signal-batch/frontend/src/features/vessel-map/utils/viewport.ts

import type maplibregl from 'maplibre-gl'
import type { ViewportBounds, VesselPosition } from '../types'

/** 맵 인스턴스에서 현재 뷰포트 바운드 추출 */
export function getViewportBounds(map: maplibregl.Map): ViewportBounds {
  const bounds = map.getBounds()
  return {
    west: bounds.getWest(),
    south: bounds.getSouth(),
    east: bounds.getEast(),
    north: bounds.getNorth(),
  }
}

/** 바운드 내부에 있는 선박만 필터링 */
export function filterByViewport<T extends { lon: number; lat: number }>(
  positions: T[],
  bounds: ViewportBounds,
): T[] {
  return positions.filter(
    (p) =>
      p.lon >= bounds.west &&
      p.lon <= bounds.east &&
      p.lat >= bounds.south &&
      p.lat <= bounds.north,
  )
}

/** 바운드를 마진(비율)만큼 확장 */
export function expandBounds(bounds: ViewportBounds, margin = 0.1): ViewportBounds {
  const lonSpan = bounds.east - bounds.west
  const latSpan = bounds.north - bounds.south
  return {
    west: bounds.west - lonSpan * margin,
    south: bounds.south - latSpan * margin,
    east: bounds.east + lonSpan * margin,
    north: bounds.north + latSpan * margin,
  }
}

/** VesselPosition 배열의 전체 바운드 계산 (fitBounds용) */
export function calcPositionBounds(positions: VesselPosition[]): ViewportBounds | null {
  if (positions.length === 0) return null
  let west = Infinity, south = Infinity, east = -Infinity, north = -Infinity
  for (const p of positions) {
    if (p.lon < west) west = p.lon
    if (p.lon > east) east = p.lon
    if (p.lat < south) south = p.lat
    if (p.lat > north) north = p.lat
  }
  return { west, south, east, north }
}