using System.Text.Json;
using OpenTheBox.Core;
using OpenTheBox.Core.Boxes;
using OpenTheBox.Core.Enums;
using OpenTheBox.Core.Interactions;
using OpenTheBox.Core.Items;
using OpenTheBox.Data;
using OpenTheBox.Simulation;
using OpenTheBox.Simulation.Actions;
using OpenTheBox.Simulation.Events;

namespace OpenTheBox.Tests;

/// <summary>
/// Validates that all JSON content files deserialize correctly and are internally consistent.
/// These tests catch data issues (typos, missing references, schema mismatches) before runtime.
/// </summary>
public class ContentValidationTests
{
    private static readonly string ContentRoot = "content";
    private static readonly string ItemsPath = Path.Combine(ContentRoot, "data", "items.json");
    private static readonly string BoxesPath = Path.Combine(ContentRoot, "data", "boxes.json");
    private static readonly string InteractionsPath = Path.Combine(ContentRoot, "data", "interactions.json");
    private static readonly string RecipesPath = Path.Combine(ContentRoot, "data", "recipes.json");
    private static readonly string EnStringsPath = Path.Combine(ContentRoot, "strings", "en.json");
    private static readonly string FrStringsPath = Path.Combine(ContentRoot, "strings", "fr.json");

    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        PropertyNameCaseInsensitive = true,
        Converters = { new System.Text.Json.Serialization.JsonStringEnumConverter() }
    };

    // ── Items ────────────────────────────────────────────────────────────

    [Fact]
    public void ItemsJson_Deserializes()
    {
        var json = File.ReadAllText(ItemsPath);
        var items = JsonSerializer.Deserialize<List<ItemDefinition>>(json, JsonOptions);

        Assert.NotNull(items);
        Assert.NotEmpty(items);
    }

    [Fact]
    public void ItemsJson_AllIdsAreUnique()
    {
        var items = LoadItems();
        var duplicates = items.GroupBy(i => i.Id).Where(g => g.Count() > 1).Select(g => g.Key).ToList();

        Assert.Empty(duplicates);
    }

    [Fact]
    public void ItemsJson_AllHaveNameKeys()
    {
        var items = LoadItems();
        var missing = items.Where(i => string.IsNullOrWhiteSpace(i.NameKey)).Select(i => i.Id).ToList();

        Assert.Empty(missing);
    }

    [Fact]
    public void ItemsJson_AllHaveValidCategory()
    {
        var items = LoadItems();
        // If deserialization succeeded with JsonStringEnumConverter, all categories are valid
        Assert.All(items, item => Assert.True(Enum.IsDefined(item.Category),
            $"Item '{item.Id}' has invalid category"));
    }

    [Fact]
    public void ItemsJson_AllHaveValidRarity()
    {
        var items = LoadItems();
        Assert.All(items, item => Assert.True(Enum.IsDefined(item.Rarity),
            $"Item '{item.Id}' has invalid rarity"));
    }

    // ── Boxes ────────────────────────────────────────────────────────────

    [Fact]
    public void BoxesJson_Deserializes()
    {
        var json = File.ReadAllText(BoxesPath);
        var boxes = JsonSerializer.Deserialize<List<BoxDefinition>>(json, JsonOptions);

        Assert.NotNull(boxes);
        Assert.NotEmpty(boxes);
    }

    [Fact]
    public void BoxesJson_AllIdsAreUnique()
    {
        var boxes = LoadBoxes();
        var duplicates = boxes.GroupBy(b => b.Id).Where(g => g.Count() > 1).Select(g => g.Key).ToList();

        Assert.Empty(duplicates);
    }

    [Fact]
    public void BoxesJson_GuaranteedRollsReferenceValidItems()
    {
        var items = LoadItems().Select(i => i.Id).ToHashSet();
        var boxes = LoadBoxes();
        var boxIds = boxes.Select(b => b.Id).ToHashSet();

        var invalid = new List<string>();
        foreach (var box in boxes)
        {
            foreach (var guaranteedId in box.LootTable.GuaranteedRolls)
            {
                if (!items.Contains(guaranteedId) && !boxIds.Contains(guaranteedId))
                    invalid.Add($"{box.Id} -> {guaranteedId}");
            }
        }

        Assert.Empty(invalid);
    }

    [Fact]
    public void BoxesJson_LootEntryItemsExist()
    {
        var items = LoadItems().Select(i => i.Id).ToHashSet();
        var boxes = LoadBoxes();
        var boxIds = boxes.Select(b => b.Id).ToHashSet();

        var invalid = new List<string>();
        foreach (var box in boxes)
        {
            foreach (var entry in box.LootTable.Entries)
            {
                if (!items.Contains(entry.ItemDefinitionId) && !boxIds.Contains(entry.ItemDefinitionId))
                    invalid.Add($"{box.Id} -> {entry.ItemDefinitionId}");
            }
        }

        Assert.Empty(invalid);
    }

    [Fact]
    public void BoxesJson_AllEntriesHavePositiveWeight()
    {
        var boxes = LoadBoxes();
        var invalid = new List<string>();
        foreach (var box in boxes)
        {
            foreach (var entry in box.LootTable.Entries)
            {
                if (entry.Weight <= 0)
                    invalid.Add($"{box.Id} -> {entry.ItemDefinitionId} (weight={entry.Weight})");
            }
        }

        Assert.Empty(invalid);
    }

    [Fact]
    public void BoxesJson_AllHaveEitherGuaranteedOrRollEntries()
    {
        var boxes = LoadBoxes();
        var empty = boxes
            .Where(b => b.LootTable.GuaranteedRolls.Count == 0
                         && b.LootTable.Entries.Count == 0)
            .Select(b => b.Id)
            .ToList();

        Assert.Empty(empty);
    }

    [Fact]
    public void BoxesJson_LootConditionsHaveValidTypes()
    {
        var boxes = LoadBoxes();
        // If deserialization with JsonStringEnumConverter worked, all condition types are valid.
        // But let's also verify targetId makes sense for specific conditions.
        var issues = new List<string>();
        foreach (var box in boxes)
        {
            foreach (var entry in box.LootTable.Entries)
            {
                if (entry.Condition is not null)
                {
                    Assert.True(Enum.IsDefined(entry.Condition.Type),
                        $"Box '{box.Id}' entry '{entry.ItemDefinitionId}' has invalid condition type");

                    if (entry.Condition.Type == LootConditionType.BoxesOpenedAbove
                        && !entry.Condition.Value.HasValue)
                    {
                        issues.Add($"{box.Id}/{entry.ItemDefinitionId}: BoxesOpenedAbove needs a value");
                    }
                }
            }
        }

        Assert.Empty(issues);
    }

    // ── Interactions ─────────────────────────────────────────────────────

    [Fact]
    public void InteractionsJson_Deserializes()
    {
        var json = File.ReadAllText(InteractionsPath);
        var rules = JsonSerializer.Deserialize<List<InteractionRule>>(json, JsonOptions);

        Assert.NotNull(rules);
        Assert.NotEmpty(rules);
    }

    [Fact]
    public void InteractionsJson_AllIdsAreUnique()
    {
        var rules = LoadInteractions();
        var duplicates = rules.GroupBy(r => r.Id).Where(g => g.Count() > 1).Select(g => g.Key).ToList();

        Assert.Empty(duplicates);
    }

    // ── Recipes ──────────────────────────────────────────────────────────

    [Fact]
    public void RecipesJson_Deserializes()
    {
        var json = File.ReadAllText(RecipesPath);
        var doc = JsonDocument.Parse(json);

        Assert.NotNull(doc);
        Assert.True(doc.RootElement.GetArrayLength() > 0, "recipes.json is empty");
    }

    [Fact]
    public void RecipesJson_AllIngredientsExist()
    {
        var items = LoadItems().Select(i => i.Id).ToHashSet();
        var boxes = LoadBoxes().Select(b => b.Id).ToHashSet();

        var json = File.ReadAllText(RecipesPath);
        var doc = JsonDocument.Parse(json);

        var invalid = new List<string>();
        foreach (var recipe in doc.RootElement.EnumerateArray())
        {
            var recipeId = recipe.GetProperty("id").GetString()!;
            foreach (var ingredient in recipe.GetProperty("ingredients").EnumerateArray())
            {
                var itemId = ingredient.GetProperty("itemDefinitionId").GetString()!;
                if (!items.Contains(itemId) && !boxes.Contains(itemId))
                    invalid.Add($"{recipeId} -> ingredient '{itemId}'");
            }

            var resultId = recipe.GetProperty("result").GetProperty("itemDefinitionId").GetString()!;
            if (!items.Contains(resultId) && !boxes.Contains(resultId))
                invalid.Add($"{recipeId} -> result '{resultId}'");
        }

        Assert.Empty(invalid);
    }

    [Fact]
    public void RecipesJson_AllWorkstationsAreValid()
    {
        var json = File.ReadAllText(RecipesPath);
        var doc = JsonDocument.Parse(json);

        var invalid = new List<string>();
        foreach (var recipe in doc.RootElement.EnumerateArray())
        {
            var recipeId = recipe.GetProperty("id").GetString()!;
            var workstation = recipe.GetProperty("workstation").GetString()!;
            if (!Enum.TryParse<WorkstationType>(workstation, out _))
                invalid.Add($"{recipeId} -> workstation '{workstation}'");
        }

        Assert.Empty(invalid);
    }

    // ── Localization ─────────────────────────────────────────────────────

    [Fact]
    public void EnStrings_IsValidJson()
    {
        var json = File.ReadAllText(EnStringsPath);
        var dict = JsonSerializer.Deserialize<Dictionary<string, string>>(json);

        Assert.NotNull(dict);
        Assert.NotEmpty(dict);
    }

    [Fact]
    public void FrStrings_IsValidJson()
    {
        var json = File.ReadAllText(FrStringsPath);
        var dict = JsonSerializer.Deserialize<Dictionary<string, string>>(json);

        Assert.NotNull(dict);
        Assert.NotEmpty(dict);
    }

    [Fact]
    public void FrStrings_HasAllKeysFromEn()
    {
        var enJson = File.ReadAllText(EnStringsPath);
        var en = JsonSerializer.Deserialize<Dictionary<string, string>>(enJson)!;
        var frJson = File.ReadAllText(FrStringsPath);
        var fr = JsonSerializer.Deserialize<Dictionary<string, string>>(frJson)!;

        var missing = en.Keys.Where(k => !fr.ContainsKey(k)).ToList();

        Assert.Empty(missing);
    }

    [Fact]
    public void ItemNameKeys_ExistInLocalization()
    {
        var items = LoadItems();
        var en = LoadEnStrings();

        var missing = items
            .Where(i => !en.ContainsKey(i.NameKey))
            .Select(i => $"{i.Id} -> nameKey '{i.NameKey}'")
            .ToList();

        Assert.Empty(missing);
    }

    [Fact]
    public void BoxNameKeys_ExistInLocalization()
    {
        var boxes = LoadBoxes();
        var en = LoadEnStrings();

        var missing = boxes
            .Where(b => !en.ContainsKey(b.NameKey))
            .Select(b => $"{b.Id} -> nameKey '{b.NameKey}'")
            .ToList();

        Assert.Empty(missing);
    }

    // ── ContentRegistry integration ──────────────────────────────────────

    [Fact]
    public void ContentRegistry_LoadsSuccessfully()
    {
        var registry = ContentRegistry.LoadFromFiles(ItemsPath, BoxesPath, InteractionsPath);

        Assert.True(registry.Items.Count > 0, "No items loaded");
        Assert.True(registry.Boxes.Count > 0, "No boxes loaded");
        Assert.True(registry.InteractionRules.Count > 0, "No interaction rules loaded");
    }

    [Fact]
    public void ContentRegistry_StarterBoxExists()
    {
        var registry = ContentRegistry.LoadFromFiles(ItemsPath, BoxesPath, InteractionsPath);
        var starter = registry.GetBox("box_starter");

        Assert.NotNull(starter);
        Assert.NotEmpty(starter.LootTable.GuaranteedRolls);
    }

    // ── Simulation smoke test ────────────────────────────────────────────

    [Fact]
    public void Simulation_OpenStarterBox_ProducesEvents()
    {
        var registry = ContentRegistry.LoadFromFiles(ItemsPath, BoxesPath, InteractionsPath);
        var simulation = new GameSimulation(registry, new Random(42));
        var state = GameState.Create("TestPlayer", Locale.EN);

        // Give the player a starter box
        var starterBox = ItemInstance.Create("box_starter");
        state.AddItem(starterBox);

        var action = new OpenBoxAction(starterBox.Id) { BoxDefinitionId = "box_starter" };
        var events = simulation.ProcessAction(action, state);

        Assert.NotEmpty(events);
        Assert.Contains(events, e => e is BoxOpenedEvent);
        Assert.Contains(events, e => e is ItemReceivedEvent);
    }

    // ── Black Box invariant: simulation owns all state mutations ─────────

    [Fact]
    public void Simulation_ProcessAction_HandlesAllStateMutations()
    {
        // The simulation (ProcessAction) must be the SOLE mutator of GameState.
        // After calling ProcessAction, the inventory should already reflect all
        // items received and consumed. External code (game loop, renderer) must
        // NOT call AddItem/RemoveItem — that would cause duplicates.

        var registry = ContentRegistry.LoadFromFiles(ItemsPath, BoxesPath, InteractionsPath);
        var simulation = new GameSimulation(registry, new Random(42));
        var state = GameState.Create("TestPlayer", Locale.EN);

        var starterBox = ItemInstance.Create("box_starter");
        state.AddItem(starterBox);

        int inventoryBefore = state.Inventory.Count; // 1 (the starter box)

        var action = new OpenBoxAction(starterBox.Id) { BoxDefinitionId = "box_starter" };
        var events = simulation.ProcessAction(action, state);

        // Count events
        int received = events.OfType<ItemReceivedEvent>().Count();
        int consumed = events.OfType<ItemConsumedEvent>().Count();

        // The simulation already mutated state. Verify the inventory matches
        // exactly: initial - consumed + received
        int expectedCount = inventoryBefore - consumed + received;
        Assert.Equal(expectedCount, state.Inventory.Count);
    }

    [Fact]
    public void Simulation_NoDuplicateItemInstances_InInventory()
    {
        // Each ItemInstance has a unique Guid. After opening a box,
        // no two inventory entries should share the same Id.
        var registry = ContentRegistry.LoadFromFiles(ItemsPath, BoxesPath, InteractionsPath);
        var simulation = new GameSimulation(registry, new Random(42));
        var state = GameState.Create("TestPlayer", Locale.EN);

        var starterBox = ItemInstance.Create("box_starter");
        state.AddItem(starterBox);

        var action = new OpenBoxAction(starterBox.Id) { BoxDefinitionId = "box_starter" };
        simulation.ProcessAction(action, state);

        var duplicateIds = state.Inventory
            .GroupBy(i => i.Id)
            .Where(g => g.Count() > 1)
            .Select(g => g.Key)
            .ToList();

        Assert.Empty(duplicateIds);
    }

    // ── Adventures ───────────────────────────────────────────────────────

    [Theory]
    [InlineData("space")]
    [InlineData("medieval")]
    [InlineData("pirate")]
    [InlineData("contemporary")]
    [InlineData("sentimental")]
    [InlineData("prehistoric")]
    [InlineData("cosmic")]
    [InlineData("microscopic")]
    [InlineData("darkfantasy")]
    public void Adventure_ScriptFileExists(string theme)
    {
        var path = Path.Combine(ContentRoot, "adventures", theme, "intro.lor");
        Assert.True(File.Exists(path), $"Missing adventure script: {path}");
    }

    [Theory]
    [InlineData("space")]
    [InlineData("medieval")]
    [InlineData("pirate")]
    [InlineData("contemporary")]
    [InlineData("sentimental")]
    [InlineData("prehistoric")]
    [InlineData("cosmic")]
    [InlineData("microscopic")]
    [InlineData("darkfantasy")]
    public void Adventure_FrenchTranslationExists(string theme)
    {
        var path = Path.Combine(ContentRoot, "adventures", theme, "intro.fr.lor");
        Assert.True(File.Exists(path), $"Missing French translation: {path}");
    }

    // ── Full run integration tests ─────────────────────────────────────

    [Fact]
    public void FullRun_AllReachableContentIsObtained()
    {
        // Simulates an entire game playthrough by repeatedly opening boxes
        // until all content reachable via box openings is unlocked.
        // Uses only the simulation (zero I/O) to prove game completability.

        var registry = ContentRegistry.LoadFromFiles(ItemsPath, BoxesPath, InteractionsPath);
        var simulation = new GameSimulation(registry, new Random(42));
        var state = GameState.Create("CompletionTest", Locale.EN);

        // ── Compute the "reachable set" dynamically from item definitions ──

        var allItems = registry.Items.Values.ToList();

        // All MetaUnlock values that exist on items → expected UI features
        var expectedUIFeatures = allItems
            .Where(i => i.MetaUnlock.HasValue)
            .Select(i => i.MetaUnlock!.Value)
            .ToHashSet();

        // All cosmetic definition IDs → expected cosmetics
        var expectedCosmetics = allItems
            .Where(i => i.CosmeticSlot.HasValue)
            .Select(i => i.Id)
            .ToHashSet();

        // All AdventureTheme values that exist on items → expected adventures
        var expectedAdventures = allItems
            .Where(i => i.AdventureTheme.HasValue)
            .Select(i => i.AdventureTheme!.Value)
            .ToHashSet();

        // All ResourceType values that exist on items → expected visible resources
        var expectedResources = allItems
            .Where(i => i.ResourceType.HasValue)
            .Select(i => i.ResourceType!.Value)
            .ToHashSet();

        // All lore fragment definition IDs
        var expectedLore = allItems
            .Where(i => i.Category == ItemCategory.LoreFragment)
            .Select(i => i.Id)
            .ToHashSet();

        // All StatType values that exist on items → expected visible stats
        var expectedStats = allItems
            .Where(i => i.StatType.HasValue)
            .Select(i => i.StatType!.Value)
            .ToHashSet();

        // All FontStyle values that exist on items → expected fonts
        var expectedFonts = allItems
            .Where(i => i.FontStyle.HasValue)
            .Select(i => i.FontStyle!.Value)
            .ToHashSet();

        // Track all unique item definition IDs ever received
        var seenDefinitionIds = new HashSet<string>();

        // ── Give starter box and run the game loop ──

        var starterBox = ItemInstance.Create("box_starter");
        state.AddItem(starterBox);

        const int maxBoxOpenings = 10_000;
        int totalBoxesOpened = 0;

        for (int i = 0; i < maxBoxOpenings; i++)
        {
            // Pick one box from inventory
            var box = state.Inventory
                .FirstOrDefault(item => registry.IsBox(item.DefinitionId));

            if (box is null)
                break; // Game loop broke — will be caught by asserts

            var action = new OpenBoxAction(box.Id) { BoxDefinitionId = box.DefinitionId };
            var events = simulation.ProcessAction(action, state);

            // Track all received items
            foreach (var evt in events.OfType<ItemReceivedEvent>())
            {
                seenDefinitionIds.Add(evt.Item.DefinitionId);
            }

            totalBoxesOpened++;

            // Check if we've covered everything
            bool allUIFeatures = expectedUIFeatures.IsSubsetOf(state.UnlockedUIFeatures);
            bool allCosmetics = expectedCosmetics.IsSubsetOf(state.UnlockedCosmetics);
            bool allAdventures = expectedAdventures.IsSubsetOf(state.UnlockedAdventures);
            bool allResources = expectedResources.IsSubsetOf(state.VisibleResources);
            bool allLore = expectedLore.IsSubsetOf(seenDefinitionIds);
            bool allStats = expectedStats.IsSubsetOf(state.VisibleStats);
            bool allFonts = expectedFonts.IsSubsetOf(state.AvailableFonts);

            if (allUIFeatures && allCosmetics && allAdventures && allResources && allLore && allStats && allFonts)
                break; // 100% completion reached
        }

        // ── Assertions with detailed failure messages ──

        var missingUIFeatures = expectedUIFeatures.Except(state.UnlockedUIFeatures).ToList();
        Assert.True(missingUIFeatures.Count == 0,
            $"Missing UI features after {totalBoxesOpened} boxes: {string.Join(", ", missingUIFeatures)}");

        var missingCosmetics = expectedCosmetics.Except(state.UnlockedCosmetics).ToList();
        Assert.True(missingCosmetics.Count == 0,
            $"Missing cosmetics after {totalBoxesOpened} boxes: {string.Join(", ", missingCosmetics)}");

        var missingAdventures = expectedAdventures.Except(state.UnlockedAdventures).ToList();
        Assert.True(missingAdventures.Count == 0,
            $"Missing adventures after {totalBoxesOpened} boxes: {string.Join(", ", missingAdventures)}");

        var missingResources = expectedResources.Except(state.VisibleResources).ToList();
        Assert.True(missingResources.Count == 0,
            $"Missing visible resources after {totalBoxesOpened} boxes: {string.Join(", ", missingResources)}");

        var missingLore = expectedLore.Except(seenDefinitionIds).ToList();
        Assert.True(missingLore.Count == 0,
            $"Missing lore fragments after {totalBoxesOpened} boxes: {string.Join(", ", missingLore)}");

        var missingStats = expectedStats.Except(state.VisibleStats).ToList();
        Assert.True(missingStats.Count == 0,
            $"Missing visible stats after {totalBoxesOpened} boxes: {string.Join(", ", missingStats)}");

        var missingFonts = expectedFonts.Except(state.AvailableFonts).ToList();
        Assert.True(missingFonts.Count == 0,
            $"Missing fonts after {totalBoxesOpened} boxes: {string.Join(", ", missingFonts)}");
    }

    [Fact]
    public void FullRun_GameLoopNeverBreaks()
    {
        // After 500 box openings, the player must still have at least 1 box
        // in inventory. This validates the box_of_boxes guaranteed roll
        // sustains the game loop indefinitely.

        var registry = ContentRegistry.LoadFromFiles(ItemsPath, BoxesPath, InteractionsPath);
        var simulation = new GameSimulation(registry, new Random(123));
        var state = GameState.Create("LoopTest", Locale.EN);

        var starterBox = ItemInstance.Create("box_starter");
        state.AddItem(starterBox);

        for (int i = 0; i < 500; i++)
        {
            var box = state.Inventory
                .FirstOrDefault(item => registry.IsBox(item.DefinitionId));

            Assert.True(box is not null,
                $"No boxes left in inventory after opening {i} boxes. Game loop is broken.");

            var action = new OpenBoxAction(box.Id) { BoxDefinitionId = box.DefinitionId };
            simulation.ProcessAction(action, state);
        }

        // After 500 openings, player should still have boxes
        var remainingBoxes = state.Inventory.Count(i => registry.IsBox(i.DefinitionId));
        Assert.True(remainingBoxes > 0,
            "No boxes remaining after 500 openings. Game loop is unsustainable.");
    }

    [Fact]
    public void FullRun_PacingReport()
    {
        // Diagnostic test: outputs a pacing report showing when each piece
        // of content is first unlocked. Not a pass/fail test — it always
        // passes but prints progression milestones to the test output.

        var registry = ContentRegistry.LoadFromFiles(ItemsPath, BoxesPath, InteractionsPath);
        var simulation = new GameSimulation(registry, new Random(42));
        var state = GameState.Create("PacingTest", Locale.EN);

        var allItems = registry.Items.Values.ToList();

        var expectedUIFeatures = allItems
            .Where(i => i.MetaUnlock.HasValue)
            .Select(i => i.MetaUnlock!.Value)
            .ToHashSet();
        var expectedCosmetics = allItems
            .Where(i => i.CosmeticSlot.HasValue)
            .Select(i => i.Id)
            .ToHashSet();
        var expectedAdventures = allItems
            .Where(i => i.AdventureTheme.HasValue)
            .Select(i => i.AdventureTheme!.Value)
            .ToHashSet();
        var expectedResources = allItems
            .Where(i => i.ResourceType.HasValue)
            .Select(i => i.ResourceType!.Value)
            .ToHashSet();
        var expectedLore = allItems
            .Where(i => i.Category == ItemCategory.LoreFragment)
            .Select(i => i.Id)
            .ToHashSet();

        var seenDefinitionIds = new HashSet<string>();

        // Track unlock milestones: (box#, description)
        var milestones = new List<(int boxNum, string description)>();

        // Track previous counts to detect new unlocks
        int prevUI = 0, prevCos = 0, prevAdv = 0, prevRes = 0, prevLore = 0;

        var starterBox = ItemInstance.Create("box_starter");
        state.AddItem(starterBox);

        const int maxBoxOpenings = 10_000;
        int totalBoxesOpened = 0;
        bool complete = false;

        for (int i = 0; i < maxBoxOpenings && !complete; i++)
        {
            var box = state.Inventory
                .FirstOrDefault(item => registry.IsBox(item.DefinitionId));
            if (box is null) break;

            var action = new OpenBoxAction(box.Id) { BoxDefinitionId = box.DefinitionId };
            var events = simulation.ProcessAction(action, state);

            foreach (var evt in events.OfType<ItemReceivedEvent>())
                seenDefinitionIds.Add(evt.Item.DefinitionId);

            totalBoxesOpened++;

            // Detect new unlocks
            int curUI = state.UnlockedUIFeatures.Count(f => expectedUIFeatures.Contains(f));
            int curCos = state.UnlockedCosmetics.Count(c => expectedCosmetics.Contains(c));
            int curAdv = state.UnlockedAdventures.Count(a => expectedAdventures.Contains(a));
            int curRes = state.VisibleResources.Count(r => expectedResources.Contains(r));
            int curLore = seenDefinitionIds.Count(id => expectedLore.Contains(id));

            if (curUI > prevUI)
                milestones.Add((totalBoxesOpened, $"UI Feature {curUI}/{expectedUIFeatures.Count}: +{string.Join(", ", state.UnlockedUIFeatures.Where(f => expectedUIFeatures.Contains(f)).Except(milestones.Where(m => m.description.StartsWith("UI")).SelectMany(_ => Array.Empty<UIFeature>())))}"));
            if (curCos > prevCos)
                milestones.Add((totalBoxesOpened, $"Cosmetics: {curCos}/{expectedCosmetics.Count}"));
            if (curAdv > prevAdv)
                milestones.Add((totalBoxesOpened, $"Adventures: {curAdv}/{expectedAdventures.Count}"));
            if (curRes > prevRes)
                milestones.Add((totalBoxesOpened, $"Resources: {curRes}/{expectedResources.Count}"));
            if (curLore > prevLore)
                milestones.Add((totalBoxesOpened, $"Lore: {curLore}/{expectedLore.Count}"));

            prevUI = curUI; prevCos = curCos; prevAdv = curAdv; prevRes = curRes; prevLore = curLore;

            complete = curUI == expectedUIFeatures.Count
                    && curCos == expectedCosmetics.Count
                    && curAdv == expectedAdventures.Count
                    && curRes == expectedResources.Count
                    && curLore == expectedLore.Count;
        }

        // Build the pacing report
        var report = new System.Text.StringBuilder();
        report.AppendLine();
        report.AppendLine("╔══════════════════════════════════════════════════════╗");
        report.AppendLine("║            PACING REPORT (seed=42)                  ║");
        report.AppendLine("╠══════════════════════════════════════════════════════╣");
        report.AppendLine($"║ Total boxes opened: {totalBoxesOpened,-32}║");
        report.AppendLine($"║ Game completed: {(complete ? "YES" : "NO"),-36}║");
        report.AppendLine("╠══════════════════════════════════════════════════════╣");
        report.AppendLine("║  Box#  │ Milestone                                  ║");
        report.AppendLine("╟────────┼────────────────────────────────────────────╢");
        foreach (var (boxNum, desc) in milestones)
        {
            report.AppendLine($"║ {boxNum,5}  │ {desc,-42} ║");
        }
        report.AppendLine("╠══════════════════════════════════════════════════════╣");

        // Summary by category with completion box#
        int uiDoneAt = milestones.LastOrDefault(m => m.description.Contains($"UI Feature {expectedUIFeatures.Count}/")).boxNum;
        int cosDoneAt = milestones.LastOrDefault(m => m.description.Contains($"Cosmetics: {expectedCosmetics.Count}/")).boxNum;
        int advDoneAt = milestones.LastOrDefault(m => m.description.Contains($"Adventures: {expectedAdventures.Count}/")).boxNum;
        int resDoneAt = milestones.LastOrDefault(m => m.description.Contains($"Resources: {expectedResources.Count}/")).boxNum;
        int loreDoneAt = milestones.LastOrDefault(m => m.description.Contains($"Lore: {expectedLore.Count}/")).boxNum;

        report.AppendLine($"║ UI Features  ({expectedUIFeatures.Count,2}) complete at box #{uiDoneAt,-17}║");
        report.AppendLine($"║ Cosmetics    ({expectedCosmetics.Count,2}) complete at box #{cosDoneAt,-17}║");
        report.AppendLine($"║ Adventures   ({expectedAdventures.Count,2}) complete at box #{advDoneAt,-17}║");
        report.AppendLine($"║ Resources    ({expectedResources.Count,2}) complete at box #{resDoneAt,-17}║");
        report.AppendLine($"║ Lore         ({expectedLore.Count,2}) complete at box #{loreDoneAt,-17}║");
        report.AppendLine("╚══════════════════════════════════════════════════════╝");

        // Output via ITestOutputHelper would be ideal, but Assert message works too
        Assert.True(true, report.ToString());

        // Also write to console for visibility in test runners
        Console.WriteLine(report.ToString());
    }

    // ── Helpers ──────────────────────────────────────────────────────────

    private static List<ItemDefinition> LoadItems()
    {
        var json = File.ReadAllText(ItemsPath);
        return JsonSerializer.Deserialize<List<ItemDefinition>>(json, JsonOptions)!;
    }

    private static List<BoxDefinition> LoadBoxes()
    {
        var json = File.ReadAllText(BoxesPath);
        return JsonSerializer.Deserialize<List<BoxDefinition>>(json, JsonOptions)!;
    }

    private static List<InteractionRule> LoadInteractions()
    {
        var json = File.ReadAllText(InteractionsPath);
        return JsonSerializer.Deserialize<List<InteractionRule>>(json, JsonOptions)!;
    }

    private static Dictionary<string, string> LoadEnStrings()
    {
        var json = File.ReadAllText(EnStringsPath);
        return JsonSerializer.Deserialize<Dictionary<string, string>>(json)!;
    }
}