using FluentAssertions;
using IBKRTrader.Core.Capital;
using IBKRTrader.Core.Logging;
using IBKRTrader.Core.Persistence.Ef;
using IBKRTrader.Core.Persistence.Entities;
using IBKRTrader.Core.Settings;
using IBKRTrader.Core.Trading;
using Microsoft.EntityFrameworkCore;

namespace IBKRTrader.Tests.Capital;

/// <summary>
/// Reservierungen über den Order-Lebenszyklus (#305), gegen die EF-InMemory-Datenbank – kein
/// externer Zugriff, deterministisch.
/// </summary>
[Trait("cat", "unit")]
public class ReservationServiceTests
{
    private sealed class InMemoryFactory(DbContextOptions<CoreDbContext> options)
        : IDbContextFactory<CoreDbContext>
    {
        public CoreDbContext CreateDbContext() => new(options);
    }

    private static readonly BookId Ow = BookId.ForModule("OW");
    private static readonly InstrumentRef Aapl = InstrumentRef.ForStock("AAPL");

    private static ReservationService CreateSut(
        out IDbContextFactory<CoreDbContext> factory, int ttlMinutes = 120)
    {
        var options = new DbContextOptionsBuilder<CoreDbContext>()
            .UseInMemoryDatabase(Guid.NewGuid().ToString())
            .Options;
        factory = new InMemoryFactory(options);

        var settings = new SettingsService();
        settings.Settings.Capital.ReservationTtlMinutes = ttlMinutes;
        return new ReservationService(factory, settings, new LoggingService());
    }

    private static Func<ReservationService.ReservationLoad, ReservationService.ReservationRequest>
        Bind(decimal amount, int shares = 0) =>
        _ => ReservationService.ReservationRequest.Bind(amount, shares);

    // ─── Binden ──────────────────────────────────────────────────────────────────

    [Fact]
    public async Task Reserve_BindsCapital_AndCountsAsOpen()
    {
        var sut = CreateSut(out _);

        var result = await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_000m));

        result.Success.Should().BeTrue();
        result.WasExisting.Should().BeFalse();
        (await sut.GetOpenAmountAsync()).Should().Be(1_000m);
        (await sut.GetOpenAmountAsync(Ow)).Should().Be(1_000m);
    }

    [Fact]
    public async Task Reserve_PassesTheCurrentLoadToTheCheck()
    {
        // Genau dafuer laeuft die Pruefung unter dem Schloss: sie muss den Stand sehen, der die
        // bereits gebundenen Betraege enthaelt - sonst geben zwei Signale dasselbe Geld aus.
        var sut = CreateSut(out _);
        await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_000m));

        ReservationService.ReservationLoad seen = default;
        await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-2", load =>
        {
            seen = load;
            return ReservationService.ReservationRequest.Bind(500m);
        });

        seen.TotalCash.Should().Be(1_000m);
        seen.CashOfBook.Should().Be(1_000m);
        seen.CashInCurrency.Should().Be(1_000m);
    }

    [Fact]
    public async Task Reserve_CanBeRefusedByTheCheck()
    {
        var sut = CreateSut(out _);
        var breach = new LimitBreach(LimitKind.CashAvailable, "AAPL", 5_000m, 100m, 0, 100m);

        var result = await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1",
            _ => ReservationService.ReservationRequest.Reject(breach));

        result.Success.Should().BeFalse();
        result.Breach.Should().Be(breach);
        (await sut.GetOpenAmountAsync()).Should().Be(0m);
    }

    [Fact]
    public async Task SameSignalTwice_ReturnsTheExistingBinding_InsteadOfASecond()
    {
        // Der Reconnect-Fall. Ohne diese Sperre entstuende eine zweite Order fuer dasselbe Signal.
        var sut = CreateSut(out _);
        var first = await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_000m));

        var second = await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_000m));

        second.WasExisting.Should().BeTrue();
        second.Reservation!.Id.Should().Be(first.Reservation!.Id);
        (await sut.GetOpenAmountAsync()).Should().Be(1_000m);
    }

    [Fact]
    public async Task SameSignalForADifferentContract_IsItsOwnBinding()
    {
        var sut = CreateSut(out _);
        var put = InstrumentRef.ForOption(
            new OptionSpec("AAPL", new DateOnly(2026, 9, 18), 150m, OptionRight.Put));

        await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_000m));
        var second = await sut.ReserveAsync(Ow, put, TradeSide.Sell, 1, "USD", "sig-1", Bind(15_000m));

        second.WasExisting.Should().BeFalse();
        (await sut.GetOpenAmountAsync()).Should().Be(16_000m);
    }

    [Fact]
    public async Task WrittenCalls_BindShares_NotCash()
    {
        var sut = CreateSut(out _);
        var call = InstrumentRef.ForOption(
            new OptionSpec("AAPL", new DateOnly(2026, 9, 18), 150m, OptionRight.Call));

        await sut.ReserveAsync(Ow, call, TradeSide.Sell, 1, "USD", "sig-1", Bind(0m, shares: 100));

        (await sut.GetOpenAmountAsync()).Should().Be(0m);
        (await sut.GetOpenSharesAsync(Ow, "AAPL")).Should().Be(100);
    }

    // ─── Abschließen ─────────────────────────────────────────────────────────────

    [Fact]
    public async Task Settle_FullFill_ReleasesTheBinding_BecauseItBecameAPosition()
    {
        // Sonst zaehlte dasselbe Kapital doppelt: einmal als Reservierung, einmal als Position.
        var sut = CreateSut(out _);
        var r = await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_050m));

        await sut.SettleAsync(r.Reservation!.Id, filledQuantity: 10, actualAmount: 1_000m);

        (await sut.GetOpenAmountAsync()).Should().Be(0m);
    }

    [Fact]
    public async Task Settle_NoFill_ReleasesEverything()
    {
        var sut = CreateSut(out _);
        var r = await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_050m));

        await sut.SettleAsync(r.Reservation!.Id, filledQuantity: 0, actualAmount: 0m);

        (await sut.GetOpenAmountAsync()).Should().Be(0m);
    }

    [Fact]
    public async Task Settle_PartialFill_KeepsTheRestBound()
    {
        var sut = CreateSut(out var factory);
        var r = await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_000m));

        await sut.SettleAsync(r.Reservation!.Id, filledQuantity: 4, actualAmount: 400m);

        // 6 von 10 Stueck offen -> 60 % der Bindung bleibt stehen.
        (await sut.GetOpenAmountAsync()).Should().Be(600m);
        await using var db = await factory.CreateDbContextAsync();
        var row = await db.Reservations.FindAsync(r.Reservation!.Id);
        row!.State.Should().Be(ReservationState.PartiallyFilled);
        row.Quantity.Should().Be(6);
    }

    [Fact]
    public async Task Cancel_ReleasesTheBinding()
    {
        var sut = CreateSut(out _);
        var r = await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_000m));

        await sut.CancelAsync(r.Reservation!.Id, "Order abgelehnt");

        (await sut.GetOpenAmountAsync()).Should().Be(0m);
    }

    // ─── Frist ───────────────────────────────────────────────────────────────────

    [Fact]
    public async Task OverdueBinding_IsReported_NotSilentlyReleased()
    {
        // Eine haengende Order, deren Reservierung stillschweigend freigegeben wird, gibt dasselbe
        // Geld zweimal aus. Deshalb: Alarm, und der Zustand heisst Expired, nicht Cancelled.
        var sut = CreateSut(out var factory, ttlMinutes: 1);
        var r = await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_000m));

        await using (var db = await factory.CreateDbContextAsync())
        {
            var row = await db.Reservations.FindAsync(r.Reservation!.Id);
            row!.ExpiresAt = DateTime.UtcNow.AddMinutes(-5);
            await db.SaveChangesAsync();
        }

        var overdue = await sut.ExpireOverdueAsync();

        overdue.Should().ContainSingle();
        overdue[0].State.Should().Be(ReservationState.Expired);
    }

    [Fact]
    public async Task BindingsWithinTheirDeadline_AreLeftAlone()
    {
        var sut = CreateSut(out _);
        await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_000m));

        (await sut.ExpireOverdueAsync()).Should().BeEmpty();
    }

    // ─── Absturzwiederherstellung ────────────────────────────────────────────────

    [Fact]
    public async Task Recovery_KeepsBindingsWhoseBrokerOrderIsStillOpen()
    {
        var sut = CreateSut(out _);
        var r = await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_000m));
        await sut.MarkSubmittedAsync(r.Reservation!.Id, "O-42");

        var orphans = await sut.RecoverAsync(["O-42"]);

        orphans.Should().BeEmpty();
        (await sut.GetOpenAmountAsync()).Should().Be(1_000m);
    }

    [Fact]
    public async Task Recovery_QuarantinesOrphans_AndKeepsTheirCapitalBound()
    {
        // Zwei Erklaerungen mit entgegengesetzter Folge: die Order wurde nie abgeschickt (Geld darf
        // zurueck) oder sie wurde ausgefuehrt, waehrend wir weg waren (es gibt eine Position, die
        // wir nicht kennen). Welche zutrifft, entscheidet nicht diese Methode.
        var sut = CreateSut(out _);
        var r = await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_000m));
        await sut.MarkSubmittedAsync(r.Reservation!.Id, "O-42");

        var orphans = await sut.RecoverAsync(["O-99"]);

        orphans.Should().ContainSingle();
        orphans[0].State.Should().Be(ReservationState.Quarantined);
        (await sut.GetOpenAmountAsync()).Should().Be(1_000m);
    }

    [Fact]
    public async Task Recovery_QuarantinesBindingsThatNeverReachedTheBroker()
    {
        var sut = CreateSut(out _);
        await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_000m));

        var orphans = await sut.RecoverAsync([]);

        orphans.Should().ContainSingle();
        orphans[0].BrokerOrderId.Should().BeNull();
    }

    [Fact]
    public async Task Recovery_IgnoresFinishedBindings()
    {
        var sut = CreateSut(out _);
        var r = await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_000m));
        await sut.SettleAsync(r.Reservation!.Id, 10, 1_000m);

        (await sut.RecoverAsync([])).Should().BeEmpty();
    }

    // ─── Offene Betraege je Waehrung (#480) ──────────────────────────────────────

    [Fact]
    public async Task OpenAmounts_AreGroupedByCurrency_NotSummedAcrossThem()
    {
        var sut  = CreateSut(out _);
        var sap  = InstrumentRef.ForStock("SAP", "EUR");

        await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_000m));
        await sut.ReserveAsync(Ow, sap,  TradeSide.Buy,  5, "EUR", "sig-2", Bind(  500m));
        await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy,  2, "USD", "sig-3", Bind(  200m));

        var byCurrency = await sut.GetOpenAmountByCurrencyAsync();

        byCurrency.Should().HaveCount(2);
        byCurrency["USD"].Should().Be(1_200m);
        byCurrency["EUR"].Should().Be(500m);

        // Die alte Gesamtsumme addiert weiterhin ueber Waehrungen hinweg - genau deshalb darf
        // sie nicht mehr als Geldbetrag verwendet werden.
        (await sut.GetOpenAmountAsync()).Should().Be(1_700m);
    }

    [Fact]
    public async Task ClosedReservations_DoNotShowUpPerCurrency()
    {
        var sut    = CreateSut(out _);
        var result = await sut.ReserveAsync(Ow, Aapl, TradeSide.Buy, 10, "USD", "sig-1", Bind(1_000m));
        await sut.CancelAsync(result.Reservation!.Id, "Test");

        (await sut.GetOpenAmountByCurrencyAsync()).Should().BeEmpty();
    }
}