changes RuleSet/Rule structure and introduce RulesEvaluator

IDEAS.md

@@ -13,7 +13,7 @@ Rule
 * enabled?
 * criteria_type (Header, Body…)
 * criteria_value
-* operator (match, equal, start, end, contain)
+* operator (match, equal, start, end, contain, exist, empty)
 * operator_inverted?
 * value
 

app/mailboxes/in_mailbox.rb

@@ -1,9 +1,22 @@
 class InMailbox < ApplicationMailbox
   def process
-    email_importer = EmailImporter.new()
+    email_importer = EmailImporter.new
     repository = EmailRepository.new
+    rules_evaluator = RulesEvaluator.new
 
     email = email_importer.import(mail)
+
+    RuleSet.enabled.each do |rule_set|
+      if rules_evaluator.evaluate(email, rule_set)
+        rule_set.actions.enabled.each do |action|
+          klass = action.class_name.constantize
+          email = klass.new.process(email)
+        rescue NameError => ex
+          # TODO: log a warning
+        end
+      end
+    end
+
     repository.save(email)
   end
 end

app/models/action.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
 class Action < ApplicationRecord
-  belongs_to :ruleset
+  belongs_to :rule_set
+
+  scope :enabled, -> { where(enabled: true) }
 end

app/models/rule.rb

@@ -1,5 +1,8 @@
 # frozen_string_literal: true
 
 class Rule < ApplicationRecord
-  belongs_to :ruleset
+  belongs_to :rule_set
+  has_many :actions
+
+  scope :enabled, -> { where(enabled: true) }
 end

app/models/rule_set.rb

@@ -1,4 +1,8 @@
 # frozen_string_literal: true
 
 class RuleSet < ApplicationRecord
+  has_many :rules
+  has_many :actions
+
+  scope :enabled, -> { where(enabled: true) }
 end

app/services/rules_evaluator.rb

@@ -0,0 +1,89 @@
+class RulesEvaluator
+
+  def evaluate(email, rule_set)
+    rules_state = true
+
+    rule_set.rules.enabled.each do |rule|
+      subjects = prepare_subjects(email, rule)
+      result = apply_rule(subjects, rule)
+      result = ! result if rule.inverted?
+      rules_state = apply_operator(rules_state, rule_set.operator, result)
+
+      break unless rules_state
+    end
+
+    rules_state
+  end
+
+  private
+
+  def prepare_subjects(email, rule)
+    case rule.subject_type
+      when "header"
+        Array(email.header_values(rule.subject_value))
+      when "body"
+        Array(email.plain_body)
+      else
+        raise ArgumentError, "Unrecognized subject type '#{rule.subject_type}'"
+    end
+  end
+
+  def apply_rule(subjects, rule)
+    case rule.condition_type
+      when "match", "matches"
+        subjects.any? { |subject|
+          pattern = Regexp.new(rule.condition_value)
+          subject.match?
+        }
+      when "equal", "equals"
+        subjects.any? { |subject|
+          subject == rule.condition_value
+        }
+      when "start", "starts"
+        subjects.any? { |subject|
+          subject.starts_with? rule.condition_value
+        }
+      when "end", "ends"
+        subjects.any? { |subject|
+          subject.ends_with? rule.condition_value
+        }
+      when "contain", "contains"
+        subjects.any? { |subject|
+          subject.include? rule.condition_value
+        }
+      when "exist", "exists"
+        subjects.any? { |subject|
+          subject.exists?
+        }
+      when "empty"
+        subjects.all? { |subject|
+          subject.empty?
+        }
+      when "date_before"
+        # subjects.all? { |subject|
+        #   subject.empty?
+        # }
+      when "date_after"
+        # subjects.all? { |subject|
+        #   subject.empty?
+        # }
+      else
+        true
+    end
+
+    def apply_operator(state, operator, result)
+      case operator
+        when "AND"
+          (state and result)
+        when "OR"
+          (state or result)
+        when "XOR"
+          (state or result) and not (rules_state and result)
+        else
+          raise ArgumentError, "Unrecognized logic '#{rule_set.operator}'"
+      end
+    end
+
+  end
+
+end

db/migrate/20210118130305_create_rule_sets.rb

@@ -4,6 +4,8 @@ class CreateRuleSets < ActiveRecord::Migration[6.1]
       t.string :name
       t.text :description
       t.boolean :enabled, default: true
+      t.string :operator, default: "AND", limit: 3
+      t.boolean :inverted, default: false
 
       t.timestamps
     end

db/migrate/20210118130313_create_rules.rb

@@ -1,14 +1,14 @@
 class CreateRules < ActiveRecord::Migration[6.1]
   def change
     create_table :rules do |t|
-      t.references :ruleset, null: false, foreign_key: true
+      t.references :rule_set, null: false, foreign_key: true
       t.string :name
       t.boolean :enabled, default: true
-      t.string :criteria_type
-      t.string :criteria_value
-      t.string :operator, default: "contain"
-      t.boolean :operator_inverted, default: false
-      t.string :value
+      t.string :subject_type
+      t.string :subject_value
+      t.string :condition_type, default: "contain"
+      t.string :condition_value
+      t.boolean :inverted, default: false
 
       t.timestamps
     end

db/migrate/20210118132809_create_actions.rb

@@ -1,10 +1,10 @@
 class CreateActions < ActiveRecord::Migration[6.1]
   def change
     create_table :actions do |t|
-      t.references :ruleset, null: false, foreign_key: true
+      t.references :rule_set, null: false, foreign_key: true
       t.string :name
       t.boolean :enabled, default: true
-      t.string :action_class
+      t.string :class_name
 
       t.timestamps
     end

db/schema.rb

@@ -22,13 +22,13 @@ ActiveRecord::Schema.define(version: 2021_01_18_132809) do
   end
 
   create_table "actions", force: :cascade do |t|
-    t.integer "ruleset_id", null: false
+    t.integer "rule_set_id", null: false
     t.string "name"
     t.boolean "enabled", default: true
-    t.string "action_class"
+    t.string "class_name"
     t.datetime "created_at", precision: 6, null: false
     t.datetime "updated_at", precision: 6, null: false
-    t.index ["ruleset_id"], name: "index_actions_on_ruleset_id"
+    t.index ["rule_set_id"], name: "index_actions_on_rule_set_id"
   end
 
   create_table "active_storage_attachments", force: :cascade do |t|
@@ -91,22 +91,24 @@ ActiveRecord::Schema.define(version: 2021_01_18_132809) do
     t.string "name"
     t.text "description"
     t.boolean "enabled", default: true
+    t.string "operator", limit: 3, default: "AND"
+    t.boolean "inverted", default: false
     t.datetime "created_at", precision: 6, null: false
     t.datetime "updated_at", precision: 6, null: false
   end
 
   create_table "rules", force: :cascade do |t|
-    t.integer "ruleset_id", null: false
+    t.integer "rule_set_id", null: false
     t.string "name"
     t.boolean "enabled", default: true
-    t.string "criteria_type"
-    t.string "criteria_value"
-    t.string "operator", default: "contain"
-    t.boolean "operator_inverted", default: false
-    t.string "value"
+    t.string "subject_type"
+    t.string "subject_value"
+    t.string "condition_type", default: "contain"
+    t.string "condition_value"
+    t.boolean "inverted", default: false
     t.datetime "created_at", precision: 6, null: false
     t.datetime "updated_at", precision: 6, null: false
-    t.index ["ruleset_id"], name: "index_rules_on_ruleset_id"
+    t.index ["rule_set_id"], name: "index_rules_on_rule_set_id"
   end
 
   create_table "users", force: :cascade do |t|
@@ -126,8 +128,8 @@ ActiveRecord::Schema.define(version: 2021_01_18_132809) do
     t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
   end
 
-  add_foreign_key "actions", "rulesets"
+  add_foreign_key "actions", "rule_sets"
   add_foreign_key "active_storage_attachments", "active_storage_blobs", column: "blob_id"
   add_foreign_key "active_storage_variant_records", "active_storage_blobs", column: "blob_id"
-  add_foreign_key "rules", "rulesets"
+  add_foreign_key "rules", "rule_sets"
 end