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

namespace Chessistics.Tests.Simulation;

public class TransformerTests
{
    /// <summary>
    /// Build a campaign with a production, a transformer, and a demand:
    /// Production(Wood) → [Transformer: Wood→Tools] → Demand(Tools)
    /// Layout (5x1):
    ///   (0,0) Production(Wood,4)
    ///   (2,0) Transformer(Wood→Tools, input=2, output=1)
    ///   (4,0) Demand(Tools, 2)
    /// </summary>
    private static CampaignDef CreateTransformerCampaign()
    {
        return new CampaignDef
        {
            Name = "Transformer Test",
            InitialWidth = 5,
            InitialHeight = 1,
            Missions =
            [
                new MissionDef
                {
                    Id = 1,
                    Name = "Forge",
                    TerrainPatch = new TerrainPatch
                    {
                        NewWidth = 5,
                        NewHeight = 1,
                        Cells =
                        [
                            new PatchCell { Col = 0, Row = 0, Type = CellType.Production,
                                Production = new ProductionDef(new Coords(0, 0), "Scierie", CargoType.Wood, 4) },
                            new PatchCell { Col = 2, Row = 0, Type = CellType.Transformer,
                                Transformer = new TransformerDef(new Coords(2, 0), "Forge", CargoType.Wood, 2, CargoType.Tools, 1) },
                            new PatchCell { Col = 4, Row = 0, Type = CellType.Demand,
                                Demand = new DemandDef(new Coords(4, 0), "Armurerie", CargoType.Tools, 2) }
                        ]
                    },
                    UnlockedPieces = [PieceKind.Rook],
                    UnlockedLevels = [new PieceUpgrade(PieceKind.Rook, 1)],
                    Stock = [new PieceStock(PieceKind.Rook, 3)]
                }
            ]
        };
    }

    [Fact]
    public void Transformer_ReceivesInputCargo()
    {
        var campaign = CreateTransformerCampaign();
        var sim = SimHelper.FromCampaign(campaign);
        sim.Sim.ProcessCommand(new LoadCampaignCommand());

        // Place rook between production and transformer: (1,0)↔(2,0)
        // Rook oscillates between (1,0) and (2,0), picking up wood and delivering to transformer
        sim.Place(PieceKind.Rook, (0, 0), (1, 0));

        var events = sim.StepN(5);

        // Should see cargo transferred to the transformer position
        Assert.Contains(events, e => e is CargoTransferredEvent ct
            && ct.To == new Coords(2, 0) && ct.Type == CargoType.Wood);
    }

    [Fact]
    public void Transformer_ConvertsAfterInputThreshold()
    {
        var campaign = CreateTransformerCampaign();
        var sim = SimHelper.FromCampaign(campaign);
        sim.Sim.ProcessCommand(new LoadCampaignCommand());

        // Rook delivers wood to transformer
        sim.Place(PieceKind.Rook, (0, 0), (1, 0));

        var events = sim.StepN(10);

        // After enough deliveries, transformation should occur
        Assert.Contains(events, e => e is CargoConvertedEvent cc
            && cc.TransformerCell == new Coords(2, 0)
            && cc.InputCargo == CargoType.Wood
            && cc.OutputCargo == CargoType.Tools);
    }

    [Fact]
    public void Transformer_OutputPickedUpByPiece()
    {
        var campaign = CreateTransformerCampaign();
        var sim = SimHelper.FromCampaign(campaign);
        sim.Sim.ProcessCommand(new LoadCampaignCommand());

        // Rook 1: delivers wood to transformer
        sim.Place(PieceKind.Rook, (0, 0), (1, 0));
        // Rook 2: picks up tools from transformer and delivers to demand
        sim.Place(PieceKind.Rook, (3, 0), (4, 0));

        var events = sim.StepN(20);

        // Should see tools being transferred from transformer to rook 2
        Assert.Contains(events, e => e is CargoTransferredEvent ct
            && ct.From == new Coords(2, 0) && ct.Type == CargoType.Tools);
    }

    [Fact]
    public void Transformer_FullChain_CompleteMission()
    {
        var campaign = CreateTransformerCampaign();
        var sim = SimHelper.FromCampaign(campaign);
        sim.Sim.ProcessCommand(new LoadCampaignCommand());

        // Full chain: Production → Rook1 → Transformer → Rook2 → Demand
        sim.Place(PieceKind.Rook, (0, 0), (1, 0));  // delivers wood to transformer
        sim.Place(PieceKind.Rook, (3, 0), (4, 0));  // picks up tools, delivers to demand

        var events = sim.StepN(50);

        // Mission should complete (2 tools delivered)
        Assert.Contains(events, e => e is MissionCompleteEvent);
    }

    [Fact]
    public void Transformer_DoesNotConvertWrongCargo()
    {
        // Transformer expects Wood but receives Stone — should not convert
        var campaign = new CampaignDef
        {
            Name = "Wrong Cargo",
            InitialWidth = 4,
            InitialHeight = 1,
            Missions =
            [
                new MissionDef
                {
                    Id = 1, Name = "M1",
                    TerrainPatch = new TerrainPatch
                    {
                        NewWidth = 4, NewHeight = 1,
                        Cells =
                        [
                            new PatchCell { Col = 0, Row = 0, Type = CellType.Production,
                                Production = new ProductionDef(new Coords(0, 0), "Carriere", CargoType.Stone, 4) },
                            new PatchCell { Col = 2, Row = 0, Type = CellType.Transformer,
                                Transformer = new TransformerDef(new Coords(2, 0), "Forge", CargoType.Wood, 1, CargoType.Tools, 1) },
                            new PatchCell { Col = 3, Row = 0, Type = CellType.Demand,
                                Demand = new DemandDef(new Coords(3, 0), "D", CargoType.Tools, 1) }
                        ]
                    },
                    UnlockedPieces = [PieceKind.Rook],
                    UnlockedLevels = [new PieceUpgrade(PieceKind.Rook, 1)],
                    Stock = [new PieceStock(PieceKind.Rook, 2)]
                }
            ]
        };
        var sim = SimHelper.FromCampaign(campaign);
        sim.Sim.ProcessCommand(new LoadCampaignCommand());

        sim.Place(PieceKind.Rook, (0, 0), (1, 0));

        var events = sim.StepN(10);

        // No conversion should happen (stone != wood)
        Assert.DoesNotContain(events, e => e is CargoConvertedEvent);
    }

    [Fact]
    public void Transformer_AccumulatesInput()
    {
        // Transformer with inputRequired=3 should accumulate over multiple deliveries
        var campaign = new CampaignDef
        {
            Name = "Accumulate",
            InitialWidth = 4,
            InitialHeight = 1,
            Missions =
            [
                new MissionDef
                {
                    Id = 1, Name = "M1",
                    TerrainPatch = new TerrainPatch
                    {
                        NewWidth = 4, NewHeight = 1,
                        Cells =
                        [
                            new PatchCell { Col = 0, Row = 0, Type = CellType.Production,
                                Production = new ProductionDef(new Coords(0, 0), "Scierie", CargoType.Wood, 4) },
                            new PatchCell { Col = 2, Row = 0, Type = CellType.Transformer,
                                Transformer = new TransformerDef(new Coords(2, 0), "Forge", CargoType.Wood, 3, CargoType.Tools, 2) },
                            new PatchCell { Col = 3, Row = 0, Type = CellType.Demand,
                                Demand = new DemandDef(new Coords(3, 0), "D", CargoType.Tools, 2) }
                        ]
                    },
                    UnlockedPieces = [PieceKind.Rook],
                    UnlockedLevels = [new PieceUpgrade(PieceKind.Rook, 1)],
                    Stock = [new PieceStock(PieceKind.Rook, 2)]
                }
            ]
        };
        var sim = SimHelper.FromCampaign(campaign);
        sim.Sim.ProcessCommand(new LoadCampaignCommand());

        sim.Place(PieceKind.Rook, (0, 0), (1, 0));
        sim.Place(PieceKind.Rook, (2, 0), (3, 0));

        var events = sim.StepN(30);

        // After 3 wood deliveries, conversion should produce 2 tools
        var conversions = events.Where(e => e is CargoConvertedEvent cc && cc.OutputAmount == 2).ToList();
        Assert.NotEmpty(conversions);

        // Mission should complete (2 tools delivered)
        Assert.Contains(events, e => e is MissionCompleteEvent);
    }
}