export type LngLat = [number, number]

/**
 * generateInnerPolygon (noop)
 * 外圈/回字形内圈生成逻辑已移除 — 保留同名导出以避免调用处报错。
 * 返回空数组表示不生成内圈。
 */
export function generateInnerPolygon(outer: Array<LngLat>, insetRatio = 0.25): Array<LngLat> {
  // outer: expected 4 points in order (clockwise or ccw). We compute the polygon
  // that is an inward-scaled rectangle centered at the outer centroid.
  // insetRatio: 0..0.5, how far the inner polygon is from the outer towards center.
  if (!outer || outer.length < 4) return []

  // clamp insetRatio
  const r = Math.max(0, Math.min(0.49, insetRatio))

  // compute centroid (average)
  let cx = 0
  let cy = 0
  outer.forEach(p => {
    cx += p[0]
    cy += p[1]
  })
  cx = cx / outer.length
  cy = cy / outer.length

  // for each corner, move it toward centroid by ratio r
  const inner: Array<LngLat> = outer.map((p): LngLat => {
    const dx = p[0] - cx
    const dy = p[1] - cy
    return [cx + dx * (1 - r), cy + dy * (1 - r)]
  })

  return inner
}