factorio-calc/tests/FactorioCalc.Tests/SolverTests.cs

using FactorioCalc.Domain;
using FactorioCalc.Solver;
using Xunit;

namespace FactorioCalc.Tests;

public class SolverTests
{
    private IRecipeRepository CreateRepository()
    {
        var resources = new Dictionary<int, Resource>
        {
            { 1, new Resource(1, "Iron Ore") },
            { 7, new Resource(7, "Iron Plate") },
            { 9, new Resource(9, "Steel Plate") },
            { 5, new Resource(5, "Coal") },
            { 2, new Resource(2, "Copper Ore") },
            { 8, new Resource(8, "Copper Plate") },
            { 10, new Resource(10, "Copper Cable") },
            { 11, new Resource(11, "Electronic Circuit") },
        };

        var machines = new Dictionary<int, Machine>
        {
            { 3, new Machine(3, "Smelter", 0.5, 3.0, 2, new[] { "smelting" }) },
            { 5, new Machine(5, "Assembler 1", 0.5, 3.0, 2, new[] { "basic-crafting" }) },
            { 6, new Machine(6, "Assembler 2", 0.5, 4.0, 2, new[] { "basic-crafting" }) },
        };

        var recipes = new Dictionary<int, Recipe>
        {
            // Iron Plate: 1 Iron Ore → 1 Iron Plate (3s)
            {
                1, new Recipe(1, "Iron Plate", "smelting", 3.0, "smelting",
                    new[] { new Ingredient(1, 1) },
                    new[] { new Product(7, 1) })
            },
            // Steel Plate: 2 Iron Plate + 1 Coal → 1 Steel Plate (5s)
            {
                2, new Recipe(2, "Steel Plate", "smelting", 5.0, "smelting",
                    new[] { new Ingredient(7, 2), new Ingredient(5, 1) },
                    new[] { new Product(9, 1) })
            },
            // Copper Cable: 1 Copper Plate → 5 Copper Cable (0.5s)
            {
                3, new Recipe(3, "Copper Cable", "basic-crafting", 0.5, "basic-crafting",
                    new[] { new Ingredient(8, 1) },
                    new[] { new Product(10, 5) })
            },
            // Electronic Circuit: 2 Copper Cable + 1 Iron Plate → 1 EC (3s)
            {
                4, new Recipe(4, "Electronic Circuit", "basic-crafting", 3.0, "basic-crafting",
                    new[] { new Ingredient(10, 2), new Ingredient(7, 1) },
                    new[] { new Product(11, 1) })
            },
        };

        var modules = new Dictionary<int, Module>();

        return new TestRepository(recipes, resources, machines, modules);
    }

    [Fact]
    public void Solve_SingleTarget_ReturnsExecution()
    {
        var repo = CreateRepository();
        var solver = new ProductionSolver(repo);

        // Target: 10 Iron Plate/sec
        var targets = new[] { new ProductionTarget(7, 10) };
        var result = solver.Solve(targets);

        Assert.Single(result.Executions);
        var exec = result.Executions.First();
        Assert.Equal(1, exec.RecipeId); // Iron Plate recipe
        Assert.Equal(3, exec.MachineId); // Smelter
    }

    [Fact]
    public void Solve_ChainedRecipe_ResolveDependencies()
    {
        var repo = CreateRepository();
        var solver = new ProductionSolver(repo);

        // Target: 2 Steel Plate/sec → matrix resolves Iron Plate automatically
        var targets = new[] { new ProductionTarget(9, 2) };
        var result = solver.Solve(targets);

        // Should have Steel Plate + Iron Plate executions
        Assert.Equal(2, result.Executions.Count);

        var steelExec = result.Executions.First(e => e.RecipeId == 2);
        Assert.NotNull(steelExec);
    }

    [Fact]
    public void Solve_ElectronicCircuit_FullChain()
    {
        var repo = CreateRepository();
        var solver = new ProductionSolver(repo);

        // Target: 10 EC/sec → needs Copper Cable + Iron Plate (matrix resolves all)
        var targets = new[] { new ProductionTarget(11, 10) };
        var result = solver.Solve(targets);

        // Should have EC + Copper Cable + Iron Plate executions
        Assert.Equal(3, result.Executions.Count);
    }

    [Fact]
    public void Solve_IntermediateResources_BalanceNearZero()
    {
        var repo = CreateRepository();
        var solver = new ProductionSolver(repo);

        // Target: 10 Steel Plate/sec
        var targets = new[] { new ProductionTarget(9, 10) };
        var result = solver.Solve(targets);

        // Iron Plate (id=7) is intermediate — should be near zero in flows
        // (produced by Iron Plate recipe, consumed by Steel Plate recipe)
        // Note: with ceiling on machine count, there may be slight overproduction
        Assert.True(result.ResourceFlows.TryGetValue(7, out var ironPlateFlow));
        // Should be >= 0 (overproduction due to ceiling, not underproduction)
        Assert.True(ironPlateFlow >= -0.5,
            $"Iron Plate flow {ironPlateFlow:F2} should be near zero or positive");
    }

    [Fact]
    public void Solve_WithSpeedModules_AffectsMachineCount()
    {
        var repo = CreateRepository();
        var solver = new ProductionSolver(repo);

        var speedModule = new Module(1, "Speed Module 1", ModuleType.Speed, 0.10, 0, -0.05);
        var targets = new[] { new ProductionTarget(7, 10) };

        var resultNoModules = solver.Solve(targets);
        var resultWithModules = solver.SolveWithModules(targets, new[] { speedModule });

        Assert.NotEmpty(resultWithModules.Executions);

        // Speed modules increase effective speed → fewer machines needed for same output
        var execNoModules = resultNoModules.Executions.First();
        var execWithModules = resultWithModules.Executions.First();

        // With +10% speed, each machine does more cycles/sec → need fewer machines
        Assert.True(execWithModules.MachineCount <= execNoModules.MachineCount,
            $"Speed modules should not increase machine count: {execWithModules.MachineCount} vs {execNoModules.MachineCount}");
    }

    [Fact]
    public void Solve_WithProductivityModules_ScaledOutput()
    {
        var resources = new Dictionary<int, Resource>
        {
            { 1, new Resource(1, "Iron Ore") },
            { 7, new Resource(7, "Iron Plate") },
        };
        var machines = new Dictionary<int, Machine>
        {
            { 3, new Machine(3, "Smelter", 0.5, 3.0, 2, new[] { "smelting" }) },
        };
        var prodModule = new Module(4, "Productivity Module 1", ModuleType.Productivity, -0.10, 0.10, -0.05);

        var recipes = new Dictionary<int, Recipe>
        {
            {
                1, new Recipe(1, "Iron Plate", "smelting", 3.0, "smelting",
                    new[] { new Ingredient(1, 1) },
                    new[] { new Product(7, 1) })
            },
        };

        var moduleDict = new Dictionary<int, Module> { { 4, prodModule } };
        var repo = new TestRepository(recipes, resources, machines, moduleDict);
        var solver = new ProductionSolver(repo);

        var targets = new[] { new ProductionTarget(7, 10) };
        var result = solver.SolveWithModules(targets, new[] { prodModule });

        Assert.Single(result.Executions);
        var exec = result.Executions.First();
        Assert.True(exec.EffectiveProductivity > 0, "Productivity bonus should be positive");
    }

    [Fact]
    public void Solve_RawResource_NoExecution()
    {
        var repo = CreateRepository();
        var solver = new ProductionSolver(repo);

        // Iron Ore has no recipe — it's a raw resource
        var targets = new[] { new ProductionTarget(1, 100) };
        var result = solver.Solve(targets);

        Assert.Empty(result.Executions);
    }

    [Fact]
    public void Solve_RequiredInputs_ContainsRawResources()
    {
        var repo = CreateRepository();
        var solver = new ProductionSolver(repo);

        // Steel Plate needs Iron Ore and Coal (both raw)
        var targets = new[] { new ProductionTarget(9, 1) };
        var result = solver.Solve(targets);

        // Iron Ore (id=1) and Coal (id=5) should be in required inputs
        Assert.Contains(1, result.RequiredInputs.Keys);
        Assert.Contains(5, result.RequiredInputs.Keys);
    }

    [Fact]
    public void Solve_MultipleTargets_MatrixAggregatesDemand()
    {
        var repo = CreateRepository();
        var solver = new ProductionSolver(repo);

        // Two targets that both need Iron Plate:
        // Steel Plate needs 2× Iron Plate, plus direct 5/sec Iron Plate
        var targets = new[]
        {
            new ProductionTarget(9, 2),  // Steel Plate → needs 4 Iron Plate/sec
            new ProductionTarget(7, 5),  // Iron Plate direct
        };
        var result = solver.Solve(targets);

        // Should have Steel Plate + Iron Plate executions
        Assert.Equal(2, result.Executions.Count);

        var ironPlateExec = result.Executions.First(e => e.RecipeId == 1);
        // Iron Plate should account for BOTH demands (4 from steel + 5 direct = 9 total)
        Assert.True(ironPlateExec.MachineCount >= 9,
            $"Expected at least 9 machines for Iron Plate (demand=9/sec), got {ironPlateExec.MachineCount}");
    }

    [Fact]
    public void Solve_MatrixApproach_NoRecursion()
    {
        // Verify the solver uses matrix algebra, not DFS
        var repo = CreateRepository();
        var solver = new ProductionSolver(repo);

        var targets = new[] { new ProductionTarget(11, 10) };
        var result = solver.Solve(targets);

        // All three recipes should be resolved (no tree traversal needed)
        Assert.Equal(3, result.Executions.Count);

        // Resource flows should be consistent
        // Electronic Circuit (target) should have positive flow
        Assert.True(result.ResourceFlows[11] > 9, "Target resource should have positive flow");
    }
}

/// <summary>
/// In-memory test repository.
/// </summary>
public sealed class TestRepository : IRecipeRepository
{
    public IReadOnlyDictionary<int, Recipe> Recipes { get; }
    public IReadOnlyDictionary<int, Resource> Resources { get; }
    public IReadOnlyDictionary<int, Machine> Machines { get; }
    public IReadOnlyDictionary<int, Module> Modules { get; }

    public TestRepository(
        IReadOnlyDictionary<int, Recipe> recipes,
        IReadOnlyDictionary<int, Resource> resources,
        IReadOnlyDictionary<int, Machine> machines,
        IReadOnlyDictionary<int, Module> modules)
    {
        Recipes = recipes;
        Resources = resources;
        Machines = machines;
        Modules = modules;
    }
}