using System.Text.Json;
using MeterVault.Core.Analysis;
using MeterVault.Core.Analysis.Virtual;
using MeterVault.Core.Domain;
using MeterVault.Infrastructure.Backup;
using MeterVault.Infrastructure.Persistence;
using Microsoft.EntityFrameworkCore;

namespace MeterVault.Integration.Tests;

/// <summary>
/// JSON config export/import (SDD §10): a round-trip through an emptied database preserves the
/// relationships (meter → energy type, meter-scoped tariff, category membership, meter topology links)
/// after id remapping — and the meter ids inside virtual-meter definitions follow their meters (D-32).
/// </summary>
[Collection("Timescale")]
public sealed class ExportRoundTripTests(TimescaleFixture fx)
{
    [Fact]
    public async Task Export_then_import_preserves_relationships()
    {
        string json;

        await using (var db = fx.CreateContext())
        {
            await WipeAllAsync(db);
            await DatabaseSeeder.SeedAsync(db);

            var elec = await db.EnergyTypes.FirstAsync(t => t.Key == "electricity");
            var strom = await db.CostCategories.FirstAsync(c => c.Name == "Strom");
            var meter = new Meter { Name = "Export Meter", EnergyTypeId = elec.Id, Mode = MeterMode.CumulativeCounter, Unit = "kWh" };
            db.Meters.Add(meter);
            await db.SaveChangesAsync();

            db.Tariffs.Add(new Tariff { ScopeType = TariffScope.Meter, ScopeId = meter.Id, Component = TariffComponent.UnitPrice, Value = 0.30, Unit = "EUR/kWh", ValidFrom = new DateOnly(2024, 1, 1) });
            db.CostCategoryMembers.Add(new CostCategoryMember { CategoryId = strom.Id, MeterId = meter.Id });
            await db.SaveChangesAsync();

            json = await new ExportService(db).ExportJsonAsync();
        }

        await using (var db = fx.CreateContext())
        {
            await WipeAllAsync(db);
            await new ExportService(db).ImportJsonAsync(json);
        }

        await using (var db = fx.CreateContext())
        {
            var meter = await db.Meters.SingleAsync(m => m.Name == "Export Meter");
            Assert.True(await db.EnergyTypes.AnyAsync(t => t.Id == meter.EnergyTypeId));

            var tariff = await db.Tariffs.SingleAsync(t => t.ScopeType == TariffScope.Meter);
            Assert.Equal(meter.Id, tariff.ScopeId);

            var member = await db.CostCategoryMembers.SingleAsync();
            Assert.Equal(meter.Id, member.MeterId);
            Assert.True(await db.CostCategories.AnyAsync(c => c.Id == member.CategoryId));

            await WipeAllAsync(db);
        }
    }

    [Fact]
    public async Task Links_and_virtual_definitions_follow_their_meters_to_new_ids()
    {
        string json;
        (int Meter, int Solar, int Sum, int Broken) old;

        await using (var db = fx.CreateContext())
        {
            await WipeAllAsync(db);
            await DatabaseSeeder.SeedAsync(db);
            var elec = await db.EnergyTypes.FirstAsync(t => t.Key == "electricity");

            var ghost = new Meter { Name = "Deleted before the export", EnergyTypeId = elec.Id, Mode = MeterMode.CumulativeCounter, Unit = "kWh" };
            var meter = new Meter { Name = "Export Haus", EnergyTypeId = elec.Id, Mode = MeterMode.CumulativeCounter, Unit = "kWh" };
            var solar = new Meter { Name = "Export Solar", EnergyTypeId = elec.Id, Mode = MeterMode.GenerationCounter, Unit = "kWh" };
            var sum = new Meter { Name = "Export Net", EnergyTypeId = elec.Id, Mode = MeterMode.Virtual, Unit = "kWh" };
            var broken = new Meter { Name = "Export Broken", EnergyTypeId = elec.Id, Mode = MeterMode.Virtual, Unit = "kWh" };
            db.Meters.AddRange(ghost, meter, solar, sum, broken);
            await db.SaveChangesAsync();

            // A definition with a key of its own next to it (the role, a totals override, …), and one naming a meter the
            // export will not contain.
            sum.Meta = VirtualDefinitionJson.Write(
                """{"totals":"never"}""",
                new VirtualDefinition($"(m{solar.Id} + m{meter.Id})", QuantityKind.Net, "kWh", VirtualCostRule.None));
            broken.Meta = VirtualDefinitionJson.Write(
                "{}", new VirtualDefinition($"m{solar.Id} + m{ghost.Id}", QuantityKind.Generation, "kWh", VirtualCostRule.SourceCosts));
            db.MeterLinks.AddRange(
                new MeterLink { FromMeterId = solar.Id, ToMeterId = sum.Id },
                new MeterLink { FromMeterId = meter.Id, ToMeterId = sum.Id },
                new MeterLink { FromMeterId = meter.Id, ToMeterId = solar.Id });
            await db.SaveChangesAsync();
            await db.Meters.Where(m => m.Id == ghost.Id).ExecuteDeleteAsync();
            old = (meter.Id, solar.Id, sum.Id, broken.Id);

            json = await new ExportService(db).ExportJsonAsync();
        }

        await using (var db = fx.CreateContext())
        {
            await WipeAllAsync(db);
            await new ExportService(db).ImportJsonAsync(json);
        }

        await using (var db = fx.CreateContext())
        {
            var ids = await db.Meters.ToDictionaryAsync(m => m.Name, m => m.Id);
            var (meter, solar, sum, broken) = (ids["Export Haus"], ids["Export Solar"], ids["Export Net"], ids["Export Broken"]);

            // The restore numbered the meters anew, so a formula still naming the old ids would read other meters.
            Assert.NotEqual(old.Solar, solar);
            Assert.NotEqual(old.Meter, meter);

            var links = await db.MeterLinks.Select(l => new { l.FromMeterId, l.ToMeterId }).ToListAsync();
            Assert.Equal(
                new[] { (meter, solar), (meter, sum), (solar, sum) }.Order(),
                links.Select(l => (l.FromMeterId, l.ToMeterId)).Order());

            var metas = await db.Meters.ToDictionaryAsync(m => m.Id, m => m.Meta);
            var read = VirtualDefinitionJson.Read(metas[sum]);
            Assert.Equal(VirtualDefinitionReadStatus.Present, read.Status);
            Assert.Equal($"(m{solar} + m{meter})", read.Definition!.Expression);
            Assert.Equal(new[] { meter, solar }.Order(), read.Definition.ReferencedMeterIds);
            Assert.False(read.ReferencedIdsStale);
            Assert.Equal(QuantityKind.Net, read.Definition.ResultKind);
            Assert.Equal(VirtualCostRule.None, read.Definition.CostRule);
            using (var doc = JsonDocument.Parse(metas[sum]))
            {
                Assert.Equal("never", doc.RootElement.GetProperty("totals").GetString());
            }

            // A meter the document has no row for becomes m0, which no meter has: an unknown reference, never another meter.
            var brokenRead = VirtualDefinitionJson.Read(metas[broken]);
            Assert.Equal($"m{solar} + m0", brokenRead.Definition!.Expression);
            Assert.Equal([0, solar], brokenRead.Definition.ReferencedMeterIds);
            Assert.False(await db.Meters.AnyAsync(m => m.Id == 0));

            await WipeAllAsync(db);
        }
    }

    [Fact]
    public async Task A_tariff_of_a_deleted_meter_is_not_restored_onto_another_meter()
    {
        // Review virtual F2: tariff.scope_id has no foreign key, so deleting a meter the old way left its meter-scoped
        // price behind. A fresh instance numbers its meters from where the original did, so the dead id is given to
        // another restored meter, which the orphaned 0.99 EUR/kWh would then bill.
        string json;
        int firstId;

        await using (var db = fx.CreateContext())
        {
            await WipeAllAsync(db);
            await DatabaseSeeder.SeedAsync(db);
            var elec = await db.EnergyTypes.FirstAsync(t => t.Key == "electricity");
            var a = new Meter { Name = "Meter A", EnergyTypeId = elec.Id, Mode = MeterMode.CumulativeCounter, Unit = "kWh" };
            var b = new Meter { Name = "Old wallbox", EnergyTypeId = elec.Id, Mode = MeterMode.CumulativeCounter, Unit = "kWh" };
            var c = new Meter { Name = "Netz", EnergyTypeId = elec.Id, Mode = MeterMode.CumulativeCounter, Unit = "kWh", Meta = """{"role":"grid_import"}""" };
            db.Meters.Add(a);
            await db.SaveChangesAsync();
            db.Meters.Add(b);
            await db.SaveChangesAsync();
            db.Meters.Add(c);
            await db.SaveChangesAsync();
            firstId = a.Id;

            db.Tariffs.Add(new Tariff { ScopeType = TariffScope.Meter, ScopeId = b.Id, Component = TariffComponent.UnitPrice, Value = 0.99, Unit = "EUR/kWh", ValidFrom = new DateOnly(2024, 1, 1) });
            await db.SaveChangesAsync();

            // An orphan an older delete left behind: the meter goes, its price stays.
            await db.Meters.Where(m => m.Id == b.Id).ExecuteDeleteAsync();
            json = await new ExportService(db).ExportJsonAsync();
        }

        await using (var db = fx.CreateContext())
        {
            await WipeAllAsync(db);
            await db.Database.ExecuteSqlRawAsync($"ALTER TABLE meter ALTER COLUMN id RESTART WITH {firstId}");
            await new ExportService(db).ImportJsonAsync(json);
        }

        await using (var db = fx.CreateContext())
        {
            var restored = await db.Meters.Select(m => m.Id).ToListAsync();
            var meterTariffs = await db.Tariffs.Where(t => t.ScopeType == TariffScope.Meter).ToListAsync();
            Assert.DoesNotContain(meterTariffs, t => restored.Contains(t.ScopeId!.Value));
            Assert.Empty(meterTariffs);
            await WipeAllAsync(db);
        }
    }

    [Fact]
    public async Task A_tariff_of_a_deleted_energy_type_is_not_restored_onto_another_type()
    {
        string json;
        short firstId;

        await using (var db = fx.CreateContext())
        {
            await WipeAllAsync(db);
            var kept = new EnergyType { Key = "kept", DisplayName = "Kept", BaseUnit = "kWh", DefaultMode = MeterMode.CumulativeCounter };
            var gone = new EnergyType { Key = "gone", DisplayName = "Gone", BaseUnit = "kWh", DefaultMode = MeterMode.CumulativeCounter };
            var other = new EnergyType { Key = "other", DisplayName = "Other", BaseUnit = "kWh", DefaultMode = MeterMode.CumulativeCounter };
            db.EnergyTypes.Add(kept);
            await db.SaveChangesAsync();
            db.EnergyTypes.Add(gone);
            await db.SaveChangesAsync();
            db.EnergyTypes.Add(other);
            await db.SaveChangesAsync();
            firstId = kept.Id;

            db.Tariffs.Add(new Tariff { ScopeType = TariffScope.EnergyType, ScopeId = gone.Id, Component = TariffComponent.UnitPrice, Value = 0.99, Unit = "EUR/kWh", ValidFrom = new DateOnly(2024, 1, 1) });
            await db.SaveChangesAsync();
            await db.EnergyTypes.Where(t => t.Id == gone.Id).ExecuteDeleteAsync();
            json = await new ExportService(db).ExportJsonAsync();
        }

        await using (var db = fx.CreateContext())
        {
            await WipeAllAsync(db);
            await db.Database.ExecuteSqlRawAsync($"ALTER TABLE energy_type ALTER COLUMN id RESTART WITH {firstId}");
            await new ExportService(db).ImportJsonAsync(json);
        }

        await using (var db = fx.CreateContext())
        {
            Assert.Empty(await db.Tariffs.Where(t => t.ScopeType == TariffScope.EnergyType).ToListAsync());
            await WipeAllAsync(db);
        }
    }

    [Fact]
    public async Task Deleting_a_meter_or_an_energy_type_takes_its_own_prices_with_it()
    {
        await using var db = fx.CreateContext();
        await WipeAllAsync(db);
        var type = new EnergyType { Key = "deleting", DisplayName = "Deleting", BaseUnit = "kWh", DefaultMode = MeterMode.CumulativeCounter };
        db.EnergyTypes.Add(type);
        await db.SaveChangesAsync();
        var meter = new Meter { Name = "Wallbox", EnergyTypeId = type.Id, Mode = MeterMode.CumulativeCounter, Unit = "kWh" };
        db.Meters.Add(meter);
        await db.SaveChangesAsync();
        db.Readings.Add(new Reading { MeterId = meter.Id, Time = new DateTimeOffset(2026, 1, 1, 0, 0, 0, TimeSpan.Zero), Value = 1 });
        db.Tariffs.AddRange(
            new Tariff { ScopeType = TariffScope.Meter, ScopeId = meter.Id, Component = TariffComponent.UnitPrice, Value = 0.99, Unit = "EUR/kWh", ValidFrom = new DateOnly(2024, 1, 1) },
            new Tariff { ScopeType = TariffScope.EnergyType, ScopeId = type.Id, Component = TariffComponent.BasePrice, Value = 9, Unit = "EUR/month", ValidFrom = new DateOnly(2024, 1, 1) },
            new Tariff { ScopeType = TariffScope.Global, Component = TariffComponent.BasePrice, Value = 1, Unit = "EUR/month", ValidFrom = new DateOnly(2024, 1, 1) });
        await db.SaveChangesAsync();

        await EntityDeletion.DeleteMeterAsync(db, meter.Id);
        Assert.False(await db.Meters.AnyAsync(m => m.Id == meter.Id));
        Assert.False(await db.Tariffs.AnyAsync(t => t.ScopeType == TariffScope.Meter));

        await EntityDeletion.DeleteEnergyTypeAsync(db, type.Id);
        Assert.False(await db.EnergyTypes.AnyAsync(t => t.Id == type.Id));
        Assert.Equal(TariffScope.Global, (await db.Tariffs.SingleAsync()).ScopeType);
        await WipeAllAsync(db);
    }

    private static async Task WipeAllAsync(MeterVaultDbContext db)
    {
        await db.Consumption.ExecuteDeleteAsync();
        await db.Readings.ExecuteDeleteAsync();
        await db.MeterEvents.ExecuteDeleteAsync();
        await db.ManualCosts.ExecuteDeleteAsync();
        await db.CostCategoryMembers.ExecuteDeleteAsync();
        await db.Tariffs.ExecuteDeleteAsync();
        await db.Tanks.ExecuteDeleteAsync();
        await db.MeterSources.ExecuteDeleteAsync();
        await db.Meters.ExecuteDeleteAsync();
        await db.IngestionEndpoints.ExecuteDeleteAsync();
        await db.CostCategories.ExecuteDeleteAsync();
        await db.EnergyTypes.ExecuteDeleteAsync();
        await db.AppSettings.ExecuteDeleteAsync();
    }
}