Support FeatureCollection and MultiPolygon in geozones

We're reworking the format validation to correctly interpret feature
collection, feature, and geometry, according to RFC 7946 [1].

Since Leaflet interprets GeoJSON format, we're rendering the GeoJSON as
a layer instead of as a set of points. For that, we're normalizing the
GeoJSON to make sure it contains either a Feature or a
FeatureCollection. We're also adding the Leaflet images to the assets
path so the markers used for point geometries are rendered correctly.

Note we no longer allow a GeoJSON containing a geometry but not a
defined type. Since there might be invalid GeoJSON in existing Consul
Democracy databases, we're normalizing these existing geometry objects
to be part of a feature object.

We're also wrapping the outline points in a FeatureCollection object
because most of the large GIS systems eg ArcGIS, QGIS export geojson as
a complete FeatureCollection.

[1] https://datatracker.ietf.org/doc/html/rfc7946

Co-authored-by: Javi Martín <javim@elretirao.net>

spec/models/geozone_spec.rb

@@ -18,10 +18,20 @@ describe Geozone do
   end
 
   it "is not valid with invalid geojson file format" do
-    geozone.geojson = '{"geo\":{"type":"Incorrect key","coordinates": [
-                                 [40.8792937308316, -3.9259027239257],
-                                 [40.8788966596619, -3.9249047078766],
-                                 [40.8789131852224, -3.9247799675785]]}}'
+    geozone.geojson = <<~JSON
+      {
+        "type": "Feature",
+        "geometry": {
+          "type": "Incorrect",
+          "coordinates": [
+            [40.8792937308316, -3.9259027239257],
+            [40.8788966596619, -3.9249047078766],
+            [40.8789131852224, -3.9247799675785]
+          ]
+        }
+      }
+    JSON
+
     expect(geozone).not_to be_valid
   end
 
@@ -54,99 +64,149 @@ describe Geozone do
   end
 
   describe "#outline_points" do
-    it "returns empty array when geojson is nil" do
-      expect(geozone.outline_points).to eq([])
+    it "returns nil when geojson is nil" do
+      geozone.geojson = nil
+
+      expect(geozone.outline_points).to be nil
     end
 
-    it "returns coordinates array when geojson is not nil" do
-      geozone = build(:geozone, geojson: '{
-        "geometry": {
-          "type": "Polygon",
-          "coordinates": [
-            [40.8792937308316, -3.9259027239257],
-            [40.8788966596619, -3.9249047078766],
-            [40.8789131852224, -3.9247799675785]
-          ]
+    it "returns normalized feature collection when geojson is a valid FeatureCollection" do
+      geozone.geojson = <<~JSON
+        {
+          "type": "FeatureCollection",
+          "features": [{
+            "type": "Feature",
+            "geometry": {
+              "type": "Polygon",
+              "coordinates": [[
+                [-3.9259027239257, 40.8792937308316],
+                [-3.9249047078766, 40.8788966596619],
+                [-3.9247799675785, 40.8789131852224],
+                [-3.9259027239257, 40.8792937308316]
+              ]]
+            }
+          }]
         }
-      }')
+      JSON
 
-      expect(geozone.outline_points).to eq(
-        [[-3.9259027239257, 40.8792937308316],
-         [-3.9249047078766, 40.8788966596619],
-         [-3.9247799675785, 40.8789131852224]]
-      )
+      expected = {
+        type: "FeatureCollection",
+        features: [{
+          type: "Feature",
+          geometry: {
+            type: "Polygon",
+            coordinates: [[
+              [-3.9259027239257, 40.8792937308316],
+              [-3.9249047078766, 40.8788966596619],
+              [-3.9247799675785, 40.8789131852224],
+              [-3.9259027239257, 40.8792937308316]
+            ]]
+          }
+        }]
+      }
+
+      expect(geozone.outline_points).to eq expected.to_json
     end
 
-    it "handles coordinates with three-dimensional arrays" do
-      geozone = build(:geozone, geojson: '{
-        "geometry": {
-          "type": "Polygon",
-          "coordinates": [[[40.8792937308316, -3.9259027239257],
-            [40.8788966596619, -3.9249047078766],
-            [40.8789131852224, -3.9247799675785]]]
+    it "returns normalized feature collection when geojson is a valid Feature" do
+      geozone.geojson = <<~JSON
+        {
+          "type": "Feature",
+          "geometry": {
+            "type": "Polygon",
+            "coordinates": [[
+              [-3.9259027239257, 40.8792937308316],
+              [-3.9249047078766, 40.8788966596619],
+              [-3.9247799675785, 40.8789131852224],
+              [-3.9259027239257, 40.8792937308316]
+            ]]
+          }
         }
-      }')
+      JSON
 
-      expect(geozone.outline_points).to eq(
-        [[-3.9259027239257, 40.8792937308316],
-         [-3.9249047078766, 40.8788966596619],
-         [-3.9247799675785, 40.8789131852224]]
-      )
+      expected = {
+        type: "FeatureCollection",
+        features: [{
+          type: "Feature",
+          geometry: {
+            type: "Polygon",
+            coordinates: [[
+              [-3.9259027239257, 40.8792937308316],
+              [-3.9249047078766, 40.8788966596619],
+              [-3.9247799675785, 40.8789131852224],
+              [-3.9259027239257, 40.8792937308316]
+            ]]
+          }
+        }]
+      }
+
+      expect(geozone.outline_points).to eq expected.to_json
     end
 
-    it "handles coordinates with three-dimensional arrays with spaces between brackets" do
-      geozone = build(:geozone, geojson: '{
-        "geometry": {
+    it "returns normalized feature collection when geojson is a valid Geometry object" do
+      geozone.geojson = <<~JSON
+        {
+          "geometry": {
+            "type": "Polygon",
+            "coordinates": [[
+              [-3.9259027239257, 40.8792937308316],
+              [-3.9249047078766, 40.8788966596619],
+              [-3.9247799675785, 40.8789131852224],
+              [-3.9259027239257, 40.8792937308316]
+            ]]
+          }
+        }
+      JSON
+
+      expected = {
+        type: "FeatureCollection",
+        features: [{
+          type: "Feature",
+          geometry: {
+            type: "Polygon",
+            coordinates: [[
+              [-3.9259027239257, 40.8792937308316],
+              [-3.9249047078766, 40.8788966596619],
+              [-3.9247799675785, 40.8789131852224],
+              [-3.9259027239257, 40.8792937308316]
+            ]]
+          }
+        }]
+      }
+
+      expect(geozone.outline_points).to eq expected.to_json
+    end
+
+    it "returns normalized feature collection when geojson is a valid top-level Geometry object" do
+      geozone.geojson = <<~JSON
+        {
           "type": "Polygon",
           "coordinates": [[
-            [40.8792937308316, -3.9259027239257],
-            [40.8788966596619, -3.9249047078766],
-            [40.8789131852224, -3.9247799675785]
+            [-3.9259027239257, 40.8792937308316],
+            [-3.9249047078766, 40.8788966596619],
+            [-3.9247799675785, 40.8789131852224],
+            [-3.9259027239257, 40.8792937308316]
           ]]
         }
-      }')
+      JSON
 
-      expect(geozone.outline_points).to eq(
-        [[-3.9259027239257, 40.8792937308316],
-         [-3.9249047078766, 40.8788966596619],
-         [-3.9247799675785, 40.8789131852224]]
-      )
-    end
+      expected = {
+        type: "FeatureCollection",
+        features: [{
+          type: "Feature",
+          geometry: {
+            type: "Polygon",
+            coordinates: [[
+              [-3.9259027239257, 40.8792937308316],
+              [-3.9249047078766, 40.8788966596619],
+              [-3.9247799675785, 40.8789131852224],
+              [-3.9259027239257, 40.8792937308316]
+            ]]
+          }
+        }]
+      }
 
-    it "handles coordinates with four-dimensional arrays" do
-      geozone = build(:geozone, geojson: '{
-        "geometry": {
-          "type": "Polygon",
-          "coordinates": [[[[40.8792937308316, -3.9259027239257],
-            [40.8788966596619, -3.9249047078766],
-            [40.8789131852224, -3.9247799675785]]]]
-        }
-      }')
-
-      expect(geozone.outline_points).to eq(
-        [[-3.9259027239257, 40.8792937308316],
-         [-3.9249047078766, 40.8788966596619],
-         [-3.9247799675785, 40.8789131852224]]
-      )
-    end
-
-    it "handles coordinates with four-dimensional arrays with spaces between brackets" do
-      geozone = build(:geozone, geojson: '{
-        "geometry": {
-          "type": "Polygon",
-          "coordinates": [[[
-            [40.8792937308316, -3.9259027239257],
-            [40.8788966596619, -3.9249047078766],
-            [40.8789131852224, -3.9247799675785]
-          ]]]
-        }
-      }')
-
-      expect(geozone.outline_points).to eq(
-        [[-3.9259027239257, 40.8792937308316],
-         [-3.9249047078766, 40.8788966596619],
-         [-3.9247799675785, 40.8789131852224]]
-      )
+      expect(geozone.outline_points).to eq expected.to_json
     end
   end
 end