ttrpg-tools/src/plotcutter/contour.ts

export type CardShape = 'rectangle' | 'circle' | 'triangle' | 'hexagon';

export interface ContourPoint {
  x: number;
  y: number;
}

export interface ContourBounds {
  minX: number;
  minY: number;
  maxX: number;
  maxY: number;
}

/**
 * 生成带圆角的矩形轮廓点
 * @param width 矩形宽度
 * @param height 矩形高度
 * @param cornerRadius 圆角半径（mm）
 * @param segmentsPerCorner 每个圆角的分段数
 */
export function getRoundedRectPoints(
  width: number,
  height: number,
  cornerRadius: number,
  segmentsPerCorner: number = 4
): [number, number][] {
  const points: [number, number][] = [];
  const r = Math.min(cornerRadius, width / 2, height / 2);

  if (r <= 0) {
    // 无圆角，返回普通矩形
    points.push([0, 0]);
    points.push([width, 0]);
    points.push([width, height]);
    points.push([0, height]);
    return points;
  }

  // 左上角圆角（从顶部开始，顺时针）
  for (let i = 0; i <= segmentsPerCorner; i++) {
    const angle = (Math.PI / 2) * (i / segmentsPerCorner) - Math.PI;
    points.push([
      r + r * Math.cos(angle),
      r + r * Math.sin(angle)
    ]);
  }

  // 右上角圆角
  for (let i = 0; i <= segmentsPerCorner; i++) {
    const angle = (Math.PI / 2) * (i / segmentsPerCorner) - Math.PI/2;
    points.push([
      width - r + r * Math.cos(angle),
      r + r * Math.sin(angle)
    ]);
  }

  // 右下角圆角
  for (let i = 0; i <= segmentsPerCorner; i++) {
    const angle = (Math.PI / 2) * (i / segmentsPerCorner);
    points.push([
      width - r + r * Math.cos(angle),
      height - r + r * Math.sin(angle)
    ]);
  }

  // 左下角圆角
  for (let i = 0; i <= segmentsPerCorner; i++) {
    const angle = (Math.PI / 2) * (i / segmentsPerCorner) + Math.PI/2;
    points.push([
      r + r * Math.cos(angle),
      height - r + r * Math.sin(angle)
    ]);
  }

  return points;
}

/**
 * 根据形状生成卡片轮廓点（单位：mm，相对于卡片左下角）
 */
export function getCardShapePoints(
  shape: CardShape,
  width: number,
  height: number,
  cornerRadius: number = 0
): [number, number][] {
  if (shape === 'rectangle' && cornerRadius > 0) {
    return getRoundedRectPoints(width, height, cornerRadius);
  }

  const points: [number, number][] = [];

  switch (shape) {
    case 'circle': {
      const radius = Math.min(width, height) / 2;
      const centerX = width / 2;
      const centerY = height / 2;
      for (let i = 0; i < 36; i++) {
        const angle = (i / 36) * Math.PI * 2;
        points.push([
          centerX + radius * Math.cos(angle),
          centerY + radius * Math.sin(angle)
        ]);
      }
      break;
    }
    case 'triangle': {
      points.push([width / 2, 0]);
      points.push([0, height]);
      points.push([width, height]);
      break;
    }
    case 'hexagon': {
      const halfW = width / 2;
      const quarterH = height / 4;
      points.push([halfW, 0]);
      points.push([width, quarterH]);
      points.push([width, height - quarterH]);
      points.push([halfW, height]);
      points.push([0, height - quarterH]);
      points.push([0, quarterH]);
      break;
    }
    case 'rectangle':
    default: {
      points.push([0, 0]);
      points.push([width, 0]);
      points.push([width, height]);
      points.push([0, height]);
      break;
    }
  }

  return points;
}

/**
 * 计算多边形的中心点
 */
export function calculateCenter(points: [number, number][]): { x: number; y: number } {
  let sumX = 0;
  let sumY = 0;
  for (const [x, y] of points) {
    sumX += x;
    sumY += y;
  }
  return {
    x: sumX / points.length,
    y: sumY / points.length
  };
}

/**
 * 计算轮廓的边界框
 */
export function calculateBounds(points: [number, number][]): ContourBounds {
  if (points.length === 0) {
    return { minX: 0, minY: 0, maxX: 0, maxY: 0 };
  }

  let minX = Infinity;
  let minY = Infinity;
  let maxX = -Infinity;
  let maxY = -Infinity;

  for (const [x, y] of points) {
    minX = Math.min(minX, x);
    minY = Math.min(minY, y);
    maxX = Math.max(maxX, x);
    maxY = Math.max(maxY, y);
  }

  return { minX, minY, maxX, maxY };
}

/**
 * 根据进度计算点在路径上的位置
 */
export function getPointOnPath(points: [number, number][], progress: number): [number, number] {
  if (points.length === 0) return [0, 0];
  if (points.length === 1) return points[0];

  const totalSegments = points.length;
  const scaledProgress = progress * totalSegments;
  const segmentIndex = Math.floor(scaledProgress);
  const segmentProgress = scaledProgress - segmentIndex;

  const currentIndex = Math.min(segmentIndex, points.length - 1);
  const nextIndex = (currentIndex + 1) % points.length;

  const [x1, y1] = points[currentIndex];
  const [x2, y2] = points[nextIndex];

  return [
    x1 + (x2 - x1) * segmentProgress,
    y1 + (y2 - y1) * segmentProgress
  ];
}

/**
 * 将轮廓点转换为 SVG path 命令
 * @param points 轮廓点数组
 * @param closed 是否闭合路径
 */
export function contourToSvgPath(points: [number, number][], closed = true): string {
  if (points.length === 0) return '';

  const [startX, startY] = points[0];
  let d = `M ${startX} ${startY}`;

  for (let i = 1; i < points.length; i++) {
    const [x, y] = points[i];
    d += ` L ${x} ${y}`;
  }

  if (closed) {
    d += ' Z';
  }

  return d;
}

/**
 * 平移轮廓点（添加偏移量）
 */
export function translateContour(
  points: [number, number][],
  offsetX: number,
  offsetY: number
): [number, number][] {
  return points.map(([x, y]) => [x + offsetX, y + offsetY] as [number, number]);
}

/**
 * 翻转轮廓（用于 SVG 坐标转换，Y 轴翻转）
 * @param points 轮廓点
 * @param height 画布高度
 */
export function flipContourY(
  points: [number, number][],
  height: number
): [number, number][] {
  return points.map(([x, y]) => [x, height - y] as [number, number]);
}