feat: (#1113) save map view state

src/app/(maps)/components/FullScreenMap.tsx

@@ -1,11 +1,24 @@
 'use client'
-import { useEffect, useState } from 'react'
-import { GlobalMap } from '@/components/maps/GlobalMap'
+import { useCallback, useEffect, useState } from 'react'
+import { CameraInfo, GlobalMap } from '@/components/maps/GlobalMap'
+import { usePathname, useRouter, useSearchParams } from 'next/navigation'
 
 export const FullScreenMap: React.FC = () => {
   const [initialCenter, setInitialCenter] = useState<[number, number] | undefined>(undefined)
+  const [initialZoom, setInitialZoom] = useState<number | undefined>(undefined)
+  const router = useRouter()
+
+  const cameraParams = useCameraParams()
 
   useEffect(() => {
+    const initialStateFromUrl = cameraParams.fromUrl()
+
+    if (initialStateFromUrl != null) {
+      setInitialCenter([initialStateFromUrl.center.lng, initialStateFromUrl.center.lat])
+      setInitialZoom(initialStateFromUrl.zoom)
+      return
+    }
+
     getVisitorLocation().then((visitorLocation) => {
       if (visitorLocation != null) {
         setInitialCenter([visitorLocation.longitude, visitorLocation.latitude])
@@ -15,10 +28,18 @@ export const FullScreenMap: React.FC = () => {
     })
   }, [])
 
+  const handleCamerMovement = useCallback((camera: CameraInfo) => {
+    const url = cameraParams.toUrl(camera)
+
+    router.replace(url, { scroll: false })
+  }, [])
+
   return (
     <GlobalMap
       showFullscreenControl={false}
       initialCenter={initialCenter}
+      initialZoom={initialZoom}
+      onCameraMovement={handleCamerMovement}
     />
   )
 }
@@ -32,3 +53,51 @@ const getVisitorLocation = async (): Promise<{ longitude: number, latitude: numb
     return undefined
   }
 }
+
+function useCameraParams (): { toUrl: (camera: CameraInfo) => string, fromUrl: () => CameraInfo | null } {
+  const pathname = usePathname()
+  const initialSearchParams = useSearchParams()
+
+  function toUrl (camera: CameraInfo): string {
+    const params = new URLSearchParams(initialSearchParams)
+    params.delete('camera')
+
+    const queryParams = [
+      params.toString(),
+      `camera=${cameraInfoToQuery(camera)}`
+    ]
+
+    return `${pathname}?${queryParams.filter(Boolean).join('&')}`
+  }
+
+  function fromUrl (): CameraInfo | null {
+    const cameraParams = initialSearchParams.get('camera')
+    if (cameraParams == null) {
+      return null
+    }
+
+    return queryToCameraInfo(cameraParams)
+  }
+
+  return { toUrl, fromUrl }
+}
+
+const cameraInfoToQuery = ({ zoom, center }: CameraInfo): string => {
+  return `${Math.ceil(zoom)}/${center.lat.toFixed(5)}/${center.lng.toFixed(5)}`
+}
+
+const queryToCameraInfo = (cameraParam: string): CameraInfo | null => {
+  const [zoomRaw, latitude, longitude] = cameraParam.split('/')
+  const lat = parseFloat(latitude)
+  const lng = parseFloat(longitude)
+  const zoom = parseInt(zoomRaw, 10)
+
+  if ([lat, lng, zoom].some(isNaN)) {
+    return null
+  }
+
+  return {
+    center: { lat, lng },
+    zoom
+  }
+}

src/components/maps/GlobalMap.tsx

@@ -1,6 +1,6 @@
 'use client'
 import { useCallback, useState } from 'react'
-import { Map, FullscreenControl, ScaleControl, NavigationControl, MapLayerMouseEvent, MapInstance } from 'react-map-gl/maplibre'
+import { Map, FullscreenControl, ScaleControl, NavigationControl, MapLayerMouseEvent, MapInstance, ViewStateChangeEvent } from 'react-map-gl/maplibre'
 import maplibregl, { MapLibreEvent } from 'maplibre-gl'
 import { Point, Polygon } from '@turf/helpers'
 import dynamic from 'next/dynamic'
@@ -13,6 +13,7 @@ import { OBCustomLayers } from './OBCustomLayers'
 import { AreaType, ClimbType, MediaWithTags } from '@/js/types'
 import { TileProps, transformTileProps } from './utils'
 import MapLayersSelector from './MapLayersSelector'
+import { debounce } from 'underscore'
 
 export type SimpleClimbType = Pick<ClimbType, 'id' | 'name' | 'type'>
 
@@ -28,21 +29,31 @@ export interface HoverInfo {
   mapInstance: MapInstance
 }
 
+export interface CameraInfo {
+  center: {
+    lng: number
+    lat: number
+  }
+  zoom: number
+}
+
 interface GlobalMapProps {
   showFullscreenControl?: boolean
   initialCenter?: [number, number]
+  initialZoom?: number
   initialViewState?: {
     bounds: maplibregl.LngLatBoundsLike
     fitBoundsOptions: maplibregl.FitBoundsOptions
   }
+  onCameraMovement?: (camera: CameraInfo) => void
   children?: React.ReactNode
 }
 
 /**
  * Global map
  */
 export const GlobalMap: React.FC<GlobalMapProps> = ({
-  showFullscreenControl = true, initialCenter, initialViewState, children
+  showFullscreenControl = true, initialCenter, initialZoom, initialViewState, onCameraMovement, children
 }) => {
   const [clickInfo, setClickInfo] = useState<MapAreaFeatureProperties | null>(null)
   const [hoverInfo, setHoverInfo] = useState<HoverInfo | null>(null)
@@ -51,11 +62,23 @@ export const GlobalMap: React.FC<GlobalMapProps> = ({
   const [cursor, setCursor] = useState<string>('default')
   const [mapStyle, setMapStyle] = useState<string>(MAP_STYLES.standard.style)
 
+  const onMove = useCallback(debounce((e: ViewStateChangeEvent) => {
+    if (onCameraMovement != null) {
+      onCameraMovement({
+        center: {
+          lat: e.viewState.latitude,
+          lng: e.viewState.longitude
+        },
+        zoom: e.viewState.zoom
+      })
+    }
+  }, 300), [])
+
   const onLoad = useCallback((e: MapLibreEvent) => {
     if (e.target == null) return
     setMapInstance(e.target)
-    if (initialCenter != null) {
-      e.target.jumpTo({ center: initialCenter, zoom: 6 })
+    if (initialCenter != null && initialZoom != null) {
+      e.target.jumpTo({ center: initialCenter, zoom: initialZoom })
     } else if (initialViewState != null) {
       e.target.fitBounds(initialViewState.bounds, initialViewState.fitBoundsOptions)
     }
@@ -121,6 +144,7 @@ export const GlobalMap: React.FC<GlobalMapProps> = ({
         onDragStart={() => {
           setCursor('move')
         }}
+        onMove={onMove}
         onDragEnd={() => {
           setCursor('default')
         }}