using Chessistics.Engine.Commands;
using Chessistics.Engine.Events;
using Chessistics.Engine.Model;
using Chessistics.Tests.Helpers;
using Xunit;

namespace Chessistics.Tests.Simulation;

public class RecurringDemandTests
{
    private SimHelper BuildRecurringLevel()
    {
        var level = new LevelDef
        {
            Width = 3,
            Height = 1,
            Productions = new List<ProductionDef>
            {
                new(new Coords(0, 0), "Scierie", CargoType.Wood, 1)
            },
            Demands = new List<DemandDef>
            {
                new(new Coords(2, 0), "Ville", CargoType.Wood, Amount: 1,
                    Deadline: 0, ConsumptionPerTurn: 1, SustainTurns: 3)
            },
            Walls = new List<Coords>(),
            Stock = new List<PieceStock>
            {
                new(PieceKind.Rook, 1)
            }
        };
        return SimHelper.FromLevel(level);
    }

    [Fact]
    public void RecurringDemand_WithoutSupply_EntersShortage()
    {
        var sim = BuildRecurringLevel();
        // No piece placed — demand never fed, but doesn't consume anything
        // it doesn't have. The first turn should already flag shortage.
        var events = sim.Step();
        Assert.Contains(events, e => e is DemandShortageStartedEvent);

        // SustainedTurns should stay 0 while in shortage
        var demand = sim.Snapshot.Demands[0];
        Assert.False(demand.IsSatisfied);
    }

    [Fact]
    public void RecurringDemand_BufferFeedsConsumption()
    {
        // Direct unit-style test: start a recurring demand with a filled
        // buffer and confirm consumption + sustain counter tick correctly.
        var demand = new DemandState(
            new DemandDef(new Coords(0, 0), "V", CargoType.Wood, Amount: 0,
                Deadline: 0, ConsumptionPerTurn: 1, SustainTurns: 3))
        {
            Buffer = 5
        };

        // Simulate 3 turns of consumption with no deliveries: should not
        // shortage (buffer covers), SustainedTurns accrues.
        for (int i = 0; i < 3; i++)
        {
            var consumed = System.Math.Min(demand.Buffer, demand.Definition.ConsumptionPerTurn);
            demand.Buffer -= consumed;
            if (demand.Buffer <= 0)
            {
                demand.InShortage = true;
                demand.SustainedTurns = 0;
            }
            else
            {
                demand.InShortage = false;
                demand.SustainedTurns++;
            }
        }

        Assert.False(demand.InShortage);
        Assert.Equal(3, demand.SustainedTurns);
        Assert.True(demand.IsSatisfied);
    }

    [Fact]
    public void ClassicDemand_NotRecurring_BehavesAsBefore()
    {
        var level = new BoardBuilder(3, 1)
            .WithProduction(0, 0, "S", CargoType.Wood)
            .WithDemand(2, 0, "D", CargoType.Wood, 2, 20)
            .WithStock(PieceKind.Rook, 1)
            .Build();
        var sim = SimHelper.FromLevel(level);
        sim.Place(PieceKind.Rook, (1, 0), (2, 0));

        var events = sim.StepN(20);
        Assert.DoesNotContain(events, e => e is DemandShortageStartedEvent);
        Assert.Contains(events, e => e is MissionCompleteEvent);
    }
}