Sketch out business logic and basic tests

app/jobs/rule_processor_job.rb

@@ -0,0 +1,9 @@
+class RuleProcessorJob < ApplicationJob
+  queue_as :default
+
+  def perform(family)
+    family.rules.each do |rule|
+      rule.apply
+    end
+  end
+end

app/models/account.rb

@@ -78,6 +78,8 @@ class Account < ApplicationRecord
 
     Rails.logger.info("Processing balances (#{linked? ? 'reverse' : 'forward'})")
     sync_balances
+
+    RuleProcessorJob.perform_later(family)
   end
 
   def post_sync

app/models/demo/generator.rb

@@ -40,7 +40,7 @@ class Demo::Generator
         create_tags!(family)
         create_categories!(family)
         create_merchants!(family)
-
+        create_rules!(family)
         puts "tags, categories, merchants created for #{family_name}"
 
         create_credit_card_account!(family)
@@ -184,6 +184,19 @@ class Demo::Generator
         onboarded_at: Time.current
     end
 
+    def create_rules!(family)
+      family.rules.create!(
+        effective_date: 1.year.ago.to_date,
+        active: true,
+        conditions: [
+          Rule::Condition.new(condition_type: "match_merchant", value: "Whole Foods")
+        ],
+        actions: [
+          Rule::Action.new(action_type: "set_category", value: "Groceries")
+        ]
+      )
+    end
+
     def create_tags!(family)
       [ "Trips", "Emergency Fund", "Demo Tag" ].each do |tag|
         family.tags.create!(name: tag)

app/models/family.rb

@@ -22,6 +22,7 @@ class Family < ApplicationRecord
 
   has_many :entries, through: :accounts
   has_many :transactions, through: :accounts
+  has_many :rules, dependent: :destroy
   has_many :trades, through: :accounts
   has_many :holdings, through: :accounts
 

app/models/rule.rb

@@ -1,7 +1,72 @@
 class Rule < ApplicationRecord
   belongs_to :family
-  has_many :triggers, dependent: :destroy
+  has_many :conditions, dependent: :destroy
   has_many :actions, dependent: :destroy
 
   validates :effective_date, presence: true
+
+  def get_operator_symbol(operator)
+    case operator
+    when "gt"
+      ">"
+    when "lt"
+      "<"
+    when "eq"
+      "="
+    end
+  end
+
+  def apply
+    case resource_type
+    when "transaction"
+      scope = family.transactions
+
+      conditions.each do |condition|
+        case condition.condition_type
+        when "match_merchant"
+          scope = scope.left_joins(:merchant).where(merchant: { name: condition.value })
+        when "compare_amount"
+          operator_symbol = get_operator_symbol(condition.operator)
+          scope = scope.joins(:entry)
+                       .where("account_entries.amount #{Arel.sql(operator_symbol)} ?", condition.value)
+        when "compound"
+          subconditions = condition.conditions
+
+          subconditions.each do |subcondition|
+            case condition.operator
+            when "and"
+              case subcondition.condition_type
+              when "match_merchant"
+                scope = scope.left_joins(:merchant).where(merchant: { name: subcondition.value })
+              when "compare_amount"
+                operator_symbol = get_operator_symbol(subcondition.operator)
+                scope = scope.joins(:entry)
+                             .where("account_entries.amount #{Arel.sql(operator_symbol)} ?", subcondition.value.to_f)
+              end
+            when "or"
+              raise "not implemented yet"
+            else
+              raise "Invalid compound operator"
+            end
+          end
+        else
+          raise "Unsupported condition type: #{condition.condition_type}"
+        end
+      end
+
+      scope.each do |transaction|
+        actions.each do |action|
+          case action.action_type
+          when "set_category"
+            category = family.categories.find_by(name: action.value)
+            transaction.update!(category: category)
+          else
+            raise "Unsupported action type: #{action.action_type}"
+          end
+        end
+      end
+    else
+      raise "Unsupported resource type: #{resource_type}"
+    end
+  end
 end

app/models/rule/condition.rb

@@ -0,0 +1,11 @@
+class Rule::Condition < ApplicationRecord
+  OPERATORS = [ "and", "or", "gt", "lt", "eq" ]
+  TYPES = [ "match_merchant", "compare_amount", "compound" ]
+
+  belongs_to :rule, optional: true
+  belongs_to :parent, class_name: "Rule::Condition", optional: true
+  has_many :conditions, class_name: "Rule::Condition", foreign_key: :parent_id, dependent: :destroy
+
+  validates :operator, inclusion: { in: OPERATORS }, allow_nil: true
+  validates :condition_type, presence: true, inclusion: { in: TYPES }
+end

app/models/rule/trigger.rb

@@ -1,7 +0,0 @@
-class Rule::Trigger < ApplicationRecord
-  self.table_name = "rule_triggers"
-
-  belongs_to :rule
-
-  validates :trigger_type, presence: true
-end

db/migrate/20250225135843_add_rules.rb

@@ -1,25 +0,0 @@
-class AddRules < ActiveRecord::Migration[7.2]
-  def change
-    create_table :rules, id: :uuid do |t|
-      t.references :family, null: false, foreign_key: true, type: :uuid
-
-      t.date :effective_date, null: false
-      t.boolean :active, null: false, default: true
-      t.timestamps
-    end
-
-    create_table :rule_triggers do |t|
-      t.references :rule, null: false, foreign_key: true, type: :uuid
-
-      t.string :trigger_type, null: false
-      t.timestamps
-    end
-
-    create_table :rule_actions do |t|
-      t.references :rule, null: false, foreign_key: true, type: :uuid
-
-      t.string :action_type, null: false
-      t.timestamps
-    end
-  end
-end

db/migrate/20250401194500_create_rules.rb

@@ -0,0 +1,30 @@
+class CreateRules < ActiveRecord::Migration[7.2]
+  def change
+    create_table :rules, id: :uuid do |t|
+      t.references :family, null: false, foreign_key: true, type: :uuid
+
+      t.string :resource_type, null: false
+      t.date :effective_date, null: false
+      t.boolean :active, null: false, default: true
+      t.timestamps
+    end
+
+    create_table :rule_conditions, id: :uuid do |t|
+      t.references :rule, foreign_key: true, type: :uuid
+      t.references :parent, foreign_key: { to_table: :rule_conditions }, type: :uuid
+
+      t.string :condition_type, null: false
+      t.string :operator, null: false
+      t.string :value
+      t.timestamps
+    end
+
+    create_table :rule_actions, id: :uuid do |t|
+      t.references :rule, null: false, foreign_key: true, type: :uuid
+
+      t.string :action_type, null: false
+      t.string :value, null: false
+      t.timestamps
+    end
+  end
+end

db/schema.rb

@@ -468,24 +468,30 @@ ActiveRecord::Schema[7.2].define(version: 2025_03_19_212839) do
     t.index ["outflow_transaction_id"], name: "index_rejected_transfers_on_outflow_transaction_id"
   end
 
-  create_table "rule_actions", force: :cascade do |t|
+  create_table "rule_actions", id: :uuid, default: -> { "gen_random_uuid()" }, force: :cascade do |t|
     t.uuid "rule_id", null: false
     t.string "action_type", null: false
+    t.string "value", null: false
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.index ["rule_id"], name: "index_rule_actions_on_rule_id"
   end
 
-  create_table "rule_triggers", force: :cascade do |t|
-    t.uuid "rule_id", null: false
-    t.string "trigger_type", null: false
+  create_table "rule_conditions", id: :uuid, default: -> { "gen_random_uuid()" }, force: :cascade do |t|
+    t.uuid "rule_id"
+    t.uuid "parent_id"
+    t.string "condition_type", null: false
+    t.string "operator", null: false
+    t.string "value"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
-    t.index ["rule_id"], name: "index_rule_triggers_on_rule_id"
+    t.index ["parent_id"], name: "index_rule_conditions_on_parent_id"
+    t.index ["rule_id"], name: "index_rule_conditions_on_rule_id"
   end
 
   create_table "rules", id: :uuid, default: -> { "gen_random_uuid()" }, force: :cascade do |t|
     t.uuid "family_id", null: false
+    t.string "resource_type", null: false
     t.date "effective_date", null: false
     t.boolean "active", default: true, null: false
     t.datetime "created_at", null: false
@@ -687,7 +693,8 @@ ActiveRecord::Schema[7.2].define(version: 2025_03_19_212839) do
   add_foreign_key "rejected_transfers", "account_transactions", column: "inflow_transaction_id"
   add_foreign_key "rejected_transfers", "account_transactions", column: "outflow_transaction_id"
   add_foreign_key "rule_actions", "rules"
-  add_foreign_key "rule_triggers", "rules"
+  add_foreign_key "rule_conditions", "rule_conditions", column: "parent_id"
+  add_foreign_key "rule_conditions", "rules"
   add_foreign_key "rules", "families"
   add_foreign_key "security_prices", "securities"
   add_foreign_key "sessions", "impersonation_sessions", column: "active_impersonator_session_id"

test/models/rule_test.rb

@@ -0,0 +1,57 @@
+require "test_helper"
+
+class RuleTest < ActiveSupport::TestCase
+  include Account::EntriesTestHelper
+
+  setup do
+    @family = families(:empty)
+    @account = @family.accounts.create!(name: "Rule test", balance: 1000, currency: "USD", accountable: Depository.new)
+    @whole_foods_merchant = @family.merchants.create!(name: "Whole Foods")
+    @groceries_category = @family.categories.create!(name: "Groceries")
+  end
+
+  test "can apply categories to transactions" do
+    transaction_entry = create_transaction(date: Date.current, account: @account, merchant: @whole_foods_merchant)
+
+    rule = Rule.create!(
+      family: @family,
+      resource_type: "transaction",
+      effective_date: 1.day.ago.to_date,
+      conditions: [ Rule::Condition.new(condition_type: "match_merchant", operator: "eq", value: "Whole Foods") ],
+      actions: [ Rule::Action.new(action_type: "set_category", value: "Groceries") ]
+    )
+
+    rule.apply
+
+    transaction_entry.reload
+
+    assert_equal @groceries_category, transaction_entry.account_transaction.category
+  end
+
+  test "can create compound rules" do
+    transaction_entry1 = create_transaction(date: Date.current, amount: 50, account: @account, merchant: @whole_foods_merchant)
+    transaction_entry2 = create_transaction(date: Date.current, amount: 100, account: @account, merchant: @whole_foods_merchant)
+
+    # Assign "Groceries" to transactions with a merchant of "Whole Foods" and an amount greater than $60
+    rule = Rule.create!(
+      family: @family,
+      resource_type: "transaction",
+      effective_date: 1.day.ago.to_date,
+      conditions: [
+        Rule::Condition.new(condition_type: "compound", operator: "and", conditions: [
+          Rule::Condition.new(condition_type: "match_merchant", operator: "eq", value: "Whole Foods"),
+          Rule::Condition.new(condition_type: "compare_amount", operator: "gt", value: 60)
+        ])
+      ],
+      actions: [ Rule::Action.new(action_type: "set_category", value: "Groceries") ]
+    )
+
+    rule.apply
+
+    transaction_entry1.reload
+    transaction_entry2.reload
+
+    assert_nil transaction_entry1.account_transaction.category
+    assert_equal @groceries_category, transaction_entry2.account_transaction.category
+  end
+end