read: loading the meter throws, as any unexpected data would.
        await db.Database.ExecuteSqlInterpolatedAsync($"UPDATE meter SET mode = 'FromTheFuture' WHERE id = {broken}");
        await SetRevisionAsync(db, "1");

        try
        {
            var rebuilt = await Upgrade(db).RunAsync();

            Assert.True(rebuilt >= 1);
            Assert.True((await MonthlyAsync(db, good)).ContainsKey(new DateOnly(2026, 8, 1)), "The healthy meter was not rebuilt.");
            Assert.Contains(broken, await PendingAsync(db));

            // The next start retries only what failed — and once it can be read, it is rebuilt.
            Assert.Equal(0, await Upgrade(db).RunAsync());
            await db.Database.ExecuteSqlInterpolatedAsync($"UPDATE meter SET mode = 'CumulativeCounter' WHERE id = {broken}");
            Assert.Equal(1, await Upgrade(db).RunAsync());
            Assert.Empty(await PendingAsync(db));
            Assert.Equal(0, await Upgrade(db).RunAsync());
        }
        finally
        {
            await db.Database.ExecuteSqlInterpolatedAsync($"UPDATE meter SET mode = 'CumulativeCounter' WHERE id = {broken}");
            await CleanupAsync(db, good);
            await CleanupAsync(db, broken);
        }
    }

    [Fact]
    public async Task Rows_of_earlier_monthly_imports_are_marked_as_months_before_the_rebuild()
    {
        await using var db = fx.CreateContext();
        var monthly = await CreateMeterAsync(db);
        var autoMonthly = await CreateMeterAsync(db);
        var daily = await CreateMeterAsync(db);
        var monthBatch = new ImportBatch { SourceName = "months.csv", Mapping = """{"dateKind":"MonthName"}""" };
        // The wizard's default: auto-detected dates, which do not say whether a row named a month or a day.
        var autoMonthBatch = new ImportBatch { SourceName = "auto-months.csv", Mapping = """{"dateKind":"Auto"}""" };
        var dayBatch = new ImportBatch { SourceName = "days.csv", Mapping = """{"dateKind":"Auto"}""" };
        db.ImportBatches.AddRange(monthBatch, autoMonthBatch, dayBatch);
        await db.SaveChangesAsync();

        // As an import before revision 2 stored them: nothing but the midnight stamp on the 1st.
        foreach (var (meter, batch) in new[] { (monthly, monthBatch.Id), (autoMonthly, autoMonthBatch.Id), (daily, dayBatch.Id) })
        {
            db.Readings.AddRange(
                new Reading { MeterId = meter, Time = Utc(2026, 6, 1), Value = 100, Quality = ReadingQuality.Imported, ImportBatchId = batch },
                new Reading { MeterId = meter, Time = Utc(2026, 7, 1), Value = 130, Quality = ReadingQuality.Imported, ImportBatchId = batch });
        }

        // A reading off the 1st gives the auto-detected batch away as day-dated.
        db.Readings.Add(new Reading { MeterId = daily, Time = Utc(2026, 7, 15), Value = 140, Quality = ReadingQuality.Imported, ImportBatchId = dayBatch.Id });
        await db.SaveChangesAsync();
        db.ChangeTracker.Clear();
        await SetRevisionAsync(db, "1");

        try
        {
            await Upgrade(db).RunAsync();

            var flags = await db.Readings.AsNoTracking()
                .Where(r => r.MeterId == monthly || r.MeterId == autoMonthly || r.MeterId == daily)
                .Select(r => new { r.MeterId, r.Flags })
                .ToListAsync();
            Assert.All(flags.Where(f => f.MeterId == monthly), f => Assert.True(f.Flags.HasFlag(ReadingFlags.MonthLabel)));
            // Every row on the 1st across months: a monthly table, as those rows were always attributed.
            Assert.All(flags.Where(f => f.MeterId == autoMonthly), f => Assert.True(f.Flags.HasFlag(ReadingFlags.MonthLabel)));
            Assert.All(flags.Where(f => f.MeterId == daily), f => Assert.False(f.Flags.HasFlag(ReadingFlags.MonthLabel)));

            // "Juli 2026" now books July's 30 under July, not June.
            Assert.Equal(30, (await MonthlyAsync(db, monthly))[new DateOnly(2026, 7, 1)], 6);
            Assert.Equal(30, (await MonthlyAsync(db, autoMonthly))[new DateOnly(2026, 7, 1)], 6);
        }
        finally
        {
            await CleanupAsync(db, monthly);
            await CleanupAsync(db, autoMonthly);
            await CleanupAsync(db, daily);
            await db.ImportBatches.Where(b => b.Id == monthBatch.Id || b.Id == autoMonthBatch.Id || b.Id == dayBatch.Id).ExecuteDeleteAsync();
        }
    }

    [Fact]
    public async Task Costs_are_bucketed_in_the_zone_months_are_divided_in()
    {
        // London is an hour behind Berlin: August's share is stamped at 23:59:59 London time, which is
        // already September in Berlin. Bucketed in a hard-coded Berlin, the fix would not show.
        await using var db = fx.CreateContext();
        var meterId = await CreateMeterAsync(db);
        var london = Microsoft.Extensions.Options.Options.Create(new MeterVaultOptions { TimeZone = "Europe/London" });
        var ingestion = new IngestionService(db, new NormalizationService(db, NormalizationEngine.CreateDefault(), london));

        await ingestion.IngestByMeterAsync(meterId, Utc(2026, 8, 1).AddHours(8), 700, quality: ReadingQuality.Manual);
        await ingestion.IngestByMeterAsync(meterId, Utc(2026, 9, 16).AddHours(17), 746, quality: ReadingQuality.Manual);

        try
        {
            // A clock after the range (D-01): the service stops actuals at now, and the September reading must be past.
            var costs = await new CostService(fx, london, new FixedTimeProvider(Utc(2026, 10, 1))).GetMeterCostsAsync(meterId, Utc(2026, 7, 1), Utc(2026, 10, 1));
            var august = Assert.Single(costs, c => c.Period == new DateOnly(2026, 8, 1));
            var september = Assert.Single(costs, c => c.Period == new DateOnly(2026, 9, 1));

            Assert.True(august.Consumption > 730, $"August holds {august.Consumption}");
            Assert.True(september.Consumption < 16, $"September holds {september.Consumption}");
        }
        finally
        {
            await CleanupAsync(db, meterId);
        }
    }

    [Fact]
    public async Task A_reading_inside_an_imported_month_is_judged_against_the_month_before_it()
    {
        // "August 2026" = 731 is stamped on 1 August but is the register on 31 August. A photo of the meter
        // from 20 August showing 720 is not a drop from 731.
        await using var db = fx.CreateContext();
        var meterId = await CreateMeterAsync(db);
        db.Readings.AddRange(
            new Reading { MeterId = meterId, Time = Utc(2026, 7, 1), Value = 699, Quality = ReadingQuality.Imported, Flags = ReadingFlags.MonthLabel },
            new Reading { MeterId = meterId, Time = Utc(2026, 8, 1), Value = 731, Quality = ReadingQuality.Imported, Flags = ReadingFlags.MonthLabel });
        await db.SaveChangesAsync();
        db.ChangeTracker.Clear();
        var ingestion = new IngestionService(db, BerlinNormalization(db));

        try
        {
            Assert.Equal(IngestionOutcome.Written, await ingestion.IngestByMeterAsync(meterId, BerlinTime(2026, 8, 20, 9), 720, quality: ReadingQuality.Manual));
            // ...while a real drop below July's register still is one.
            Assert.Equal(IngestionOutcome.RejectedDecrease, await ingestion.IngestByMeterAsync(meterId, BerlinTime(2026, 8, 21, 9), 650, quality: ReadingQuality.Manual));

            var months = await MonthlyAsync(db, meterId);
            Assert.Equal(32, months[new DateOnly(2026, 8, 1)], 6);
        }
        finally
        {
            await CleanupAsync(db, meterId);
        }
    }

    [Fact]
    public async Task A_live_value_written_onto_a_month_row_turns_it_into_a_reading_at_that_instant()
    {
        await using var db = fx.CreateContext();
        var meterId = await CreateMeterAsync(db);
        db.Readings.AddRange(
            new Reading { MeterId = meterId, Time = Utc(2026, 7, 1), Value = 699, Quality = ReadingQuality.Imported, Flags = ReadingFlags.MonthLabel },
            new Reading { MeterId = meterId, Time = Utc(2026, 8, 1), Value = 731, Quality = ReadingQuality.Imported, Flags = ReadingFlags.MonthLabel });
        await db.SaveChangesAsync();
        db.ChangeTracker.Clear();
        var ingestion = new IngestionService(db, BerlinNormalization(db));

        try
        {
            // A hand correction keeps the month row a month row...
            await ingestion.IngestByMeterAsync(meterId, Utc(2026, 7, 1), 700, quality: ReadingQuality.Manual);
            // ...an API/HA value at that instant is what the register showed then.
            await ingestion.IngestByMeterAsync(meterId, Utc(2026, 8, 1), 702);

            var rows = await db.Readings.AsNoTracking().Where(r => r.MeterId == meterId).OrderBy(r => r.Time).ToListAsync();
            Assert.True(rows[0].Flags.HasFlag(ReadingFlags.MonthLabel));
            Assert.False(rows[1].Flags.HasFlag(ReadingFlags.MonthLabel));
            Assert.Equal(ReadingQuality.Measured, rows[1].Quality);
        }
        finally
        {
            await CleanupAsync(db, meterId);
        }
    }

    [Fact]
    public async Task Behind_utc_a_period_starts_at_local_midnight_so_month_end_shares_stay_in_it()
    {
        // New York: December's share of a 10 December to 20 January interval is stamped at 23:59:59 on
        // 31 December local, which is already 1 January in UTC. A year requested as UTC midnights lost it.
        await using var db = fx.CreateContext();
        var newYork = Microsoft.Extensions.Options.Options.Create(new MeterVaultOptions { TimeZone = "America/New_York" });
        var type = new EnergyType { Key = $"flow-{Guid.NewGuid():N}", DisplayName = "Flow test", BaseUnit = "m3", DefaultMode = MeterMode.CumulativeCounter };
        db.EnergyTypes.Add(type);
        await db.SaveChangesAsync();
        var meter = new Meter { Name = $"ny-{Guid.NewGuid():N}", EnergyTypeId = type.Id, Mode = MeterMode.CumulativeCounter, Unit = "m3" };
        db.Meters.Add(meter);
        await db.SaveChangesAsync();
        var ingestion = new IngestionService(db, new NormalizationService(db, NormalizationEngine.CreateDefault(), newYork));
        await ingestion.IngestByMeterAsync(meter.Id, new DateTimeOffset(2026, 12, 10, 17, 0, 0, TimeSpan.Zero), 100, quality: ReadingQuality.Manual);
        await ingestion.IngestByMeterAsync(meter.Id, new DateTimeOffset(2027, 1, 20, 17, 0, 0, TimeSpan.Zero), 141, quality: ReadingQuality.Manual);

        try
        {
            // Read once both readings lie in the past: actuals stop at now (D-04), and both are after today.
            var later = new FixedTimeProvider(new DateTimeOffset(2027, 6, 1, 0, 0, 0, TimeSpan.Zero));
            var december = await new MeterVault.Infrastructure.Dashboard.FlowService(fx, newYork, later)
                .GetFlowAsync(type.Id, new DateOnly(2026, 12, 1), new DateOnly(2027, 1, 1));
            var node = Assert.Single(december.Nodes, n => n.MeterId == meter.Id);

            // The first reading's 100 plus December's 21.5 of the 41 days' 41 m3 (noon on the 10th to midnight).
            Assert.Equal(121.5, node.Value, 3);
        }
        finally
        {
            await CleanupAsync(db, meter.Id);
            await db.EnergyTypes.Where(t => t.Id == type.Id).ExecuteDeleteAsync();
        }
    }

    private static DateTimeOffset Utc(int year, int month, int day) => new(year, month, day, 0, 0, 0, TimeSpan.Zero);

    private static NormalizationUpgrade Upgrade(MeterVaultDbContext db) =>
        new(db, BerlinNormalization(db), NullLogger<NormalizationUpgrade>.Instance);

    private static async Task<int[]> PendingAsync(MeterVaultDbContext db)
    {
        var setting = await db.AppSettings.AsNoTracking().FirstOrDefaultAsync(s => s.Key == NormalizationUpgrade.PendingSettingKey);
        return setting is null ? [] : System.Text.Json.JsonSerializer.Deserialize<int[]>(setting.Value) ?? [];
    }

    private static NormalizationService BerlinNormalization(MeterVaultDbContext db) =>
        new(db, NormalizationEngine.CreateDefault(),
            Microsoft.Extensions.Options.Options.Create(new MeterVaultOptions { TimeZone = "Europe/Berlin" }));

    private static async Task<Dictionary<DateOnly, double>> MonthlyAsync(MeterVaultDbContext db, int meterId)
    {
        const string sql =
            "SELECT (time_bucket(INTERVAL '1 month', \"time\", 'Europe/Berlin') AT TIME ZONE 'Europe/Berlin')::date AS period, " +
            "sum(amount) AS amount FROM consumption WHERE meter_id = @meterId GROUP BY period ORDER BY period";
        var rows = await db.Database.GetDbConnection().QueryAsync<(DateOnly Period, double Amount)>(sql, new { meterId });
        return rows.ToDictionary(r => r.Period, r => r.Amount);
    }

    private static async Task SetRevisionAsync(MeterVaultDbContext db, string revision)
    {
        var setting = await db.AppSettings.FirstOrDefaultAsync(s => s.Key == NormalizationUpgrade.SettingKey);
        if (setting is null)
        {
            db.AppSettings.Add(new AppSetting { Key = NormalizationUpgrade.SettingKey, Value = revision });
        }
        else
        {
            setting.Value = revision;
        }

        await db.SaveChangesAsync();
        db.ChangeTracker.Clear();
    }

    private static async Task<int> CreateMeterAsync(MeterVaultDbContext db)
    {
        await DatabaseSeeder.SeedAsync(db);
        var type = await db.EnergyTypes.FirstAsync(t => t.Key == "water");
        var meter = new Meter { Name = $"months-{Guid.NewGuid():N}", EnergyTypeId = type.Id, Mode = MeterMode.CumulativeCounter, Unit = "m3" };
        db.Meters.Add(meter);
        await db.SaveChangesAsync();
        return meter.Id;
    }

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