/**
 * Integration Workflow Test — Full CAD workflow across ALL components.
 *
 * Tests the complete lifecycle: init → layers → elements → render → zoom/pan →
 * selection → grouping → snap → history → layer toggle → zoom fit → reset.
 */
import { describe, it, expect, beforeEach } from 'vitest';
import { RenderEngine } from '../src/canvas/RenderEngine';
import { SelectionEngine } from '../src/canvas/SelectionEngine';
import { ZoomPanController } from '../src/canvas/ZoomPanController';
import { SpatialIndex } from '../src/canvas/SpatialIndex';
import { LayerManager } from '../src/canvas/LayerManager';
import { SnapEngine } from '../src/canvas/SnapEngine';
import { HistoryManager } from '../src/history/HistoryManager';
import { GroupManager } from '../src/tools/modification/GroupTool';
import { CommandRegistry } from '../src/services/commandRegistry';
import type { CADElement, CADLayer, BlockDefinition } from '../src/types/cad.types';
import type { BackgroundConfig } from '../src/services/backgroundService';

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

function createMockCanvas(w = 800, h = 600): HTMLCanvasElement {
  const canvas = document.createElement('canvas');
  canvas.width = w;
  canvas.height = h;
  return canvas;
}

function makeLayer(id: string, overrides: Partial<CADLayer> = {}): CADLayer {
  return {
    id,
    name: id,
    visible: true,
    locked: false,
    color: '#ffffff',
    lineType: 'solid' as const,
    transparency: 0,
    sortOrder: 0,
    parentId: null,
    ...overrides,
  };
}

function makeLine(
  id: string,
  x1: number, y1: number,
  x2: number, y2: number,
  layerId = 'layer-default',
): CADElement {
  return {
    id,
    type: 'line',
    layerId,
    x: (x1 + x2) / 2,
    y: (y1 + y2) / 2,
    width: Math.abs(x2 - x1),
    height: Math.abs(y2 - y1),
    properties: { x1, y1, x2, y2, stroke: '#ffffff' },
  };
}

function makeRect(
  id: string,
  cx: number, cy: number,
  w: number, h: number,
  layerId = 'layer-default',
): CADElement {
  return {
    id,
    type: 'rect',
    layerId,
    x: cx,
    y: cy,
    width: w,
    height: h,
    properties: { stroke: '#ffffff' },
  };
}

function makeCircle(
  id: string,
  cx: number, cy: number,
  r: number,
  layerId = 'layer-default',
): CADElement {
  return {
    id,
    type: 'circle',
    layerId,
    x: cx,
    y: cy,
    width: r * 2,
    height: r * 2,
    properties: { radius: r, stroke: '#ffffff' },
  };
}

function makeSnapshot(
  elements: CADElement[],
  layers: CADLayer[],
  blocks: BlockDefinition[] = [],
  groups: ReturnType<GroupManager['toJSON']> = [],
  bgConfig: BackgroundConfig | null = null,
) {
  return { elements, layers, blocks, groups, bgConfig };
}

// ─── Integration Test ─────────────────────────────────────────────────────────

describe('Integration Workflow — Full CAD Lifecycle', () => {
  // Component instances
  let canvas: HTMLCanvasElement;
  let layerManager: LayerManager;
  let spatialIndex: SpatialIndex;
  let zoomPan: ZoomPanController;
  let renderEngine: RenderEngine;
  let selectionEngine: SelectionEngine;
  let snapEngine: SnapEngine;
  let historyManager: HistoryManager;
  let groupManager: GroupManager;
  let commandRegistry: CommandRegistry;

  // Shared state
  let layers: CADLayer[];
  let elements: CADElement[];

  beforeEach(() => {
    canvas = createMockCanvas(800, 600);

    // Step 1: Initialize all components
    layerManager = new LayerManager();
    spatialIndex = new SpatialIndex();
    zoomPan = new ZoomPanController(canvas);
    renderEngine = new RenderEngine(canvas, zoomPan, spatialIndex, layerManager);
    selectionEngine = new SelectionEngine(renderEngine, spatialIndex, layerManager);
    snapEngine = new SnapEngine({ tolerance: 10 });
    historyManager = new HistoryManager();
    groupManager = new GroupManager();
    commandRegistry = new CommandRegistry();

    elements = [];
    layers = [];
  });

  // ─── Step 1: Initialize all components ──────────────────────────────────────
  describe('Step 1: Component initialization', () => {
    it('should instantiate all components without errors', () => {
      expect(layerManager).toBeDefined();
      expect(spatialIndex).toBeDefined();
      expect(zoomPan).toBeDefined();
      expect(renderEngine).toBeDefined();
      expect(selectionEngine).toBeDefined();
      expect(snapEngine).toBeDefined();
      expect(historyManager).toBeDefined();
      expect(groupManager).toBeDefined();
      expect(commandRegistry).toBeDefined();
    });

    it('should have correct initial state', () => {
      expect(layerManager.getLayers()).toHaveLength(0);
      expect(layerManager.getActiveLayerId()).toBe('');
      expect(zoomPan.getScale()).toBe(1);
      expect(selectionEngine.getSelectedIds().size).toBe(0);
      expect(groupManager.getGroups()).toHaveLength(0);
      expect(historyManager.getCurrentState()).toBeNull();
      expect(historyManager.canUndo()).toBe(false);
      expect(historyManager.canRedo()).toBe(false);
    });
  });

  // ─── Step 2: Create layers, set visibility/lock ─────────────────────────────
  describe('Step 2: Layer management', () => {
    it('should create default and additional layers, set visibility/lock', () => {
      const defaultLayer = makeLayer('layer-default', { name: 'Default', sortOrder: 0 });
      const archLayer = makeLayer('layer-arch', { name: 'Architecture', sortOrder: 1, color: '#ff0000' });
      const hiddenLayer = makeLayer('layer-hidden', { name: 'Hidden', sortOrder: 2, visible: false });
      const lockedLayer = makeLayer('layer-locked', { name: 'Locked', sortOrder: 3, locked: true });

      layerManager.addLayer(defaultLayer);
      layerManager.addLayer(archLayer);
      layerManager.addLayer(hiddenLayer);
      layerManager.addLayer(lockedLayer);

      layers = layerManager.getLayers();
      expect(layers).toHaveLength(4);
      expect(layers[0].id).toBe('layer-default'); // sortOrder 0
      expect(layers[3].id).toBe('layer-locked'); // sortOrder 3

      // Active layer should be first added
      expect(layerManager.getActiveLayerId()).toBe('layer-default');

      // Set active layer
      layerManager.setActiveLayer('layer-arch');
      expect(layerManager.getActiveLayerId()).toBe('layer-arch');
      expect(layerManager.getActiveLayer()?.name).toBe('Architecture');

      // Toggle visibility on arch layer
      layerManager.toggleVisibility('layer-arch');
      expect(layerManager.getLayer('layer-arch')?.visible).toBe(false);

      // Toggle back
      layerManager.toggleVisibility('layer-arch');
      expect(layerManager.getLayer('layer-arch')?.visible).toBe(true);

      // Toggle lock on default layer
      layerManager.toggleLock('layer-default');
      expect(layerManager.isLocked('layer-default')).toBe(true);

      // getVisibleLayers returns visible && !locked
      const visible = layerManager.getVisibleLayers();
      const visibleIds = visible.map(l => l.id);
      // layer-default: visible=true but locked=true → excluded
      // layer-arch: visible=true, locked=false → included
      // layer-hidden: visible=false → excluded
      // layer-locked: visible=true but locked=true → excluded
      expect(visibleIds).toContain('layer-arch');
      expect(visibleIds).not.toContain('layer-default');
      expect(visibleIds).not.toContain('layer-hidden');
      expect(visibleIds).not.toContain('layer-locked');

      // Unlock default for subsequent tests
      layerManager.toggleLock('layer-default');
      expect(layerManager.isLocked('layer-default')).toBe(false);
    });
  });

  // ─── Step 3: Add elements to different layers, insert into SpatialIndex ──────
  describe('Step 3: Add elements to layers and SpatialIndex', () => {
    beforeEach(() => {
      layerManager.addLayer(makeLayer('layer-default', { sortOrder: 0 }));
      layerManager.addLayer(makeLayer('layer-arch', { sortOrder: 1, color: '#ff0000' }));
    });

    it('should add line, rect, circle to different layers and insert into SpatialIndex', () => {
      const line1 = makeLine('el-line-1', 0, 0, 100, 100, 'layer-default');
      const rect1 = makeRect('el-rect-1', 50, 50, 80, 60, 'layer-arch');
      const circle1 = makeCircle('el-circle-1', 200, 200, 40, 'layer-default');

      elements = [line1, rect1, circle1];

      // Insert into spatial index
      for (const el of elements) {
        spatialIndex.insert(el);
      }

      // Verify spatial index search returns elements in viewport
      const viewport = { minX: -100, minY: -100, maxX: 300, maxY: 300 };
      const found = spatialIndex.search(viewport);
      expect(found).toHaveLength(3);
      expect(found.map(e => e.id).sort()).toEqual(['el-circle-1', 'el-line-1', 'el-rect-1']);

      // Verify search with smaller viewport
      const smallVp = { minX: -10, minY: -10, maxX: 60, maxY: 60 };
      const smallFound = spatialIndex.search(smallVp);
      // line1 bbox: minX=-50, minY=-50, maxX=150, maxY=150 → intersects
      // rect1 bbox: minX=10, minY=20, maxX=90, maxY=80 → intersects
      // circle1 bbox: minX=160, minY=160, maxX=240, maxY=240 → no
      expect(smallFound.map(e => e.id).sort()).toEqual(['el-line-1', 'el-rect-1']);
    });
  });

  // ─── Step 4: Render (verify no crash) ───────────────────────────────────────
  describe('Step 4: Rendering', () => {
    beforeEach(() => {
      layerManager.addLayer(makeLayer('layer-default', { sortOrder: 0 }));
      layerManager.addLayer(makeLayer('layer-arch', { sortOrder: 1, color: '#ff0000' }));

      elements = [
        makeLine('el-line-1', 0, 0, 100, 100, 'layer-default'),
        makeRect('el-rect-1', 50, 50, 80, 60, 'layer-arch'),
        makeCircle('el-circle-1', 200, 200, 40, 'layer-default'),
      ];
      for (const el of elements) spatialIndex.insert(el);
    });

    it('should render without crashing', () => {
      expect(() => renderEngine.render()).not.toThrow();
    });

    it('should render with grid enabled', () => {
      renderEngine.setOptions({ showGrid: true });
      expect(() => renderEngine.render()).not.toThrow();
    });

    it('should render with grid disabled', () => {
      renderEngine.setOptions({ showGrid: false });
      expect(() => renderEngine.render()).not.toThrow();
    });
  });

  // ─── Step 5: Zoom/Pan ────────────────────────────────────────────────────────
  describe('Step 5: Zoom and Pan', () => {
    it('should zoomAt, pan, and verify worldToScreen/screenToWorld roundtrip', () => {
      // Initial state
      expect(zoomPan.getScale()).toBe(1);
      const initialViewport = zoomPan.getViewport();
      expect(initialViewport.minX).toBe(0);
      expect(initialViewport.minY).toBe(0);

      // Zoom in at center (400, 300) with factor 2
      zoomPan.zoomAt(400, 300, 2);
      expect(zoomPan.getScale()).toBe(2);

      // After zoom, viewport should be smaller in world space
      const zoomedViewport = zoomPan.getViewport();
      expect(zoomedViewport.maxX - zoomedViewport.minX).toBe(400); // 800/2
      expect(zoomedViewport.maxY - zoomedViewport.minY).toBe(300); // 600/2

      // Pan by (50, 30) — adds to offset set by zoomAt
      // zoomAt(400,300,2): offsetX = 400-(400-0)*2 = -400, offsetY = 300-(300-0)*2 = -300
      zoomPan.pan(50, 30);
      const transform = zoomPan.getTransform();
      expect(transform.e).toBe(-350); // -400 + 50
      expect(transform.f).toBe(-270); // -300 + 30

      // worldToScreen / screenToWorld roundtrip
      const worldPt = { x: 150, y: 75 };
      const screenPt = zoomPan.worldToScreen(worldPt.x, worldPt.y);
      const backToWorld = zoomPan.screenToWorld(screenPt.x, screenPt.y);
      expect(backToWorld.x).toBeCloseTo(worldPt.x, 5);
      expect(backToWorld.y).toBeCloseTo(worldPt.y, 5);

      // Another roundtrip with different point
      const worldPt2 = { x: -50, y: 200 };
      const screenPt2 = zoomPan.worldToScreen(worldPt2.x, worldPt2.y);
      const back2 = zoomPan.screenToWorld(screenPt2.x, screenPt2.y);
      expect(back2.x).toBeCloseTo(worldPt2.x, 5);
      expect(back2.y).toBeCloseTo(worldPt2.y, 5);
    });
  });

  // ─── Step 6: Selection ──────────────────────────────────────────────────────
  describe('Step 6: Selection (click and box)', () => {
    beforeEach(() => {
      layerManager.addLayer(makeLayer('layer-default', { sortOrder: 0 }));
      layerManager.addLayer(makeLayer('layer-arch', { sortOrder: 1, color: '#ff0000' }));

      elements = [
        makeLine('el-line-1', 0, 0, 100, 100, 'layer-default'),
        makeRect('el-rect-1', 200, 200, 80, 60, 'layer-arch'),
        makeCircle('el-circle-1', 400, 400, 40, 'layer-default'),
      ];
      for (const el of elements) spatialIndex.insert(el);
    });

    it('should click-select a single element', () => {
      // Click near the line's midpoint (50, 50)
      const hit = selectionEngine.clickSelect(50, 50, elements);
      expect(hit).not.toBeNull();
      expect(hit?.id).toBe('el-line-1');

      const selectedIds = selectionEngine.getSelectedIds();
      expect(selectedIds.size).toBe(1);
      expect(selectedIds.has('el-line-1')).toBe(true);
    });

    it('should click-select the rect element', () => {
      // Click at rect center (200, 200)
      const hit = selectionEngine.clickSelect(200, 200, elements);
      expect(hit).not.toBeNull();
      expect(hit?.id).toBe('el-rect-1');
      expect(selectionEngine.getSelectedIds().has('el-rect-1')).toBe(true);
    });

    it('should clear selection when clicking empty space', () => {
      // First select an element
      selectionEngine.clickSelect(50, 50, elements);
      expect(selectionEngine.getSelectedIds().size).toBe(1);

      // Click in empty area (far from elements)
      const hit = selectionEngine.clickSelect(1000, 1000, elements);
      expect(hit).toBeNull();
      expect(selectionEngine.getSelectedIds().size).toBe(0);
    });

    it('should box-select multiple elements (window selection)', () => {
      // Window selection: left-to-right drag enclosing line and rect
      // line bbox: minX=-50, minY=-50, maxX=150, maxY=150
      // rect bbox: minX=160, minY=170, maxX=240, maxY=230
      // Need a box that fully encloses both
      selectionEngine.startBoxSelect(-100, -100);
      selectionEngine.updateBoxSelect(300, 300, elements);
      const selected = selectionEngine.finishBoxSelect(elements);

      // Both line and rect should be fully enclosed
      expect(selected.length).toBeGreaterThanOrEqual(2);
      const selectedIds = selectionEngine.getSelectedIds();
      expect(selectedIds.has('el-line-1')).toBe(true);
      expect(selectedIds.has('el-rect-1')).toBe(true);
    });

    it('should box-select with crossing mode (right-to-left drag)', () => {
      // Crossing selection: right-to-left drag (start X > end X)
      // Use a box that intersects the circle but doesn't fully enclose it
      // circle bbox: minX=360, minY=360, maxX=440, maxY=440
      selectionEngine.startBoxSelect(420, 420);
      selectionEngine.updateBoxSelect(380, 380, elements);
      const selected = selectionEngine.finishBoxSelect(elements);

      // Circle should be selected (intersecting)
      expect(selected.length).toBeGreaterThanOrEqual(1);
      expect(selectionEngine.getSelectedIds().has('el-circle-1')).toBe(true);
    });

    it('should support additive selection (shift-click)', () => {
      // Select line first
      selectionEngine.clickSelect(50, 50, elements);
      expect(selectionEngine.getSelectedIds().size).toBe(1);

      // Additive select rect
      selectionEngine.setOptions({ additive: true });
      selectionEngine.clickSelect(200, 200, elements);

      const selectedIds = selectionEngine.getSelectedIds();
      expect(selectedIds.size).toBe(2);
      expect(selectedIds.has('el-line-1')).toBe(true);
      expect(selectedIds.has('el-rect-1')).toBe(true);
    });
  });

  // ─── Step 7: Group selected elements ─────────────────────────────────────────
  describe('Step 7: Grouping', () => {
    beforeEach(() => {
      layerManager.addLayer(makeLayer('layer-default', { sortOrder: 0 }));
      layerManager.addLayer(makeLayer('layer-arch', { sortOrder: 1 }));

      elements = [
        makeLine('el-line-1', 0, 0, 100, 100, 'layer-default'),
        makeRect('el-rect-1', 200, 200, 80, 60, 'layer-arch'),
        makeCircle('el-circle-1', 400, 400, 40, 'layer-default'),
      ];
      for (const el of elements) spatialIndex.insert(el);
    });

    it('should group selected elements and verify membership', () => {
      // Select two elements
      selectionEngine.selectByIds(['el-line-1', 'el-rect-1']);
      const selectedIds = selectionEngine.getSelectedIds();
      expect(selectedIds.size).toBe(2);

      // Create group from selected elements
      const group = groupManager.createGroup(['el-line-1', 'el-rect-1'], 'Test Group');
      expect(group.id).toBeDefined();
      expect(group.name).toBe('Test Group');
      expect(group.elementIds).toHaveLength(2);
      expect(group.elementIds).toContain('el-line-1');
      expect(group.elementIds).toContain('el-rect-1');

      // Verify group membership
      expect(groupManager.getGroupForElement('el-line-1')).toBe(group.id);
      expect(groupManager.getGroupForElement('el-rect-1')).toBe(group.id);
      expect(groupManager.getGroupForElement('el-circle-1')).toBeNull();

      // Verify grouped elements set
      const grouped = groupManager.getGroupedElements();
      expect(grouped.size).toBe(2);
      expect(grouped.has('el-line-1')).toBe(true);
      expect(grouped.has('el-rect-1')).toBe(true);

      // Verify group retrieval
      const retrieved = groupManager.getGroup(group.id);
      expect(retrieved).toBeDefined();
      expect(retrieved?.name).toBe('Test Group');

      // Ungroup
      const ungroupedIds = groupManager.ungroup(group.id);
      expect(ungroupedIds).toHaveLength(2);
      expect(groupManager.getGroups()).toHaveLength(0);
      expect(groupManager.getGroupedElements().size).toBe(0);
    });
  });

  // ─── Step 8: Snap to endpoints/midpoints ─────────────────────────────────────
  describe('Step 8: Snap engine', () => {
    beforeEach(() => {
      elements = [
        makeLine('el-line-1', 0, 0, 100, 100, 'layer-default'),
        makeCircle('el-circle-1', 200, 200, 40, 'layer-default'),
      ];
      snapEngine.setElements(elements);
    });

    it('should snap to line endpoint', () => {
      // Line endpoints: (0,0) and (100,100)
      // Click near (0, 0) within tolerance
      const result = snapEngine.snap(2, 2);
      expect(result.point).not.toBeNull();
      expect(result.point?.type).toBe('endpoint');
      expect(result.point?.x).toBeCloseTo(0, 1);
      expect(result.point?.y).toBeCloseTo(0, 1);
    });

    it('should snap to second line endpoint', () => {
      const result = snapEngine.snap(98, 98);
      expect(result.point).not.toBeNull();
      expect(result.point?.type).toBe('endpoint');
      expect(result.point?.x).toBeCloseTo(100, 1);
      expect(result.point?.y).toBeCloseTo(100, 1);
    });

    it('should snap to line midpoint', () => {
      // Line midpoint: (50, 50)
      const result = snapEngine.snap(52, 52);
      expect(result.point).not.toBeNull();
      // Endpoint (0,0) is ~74 units away, midpoint (50,50) is ~2.8 units away
      // But endpoint priority > midpoint priority, so if both within tolerance * 1.5...
      // tolerance=10, so endpoint at distance ~74 is NOT within 10*1.5=15
      // midpoint at distance ~2.8 IS within 15
      expect(result.point?.type).toBe('midpoint');
      expect(result.point?.x).toBeCloseTo(50, 1);
      expect(result.point?.y).toBeCloseTo(50, 1);
    });

    it('should snap to circle center', () => {
      // Circle center: (200, 200)
      const result = snapEngine.snap(202, 202);
      expect(result.point).not.toBeNull();
      expect(result.point?.type).toBe('center');
      expect(result.point?.x).toBeCloseTo(200, 1);
      expect(result.point?.y).toBeCloseTo(200, 1);
    });

    it('should return null when no snap point is near', () => {
      // Click far from any element
      const result = snapEngine.snap(500, 500);
      expect(result.point).toBeNull();
    });

    it('should return preview candidates', () => {
      const result = snapEngine.snap(2, 2);
      expect(result.preview.length).toBeGreaterThan(0);
    });
  });

  // ─── Step 9: History (push, undo, redo) ──────────────────────────────────────
  describe('Step 9: History management', () => {
    beforeEach(() => {
      layerManager.addLayer(makeLayer('layer-default', { sortOrder: 0 }));
    });

    it('should push snapshot, modify, undo, redo and verify state restored', () => {
      const initialElements = [
        makeLine('el-line-1', 0, 0, 100, 100, 'layer-default'),
      ];
      const initialLayers = layerManager.getLayers();

      // Initialize history with initial state
      historyManager.initialize(makeSnapshot(initialElements, initialLayers));
      expect(historyManager.getCurrentState()?.elements).toHaveLength(1);
      expect(historyManager.canUndo()).toBe(false);
      expect(historyManager.canRedo()).toBe(false);

      // Push a new state: add a rect element
      const modifiedElements = [
        ...initialElements,
        makeRect('el-rect-1', 50, 50, 80, 60, 'layer-default'),
      ];
      historyManager.pushSnapshot(makeSnapshot(modifiedElements, initialLayers), 'Add rect');

      expect(historyManager.getCurrentState()?.elements).toHaveLength(2);
      expect(historyManager.canUndo()).toBe(true);
      expect(historyManager.canRedo()).toBe(false);

      // Undo: should restore to 1 element
      const undone = historyManager.undo();
      expect(undone).not.toBeNull();
      expect(undone?.elements).toHaveLength(1);
      expect(undone?.elements[0].id).toBe('el-line-1');
      expect(historyManager.canRedo()).toBe(true);

      // Redo: should restore to 2 elements
      const redone = historyManager.redo();
      expect(redone).not.toBeNull();
      expect(redone?.elements).toHaveLength(2);
      expect(redone?.elements[1].id).toBe('el-rect-1');
      expect(historyManager.canUndo()).toBe(true);
      expect(historyManager.canRedo()).toBe(false);
    });

    it('should handle multiple undo/redo cycles', () => {
      const layers = layerManager.getLayers();

      // Initialize
      historyManager.initialize(makeSnapshot([], layers));

      // Push state 1
      const els1 = [makeLine('el-1', 0, 0, 50, 50, 'layer-default')];
      historyManager.pushSnapshot(makeSnapshot(els1, layers), 'Add line 1');

      // Push state 2
      const els2 = [...els1, makeLine('el-2', 100, 100, 200, 200, 'layer-default')];
      historyManager.pushSnapshot(makeSnapshot(els2, layers), 'Add line 2');

      // Push state 3
      const els3 = [...els2, makeLine('el-3', 300, 300, 400, 400, 'layer-default')];
      historyManager.pushSnapshot(makeSnapshot(els3, layers), 'Add line 3');

      expect(historyManager.getCurrentState()?.elements).toHaveLength(3);
      expect(historyManager.getUndoCount()).toBe(3);

      // Undo twice
      historyManager.undo();
      expect(historyManager.getCurrentState()?.elements).toHaveLength(2);
      historyManager.undo();
      expect(historyManager.getCurrentState()?.elements).toHaveLength(1);
      expect(historyManager.getRedoCount()).toBe(2);

      // Redo once
      historyManager.redo();
      expect(historyManager.getCurrentState()?.elements).toHaveLength(2);
      expect(historyManager.getRedoCount()).toBe(1);
    });
  });

  // ─── Step 10: Layer toggle (hide layer, verify not rendered/selectable) ──────
  describe('Step 10: Layer toggle affects rendering and selection', () => {
    beforeEach(() => {
      layerManager.addLayer(makeLayer('layer-default', { sortOrder: 0 }));
      layerManager.addLayer(makeLayer('layer-hidden', { sortOrder: 1 }));

      elements = [
        makeLine('el-line-1', 0, 0, 100, 100, 'layer-default'),
        makeRect('el-rect-1', 200, 200, 80, 60, 'layer-hidden'),
      ];
      for (const el of elements) spatialIndex.insert(el);
    });

    it('should not render elements on hidden layers', () => {
      // Initially both layers visible — render should work
      expect(() => renderEngine.render()).not.toThrow();

      // Hide layer-hidden
      layerManager.toggleVisibility('layer-hidden');
      expect(layerManager.getLayer('layer-hidden')?.visible).toBe(false);

      // Render should still not crash (just skips hidden layer elements)
      expect(() => renderEngine.render()).not.toThrow();

      // getVisibleLayers should not include hidden layer
      const visible = layerManager.getVisibleLayers();
      expect(visible.some(l => l.id === 'layer-hidden')).toBe(false);
    });

    it('should not select elements on hidden layers via hitTest', () => {
      // Hide layer-hidden
      layerManager.toggleVisibility('layer-hidden');

      // Try to click-select the rect on hidden layer
      const hit = selectionEngine.clickSelect(200, 200, elements);
      expect(hit).toBeNull();
      expect(selectionEngine.getSelectedIds().size).toBe(0);
    });

    it('should not select elements on locked layers via hitTest', () => {
      // Lock layer-hidden (visible but locked → not in getVisibleLayers)
      layerManager.toggleLock('layer-hidden');

      // Try to click-select the rect on locked layer
      const hit = selectionEngine.clickSelect(200, 200, elements);
      expect(hit).toBeNull();
    });

    it('should still select elements on visible, unlocked layers', () => {
      // Click on line (layer-default, visible, unlocked)
      const hit = selectionEngine.clickSelect(50, 50, elements);
      expect(hit).not.toBeNull();
      expect(hit?.id).toBe('el-line-1');
    });
  });

  // ─── Step 11: Zoom fit to all elements ───────────────────────────────────────
  describe('Step 11: Zoom fit to all elements', () => {
    it('should change scale when fitting to elements', () => {
      const initialScale = zoomPan.getScale();
      expect(initialScale).toBe(1);

      // Elements spread across a large area
      const fitElements = [
        { x: 0, y: 0, width: 10, height: 10 },
        { x: 500, y: 500, width: 10, height: 10 },
        { x: 1000, y: 1000, width: 10, height: 10 },
      ];

      zoomPan.zoomFit(fitElements);

      const newScale = zoomPan.getScale();
      // Canvas is 800x600, elements span ~1010 units, padding=40
      // scaleX = (800-80)/1010 ≈ 0.713, scaleY = (600-80)/1010 ≈ 0.515
      // scale = min(0.713, 0.515) ≈ 0.515
      expect(newScale).not.toBe(1);
      expect(newScale).toBeGreaterThan(0);
      expect(newScale).toBeLessThan(1);
    });

    it('should not change scale when no elements', () => {
      const initialScale = zoomPan.getScale();
      zoomPan.zoomFit([]);
      expect(zoomPan.getScale()).toBe(initialScale);
    });

    it('should fit and then reset', () => {
      zoomPan.zoomFit([{ x: 100, y: 100, width: 50, height: 50 }]);
      expect(zoomPan.getScale()).not.toBe(1);

      zoomPan.reset();
      expect(zoomPan.getScale()).toBe(1);
      const transform = zoomPan.getTransform();
      expect(transform.e).toBe(0);
      expect(transform.f).toBe(0);
    });
  });

  // ─── Step 12: Reset everything, verify clean state ───────────────────────────
  describe('Step 12: Reset everything', () => {
    beforeEach(() => {
      layerManager.addLayer(makeLayer('layer-default', { sortOrder: 0 }));
      layerManager.addLayer(makeLayer('layer-arch', { sortOrder: 1 }));

      elements = [
        makeLine('el-line-1', 0, 0, 100, 100, 'layer-default'),
        makeRect('el-rect-1', 200, 200, 80, 60, 'layer-arch'),
      ];
      for (const el of elements) spatialIndex.insert(el);

      // Modify state
      zoomPan.zoomAt(400, 300, 2);
      zoomPan.pan(50, 30);
      selectionEngine.selectByIds(['el-line-1', 'el-rect-1']);
      groupManager.createGroup(['el-line-1', 'el-rect-1'], 'Test');
      historyManager.initialize(makeSnapshot(elements, layerManager.getLayers()));
      historyManager.pushSnapshot(makeSnapshot([...elements, makeCircle('el-c', 300, 300, 20)], layerManager.getLayers()), 'Add circle');
    });

    it('should reset all components to clean state', () => {
      // Verify dirty state before reset
      expect(zoomPan.getScale()).not.toBe(1);
      expect(selectionEngine.getSelectedIds().size).toBe(2);
      expect(groupManager.getGroups().length).toBe(1);
      expect(spatialIndex.search({ minX: -1000, minY: -1000, maxX: 1000, maxY: 1000 }).length).toBe(2);
      expect(layerManager.getLayers().length).toBe(2);
      expect(historyManager.canUndo()).toBe(true);

      // Reset all
      zoomPan.reset();
      selectionEngine.clearSelection();
      groupManager.clear();
      spatialIndex.clear();
      layerManager.clear();
      historyManager.clear();

      // Verify clean state
      expect(zoomPan.getScale()).toBe(1);
      expect(zoomPan.getTransform().e).toBe(0);
      expect(zoomPan.getTransform().f).toBe(0);

      expect(selectionEngine.getSelectedIds().size).toBe(0);

      expect(groupManager.getGroups()).toHaveLength(0);
      expect(groupManager.getGroupedElements().size).toBe(0);

      expect(spatialIndex.search({ minX: -1000, minY: -1000, maxX: 1000, maxY: 1000 })).toHaveLength(0);

      expect(layerManager.getLayers()).toHaveLength(0);
      expect(layerManager.getActiveLayerId()).toBe('');

      expect(historyManager.getCurrentState()).toBeNull();
      expect(historyManager.canUndo()).toBe(false);
      expect(historyManager.canRedo()).toBe(false);
    });
  });

  // ─── Full Workflow Integration ──────────────────────────────────────────────
  describe('Full workflow: init → layers → elements → render → zoom → select → group → snap → history → toggle → fit → reset', () => {
    it('should execute the complete CAD workflow end-to-end', () => {
      // ── 1. Initialize ──
      expect(renderEngine).toBeDefined();
      expect(selectionEngine).toBeDefined();

      // ── 2. Create layers ──
      const defaultLayer = makeLayer('layer-default', { sortOrder: 0, name: 'Default' });
      const archLayer = makeLayer('layer-arch', { sortOrder: 1, name: 'Architecture', color: '#ff0000' });
      layerManager.addLayer(defaultLayer);
      layerManager.addLayer(archLayer);
      expect(layerManager.getLayers()).toHaveLength(2);

      // ── 3. Add elements to different layers ──
      const line1 = makeLine('el-line-1', 0, 0, 100, 100, 'layer-default');
      const rect1 = makeRect('el-rect-1', 200, 200, 80, 60, 'layer-arch');
      const circle1 = makeCircle('el-circle-1', 400, 300, 40, 'layer-default');
      elements = [line1, rect1, circle1];
      for (const el of elements) spatialIndex.insert(el);

      // Verify spatial index has all elements
      const allFound = spatialIndex.search({ minX: -200, minY: -200, maxX: 600, maxY: 600 });
      expect(allFound).toHaveLength(3);

      // ── 4. Render ──
      expect(() => renderEngine.render()).not.toThrow();

      // ── 5. Zoom/Pan ──
      zoomPan.zoomAt(400, 300, 1.5);
      expect(zoomPan.getScale()).toBe(1.5);
      // zoomAt(400,300,1.5): offsetX = 400-(400-0)*1.5 = -200, then pan(20,10) → -180
      zoomPan.pan(20, 10);
      expect(zoomPan.getTransform().e).toBe(-180);

      // Roundtrip
      const wpt = { x: 100, y: 100 };
      const spt = zoomPan.worldToScreen(wpt.x, wpt.y);
      const back = zoomPan.screenToWorld(spt.x, spt.y);
      expect(back.x).toBeCloseTo(wpt.x, 3);
      expect(back.y).toBeCloseTo(wpt.y, 3);

      // ── 6. Selection ──
      // Click select line at midpoint (50, 50)
      const hit = selectionEngine.clickSelect(50, 50, elements);
      expect(hit?.id).toBe('el-line-1');

      // Box select line + rect (window selection)
      selectionEngine.clearSelection();
      selectionEngine.startBoxSelect(-100, -100);
      selectionEngine.updateBoxSelect(300, 300, elements);
      const boxSelected = selectionEngine.finishBoxSelect(elements);
      expect(boxSelected.length).toBeGreaterThanOrEqual(2);

      // ── 7. Group selected elements ──
      const selectedIds = Array.from(selectionEngine.getSelectedIds());
      const group = groupManager.createGroup(selectedIds, 'Workflow Group');
      expect(group.elementIds.length).toBeGreaterThanOrEqual(2);
      expect(groupManager.getGroup(group.id)).toBeDefined();

      // ── 8. Snap ──
      snapEngine.setElements(elements);
      const snapResult = snapEngine.snap(2, 2); // Near line endpoint (0,0)
      expect(snapResult.point).not.toBeNull();
      expect(snapResult.point?.type).toBe('endpoint');

      // ── 9. History ──
      const currentLayers = layerManager.getLayers();
      historyManager.initialize(makeSnapshot(elements, currentLayers));
      const modifiedEls = [...elements, makeRect('el-rect-2', 500, 500, 30, 30, 'layer-default')];
      historyManager.pushSnapshot(makeSnapshot(modifiedEls, currentLayers), 'Add rect 2');

      expect(historyManager.getCurrentState()?.elements).toHaveLength(4);
      expect(historyManager.canUndo()).toBe(true);

      const undone = historyManager.undo();
      expect(undone?.elements).toHaveLength(3);

      const redone = historyManager.redo();
      expect(redone?.elements).toHaveLength(4);

      // ── 10. Layer toggle ──
      layerManager.toggleVisibility('layer-arch');
      expect(layerManager.getLayer('layer-arch')?.visible).toBe(false);

      // Elements on hidden layer should not be selectable
      const hitAfterHide = selectionEngine.clickSelect(200, 200, elements);
      expect(hitAfterHide).toBeNull();

      // Restore visibility
      layerManager.toggleVisibility('layer-arch');
      expect(layerManager.getLayer('layer-arch')?.visible).toBe(true);

      // ── 11. Zoom fit ──
      zoomPan.reset();
      expect(zoomPan.getScale()).toBe(1);

      zoomPan.zoomFit(elements);
      expect(zoomPan.getScale()).not.toBe(1);

      // ── 12. Reset everything ──
      zoomPan.reset();
      selectionEngine.clearSelection();
      groupManager.clear();
      spatialIndex.clear();
      layerManager.clear();
      historyManager.clear();

      expect(zoomPan.getScale()).toBe(1);
      expect(selectionEngine.getSelectedIds().size).toBe(0);
      expect(groupManager.getGroups()).toHaveLength(0);
      expect(spatialIndex.search({ minX: -1000, minY: -1000, maxX: 1000, maxY: 1000 })).toHaveLength(0);
      expect(layerManager.getLayers()).toHaveLength(0);
      expect(historyManager.getCurrentState()).toBeNull();
    });
  });

  // ─── CommandRegistry Integration ─────────────────────────────────────────────
  describe('CommandRegistry integration', () => {
    it('should look up drawing commands', () => {
      const lineCmd = commandRegistry.lookup('LINE');
      expect(lineCmd).not.toBeNull();
      expect(lineCmd?.toolId).toBe('line');

      const circleCmd = commandRegistry.lookup('C');
      expect(circleCmd?.name).toBe('CIRCLE');
      expect(circleCmd?.toolId).toBe('circle');
    });

    it('should provide autocomplete suggestions', () => {
      const suggestions = commandRegistry.autocomplete('LI');
      expect(suggestions.length).toBeGreaterThan(0);
      expect(suggestions.some(c => c.name === 'LINE')).toBe(true);
    });

    it('should return null for unknown commands', () => {
      expect(commandRegistry.lookup('UNKNOWN')).toBeNull();
    });
  });
});