using MeterVault.Core.Analysis;
using MeterVault.Core.Analysis.Costing;
using MeterVault.Core.Analysis.Virtual;
using MeterVault.Core.Domain;
using MeterVault.Core.Normalization;
using MeterVault.Infrastructure.Analysis;
using MeterVault.Infrastructure.Costing;
using MeterVault.Infrastructure.Normalization;
using MeterVault.Infrastructure.Options;
using MeterVault.Infrastructure.Persistence;
using Microsoft.EntityFrameworkCore;

namespace MeterVault.Integration.Tests.Costing;

/// <summary>
/// Builds what a cost test prices — its own energy types, meters with readings normalized in Berlin, tariffs, manual
/// costs and categories — on a frozen clock of 19 September 2026, 14:37 Berlin, and removes all of it again.
/// </summary>
internal sealed class CostSandbox(TimescaleFixture fx) : IAsyncDisposable
{
    public const string BerlinId = "Europe/Berlin";

    public static readonly TimeZoneInfo Berlin = TimeZoneInfo.FindSystemTimeZoneById(BerlinId);

    /// <summary>The frozen "now" of every request (D-01), after the reference data ends (31 May 2026).</summary>
    public static readonly DateTimeOffset Now = new DateTimeOffset(2026, 9, 19, 14, 37, 0, TimeSpan.FromHours(2)).ToUniversalTime();

    private readonly List<int> _meters = [];
    private readonly List<short> _types = [];
    private readonly List<int> _tariffs = [];
    private readonly List<int> _manualCosts = [];
    private readonly List<int> _categories = [];

    public TimescaleFixture Fixture => fx;

    public static ResolvedPeriod Custom(DateOnly first, DateOnly last) => PeriodResolver.Resolve(PeriodPreset.Custom, first, last, Now, Berlin);

    public static ResolvedPeriod Year(int year) => Custom(new DateOnly(year, 1, 1), new DateOnly(year, 12, 31));

    public static ResolvedPeriod Month(int year, int month) =>
        Custom(new DateOnly(year, month, 1), new DateOnly(year, month, DateTime.DaysInMonth(year, month)));

    public static ResolvedPeriod Preset(PeriodPreset preset) => PeriodResolver.Resolve(preset, null, null, Now, Berlin);

    public static DateTimeOffset Midnight(int year, int month, int day) => GapAttribution.LocalMidnight(new DateOnly(year, month, day), Berlin);

    public static DateOnly D(int year, int month, int day) => new(year, month, day);

    public CostReader Reader(string currency = "EUR")
    {
        var options = Microsoft.Extensions.Options.Options.Create(new MeterVaultOptions { TimeZone = BerlinId, Currency = currency });
        return new CostReader(fx, new AnalysisReader(fx, options), options);
    }

    public async Task<short> TypeAsync(string unit = "kWh")
    {
        await using var db = fx.CreateContext();
        var type = new EnergyType
        {
            Key = $"cost-{Guid.NewGuid():N}",
            DisplayName = "Cost test",
            BaseUnit = unit,
            DefaultMode = MeterMode.CumulativeCounter,
        };
        db.EnergyTypes.Add(type);
        await db.SaveChangesAsync();
        _types.Add(type.Id);
        return type.Id;
    }

    public async Task<int> MeterAsync(
        short type, MeterMode mode, string unit, DateOnly? installedAt = null, string meta = "{}", DateOnly? retiredAt = null, string? name = null)
    {
        await using var db = fx.CreateContext();
        var meter = new Meter
        {
            Name = name ?? $"cost-{Guid.NewGuid():N}",
            EnergyTypeId = type,
            Mode = mode,
            Unit = unit,
            InstalledAt = installedAt,
            RetiredAt = retiredAt,
            Meta = meta,
        };
        db.Meters.Add(meter);
        await db.SaveChangesAsync();
        _meters.Add(meter.Id);
        return meter.Id;
    }

    /// <summary>
    /// A counter installed on the 1st of <paramref name="firstMonth"/> whose consecutive local months book the given
    /// amounts: one reading at each following local midnight of the 1st.
    /// </summary>
    public async Task<int> MonthlyAsync(short type, MeterMode mode, DateOnly firstMonth, params double[] months)
    {
        var meter = await MeterAsync(type, mode, "kWh", installedAt: firstMonth);
        await MonthlyReadingsAsync(meter, firstMonth, months);
        return meter;
    }

    /// <summary>Monthly readings on an existing meter, as <see cref="MonthlyAsync"/> writes them.</summary>
    public async Task MonthlyReadingsAsync(int meter, DateOnly firstMonth, params double[] months)
    {
        var register = 0d;
        var readings = new List<(DateTimeOffset, double)>();
        for (var i = 0; i < months.Length; i++)
        {
            register += months[i];
            var next = firstMonth.AddMonths(i + 1);
            readings.Add((Midnight(next.Year, next.Month, 1), register));
        }

        await ReadingsAsync(meter, [.. readings]);
    }

    /// <summary>A counter installed on <paramref name="from"/> that rises by <paramref name="perDay"/> at every local midnight up to <paramref name="to"/>.</summary>
    public async Task<int> DailyAsync(short type, DateOnly from, DateOnly to, double perDay)
    {
        var meter = await MeterAsync(type, MeterMode.CumulativeCounter, "kWh", installedAt: from);
        var readings = new List<(DateTimeOffset, double)>();
        var register = 0d;
        for (var day = from.AddDays(1); day <= to; day = day.AddDays(1))
        {
            register += perDay;
            readings.Add((Midnight(day.Year, day.Month, day.Day), register));
        }

        await ReadingsAsync(meter, [.. readings]);
        return meter;
    }

    public async Task<int> VirtualAsync(short type, string expression, QuantityKind kind, string unit, VirtualCostRule rule, string meta = "{}")
    {
        meta = VirtualDefinitionJson.Write(meta, new VirtualDefinition(expression, kind, unit, rule));
        var meter = await MeterAsync(type, MeterMode.Virtual, unit, meta: meta);
        await RecomputeAsync(meter);
        return meter;
    }

    public async Task LinkAsync(int from, int to)
    {
        await using var db = fx.CreateContext();
        db.MeterLinks.Add(new MeterLink { FromMeterId = from, ToMeterId = to });
        await db.SaveChangesAsync();
    }

    public async Task<int> TariffAsync(
        TariffScope scope, int? scopeId, TariffComponent component, double value, string unit, DateOnly from, DateOnly? to = null)
    {
        await using var db = fx.CreateContext();
        var tariff = new Tariff
        {
            ScopeType = scope,
            ScopeId = scopeId,
            Component = component,
            Value = value,
            Unit = unit,
            ValidFrom = from,
            ValidTo = to,
        };
        db.Tariffs.Add(tariff);
        await db.SaveChangesAsync();
        _tariffs.Add(tariff.Id);
        return tariff.Id;
    }

    public Task<int> TypePriceAsync(short type, double value, DateOnly from, string unit = "EUR/kWh", DateOnly? to = null) =>
        TariffAsync(TariffScope.EnergyType, type, TariffComponent.UnitPrice, value, unit, from, to);

    public Task<int> MeterPriceAsync(int meter, double value, DateOnly from, string unit = "EUR/kWh") =>
        TariffAsync(TariffScope.Meter, meter, TariffComponent.UnitPrice, value, unit, from);

    public async Task<int> ManualCostAsync(DateOnly start, double amount, int? meterId = null, int? categoryId = null, string currency = "EUR")
    {
        await using var db = fx.CreateContext();
        var cost = new ManualCost
        {
            MeterId = meterId,
            CategoryId = categoryId,
            PeriodStart = start,
            PeriodEnd = start.AddMonths(1).AddDays(-1),
            Amount = amount,
            Currency = currency,
        };
        db.ManualCosts.Add(cost);
        await db.SaveChangesAsync();
        _manualCosts.Add(cost.Id);
        return cost.Id;
    }

    public async Task<int> CategoryAsync(string name, int sort, int[]? meters = null, short[]? types = null)
    {
        await using var db = fx.CreateContext();
        var category = new CostCategory { Name = name, Sort = sort };
        foreach (var meter in meters ?? [])
        {
            category.Members.Add(new CostCategoryMember { MeterId = meter });
        }

        foreach (var type in types ?? [])
        {
            category.Members.Add(new CostCategoryMember { EnergyTypeId = type });
        }

        db.CostCategories.Add(category);
        await db.SaveChangesAsync();
        _categories.Add(category.Id);
        return category.Id;
    }

    public async Task ReadingsAsync(int meterId, params (DateTimeOffset Time, double Value)[] readings)
    {
        await using (var db = fx.CreateContext())
        {
            db.Readings.AddRange(readings.Select(r => new Reading
            {
                MeterId = meterId,
                Time = r.Time.ToUniversalTime(),
                Value = r.Value,
                Quality = ReadingQuality.Manual,
            }));
            await db.SaveChangesAsync();
        }

        await RecomputeAsync(meterId);
    }

    public async Task RecomputeAsync(params int[] meterIds)
    {
        await using var db = fx.CreateContext();
        await using var tx = await db.Database.BeginTransactionAsync();
        foreach (var id in meterIds)
        {
            await Normalization(db).RecomputeMeterAsync(id, null);
        }

        await db.SaveChangesAsync();
        await tx.CommitAsync();
    }

    public static NormalizationService Normalization(MeterVaultDbContext db) =>
        new(db, NormalizationEngine.CreateDefault(),
            Microsoft.Extensions.Options.Options.Create(new MeterVaultOptions { TimeZone = BerlinId }),
            new FixedTimeProvider(Now));

    public async ValueTask DisposeAsync()
    {
        await using var db = fx.CreateContext();
        var ids = _meters.ToArray();
        await db.ManualCosts.Where(c => _manualCosts.Contains(c.Id)).ExecuteDeleteAsync();
        await db.CostCategories.Where(c => _categories.Contains(c.Id)).ExecuteDeleteAsync();
        await db.Tariffs.Where(t => _tariffs.Contains(t.Id)).ExecuteDeleteAsync();
        await db.MeterLinks.Where(l => ids.Contains(l.FromMeterId) || ids.Contains(l.ToMeterId)).ExecuteDeleteAsync();
        await db.Consumption.Where(c => ids.Contains(c.MeterId)).ExecuteDeleteAsync();
        await db.Readings.Where(r => ids.Contains(r.MeterId)).ExecuteDeleteAsync();
        await db.MeterEvents.Where(e => ids.Contains(e.MeterId)).ExecuteDeleteAsync();
        await db.Meters.Where(m => ids.Contains(m.Id)).ExecuteDeleteAsync();
        var types = _types.ToArray();
        await db.EnergyTypes.Where(t => types.Contains(t.Id)).ExecuteDeleteAsync();
    }
}

/// <summary>Assertions on cost figures.</summary>
internal static class CostAssert
{
    public static void Cost(double expected, CostAmount amount, int precision = 6)
    {
        Assert.NotNull(amount.Cost);
        Assert.Equal(expected, amount.Cost!.Value, precision);
    }

    /// <summary>Priced, with a value, and nothing unavailable in it (not-priced components may have been left out).</summary>
    public static void Priced(double expected, CostAmount amount, double tolerance = 1e-6)
    {
        Assert.Equal(CostStatus.Priced, amount.Status);
        Assert.NotNull(amount.Cost);
        Assert.InRange(amount.Cost!.Value, expected - tolerance, expected + tolerance);
        Assert.DoesNotContain(amount.MissingPrices, m => m.Reason is CostStatus.PriceGap or CostStatus.UnitMismatch);
    }
}