import type {
  CADElement, CADLayer, CADProperties, BoundingBox, Viewport,
} from '../types/cad.types';
import { ZoomPanController } from './ZoomPanController';
import { SpatialIndex } from './SpatialIndex';
import { LayerManager } from './LayerManager';
import { pluginRegistry } from '../plugins';

export interface RenderOptions {
  showGrid: boolean;
  gridSize: number;
  showSnapPoints: boolean;
  showOrtho: boolean;
  orthoAngle: number;
  backgroundSrc?: string;
  backgroundScale: number;
  backgroundOffsetX: number;
  backgroundOffsetY: number;
  backgroundRotation: number;
  backgroundOpacity: number;
  unit?: 'mm' | 'cm' | 'm';
  scaleFactor?: number;
  showGridLabels?: boolean;
  canvasBgColor?: string;
  gridColor?: string;
  rulerEnabled?: boolean;
}

export interface SelectionState {
  selectedIds: Set<string>;
  hoverId: string | null;
  boxStart: { x: number; y: number } | null;
  boxEnd: { x: number; y: number } | null;
}

export interface SnapPoint {
  x: number;
  y: number;
  type: 'endpoint' | 'midpoint' | 'center' | 'intersection' | 'nearest' | 'grid' | 'perpendicular' | 'tangent' | 'quadrant' | 'none';
}

export class RenderEngine {
  private ctx: CanvasRenderingContext2D;
  private canvas: HTMLCanvasElement;
  private zoomPan: ZoomPanController;
  private spatialIndex: SpatialIndex;
  private layerManager: LayerManager;
  private options: RenderOptions;
  private selection: SelectionState;
  private snapPoints: SnapPoint[] = [];
  private activeSnapPoint: SnapPoint | null = null;
  private previewElement: CADElement | null = null;
  private dpr = 1;

  constructor(
    canvas: HTMLCanvasElement,
    zoomPan: ZoomPanController,
    spatialIndex: SpatialIndex,
    layerManager: LayerManager,
  ) {
    this.canvas = canvas;
    const ctx = canvas.getContext('2d');
    if (!ctx) throw new Error('Canvas 2D context not available');
    this.ctx = ctx;
    this.zoomPan = zoomPan;
    this.spatialIndex = spatialIndex;
    this.layerManager = layerManager;
    this.options = {
      showGrid: true,
      gridSize: 20,
      showSnapPoints: false,
      showOrtho: false,
      orthoAngle: 0,
      backgroundScale: 1,
      backgroundOffsetX: 0,
      backgroundOffsetY: 0,
      backgroundRotation: 0,
      backgroundOpacity: 0.5,
      canvasBgColor: '#1e1e2e',
      gridColor: '#3a3a4a',
      rulerEnabled: true,
    };
    this.selection = {
      selectedIds: new Set(),
      hoverId: null,
      boxStart: null,
      boxEnd: null,
    };
  }

  setOptions(opts: Partial<RenderOptions>): void {
    this.options = { ...this.options, ...opts };
  }

  getOptions(): RenderOptions {
    return { ...this.options };
  }

  setSelection(sel: Partial<SelectionState>): void {
    this.selection = { ...this.selection, ...sel };
  }

  getSelection(): SelectionState {
    return { ...this.selection };
  }

  setSnapPoints(points: SnapPoint[]): void {
    this.snapPoints = points;
  }

  setActiveSnapPoint(pt: SnapPoint | null): void {
    this.activeSnapPoint = pt;
  }

  setPreviewElement(el: CADElement | null): void {
    this.previewElement = el;
  }

  resize(width: number, height: number): void {
    this.dpr = window.devicePixelRatio || 1;
    this.canvas.width = width * this.dpr;
    this.canvas.height = height * this.dpr;
    this.canvas.style.width = width + 'px';
    this.canvas.style.height = height + 'px';
    this.ctx.scale(this.dpr, this.dpr);
  }

  setLayers(layers: CADLayer[]): void {
    this.layerManager.clear();
    for (const layer of layers) {
      this.layerManager.addLayer(layer);
    }
  }

  private blockDefinitions: Map<string, { elements: CADElement[] }> = new Map();

  setBlockDefinitions(blocks: Array<{ id: string; elements: CADElement[] }>): void {
    this.blockDefinitions.clear();
    for (const b of blocks) {
      this.blockDefinitions.set(b.id, b);
    }
  }

  private groups: Array<{ id: string; name: string; elementIds: string[]; parentGroupId: string | null }> = [];

  setGroups(groups: Array<{ id: string; name: string; elementIds: string[]; parentGroupId: string | null }>): void {
    this.groups = groups;
  }

  render(): void {
    const w = this.canvas.width / this.dpr;
    const h = this.canvas.height / this.dpr;
    this.ctx.save();
    this.ctx.fillStyle = this.options.canvasBgColor || '#1e1e2e';
    this.ctx.fillRect(0, 0, w, h);

    if (this.options.showGrid) this.drawGrid(w, h);
    if (this.options.backgroundSrc) this.drawBackground();
    this.drawRuler(w, h);
    const viewport = this.zoomPan.getViewport();
    const visibleElements = this.spatialIndex.search({
      minX: viewport.minX, minY: viewport.minY,
      maxX: viewport.maxX, maxY: viewport.maxY,
    });

    const layers = this.layerManager.getLayers();
    for (const layer of layers) {
      if (!layer.visible) continue;
      const els = visibleElements.filter(e => e.layerId === layer.id && e.properties?.visible !== false);
      for (const el of els) {
        this.drawElement(el, layer);
      }
    }

    // Draw preview element with dashed style
    if (this.previewElement) {
      this.ctx.save();
      this.ctx.setLineDash([6, 4]);
      const previewEl: CADElement = { ...this.previewElement, properties: { ...this.previewElement.properties, stroke: '#00aaff', strokeWidth: 2 } };
      const previewLayer: CADLayer = { id: '__preview__', name: 'Preview', visible: true, locked: false, color: '#00aaff', lineType: 'solid', transparency: 0, sortOrder: 999, parentId: null };
      this.drawElement(previewEl, previewLayer);
      this.ctx.restore();
    }

    this.drawSelectionBox();
    this.drawGroupBoxes();
    if (this.options.showSnapPoints) this.drawSnapPoints();
    if (this.options.showOrtho) this.drawOrtho();
    this.ctx.restore();
  }

  private drawGrid(w: number, h: number): void {
    const scale = this.zoomPan.getScale();
    const gridSize = this.options.gridSize * scale;
    if (gridSize < 4) return;
    const offsetX = this.zoomPan.getTransform().e % gridSize;
    const offsetY = this.zoomPan.getTransform().f % gridSize;

    this.ctx.strokeStyle = this.options.gridColor || '#3a3a4a';
    this.ctx.lineWidth = 1;
    this.ctx.beginPath();
    for (let x = offsetX; x < w; x += gridSize) {
      this.ctx.moveTo(x, 0);
      this.ctx.lineTo(x, h);
    }
    for (let y = offsetY; y < h; y += gridSize) {
      this.ctx.moveTo(0, y);
      this.ctx.lineTo(w, y);
    }
    this.ctx.stroke();

    // Major grid lines every 5 cells
    const majorSize = gridSize * 5;
    if (majorSize >= 20) {
      const majOffX = this.zoomPan.getTransform().e % majorSize;
      const majOffY = this.zoomPan.getTransform().f % majorSize;
      // Major lines use a brighter variant of gridColor
      this.ctx.strokeStyle = this.lightenColor(this.options.gridColor || '#3a3a4a', 15);
      this.ctx.beginPath();
      for (let x = majOffX; x < w; x += majorSize) {
        this.ctx.moveTo(x, 0);
        this.ctx.lineTo(x, h);
      }
      for (let y = majOffY; y < h; y += majorSize) {
        this.ctx.moveTo(0, y);
        this.ctx.lineTo(w, y);
      }
      this.ctx.stroke();

      // Draw axis labels with unit at each major grid line
      if (this.options.showGridLabels !== false) {
        const unit = this.options.unit || 'mm';
        const scaleFactor = this.options.scaleFactor || 1;
        const transform = this.zoomPan.getTransform();
        const scale = this.zoomPan.getScale();
        const worldGridSize = this.options.gridSize * 5; // world units per major line

        this.ctx.fillStyle = '#666680';
        this.ctx.font = '10px sans-serif';
        this.ctx.textBaseline = 'top';

        // X-axis labels (top edge)
        const xStartWorld = Math.floor((-transform.e / scale) / worldGridSize) * worldGridSize;
        for (let i = 0; i * majorSize + majOffX < w; i++) {
          const screenX = majOffX + i * majorSize;
          const worldX = xStartWorld + i * worldGridSize;
          if (screenX < 30) continue; // skip too-close-to-edge labels
          const label = this.formatGridLabel(worldX, unit, scaleFactor);
          this.ctx.fillText(label, screenX + 2, 2);
        }

        // Y-axis labels (left edge)
        this.ctx.textAlign = 'left';
        this.ctx.textBaseline = 'middle';
        const yStartWorld = Math.floor((-transform.f / scale) / worldGridSize) * worldGridSize;
        for (let i = 0; i * majorSize + majOffY < h; i++) {
          const screenY = majOffY + i * majorSize;
          const worldY = yStartWorld + i * worldGridSize;
          if (screenY < 15) continue;
          const label = this.formatGridLabel(worldY, unit, scaleFactor);
          this.ctx.fillText(label, 2, screenY - 6);
        }

        this.ctx.textAlign = 'start';
        this.ctx.textBaseline = 'alphabetic';
      }
    }
  }

  private formatGridLabel(worldVal: number, unit: 'mm' | 'cm' | 'm', scaleFactor: number): string {
    const mm = worldVal * scaleFactor;
    switch (unit) {
      case 'mm':
        return `${mm.toFixed(0)}mm`;
      case 'cm':
        return `${(mm / 10).toFixed(0)}cm`;
      case 'm':
        return `${(mm / 1000).toFixed(2)}m`;
    }
  }

  private lightenColor(hex: string, percent: number): string {
    const num = parseInt(hex.replace('#', ''), 16);
    if (isNaN(num)) return hex;
    const r = Math.min(255, (num >> 16) + Math.round(255 * percent / 100));
    const g = Math.min(255, ((num >> 8) & 0x00FF) + Math.round(255 * percent / 100));
    const b = Math.min(255, (num & 0x0000FF) + Math.round(255 * percent / 100));
    return `#${((r << 16) | (g << 8) | b).toString(16).padStart(6, '0')}`;
  }

  private drawRuler(w: number, h: number): void {
    if (!this.options.rulerEnabled) return;
    const scale = this.zoomPan.getScale();
    const transform = this.zoomPan.getTransform();
    const unit = this.options.unit || 'mm';
    const scaleFactor = this.options.scaleFactor || 1;
    const rulerSize = 20;

    this.ctx.save();
    this.ctx.fillStyle = this.options.canvasBgColor || '#1e1e2e';
    this.ctx.fillRect(0, 0, w, rulerSize);
    this.ctx.fillRect(0, 0, rulerSize, h);

    this.ctx.strokeStyle = this.lightenColor(this.options.gridColor || '#3a3a4a', 30);
    this.ctx.lineWidth = 1;
    this.ctx.beginPath();
    this.ctx.moveTo(0, rulerSize);
    this.ctx.lineTo(w, rulerSize);
    this.ctx.moveTo(rulerSize, 0);
    this.ctx.lineTo(rulerSize, h);
    this.ctx.stroke();

    // Determine tick spacing in world units (aim for ~50px between major ticks)
    const targetPx = 50;
    const worldPerPx = 1 / scale;
    const rawTickSpacing = targetPx * worldPerPx;
    const niceSpacings = [1, 2, 5, 10, 20, 50, 100, 200, 500, 1000, 2000, 5000, 10000];
    let tickSpacing = niceSpacings[0];
    for (const ns of niceSpacings) {
      if (ns >= rawTickSpacing) { tickSpacing = ns; break; }
      tickSpacing = ns;
    }
    const tickPx = tickSpacing * scale;

    this.ctx.fillStyle = this.lightenColor(this.options.gridColor || '#3a3a4a', 50);
    this.ctx.font = '9px sans-serif';
    this.ctx.textBaseline = 'middle';

    // X-axis ruler (top)
    this.ctx.textAlign = 'center';
    const xStartWorld = Math.floor((-transform.e / scale) / tickSpacing) * tickSpacing;
    for (let i = 0; ; i++) {
      const screenX = transform.e + (xStartWorld + i * tickSpacing) * scale;
      if (screenX < rulerSize) continue;
      if (screenX > w) break;
      // Tick mark
      this.ctx.strokeStyle = this.lightenColor(this.options.gridColor || '#3a3a4a', 30);
      this.ctx.beginPath();
      this.ctx.moveTo(screenX, rulerSize - 6);
      this.ctx.lineTo(screenX, rulerSize);
      this.ctx.stroke();
      // Label
      const worldVal = (xStartWorld + i * tickSpacing) * scaleFactor;
      let label: string;
      switch (unit) {
        case 'mm': label = `${worldVal.toFixed(0)}`; break;
        case 'cm': label = `${(worldVal / 10).toFixed(0)}`; break;
        case 'm': label = `${(worldVal / 1000).toFixed(2)}`; break;
      }
      this.ctx.fillText(label, screenX, rulerSize / 2);
    }

    // Y-axis ruler (left)
    this.ctx.textAlign = 'right';
    this.ctx.textBaseline = 'middle';
    const yStartWorld = Math.floor((-transform.f / scale) / tickSpacing) * tickSpacing;
    for (let i = 0; ; i++) {
      const screenY = transform.f + (yStartWorld + i * tickSpacing) * scale;
      if (screenY < rulerSize) continue;
      if (screenY > h) break;
      this.ctx.strokeStyle = this.lightenColor(this.options.gridColor || '#3a3a4a', 30);
      this.ctx.beginPath();
      this.ctx.moveTo(rulerSize - 6, screenY);
      this.ctx.lineTo(rulerSize, screenY);
      this.ctx.stroke();
      const worldVal = (yStartWorld + i * tickSpacing) * scaleFactor;
      let label: string;
      switch (unit) {
        case 'mm': label = `${worldVal.toFixed(0)}`; break;
        case 'cm': label = `${(worldVal / 10).toFixed(0)}`; break;
        case 'm': label = `${(worldVal / 1000).toFixed(2)}`; break;
      }
      this.ctx.fillText(label, rulerSize - 2, screenY);
    }

    this.ctx.restore();
    this.ctx.textAlign = 'start';
    this.ctx.textBaseline = 'alphabetic';
  }

  private drawBackground(): void {
    // Background image rendering with transform
    const img = new Image();
    img.src = this.options.backgroundSrc!;
    if (!img.complete) {
      img.onload = () => this.render();
      return;
    }
    this.ctx.save();
    this.ctx.globalAlpha = this.options.backgroundOpacity;
    const s = this.zoomPan.getScale();
    const ox = this.zoomPan.getTransform().e;
    const oy = this.zoomPan.getTransform().f;
    const bx = this.options.backgroundOffsetX * s + ox;
    const by = this.options.backgroundOffsetY * s + oy;
    const bw = img.width * this.options.backgroundScale * s;
    const bh = img.height * this.options.backgroundScale * s;
    this.ctx.translate(bx + bw / 2, by + bh / 2);
    this.ctx.rotate(this.options.backgroundRotation);
    this.ctx.drawImage(img, -bw / 2, -bh / 2, bw, bh);
    this.ctx.restore();
  }

  private drawElement(el: CADElement, layer: CADLayer): void {
    const ctx = this.ctx;
    const s = this.zoomPan.getScale();
    const ox = this.zoomPan.getTransform().e;
    const oy = this.zoomPan.getTransform().f;
    const sx = (val: number) => val * s + ox;
    const sy = (val: number) => val * s + oy;

    const stroke = el.properties.stroke || layer.color;
    const strokeWidth = (el.properties.strokeWidth || 1) * s;
    const fill = el.properties.fill;
    const isSelected = this.selection.selectedIds.has(el.id);
    const isHover = this.selection.hoverId === el.id;

    ctx.save();
    ctx.strokeStyle = stroke;
    ctx.lineWidth = Math.max(0.5, strokeWidth);
    if (layer.lineType === 'dashed') ctx.setLineDash([8, 4]);
    if (layer.lineType === 'dotted') ctx.setLineDash([2, 4]);
    if (isSelected) {
      ctx.strokeStyle = '#00aaff';
      ctx.lineWidth = Math.max(1, strokeWidth + 1);
    } else if (isHover) {
      ctx.strokeStyle = '#ffaa00';
    }

    switch (el.type) {
      case 'line': this.drawLine(el, sx, sy); break;
      case 'rect': this.drawRect(el, sx, sy); break;
      case 'circle': this.drawCircle(el, sx, sy, s); break;
      case 'arc': this.drawArc(el, sx, sy, s); break;
      case 'polyline': this.drawPolyline(el, sx, sy); break;
      case 'polygon': this.drawPolygon(el, sx, sy, fill); break;
      case 'text': this.drawText(el, sx, sy, s); break;
      case 'dimension': this.drawDimension(el, sx, sy, s); break;
      case 'block_instance': this.drawBlockInstance(el, sx, sy, s); break;
      case 'chair': this.drawChair(el, sx, sy, s); break;
      case 'table': this.drawTable(el, sx, sy, s); break;
      case 'stage': this.drawStage(el, sx, sy, s); break;
      case 'leader': this.drawLeader(el, sx, sy, s); break;
      case 'revcloud': this.drawRevCloud(el, sx, sy, s); break;
      default: {
        // Plugin element types
        const ext = pluginRegistry.getElementType(el.type);
        if (ext?.render) {
          ext.render(this.ctx, el, s);
        }
        break;
      }
    }

    if (isSelected) this.drawSelectionHandles(el, sx, sy, s);
    ctx.restore();
  }

  private drawLine(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number): void {
    const p = el.properties;
    this.ctx.beginPath();
    this.ctx.moveTo(sx(p.x1 ?? el.x), sy(p.y1 ?? el.y));
    this.ctx.lineTo(sx(p.x2 ?? el.x + el.width), sy(p.y2 ?? el.y + el.height));
    this.ctx.stroke();
  }

  private drawRect(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number): void {
    const x = sx(el.x - el.width / 2);
    const y = sy(el.y - el.height / 2);
    const w = el.width * (this.zoomPan.getScale());
    const h = el.height * (this.zoomPan.getScale());
    if (el.properties.fill) {
      this.ctx.fillStyle = el.properties.fill;
      this.ctx.fillRect(x, y, w, h);
    }
    if (el.properties.hatch) {
      this.drawHatchRect(x, y, w, h, (el.properties.hatchSpacing as number) || 8);
    }
    this.ctx.strokeRect(x, y, w, h);
  }

  private drawHatchRect(x: number, y: number, w: number, h: number, spacing: number): void {
    this.ctx.save();
    this.ctx.beginPath();
    this.ctx.rect(x, y, w, h);
    this.ctx.clip();
    this.ctx.strokeStyle = this.ctx.strokeStyle || '#888';
    this.ctx.lineWidth = 0.5;
    for (let i = -h; i < w + h; i += spacing) {
      this.ctx.beginPath();
      this.ctx.moveTo(x + i, y);
      this.ctx.lineTo(x + i + h, y + h);
      this.ctx.stroke();
    }
    this.ctx.restore();
  }

  private drawCircle(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number, s: number): void {
    const r = (el.properties.radius || el.width / 2) * s;
    this.ctx.beginPath();
    this.ctx.arc(sx(el.x), sy(el.y), Math.max(0.5, r), 0, Math.PI * 2);
    if (el.properties.fill) {
      this.ctx.fillStyle = el.properties.fill;
      this.ctx.fill();
    }
    if (el.properties.hatch) {
      this.ctx.save();
      this.ctx.clip();
      const cx = sx(el.x);
      const cy = sy(el.y);
      const spacing = (el.properties.hatchSpacing as number) || 8;
      this.ctx.lineWidth = 0.5;
      for (let i = -r; i < r * 2; i += spacing) {
        this.ctx.beginPath();
        this.ctx.moveTo(cx - r + i, cy - r);
        this.ctx.lineTo(cx - r + i + r * 2, cy + r);
        this.ctx.stroke();
      }
      this.ctx.restore();
    }
    this.ctx.stroke();
  }

  private drawArc(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number, s: number): void {
    const r = (el.properties.radius || el.width / 2) * s;
    const start = (el.properties.startAngle || 0) * Math.PI / 180;
    const end = (el.properties.endAngle || 360) * Math.PI / 180;
    this.ctx.beginPath();
    this.ctx.arc(sx(el.x), sy(el.y), Math.max(0.5, r), start, end);
    this.ctx.stroke();
  }

  private drawPolyline(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number): void {
    const pts = el.properties.points || [];
    if (pts.length < 2) return;
    this.ctx.beginPath();
    this.ctx.moveTo(sx(pts[0].x), sy(pts[0].y));
    for (let i = 1; i < pts.length; i++) {
      this.ctx.lineTo(sx(pts[i].x), sy(pts[i].y));
    }
    this.ctx.stroke();
  }

  private drawPolygon(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number, fill?: string): void {
    const pts = el.properties.points || [];
    if (pts.length < 3) return;
    this.ctx.beginPath();
    this.ctx.moveTo(sx(pts[0].x), sy(pts[0].y));
    for (let i = 1; i < pts.length; i++) {
      this.ctx.lineTo(sx(pts[i].x), sy(pts[i].y));
    }
    this.ctx.closePath();
    if (fill || el.properties.fill) {
      this.ctx.fillStyle = fill || el.properties.fill!;
      this.ctx.fill();
    }
    this.ctx.stroke();
  }

  private drawText(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number, s: number): void {
    const fontSize = (el.properties.fontSize || 12) * s;
    this.ctx.font = `${fontSize}px sans-serif`;
    this.ctx.fillStyle = el.properties.stroke || '#e0e0e0';
    this.ctx.textBaseline = 'top';
    const text = el.properties.text || '';
    const lines = String(text).split('\n');
    const align = (el.properties.align as string) || 'left';
    this.ctx.textAlign = align as CanvasTextAlign;
    if (el.properties.rotation) {
      this.ctx.save();
      this.ctx.translate(sx(el.x), sy(el.y));
      this.ctx.rotate((el.properties.rotation as number) * Math.PI / 180);
      lines.forEach((line, i) => {
        this.ctx.fillText(line, 0, i * fontSize * 1.2);
      });
      this.ctx.restore();
    } else {
      lines.forEach((line, i) => {
        this.ctx.fillText(line, sx(el.x), sy(el.y) + i * fontSize * 1.2);
      });
    }
    this.ctx.textAlign = 'left';
  }

  private drawDimension(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number, s: number): void {
    const p = el.properties;
    const dimType = (p.dimType as string) || 'linear';
    const value = (p.value as string) || '';
    const arrowSize = 5 * s;

    if (dimType === 'angular') {
      this.drawAngularDimension(el, sx, sy, s, arrowSize, value);
      return;
    }
    if (dimType === 'radial') {
      this.drawRadialDimension(el, sx, sy, s, arrowSize, value);
      return;
    }

    // Linear dimension
    const x1 = p.x1 ?? el.x - el.width / 2;
    const y1 = p.y1 ?? el.y;
    const x2 = p.x2 ?? el.x + el.width / 2;
    const y2 = p.y2 ?? el.y;
    const offset = 15 * s;

    // Extension lines
    this.ctx.strokeStyle = '#888';
    this.ctx.lineWidth = 0.5 * s;
    this.ctx.setLineDash([]);
    this.ctx.beginPath();
    this.ctx.moveTo(sx(x1), sy(y1));
    this.ctx.lineTo(sx(x1), sy(y1) - offset);
    this.ctx.moveTo(sx(x2), sy(y2));
    this.ctx.lineTo(sx(x2), sy(y2) - offset);
    this.ctx.stroke();

    // Dimension line
    this.ctx.strokeStyle = '#aaa';
    this.ctx.lineWidth = 1 * s;
    this.ctx.beginPath();
    this.ctx.moveTo(sx(x1), sy(y1) - offset);
    this.ctx.lineTo(sx(x2), sy(y2) - offset);
    this.ctx.stroke();

    // Arrows
    this.ctx.beginPath();
    this.ctx.moveTo(sx(x1), sy(y1) - offset);
    this.ctx.lineTo(sx(x1) + arrowSize, sy(y1) - offset - arrowSize / 2);
    this.ctx.moveTo(sx(x1), sy(y1) - offset);
    this.ctx.lineTo(sx(x1) + arrowSize, sy(y1) - offset + arrowSize / 2);
    this.ctx.moveTo(sx(x2), sy(y2) - offset);
    this.ctx.lineTo(sx(x2) - arrowSize, sy(y2) - offset - arrowSize / 2);
    this.ctx.moveTo(sx(x2), sy(y2) - offset);
    this.ctx.lineTo(sx(x2) - arrowSize, sy(y2) - offset + arrowSize / 2);
    this.ctx.stroke();

    // Text
    const midX = (x1 + x2) / 2;
    const midY = (y1 + y2) / 2;
    this.ctx.font = `${10 * s}px sans-serif`;
    this.ctx.fillStyle = '#ccc';
    this.ctx.textAlign = 'center';
    this.ctx.textBaseline = 'bottom';
    this.ctx.fillText(value || Math.sqrt((x2-x1)**2+(y2-y1)**2).toFixed(1), sx(midX), sy(midY) - offset - 4);
    this.ctx.textAlign = 'left';
    this.ctx.textBaseline = 'top';
  }

  private drawAngularDimension(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number, s: number, arrowSize: number, value: string): void {
    const p = el.properties;
    const vx = Number(p.x1 ?? el.x);
    const vy = Number(p.y1 ?? el.y);
    const ax1 = Number(p.ax1 ?? vx + 50);
    const ay1 = Number(p.ay1 ?? vy);
    const ax2 = Number(p.ax2 ?? vx + 50);
    const ay2 = Number(p.ay2 ?? vy + 50);
    const r = Number(p.radius) || 30;

    const a1 = Math.atan2(ay1 - vy, ax1 - vx);
    const a2 = Math.atan2(ay2 - vy, ax2 - vx);

    // Arc
    this.ctx.strokeStyle = '#aaa';
    this.ctx.lineWidth = 1 * s;
    this.ctx.beginPath();
    this.ctx.arc(sx(vx), sy(vy), r * s, a1, a2);
    this.ctx.stroke();

    // Extension lines
    this.ctx.strokeStyle = '#888';
    this.ctx.lineWidth = 0.5 * s;
    this.ctx.beginPath();
    this.ctx.moveTo(sx(vx), sy(vy));
    this.ctx.lineTo(sx(ax1), sy(ay1));
    this.ctx.moveTo(sx(vx), sy(vy));
    this.ctx.lineTo(sx(ax2), sy(ay2));
    this.ctx.stroke();

    // Text
    const midAngle = (a1 + a2) / 2;
    const tx = vx + Math.cos(midAngle) * (r + 10);
    const ty = vy + Math.sin(midAngle) * (r + 10);
    this.ctx.font = `${10 * s}px sans-serif`;
    this.ctx.fillStyle = '#ccc';
    this.ctx.textAlign = 'center';
    this.ctx.textBaseline = 'middle';
    this.ctx.fillText(value, sx(tx), sy(ty));
    this.ctx.textAlign = 'left';
    this.ctx.textBaseline = 'top';
  }

  private drawRadialDimension(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number, s: number, arrowSize: number, value: string): void {
    const p = el.properties;
    const cx = p.x1 ?? el.x;
    const cy = p.y1 ?? el.y;
    const ex = p.x2 ?? el.x + el.width;
    const ey = p.y2 ?? el.y;

    // Radial line
    this.ctx.strokeStyle = '#aaa';
    this.ctx.lineWidth = 1 * s;
    this.ctx.beginPath();
    this.ctx.moveTo(sx(cx), sy(cy));
    this.ctx.lineTo(sx(ex), sy(ey));
    this.ctx.stroke();

    // Arrow at end
    const angle = Math.atan2(ey - cy, ex - cx);
    this.ctx.beginPath();
    this.ctx.moveTo(sx(ex), sy(ey));
    this.ctx.lineTo(sx(ex) - arrowSize * Math.cos(angle - 0.3), sy(ey) - arrowSize * Math.sin(angle - 0.3));
    this.ctx.moveTo(sx(ex), sy(ey));
    this.ctx.lineTo(sx(ex) - arrowSize * Math.cos(angle + 0.3), sy(ey) - arrowSize * Math.sin(angle + 0.3));
    this.ctx.stroke();

    // Text
    const midX = (cx + ex) / 2;
    const midY = (cy + ey) / 2;
    this.ctx.font = `${10 * s}px sans-serif`;
    this.ctx.fillStyle = '#ccc';
    this.ctx.textAlign = 'center';
    this.ctx.textBaseline = 'bottom';
    this.ctx.fillText(value, sx(midX), sy(midY) - 4);
    this.ctx.textAlign = 'left';
    this.ctx.textBaseline = 'top';
  }

  private drawLeader(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number, s: number): void {
    const p = el.properties;
    const x1 = p.x1 ?? el.x;
    const y1 = p.y1 ?? el.y;
    const x2 = p.x2 ?? el.x;
    const y2 = p.y2 ?? el.y;
    const text = (p.text as string) || '';
    const fontSize = ((p.fontSize as number) || 12) * s;

    // Arrow at start point
    const angle = Math.atan2(y2 - y1, x2 - x1);
    const arrowSize = 6 * s;
    this.ctx.strokeStyle = p.stroke || '#e0e0e0';
    this.ctx.lineWidth = (p.strokeWidth as number) || 1;
    this.ctx.setLineDash([]);
    this.ctx.beginPath();
    this.ctx.moveTo(sx(x1), sy(y1));
    this.ctx.lineTo(sx(x1) + arrowSize * Math.cos(angle - 0.4), sy(y1) + arrowSize * Math.sin(angle - 0.4));
    this.ctx.moveTo(sx(x1), sy(y1));
    this.ctx.lineTo(sx(x1) + arrowSize * Math.cos(angle + 0.4), sy(y1) + arrowSize * Math.sin(angle + 0.4));
    this.ctx.stroke();

    // Leader line
    this.ctx.beginPath();
    this.ctx.moveTo(sx(x1), sy(y1));
    this.ctx.lineTo(sx(x2), sy(y2));
    // Small horizontal dogleg
    const doglegX = (x2 > x1 ? 1 : -1) * 20;
    this.ctx.lineTo(sx(x2 + doglegX), sy(y2));
    this.ctx.stroke();

    // Text
    if (text) {
      this.ctx.font = `${fontSize}px sans-serif`;
      this.ctx.fillStyle = p.stroke || '#e0e0e0';
      this.ctx.textBaseline = 'bottom';
      this.ctx.textAlign = x2 > x1 ? 'left' : 'right';
      this.ctx.fillText(text, sx(x2 + doglegX), sy(y2) - 2);
      this.ctx.textAlign = 'left';
      this.ctx.textBaseline = 'top';
    }
  }

  private drawRevCloud(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number, s: number): void {
    const p = el.properties;
    const points = (p.points as Array<{x:number;y:number}>) || [];
    if (points.length < 2) return;
    const arcHeight = ((p.arcHeight as number) || 8) * s;

    this.ctx.strokeStyle = p.stroke || '#e0e0e0';
    this.ctx.lineWidth = (p.strokeWidth as number) || 1.5;
    this.ctx.setLineDash([]);
    if (p.fill && p.fill !== 'none') {
      this.ctx.fillStyle = p.fill;
    }

    this.ctx.beginPath();
    for (let i = 0; i < points.length; i++) {
      const cur = points[i];
      const next = points[(i + 1) % points.length];
      const mx = (cur.x + next.x) / 2;
      const my = (cur.y + next.y) / 2;
      const dist = Math.sqrt((next.x - cur.x) ** 2 + (next.y - cur.y) ** 2);
      const bulge = Math.min(arcHeight / dist, 0.5);
      // Draw arc segment as quadratic curve with bulge
      const cpX = mx + (next.y - cur.y) * bulge;
      const cpY = my - (next.x - cur.x) * bulge;
      if (i === 0) this.ctx.moveTo(sx(cur.x), sy(cur.y));
      this.ctx.quadraticCurveTo(sx(cpX), sy(cpY), sx(next.x), sy(next.y));
    }
    this.ctx.closePath();
    if (p.fill && p.fill !== 'none') this.ctx.fill();
    this.ctx.stroke();
  }

  private drawBlockInstance(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number, s: number): void {
    const blockId = el.properties.blockId as string;
    const blockDef = this.blockDefinitions.get(blockId);
    if (!blockDef) {
      // Fallback: bounding box
      const w = el.width * s;
      const h = el.height * s;
      this.ctx.strokeStyle = '#666';
      this.ctx.setLineDash([4, 4]);
      this.ctx.strokeRect(sx(el.x) - w / 2, sy(el.y) - h / 2, w, h);
      this.ctx.setLineDash([]);
      return;
    }

    const rotation = (el.properties.rotation || 0) * Math.PI / 180;
    const scale = (el.properties.scale || 1) * s;
    const ox = el.properties.offsetX || 0;
    const oy = el.properties.offsetY || 0;
    const cx = sx(el.x);
    const cy = sy(el.y);

    this.ctx.save();
    this.ctx.translate(cx, cy);
    this.ctx.rotate(rotation);

    for (const childEl of blockDef.elements) {
      const lx = (childEl.x + Number(ox)) * scale;
      const ly = (childEl.y + Number(oy)) * scale;
      const lw = childEl.width * scale;
      const lh = childEl.height * scale;
      const props = { ...childEl.properties };

      this.ctx.save();
      if (props.fill) this.ctx.fillStyle = props.fill;
      this.ctx.strokeStyle = props.stroke || '#999';
      this.ctx.lineWidth = Math.max(0.5, 1 * s);

      switch (childEl.type) {
        case 'rect':
          if (props.fill) this.ctx.fillRect(lx - lw / 2, ly - lh / 2, lw, lh);
          this.ctx.strokeRect(lx - lw / 2, ly - lh / 2, lw, lh);
          break;
        case 'circle': {
          const r = (props.radius || lw / 2) * scale / s;
          this.ctx.beginPath();
          this.ctx.arc(lx, ly, r, 0, Math.PI * 2);
          if (props.fill) this.ctx.fill();
          this.ctx.stroke();
          break;
        }
        case 'line': {
          const x1 = (Number(props.x1) + Number(ox)) * scale;
          const y1 = (Number(props.y1) + Number(oy)) * scale;
          const x2 = (Number(props.x2) + Number(ox)) * scale;
          const y2 = (Number(props.y2) + Number(oy)) * scale;
          this.ctx.beginPath();
          this.ctx.moveTo(x1, y1);
          this.ctx.lineTo(x2, y2);
          this.ctx.stroke();
          break;
        }
        case 'arc': {
          const r = (props.radius || lw / 2) * scale / s;
          const startAngle = (props.startAngle || 0) * Math.PI / 180;
          const endAngle = (props.endAngle || 360) * Math.PI / 180;
          this.ctx.beginPath();
          this.ctx.arc(lx, ly, r, startAngle, endAngle);
          this.ctx.stroke();
          break;
        }
      }
      this.ctx.restore();
    }

    this.ctx.restore();
  }

  private drawChair(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number, s: number): void {
    const w = el.width * s;
    const h = el.height * s;
    const cx = sx(el.x);
    const cy = sy(el.y);
    const rot = (el.properties.rotation || 0) * Math.PI / 180;

    this.ctx.save();
    this.ctx.translate(cx, cy);
    this.ctx.rotate(rot);

    // Seat
    if (el.properties.fill) {
      this.ctx.fillStyle = el.properties.fill;
    } else {
      this.ctx.fillStyle = '#4a90d9';
    }
    this.ctx.fillRect(-w / 2, -h / 2, w, h);

    // Backrest (top portion)
    this.ctx.fillStyle = '#3a7ac9';
    this.ctx.fillRect(-w / 2, -h / 2, w, h * 0.2);

    // Outline
    this.ctx.strokeStyle = '#2a5a99';
    this.ctx.lineWidth = 0.5;
    this.ctx.strokeRect(-w / 2, -h / 2, w, h);

    this.ctx.restore();
  }

  private drawTable(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number, s: number): void {
    const w = el.width * s;
    const h = el.height * s;
    const cx = sx(el.x);
    const cy = sy(el.y);
    const rot = (el.properties.rotation || 0) * Math.PI / 180;
    const shape = el.properties.shape || 'rect';

    this.ctx.save();
    this.ctx.translate(cx, cy);
    this.ctx.rotate(rot);

    if (shape === 'round') {
      const r = Math.min(w, h) / 2;
      this.ctx.fillStyle = el.properties.fill || '#8b6f47';
      this.ctx.beginPath();
      this.ctx.arc(0, 0, r, 0, Math.PI * 2);
      this.ctx.fill();
      this.ctx.strokeStyle = el.properties.stroke || '#5a4a37';
      this.ctx.lineWidth = (el.properties.strokeWidth || 1.5) * s;
      this.ctx.stroke();
    } else {
      this.ctx.fillStyle = el.properties.fill || '#8b6f47';
      this.ctx.fillRect(-w / 2, -h / 2, w, h);
      this.ctx.strokeStyle = el.properties.stroke || '#5a4a37';
      this.ctx.lineWidth = (el.properties.strokeWidth || 1.5) * s;
      this.ctx.strokeRect(-w / 2, -h / 2, w, h);
    }

    this.ctx.restore();
  }

  private drawStage(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number, s: number): void {
    const w = el.width * s;
    const h = el.height * s;
    const cx = sx(el.x);
    const cy = sy(el.y);
    const rot = (el.properties.rotation || 0) * Math.PI / 180;

    this.ctx.save();
    this.ctx.translate(cx, cy);
    this.ctx.rotate(rot);

    // Stage floor
    this.ctx.fillStyle = el.properties.fill || '#2c3e50';
      this.ctx.fillRect(-w / 2, -h / 2, w, h);

    // Border
    this.ctx.strokeStyle = el.properties.stroke || '#1a2e3f';
    this.ctx.lineWidth = (el.properties.strokeWidth || 2) * s;
    this.ctx.strokeRect(-w / 2, -h / 2, w, h);

    // Label
    const label = el.properties.label as string || 'Bühne';
    this.ctx.fillStyle = '#fff';
    this.ctx.font = `${Math.max(10, 14 * s)}px Inter, sans-serif`;
    this.ctx.textAlign = 'center';
    this.ctx.textBaseline = 'middle';
    this.ctx.fillText(label, 0, 0);

    this.ctx.restore();
  }

  private drawSelectionHandles(el: CADElement, sx: (v:number)=>number, sy: (v:number)=>number, s: number): void {
    const w = el.width * s;
    const h = el.height * s;
    const x = sx(el.x) - w / 2;
    const y = sy(el.y) - h / 2;
    const handleSize = 6;
    this.ctx.fillStyle = '#00aaff';
    this.ctx.strokeStyle = '#fff';
    this.ctx.lineWidth = 1;
    const corners = [
      [x, y], [x + w, y], [x, y + h], [x + w, y + h],
      [x + w / 2, y], [x + w / 2, y + h], [x, y + h / 2], [x + w, y + h / 2],
    ];
    for (const [hx, hy] of corners) {
      this.ctx.fillRect(hx - handleSize / 2, hy - handleSize / 2, handleSize, handleSize);
      this.ctx.strokeRect(hx - handleSize / 2, hy - handleSize / 2, handleSize, handleSize);
    }
  }

  private drawGroupBoxes(): void {
    if (this.groups.length === 0) return;
    const s = this.zoomPan.getScale();
    const ox = this.zoomPan.getTransform().e;
    const oy = this.zoomPan.getTransform().f;
    const visibleElements = this.spatialIndex.search(this.zoomPan.getViewport());
    const elementMap = new Map(visibleElements.map(e => [e.id, e]));

    for (const group of this.groups) {
      const els = group.elementIds.map(id => elementMap.get(id)).filter((e): e is CADElement => e !== undefined);
      if (els.length === 0) continue;

      let minX = Infinity, minY = Infinity, maxX = -Infinity, maxY = -Infinity;
      for (const el of els) {
        const bb = this.getElementBBox(el);
        minX = Math.min(minX, bb.minX);
        minY = Math.min(minY, bb.minY);
        maxX = Math.max(maxX, bb.maxX);
        maxY = Math.max(maxY, bb.maxY);
      }
      if (minX === Infinity) continue;

      const sx1 = minX * s + ox;
      const sy1 = minY * s + oy;
      const sx2 = maxX * s + ox;
      const sy2 = maxY * s + oy;
      const pad = 4;

      this.ctx.save();
      this.ctx.strokeStyle = '#ff9800';
      this.ctx.lineWidth = 1.5;
      this.ctx.setLineDash([6, 4]);
      this.ctx.strokeRect(sx1 - pad, sy1 - pad, (sx2 - sx1) + pad * 2, (sy2 - sy1) + pad * 2);
      this.ctx.setLineDash([]);

      // Group name label
      this.ctx.font = '11px sans-serif';
      this.ctx.fillStyle = '#ff9800';
      this.ctx.textAlign = 'left';
      this.ctx.textBaseline = 'top';
      this.ctx.fillText(group.name, sx1 - pad + 2, sy1 - pad - 14);
      this.ctx.restore();
    }
  }

  private drawSelectionBox(): void {
    if (!this.selection.boxStart || !this.selection.boxEnd) return;
    const s = this.zoomPan.getScale();
    const ox = this.zoomPan.getTransform().e;
    const oy = this.zoomPan.getTransform().f;
    const x1 = this.selection.boxStart.x * s + ox;
    const y1 = this.selection.boxStart.y * s + oy;
    const x2 = this.selection.boxEnd.x * s + ox;
    const y2 = this.selection.boxEnd.y * s + oy;
    this.ctx.strokeStyle = '#00aaff';
    this.ctx.fillStyle = 'rgba(0, 170, 255, 0.1)';
    this.ctx.lineWidth = 1;
    this.ctx.setLineDash([4, 4]);
    this.ctx.fillRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2 - x1), Math.abs(y2 - y1));
    this.ctx.strokeRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2 - x1), Math.abs(y2 - y1));
    this.ctx.setLineDash([]);
  }

  private drawSnapPoints(): void {
    const s = this.zoomPan.getScale();
    const ox = this.zoomPan.getTransform().e;
    const oy = this.zoomPan.getTransform().f;
    for (const pt of this.snapPoints) {
      const x = pt.x * s + ox;
      const y = pt.y * s + oy;
      const isActive = this.activeSnapPoint?.x === pt.x && this.activeSnapPoint?.y === pt.y;
      this.ctx.fillStyle = isActive ? '#ff0' : '#0f0';
      this.ctx.beginPath();
      this.ctx.arc(x, y, isActive ? 6 : 4, 0, Math.PI * 2);
      this.ctx.fill();
    }
  }

  private drawOrtho(): void {
    // Draw ortho tracking line from cursor
    // Placeholder — will be connected to interaction engine
  }

  // Hit testing
  hitTest(worldX: number, worldY: number, tolerance: number = 5): CADElement | null {
    const viewport = this.zoomPan.getViewport();
    const candidates = this.spatialIndex.search({
      minX: worldX - tolerance, minY: worldY - tolerance,
      maxX: worldX + tolerance, maxY: worldY + tolerance,
    });
    const visibleLayerIds = new Set(
      this.layerManager.getVisibleLayers().map(l => l.id),
    );
    let best: CADElement | null = null;
    let bestDist = tolerance;
    for (const el of candidates) {
      if (!visibleLayerIds.has(el.layerId)) continue;
      const dist = this.elementDistance(el, worldX, worldY);
      if (dist < bestDist) {
        bestDist = dist;
        best = el;
      }
    }
    return best;
  }

  private elementDistance(el: CADElement, x: number, y: number): number {
    const p = el.properties;
    switch (el.type) {
      case 'line': {
        const x1 = p.x1 ?? el.x;
        const y1 = p.y1 ?? el.y;
        const x2 = p.x2 ?? el.x + el.width;
        const y2 = p.y2 ?? el.y + el.height;
        return this.pointToSegmentDist(x, y, x1, y1, x2, y2);
      }
      case 'circle': {
        const r = p.radius || el.width / 2;
        const d = Math.sqrt((x - el.x) ** 2 + (y - el.y) ** 2);
        return Math.abs(d - r);
      }
      case 'rect':
      case 'table':
      case 'stage': {
        const halfW = el.width / 2;
        const halfH = el.height / 2;
        const dx = Math.max(Math.abs(x - el.x) - halfW, 0);
        const dy = Math.max(Math.abs(y - el.y) - halfH, 0);
        return Math.sqrt(dx * dx + dy * dy);
      }
      case 'polyline':
      case 'polygon': {
        const pts = p.points || [];
        let minDist = Infinity;
        for (let i = 0; i < pts.length - 1; i++) {
          const d = this.pointToSegmentDist(x, y, pts[i].x, pts[i].y, pts[i + 1].x, pts[i + 1].y);
          minDist = Math.min(minDist, d);
        }
        if (el.type === 'polygon' && pts.length > 2) {
          const d = this.pointToSegmentDist(x, y, pts[pts.length - 1].x, pts[pts.length - 1].y, pts[0].x, pts[0].y);
          minDist = Math.min(minDist, d);
        }
        return minDist;
      }
      default: {
        const halfW = el.width / 2;
        const halfH = el.height / 2;
        const dx = Math.max(Math.abs(x - el.x) - halfW, 0);
        const dy = Math.max(Math.abs(y - el.y) - halfH, 0);
        return Math.sqrt(dx * dx + dy * dy);
      }
    }
  }

  private pointToSegmentDist(px: number, py: number, x1: number, y1: number, x2: number, y2: number): number {
    const dx = x2 - x1;
    const dy = y2 - y1;
    const lenSq = dx * dx + dy * dy;
    if (lenSq === 0) return Math.sqrt((px - x1) ** 2 + (py - y1) ** 2);
    let t = ((px - x1) * dx + (py - y1) * dy) / lenSq;
    t = Math.max(0, Math.min(1, t));
    const cx = x1 + t * dx;
    const cy = y1 + t * dy;
    return Math.sqrt((px - cx) ** 2 + (py - cy) ** 2);
  }

  // Bounding box for an element
  getElementBBox(el: CADElement): BoundingBox {
    const halfW = el.width / 2;
    const halfH = el.height / 2;
    return {
      minX: el.x - halfW, minY: el.y - halfH,
      maxX: el.x + halfW, maxY: el.y + halfH,
    };
  }

  // Get elements within a world-space rectangle (for box selection)
  getElementsInRect(minX: number, minY: number, maxX: number, maxY: number): CADElement[] {
    const candidates = this.spatialIndex.search({ minX, minY, maxX, maxY });
    const visibleLayerIds = new Set(
      this.layerManager.getVisibleLayers().map(l => l.id),
    );
    return candidates.filter(el => {
      if (!visibleLayerIds.has(el.layerId)) return false;
      const bb = this.getElementBBox(el);
      return bb.minX >= minX && bb.maxX <= maxX && bb.minY >= minY && bb.maxY <= maxY;
    });
  }

  // Get elements intersecting a world-space rectangle (for crossing selection)
  getElementsIntersectingRect(minX: number, minY: number, maxX: number, maxY: number): CADElement[] {
    const candidates = this.spatialIndex.search({ minX, minY, maxX, maxY });
    const visibleLayerIds = new Set(
      this.layerManager.getVisibleLayers().map(l => l.id),
    );
    return candidates.filter(el => {
      if (!visibleLayerIds.has(el.layerId)) return false;
      const bb = this.getElementBBox(el);
      // Check if bbox intersects the rect (not necessarily fully enclosed)
      return bb.minX <= maxX && bb.maxX >= minX && bb.minY <= maxY && bb.maxY >= minY;
    });
  }
}