Add new data policy fields

- enable_forwarding allows forwarding to be enabled or disabled per
  device

- precise_location allows users to choose whether precise (5dp) or
  approxmite (3dp + 2dp of noise) locations are stored.

On deploying we will need to run migrations, then run rake
devices:truncate_and_fuzz_locations in order to truncate the existing
locations to 5dp.

app/models/device.rb

@@ -9,6 +9,7 @@ class Device < ActiveRecord::Base
 
   default_scope { with_active_state }
 
+  include ActiveModel::Dirty
   include Workflow
   include WorkflowActiverecord
   include ArchiveWorkflow
@@ -37,6 +38,7 @@ class Device < ActiveRecord::Base
     with: /\A([0-9a-fA-F]{2}[:-]){5}[0-9a-fA-F]{2}\z/, allow_nil: true
 
   before_save :nullify_other_mac_addresses, if: :mac_address
+  before_save :truncate_and_fuzz_location!, if: :location_changed?
   before_save :calculate_geohash
   after_validation :do_geocoding
 
@@ -245,6 +247,14 @@ def update_component_timestamps(timestamp, sensor_ids)
     end
   end
 
+  def data_policy(authorized=false)
+    {
+      is_private: authorized ? is_private : "[FILTERED]",
+      enable_forwarding: authorized ? enable_forwarding : "[FILTERED]",
+      precise_location: authorized ? precise_location : "[FILTERED]"
+    }
+  end
+
   def hardware(authorized=false)
     {
       name: hardware_name,
@@ -272,19 +282,33 @@ def hardware_slug
   end
 
   def forward_readings?
-    owner.forward_device_readings?
+    enable_forwarding && owner.forward_device_readings?
   end
 
   def forwarding_token
     owner.forwarding_token
   end
 
+  def truncate_and_fuzz_location!
+    if latitude && longitude
+      decimal_places = self.precise_location ? 5 : 3
+      lat_fuzz = self.precise_location ? 0.0 : (Random.rand * 1/10.0**decimal_places).truncate(5)
+      long_fuzz = self.precise_location ? 0.0 : (Random.rand * 1/10.0**decimal_places).truncate(5)
+      self.latitude = self.latitude.truncate(decimal_places) + lat_fuzz
+      self.longitude = self.longitude.truncate(decimal_places) + long_fuzz
+    end
+  end
+
   private
 
     def set_state
       self.state = self.soft_state
     end
 
+    def location_changed?
+      latitude_changed? || longitude_changed? || precise_location_changed?
+    end
+
     def calculate_geohash
       # include ActiveModel::Dirty
       # if latitude.changed? or longitude.changed?

app/views/v0/devices/_device.jbuilder

@@ -14,7 +14,6 @@ json.(
   :state,
   :system_tags,
   :user_tags,
-  :is_private,
   :last_reading_at,
   :created_at,
   :updated_at
@@ -35,6 +34,7 @@ else
 end
 json.merge!(postprocessing: device.postprocessing) if local_assigns[:with_postprocessing]
 json.merge!(location: device.formatted_location) if local_assigns[:with_location]
+json.merge!(data_policy: device.data_policy(authorized))
 json.merge!(hardware: device.hardware(authorized))
 
 if local_assigns[:with_owner] && device.owner

db/migrate/20240624161155_add_data_policy_fields_to_device.rb

@@ -0,0 +1,8 @@
+class AddDataPolicyFieldsToDevice < ActiveRecord::Migration[6.1]
+  def change
+    add_column :devices, :precise_location, :boolean, null: false, default: false
+    add_column :devices, :enable_forwarding, :boolean, null: false, default: false
+    # Existing devices have precise locations, despite the default for all new ones.
+    execute "UPDATE devices SET precise_location = true"
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2024_05_12_132257) do
+ActiveRecord::Schema.define(version: 2024_06_24_161155) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "adminpack"
@@ -105,6 +105,8 @@
     t.string "hardware_name_override"
     t.string "hardware_version_override"
     t.string "hardware_slug_override"
+    t.boolean "precise_location", default: false, null: false
+    t.boolean "enable_forwarding", default: false, null: false
     t.index ["device_token"], name: "index_devices_on_device_token", unique: true
     t.index ["geohash"], name: "index_devices_on_geohash"
     t.index ["last_reading_at"], name: "index_devices_on_last_reading_at"

lib/tasks/devices.rake

@@ -0,0 +1,8 @@
+namespace :devices do
+  task :truncate_and_fuzz_locations => :environment do
+    Device.all.each do |device|
+      device.truncate_and_fuzz_location!
+      device.save!(validate: false)
+    end
+  end
+end

spec/models/device_spec.rb

@@ -192,7 +192,7 @@
 
     it "calculates geohash on save" do
       barcelona = create(:device)
-      expect(barcelona.geohash).to match('sp3e9bh31y')
+      expect(barcelona.geohash).to match(/^sp3e/)
     end
 
     skip "calculates elevation on save", :vcr do
@@ -203,6 +203,60 @@
 
   end
 
+  describe "location truncation and fuzzing" do
+    context "when the location is changed" do
+      context "when the device has precise location set" do
+        let(:device) {
+          create(:device, precise_location: true)
+
+        }
+
+        it "truncates the location to 5 decimal places" do
+          device.update(latitude: 0.1234567, longitude: 10.1234567)
+          device.save
+          expect(device.latitude).to eq(0.12345)
+          expect(device.longitude).to eq(10.12345)
+        end
+      end
+
+      context "when the device has no precise location set" do
+        let(:device) {
+          create(:device, precise_location: false)
+
+        }
+
+
+        it "truncates the location to 3 decimal places and adds 2 extra dp of randomness" do
+          device.update(latitude: 0.12345, longitude: 10.12345)
+          device.save
+          expect(device.latitude).not_to eq(0.12345)
+          expect(device.longitude).not_to eq(10.12345)
+          expect((device.latitude - 0.12345).abs).to be <= 0.001
+          expect((device.longitude - 10.12345).abs).to be <= 0.001
+        end
+      end
+    end
+
+    context "when the location is not changed" do
+      let(:device) {
+        create(:device, precise_location: false, latitude: 0.12345, longitude: 0.12345)
+
+      }
+
+      it "does not re-fuzz the device location" do
+        lat_before = device.latitude
+        long_before = device.longitude
+
+        device.update(name: "not updating location")
+        device.save!
+
+        expect(device.reload.latitude).to eq(lat_before)
+        expect(device.reload.longitude).to eq(long_before)
+      end
+    end
+  end
+
+
   it "has to_s" do
     device = create(:device, name: 'cool device')
     expect(device.to_s).to eq('cool device')
@@ -524,10 +578,51 @@
 
   describe "forwarding" do
     describe "#forward_readings?" do
+      context "when the device has forwarding enabled" do
+        let(:device) {
+          create(:device, enable_forwarding: true)
+        }
+
+        context "when forward_device_readings is true on the owning user" do
+          it "forwardds readings" do
+            expect(device.owner).to receive(:forward_device_readings?).and_return(true)
+            expect(device.forward_readings?).to be(true)
+          end
+        end
+
+        context "when forward_device_readings is not true on the owning user" do
+          it "does not forward readings" do
+            expect(device.owner).to receive(:forward_device_readings?).and_return(false)
+            expect(device.forward_readings?).to be(false)
+          end
+        end
+      end
+
+      context "when the device does not have forwarding enabled" do
+        let(:device) {
+          create(:device, enable_forwarding: false)
+        }
+
+        context "when forward_device_readings is true on the owning user" do
+          it "does not forward readings" do
+            allow(device.owner).to receive(:forward_device_readings?).and_return(true)
+            expect(device.forward_readings?).to be(false)
+            expect(device.owner).not_to have_received(:forward_device_readings?)
+          end
+        end
+
+        context "when forward_device_readings is not true on the owning user" do
+          it "does not forward readings" do
+            allow(device.owner).to receive(:forward_device_readings?).and_return(false)
+            expect(device.forward_readings?).to be(false)
+            expect(device.owner).not_to have_received(:forward_device_readings?)
+          end
+        end
+
+
+      end
+
       it "delegates to the forward_device_readings? method on the device owner" do
-        forward_readings = double(:forward_readings)
-        expect(device.owner).to receive(:forward_device_readings?).and_return(forward_readings)
-        expect(device.forward_readings?).to eq(forward_readings)
       end
     end
 

spec/requests/v0/devices_spec.rb

@@ -24,7 +24,7 @@
       expect(json.length).to eq(2)
       # expect(json[0]['name']).to eq(first.name)
       # expect(json[1]['name']).to eq(second.name)
-      expect(json[0].keys).to eq(%w(id uuid name description state system_tags user_tags is_private last_reading_at created_at updated_at notify device_token postprocessing location hardware owner data))
+      expect(json[0].keys).to eq(%w(id uuid name description state system_tags user_tags last_reading_at created_at updated_at notify device_token postprocessing location data_policy hardware owner data))
     end
 
     describe "when not logged in" do
@@ -46,6 +46,13 @@
         json = api_get 'devices'
         expect(json[0]['hardware']['last_status_message']).to eq("[FILTERED]")
       end
+
+      it "does not show data policies" do
+        first = create(:device)
+        second = create(:device)
+        json = api_get 'devices'
+        expect(json[0]['data_policy']['enable_forwarding']).to eq("[FILTERED]")
+      end
     end
 
     describe "when logged in as a normal user" do
@@ -67,6 +74,14 @@
         json = api_get 'devices', { access_token: token.token }
         expect(json[0]['hardware']['last_status_message']).to eq("[FILTERED]")
       end
+
+      it "only shows device policies for the owning user" do
+        first = create(:device)
+        second = create(:device, owner: user)
+        json = api_get 'devices', { access_token: token.token}
+        expect(json[0]['data_policy']['enable_forwarding']).to eq('[FILTERED]')
+        expect(json[1]['data_policy']['enable_forwarding']).not_to eq('[FILTERED]')
+      end
     end
 
     describe "when logged in as an admin" do
@@ -88,6 +103,13 @@
         json = api_get 'devices', { access_token: admin_token.token}
         expect(json[0]['hardware']['last_status_message']).not_to eq('[FILTERED]')
       end
+
+      it "shows device policies" do
+        first = create(:device)
+        second = create(:device)
+        json = api_get 'devices', { access_token: admin_token.token}
+        expect(json[0]['data_policy']['enable_forwarding']).not_to eq('[FILTERED]')
+      end
     end
 
     describe "world map" do