Implement Geocoding and Geometry distance search

Gemfile

@@ -38,6 +38,12 @@ gem "sentry-ruby"
 gem "stimulus-rails"
 gem "webpacker"
 
+gem "activerecord-postgis-adapter"
+gem "geocoder"
+gem "rgeo"
+gem "rgeo-geojson"
+gem "rgeo-proj4"
+
 gem "net-imap", require: false
 gem "net-pop", require: false
 gem "net-smtp", require: false

Gemfile.lock

@@ -47,6 +47,9 @@ GEM
     activerecord (6.1.7.3)
       activemodel (= 6.1.7.3)
       activesupport (= 6.1.7.3)
+    activerecord-postgis-adapter (7.1.1)
+      activerecord (~> 6.1)
+      rgeo-activerecord (~> 7.0.0)
     activerecord-session_store (2.0.0)
       actionpack (>= 5.2.4.1)
       activerecord (>= 5.2.4.1)
@@ -178,6 +181,7 @@ GEM
       rack (>= 1.4, < 3)
       rack-protection (>= 1.5.3, <= 4.0.0)
       sanitize (< 7)
+    geocoder (1.8.1)
     globalid (1.1.0)
       activesupport (>= 5.0)
     govuk-components (3.1.1)
@@ -356,6 +360,14 @@ GEM
       actionpack (>= 5.2)
       railties (>= 5.2)
     rexml (3.2.5)
+    rgeo (3.0.0)
+    rgeo-activerecord (7.0.1)
+      activerecord (>= 5.0)
+      rgeo (>= 1.0.0)
+    rgeo-geojson (2.1.1)
+      rgeo (>= 1.0.0)
+    rgeo-proj4 (4.0.0)
+      rgeo (~> 3.0.0)
     rspec-core (3.12.2)
       rspec-support (~> 3.12.0)
     rspec-expectations (3.12.3)
@@ -507,6 +519,7 @@ PLATFORMS
   x86_64-linux
 
 DEPENDENCIES
+  activerecord-postgis-adapter
   activerecord-session_store
   axe-core-capybara
   axe-core-rspec
@@ -525,6 +538,7 @@ DEPENDENCIES
   flipper (~> 0.28.0)
   flipper-active_record (~> 0.28.0)
   flipper-ui (~> 0.28.0)
+  geocoder
   govuk-components
   govuk_design_system_formbuilder
   httparty (~> 0.21)
@@ -551,6 +565,9 @@ DEPENDENCIES
   puma (~> 6.2)
   rack-attack
   rails (~> 6.1.7)
+  rgeo
+  rgeo-geojson
+  rgeo-proj4
   rspec-rails (~> 6.0.2)
   rubocop-govuk
   scss_lint-govuk

app/lib/services/geojson_loader.rb

@@ -0,0 +1,45 @@
+module Services
+  class GeojsonLoader
+    def self.reload_geojsons(geojson_path)
+      empty_database
+      load_geojsons(geojson_path)
+    end
+
+    def self.empty_database
+      GeoLocalAuthority.delete_all
+    end
+
+    def self.read_file(geojson_path)
+      file = File.read(geojson_path)
+      features = RGeo::GeoJSON.decode(file, json_parser: :json)
+    end
+
+    def self.load_geojsons(geojson_path)
+      Rails.logger.debug("Loading #{geojson_path}")
+
+      features = read_file(geojson_path)
+
+      features.each do |feature|
+        geo_local_authority = GeoLocalAuthority.new
+        geo_local_authority.name = feature.properties["LAD22NM"]
+        geo_local_authority.geometry = feature.geometry
+        geo_local_authority.save!
+      end
+    end
+
+    class Shape
+      attr_reader :geojson_record
+
+      def initialize(geojson_record)
+        @geojson_record = geojson_record
+      end
+
+      delegate :geometry,
+               to: :geojson_record
+
+      def name
+        geojson_record.attributes["LAD22NM"]
+      end
+    end
+  end
+end

app/models/geo_local_authority.rb

@@ -0,0 +1,35 @@
+class GeoLocalAuthority < ApplicationRecord
+  include RGeo::ActiveRecord::GeometryMixin
+
+  SRID = 27_700
+
+  def self.nearest_three_to(string)
+    location = Geocoder.search(string).first
+    by_distance(location.longitude.to_f, location.latitude.to_f).limit(3)
+  end
+
+  # A method that takes in a longitude and latitude and finds the nearest GeoLocalAuthority
+  # to that point.
+  # Converts the longitude and latitude to a point in the SRID 27700 coordinate system
+  # and then finds the nearest GeoLocalAuthority to that point.
+  # Returns the nearest GeoLocalAuthority.
+  def self.by_distance(longitude, latitude)
+    # Transform the given lon/lat to have an SRID of 27700 (the SRID of the GeoLocalAuthority geometries)
+    transformed_point = RGeo::CoordSys::Proj4.transform_coords(
+      RGeo::CoordSys::Proj4.new("EPSG:4326"),
+      RGeo::CoordSys::Proj4.new("EPSG:27700"),
+      longitude,
+      latitude,
+    )
+
+    target_latitude = transformed_point[1]
+    target_longitude = transformed_point[0]
+
+    # Create a point representing the target coordinates, with the SRID specified
+    point_sql = "SRID=#{SRID};POINT(#{target_longitude} #{target_latitude})"
+
+    arel = Arel.sql("geometry <-> '#{point_sql}'::geometry")
+
+    order(arel)
+  end
+end

config/database.yml

@@ -15,12 +15,12 @@
 # gem 'pg'
 #
 default: &default
-  adapter: postgresql
+  adapter: postgis
   encoding: unicode
   # For details on connection pooling, see Rails configuration guide
   # http://guides.rubyonrails.org/configuring.html#database-pooling
   pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
-  url: <%= ENV.fetch("DATABASE_URL", "postgres://localhost:5432") %>
+  url: <%= ENV.fetch("DATABASE_URL", "postgis://localhost:5432") %>
 
 development:
   <<: *default

db/migrate/20230502125034_enable_postgis.rb

@@ -0,0 +1,5 @@
+class EnablePostgis < ActiveRecord::Migration[6.1]
+  def change
+    enable_extension "postgis"
+  end
+end

db/migrate/20230502125316_create_geo_local_authorities.rb

@@ -0,0 +1,12 @@
+class CreateGeoLocalAuthorities < ActiveRecord::Migration[6.1]
+  def change
+    create_table :geo_local_authorities do |t|
+      t.string :name
+      t.geometry :geometry, srid: 27_700
+
+      t.timestamps
+    end
+
+    add_index :geo_local_authorities, :geometry, using: :gist
+  end
+end

db/schema.rb

@@ -10,12 +10,13 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2023_04_14_121939) do
+ActiveRecord::Schema.define(version: 2023_05_02_125316) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "btree_gin"
   enable_extension "citext"
   enable_extension "plpgsql"
+  enable_extension "postgis"
 
   create_table "applications", force: :cascade do |t|
     t.bigint "user_id", null: false
@@ -110,6 +111,14 @@
     t.index ["feature_key", "key", "value"], name: "index_flipper_gates_on_feature_key_and_key_and_value", unique: true
   end
 
+  create_table "geo_local_authorities", force: :cascade do |t|
+    t.string "name"
+    t.geometry "geometry", limit: {:srid=>27700, :type=>"geometry"}
+    t.datetime "created_at", precision: 6, null: false
+    t.datetime "updated_at", precision: 6, null: false
+    t.index ["geometry"], name: "index_geo_local_authorities_on_geometry", using: :gist
+  end
+
   create_table "get_an_identity_webhook_messages", force: :cascade do |t|
     t.jsonb "raw"
     t.jsonb "message"

lib/tasks/geojson_loading.rake

@@ -0,0 +1,23 @@
+namespace :geojson do
+  desc "Load geojsons into the database, will empty local authorities table first"
+  task load: :environment do |_t, _args|
+    geojson_path = "lib/local_authority_geojson/Local_Authority_Districts_December_2022_Boundaries_UK_BUC_143497700576642915.geojson"
+
+    puts("Loading geojsons from #{geojson_path}")
+
+    Services::GeojsonLoader.reload_geojsons(geojson_path)
+  end
+
+  desc "Load geojson file and output local authorities found"
+  task test: :environment do |_t, _args|
+    geojson_path = "lib/local_authority_geojson/Local_Authority_Districts_December_2022_Boundaries_UK_BUC_143497700576642915.geojson"
+
+    features = Services::GeojsonLoader.read_file(geojson_path)
+
+    puts "File contains #{features.count} local authority geometries"
+
+    local_authorities_found = features.map { |feature| feature.properties["LAD22NM"] }.sort.join(", ")
+
+    puts "Local Authorities found: #{local_authorities_found}"
+  end
+end

spec/models/geo_local_authority_spec.rb

@@ -0,0 +1,90 @@
+require "rails_helper"
+
+RSpec.describe GeoLocalAuthority, type: :model do
+  before do
+    geojson_path = "lib/local_authority_geojsons/Local_Authority_Districts_December_2022_Boundaries_UK_BUC_143497700576642915.geojson"
+
+    Services::GeojsonLoader.reload_geojsons(geojson_path)
+
+    Geocoder.configure(lookup: :test)
+    Geocoder::Lookup::Test.add_stub(
+      "Department for Education, Westminster", [{
+        "latitude" => 51.4979314,
+        "longitude" => -0.13016544222858017,
+        "address" => "Department for Education, 20, Great Smith Street, Westminster, Millbank, London, Greater London, England, SW1P 3BT, United Kingdom",
+        "state" => "England",
+        "country" => "United Kingdom",
+        "country_code" => "gb",
+      }]
+    )
+    Geocoder::Lookup::Test.add_stub(
+      "Manchester Airport", [{
+        "latitude" => 53.350342049999995,
+        "longitude" => -2.280369252664295,
+        "address" => "Manchester Airport, Castle Mill Lane, Ashley, Manchester, Cheshire East, England, M90 1QX, United Kingdom",
+        "state" => "England",
+        "country" => "United Kingdom",
+        "country_code" => "gb",
+      }]
+    )
+    Geocoder::Lookup::Test.add_stub(
+      "Belfast City Airport", [{
+        "latitude" => 54.614828,
+        "longitude" => -5.8703437,
+        "address" => "Bushmills Bar, Sydenham Bypass, Sydenham, Belfast, County Down, Ulster, Northern Ireland, BT3 9JH, United Kingdom",
+        "state" => "Northern Ireland",
+        "country" => "United Kingdom",
+        "country_code" => "gb",
+      }]
+    )
+    Geocoder::Lookup::Test.add_stub(
+      "Edinburgh Airport", [{
+        "latitude" => 55.950128899999996,
+        "longitude" => -3.3595079855289756,
+        "address" => "Edinburgh Airport, Meadowfield Road, Gogar, City of Edinburgh, Scotland, EH12 0AU, United Kingdom",
+        "state" => "Scotland",
+        "country" => "United Kingdom",
+        "country_code" => "gb",
+      }]
+    )
+    Geocoder::Lookup::Test.add_stub(
+      "Cardiff Airport", [{
+        "latitude" => 51.397871550000005,
+        "longitude" => -3.3445890119919994,
+        "address" => "Cardiff Airport, B4265, Fonmon, Rhoose, Penmark, Vale of Glamorgan, Wales, CF62 3BL, United Kingdom",
+        "state" => "Wales",
+        "country" => "United Kingdom",
+        "country_code" => "gb",
+      }]
+    )
+
+    Geocoder::Lookup::Test.add_stub(
+      "Sydney Opera House", [{
+        "latitude" => -33.85719805,
+        "longitude" => 151.21512338473752,
+        "address" => "Sydney Opera House, 2, Macquarie Street, Quay Quarter, Sydney, Council of the City of Sydney, New South Wales, 2000, Australia",
+        "state" => "New South Wales",
+        "country" => "Australia",
+        "country_code" => "au",
+      }]
+    )
+  end
+
+  describe "#nearest_three_to" do
+    def check_nearest_three_to(location)
+      described_class.nearest_three_to(location).pluck(:name)
+    end
+
+    it "returns the three nearest local authorities" do
+      # Do some quick checks around the UK to check it works in various areas
+      expect(check_nearest_three_to("Department for Education, Westminster")).to eq(%w[Westminster Lambeth Wandsworth])
+      expect(check_nearest_three_to("Manchester Airport")).to eq(["Manchester", "Cheshire East", "Trafford"])
+      expect(check_nearest_three_to("Belfast City Airport")).to eq(["Belfast", "Ards and North Down", "Lisburn and Castlereagh"])
+      expect(check_nearest_three_to("Edinburgh Airport")).to eq(["City of Edinburgh", "West Lothian", "Fife"])
+      expect(check_nearest_three_to("Cardiff Airport")).to eq(["Vale of Glamorgan", "Cardiff", "Rhondda Cynon Taf"])
+
+      # And one across the world to check it doesn't break
+      expect(check_nearest_three_to("Sydney Opera House")).to eq(["Cornwall", "Isles of Scilly", "South Hams"])
+    end
+  end
+end