From 3952bb441b6ac5a1c92e9fe21b6fd3f59d80d0cf Mon Sep 17 00:00:00 2001
From: Bob Bol <bob@voorhoede.nl>
Date: Thu, 8 Oct 2020 17:12:22 +0200
Subject: [PATCH 1/2] keep an internal list of ordered layers that matches the
 order of layers on the mapbox instance

---
 src/components/VMapbox.vue       | 97 +++++++++++++++++++++++++++-----
 src/components/v-mapbox-layer.js | 57 +++++--------------
 src/stories/index.stories.js     |  4 +-
 src/utils/helpers.js             |  1 +
 4 files changed, 101 insertions(+), 58 deletions(-)
 create mode 100644 src/utils/helpers.js

diff --git a/src/components/VMapbox.vue b/src/components/VMapbox.vue
index 117d14e..f5d84a3 100644
--- a/src/components/VMapbox.vue
+++ b/src/components/VMapbox.vue
@@ -14,6 +14,7 @@
 <script>
 import mapboxgl from 'mapbox-gl'
 import { propsBinder, propsDefaults } from '../utils/propsBinder.js'
+import { uniqueInArrayById } from '../utils/helpers'
 import { bindMapEvents } from '../utils/eventsBinder.js'
 
 const MAP_EVENTS = [
@@ -146,31 +147,88 @@ export const props = {
 export default {
   name: 'v-mapbox',
 
-  // @QUESTION :: Why is this back? Now the whole map is reactive again..
   data () {
     return {
-	    map: null
+      map: null,  // @QUESTION :: Why is this back? Now the whole map is reactive again..
+      mapInitialized: false,
+      mapLayers: []
     }
   },
 
   props,
 
   provide () {
-    // Allows us to use inject: ['getMap'] in child components
     return {
-      getMap: () => this.map
+      getMap: () => this.map,
+      getMapMethods: () => ({
+        addLayer: this.addLayerToArray,
+        removeLayer: this.removeLayerFromArray,
+        updateLayer: this.updateLayer
+      }),
     }
   },
 
   methods: {
-    addLayers () {
-      // @TODO :: consider sorting or using slots if we run into render order problems
-      // let [...children] = this.$children
-      // children.sort(child => {
-      //   return child.key
-      // })
+    addLayerToArray(layerOptions, beforeId) {
+      // If we get a `beforeId`, we insert layer at that index
+      if(beforeId && beforeId !== layerOptions.id) {
+        const existingLayerIndex = this.mapLayers.findIndex(({ id }) => id === beforeId)
+        if(existingLayerIndex !== -1) {
+          this.mapLayers = Object.freeze([
+            ...this.mapLayers.slice(0, existingLayerIndex),
+            layerOptions,
+            ...this.mapLayers.slice(existingLayerIndex),
+          ])
+          return
+        }
+      }
+      // Otherwise we just add it at the tail
+      this.mapLayers = Object.freeze([ ...this.mapLayers, layerOptions ])
+    },
+
+    addLayerToMap(layerOptions) {
+      // We use the position in the array to predictably match
+      // the layer order in the mapbox instance
+      const thisIndex = this.mapLayers.findIndex(({ id }) => id === layerOptions.id)
+      const nextItem = this.mapLayers[thisIndex + 1]
+      const maybeBefore = nextItem ? nextItem.id : undefined
+      const existingLayer = this.map.getLayer(maybeBefore)
+      const before = existingLayer ? maybeBefore : undefined
+      this.map.addLayer(layerOptions, before)
+    },
+
+    removeLayerFromArray(layerId) {
+      this.mapLayers = this.mapLayers.filter(({ id }) => id !== layerId)
+    },
+
+    removeLayerFromMap(layerId) {
+      if(!this.map) return
+      const layer = this.map.getLayer(layerId)
+      if(!layer) return
+      const layerSource = layer.source
+      this.map.removeLayer(layerId)
+      if(layerSource && !this.map.getStyle().layers.some(({ source }) => source === layerSource)) {
+        this.map.removeSource(layerSource)
+      }
+    },
+
+    updateLayer(newLayerOptions) {
+      const index = this.mapLayers.findIndex(({ id }) => id === newLayerOptions.id)
+      if(index === -1) return
+      this.mapLayers = Object.freeze(
+        Object.assign([], this.mapLayers, { [index]: newLayerOptions })
+      )
+      this.removeLayerFromMap(newLayerOptions.id)
+      this.addLayerToMap(newLayerOptions)
+    },
+
+    addAllChildren () {
+      // Add layers
+      this.mapLayers.forEach(this.addLayerToMap)
+      // Add other children
       this.$children.forEach(child => {
-        child.deferredMountedTo(this.map)
+        if(child.deferredMountedTo)
+          child.deferredMountedTo(this.map)
       })
     },
 
@@ -205,13 +263,14 @@ export default {
 
     // Once the map is loaded, add all layers that were present during mount time
     this.$on('mb-load', () => {
-      this.addLayers()
+      this.mapInitialized = true
+      this.addAllChildren()
     })
 
     // If the style was changed, wait for the styledata to be loaded and re-add all the layers
     this.$on('style:update', () => {
       this.$once('mb-styledata', () => {
-        this.addLayers()
+        this.addAllChildren()
       })
     })
 
@@ -221,6 +280,16 @@ export default {
     let observer = new ResizeObserver(this.resize)
     observer.observe(this.$el)
     this.resizeObserver = observer
-  }
+  },
+
+  watch: {
+    mapLayers(newArr, oldArr) {
+      if(!this.mapInitialized) return
+      const addedLayers = uniqueInArrayById(newArr, oldArr)
+      const removedLayers = uniqueInArrayById(oldArr, newArr)
+      addedLayers.forEach(this.addLayerToMap)
+      removedLayers.forEach(({ id }) => { this.removeLayerFromMap(id) })
+    }
+  },
 }
 </script>
diff --git a/src/components/v-mapbox-layer.js b/src/components/v-mapbox-layer.js
index c3a67d7..99039b9 100644
--- a/src/components/v-mapbox-layer.js
+++ b/src/components/v-mapbox-layer.js
@@ -1,7 +1,7 @@
 export default {
   name: 'v-mapbox-layer',
 
-  inject: ['getMap'],
+  inject: [ 'getMapMethods' ],
 
   render: () => null,
 
@@ -10,71 +10,44 @@ export default {
       type: Object,
       default: () => ({})
     },
-
-    // Allows to place a layer before another
     before: {
       type: String,
       default: undefined
     }
   },
 
-  data: () => ({
-    isInitialized: false
-  }),
-
   methods: {
-    deferredMountedTo() {
-      if(!this.isInitialized) {
-        this.renderLayer();
-        this.isInitialized = true;
-      }
-    },
-
-    renderLayer() {
-      this.removeLayer();
-      this.addLayer();
-    },
-
     addLayer() {
-      const map = this.getMap();
-      map.addLayer(this.options, this.before);
+      const mapMethods = this.getMapMethods()
+      mapMethods.addLayer(this.options, this.before)
     },
 
     removeLayer() {
-      const map = this.getMap();
-      if(map) {
-        const layerId = this.options.id;
-        const layer = map.getLayer(layerId);
-        if(layer) {
-          const layerSource = layer.source;
-          map.removeLayer(layerId);
-          if(layerSource && !map.getStyle().layers.some(({ source }) => source === layerSource)) {
-            map.removeSource(layerSource);
-          }
-        }
-      }
+      const mapMethods = this.getMapMethods()
+      const layerId = this.options.id
+      mapMethods.removeLayer(layerId)
+    },
+
+    updateLayer() {
+      const mapMethods = this.getMapMethods()
+      mapMethods.updateLayer(this.options)
     },
   },
 
   mounted() {
-    const map = this.getMap();
-    // We can immediately initialize if we have the map ready
-    if(map && map.isStyleLoaded()) {
-      this.renderLayer();
-      this.isInitialized = true;
-    }
+    this.addLayer()
   },
 
   destroyed() {
-    this.removeLayer();
+    this.removeLayer()
   },
 
   watch: {
     options: {
       deep: true,
       handler() {
-        this.renderLayer();
+        this.updateLayer()
       }
     }
   }
-};
+}
diff --git a/src/stories/index.stories.js b/src/stories/index.stories.js
index f204a02..4d9a2d1 100644
--- a/src/stories/index.stories.js
+++ b/src/stories/index.stories.js
@@ -160,10 +160,10 @@ const sortingTemplate = `
  style="height: 300px;"
  :center="[0, 0]"
 >
- <!-- green (we want this on top) -->
- <v-mapbox-layer :options="layerA"></v-mapbox-layer>
  <!-- red -->
  <v-mapbox-layer :options="layerB"></v-mapbox-layer>
+ <!-- green (we want this on top) -->
+ <v-mapbox-layer :options="layerA" before="b"></v-mapbox-layer>
 </v-mapbox>
 `
 
diff --git a/src/utils/helpers.js b/src/utils/helpers.js
new file mode 100644
index 0000000..0cc758e
--- /dev/null
+++ b/src/utils/helpers.js
@@ -0,0 +1 @@
+export const uniqueInArrayById = (arr1, arr2) => arr1.filter(({ id }) => !arr2.some(el => el.id === id))

From 35aaa4b9f3044d2a113741eaf6e202a988729c28 Mon Sep 17 00:00:00 2001
From: Bob Bol <bob@voorhoede.nl>
Date: Thu, 8 Oct 2020 18:34:52 +0200
Subject: [PATCH 2/2] skip trying to find layer if not defined

---
 src/components/VMapbox.vue | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/components/VMapbox.vue b/src/components/VMapbox.vue
index f5d84a3..f313702 100644
--- a/src/components/VMapbox.vue
+++ b/src/components/VMapbox.vue
@@ -192,7 +192,7 @@ export default {
       const thisIndex = this.mapLayers.findIndex(({ id }) => id === layerOptions.id)
       const nextItem = this.mapLayers[thisIndex + 1]
       const maybeBefore = nextItem ? nextItem.id : undefined
-      const existingLayer = this.map.getLayer(maybeBefore)
+      const existingLayer = maybeBefore && this.map.getLayer(maybeBefore)
       const before = existingLayer ? maybeBefore : undefined
       this.map.addLayer(layerOptions, before)
     },