app/queries/expenses/total_query.rb

@@ -8,16 +8,36 @@ module Expenses
 
     def query
       <<~SQL
-        SELECT count(amount) as fixed,
+        WITH guest_count AS (#{guest_count_per_status}),
-               0 as fixed_count,
+             expense_summary AS (#{expense_summary})
-               0 as variable,
+        SELECT expense_summary.fixed,
-               0 as variable_count,
+               expense_summary.fixed_count,
-               0 as total,
+               expense_summary.variable,
-               0 as total_count,
+               expense_summary.variable_count,
-               0 as max_projected,
+               expense_summary.total_count,
-               0 as per_person
+               expense_summary.fixed + expense_summary.variable * guest_count.confirmed as total,
-        FROM EXPENSES
+               expense_summary.fixed + expense_summary.variable * guest_count.projected as max_projected,
-        LIMIT 1;
+               (expense_summary.fixed + expense_summary.variable * guest_count.confirmed) / guest_count.confirmed as per_person
+        FROM guest_count, expense_summary;
+      SQL
+    end
+
+    def expense_summary
+      <<~SQL
+        SELECT coalesce(sum(amount) filter (where pricing_type = 'fixed'), 0) as fixed,
+               coalesce(count(amount) filter (where pricing_type = 'fixed'), 0) as fixed_count,
+               coalesce(sum(amount) filter (where pricing_type = 'per_person'), 0) as variable,
+               coalesce(count(amount) filter (where pricing_type = 'per_person'), 0) as variable_count,
+               count(*) as total_count
+        FROM expenses
+      SQL
+    end
+
+    def guest_count_per_status
+      <<~SQL
+        SELECT COALESCE(count(*) filter(where status = #{Guest.statuses["confirmed"]}), 0) as confirmed,
+               COALESCE(count(*) filter(where status IN (#{Guest.statuses.values_at("confirmed", "invited", "tentative").join(",")})), 0) as projected
+        FROM guests
       SQL
     end
   end

spec/queries/expenses/total_query_spec.rb

@@ -32,7 +32,7 @@ module Expenses
           create(:expense, :fixed, amount: 200)
         end
 
-        it "returns the sum of fixed expenses" do
+        it "returns the sum of fixed expenses", :aggregate_failures do
           expect(response["fixed"]).to eq(300)
           expect(response["fixed_count"]).to eq(2)
           expect(response["variable"]).to be_zero