Record#calculated_durations

app/models/record.rb

@@ -105,6 +105,9 @@ def next_activity
     # Added guard for double-entry
     self.next.activities.where('(timestamp != end_timestamp OR end_timestamp IS NULL)').first
   end
+  def calculated_duration(provided_start_timestamp = nil, provided_end_timestamp = Time.zone.now)
+    return [Time.zone.now, provided_end_timestamp, self.end_timestamp || Time.zone.now].min - [self.timestamp, provided_start_timestamp || self.timestamp].max
+  end
   def self.recalculate_durations(user, start_time = nil, end_time = nil)
     span = user.records
     span = span.where('timestamp >= ?', start_time) if start_time

spec/models/record_spec.rb

@@ -121,6 +121,32 @@
       expect(r2.reload.end_timestamp.to_s).to eq r1.timestamp.to_s
     end
   end
+  describe '#duration' do 
+    before :all do
+      Timecop.freeze
+      @u = FactoryGirl.create(:confirmed_user)
+      @c = FactoryGirl.create(:record_category, user: @u, category_type: 'activity')
+    end
+    after :all do
+      Timecop.return
+    end
+    it 'reports proper duration if the ending timestamp is set' do
+      r1 = FactoryGirl.create(:record, user: @u, record_category: @c, timestamp: Time.zone.now - 2.hours, end_timestamp: Time.zone.now - 1.hour)
+      r1.calculated_duration.should == 1.hour
+    end
+    it 'truncates to current timestamp if the ending timestamp is not set' do
+      r1 = FactoryGirl.create(:record, user: @u, record_category: @c, timestamp: Time.zone.now - 2.hours)
+      r1.calculated_duration.should == 2.hours
+    end
+    it 'truncates to provided start time and end time' do
+      r1 = FactoryGirl.create(:record, user: @u, record_category: @c, timestamp: Time.zone.now - 2.hours)
+      r1.calculated_duration(Time.zone.now - 1.hour, Time.zone.now - 30.minutes).should == 30.minutes
+    end
+    it "stays within the activity's bounds" do
+      r1 = FactoryGirl.create(:record, user: @u, record_category: @c, timestamp: Time.zone.now - 2.hours)
+      r1.calculated_duration(Time.zone.now - 4.hour, Time.zone.now + 30.minutes).should == 2.hours
+    end
+  end
   describe '.recalculate_durations' do
     it "fixes all the durations" do
       u = FactoryGirl.create(:confirmed_user)