add condition form model

app/models/condition_form.rb

@@ -0,0 +1,58 @@
+class ConditionForm
+  include ActiveModel::Model
+  include Logic
+
+  attr_accessor :top_operator_name, :rows
+
+  def to_condition
+    case sub_conditions.count
+    when 0
+      nil
+    when 1
+      sub_conditions.first
+    else
+      top_operator_class.new(sub_conditions)
+    end
+  end
+
+  def delete_row(i)
+    rows.slice!(i)
+
+    self
+  end
+
+  def change_champ(i)
+    sub_conditions[i] = Logic.ensure_compatibility_from_left(sub_conditions[i])
+
+    self
+  end
+
+  private
+
+  def top_operator_class
+    Logic.class_from_name(top_operator_name)
+  end
+
+  def sub_conditions
+    @sub_conditions ||= rows.map { |row| row_to_condition(row) }
+  end
+
+  def row_to_condition(row)
+    left = Logic.from_json(row[:targeted_champ])
+    right = parse_value(row[:value])
+
+    Logic.class_from_name(row[:operator_name]).new(left, right)
+  end
+
+  def parse_value(value)
+    return empty if value.blank?
+
+    number = Integer(value) rescue nil
+    return constant(number) if number.present?
+
+    json = JSON.parse(value) rescue nil
+    return Logic.from_json(value) if json.present?
+
+    constant(value)
+  end
+end

spec/models/condition_form_spec.rb

@@ -0,0 +1,52 @@
+describe ConditionForm, type: :model do
+  include Logic
+
+  describe 'to_condition' do
+    let(:top_operator_name) { '' }
+
+    subject { ConditionForm.new(rows: rows, top_operator_name: top_operator_name).to_condition }
+
+    context 'when a row is added' do
+      let(:rows) { [{ targeted_champ: champ_value(1).to_json, operator_name: Logic::Eq.name, value: '1' }] }
+      it { is_expected.to eq(ds_eq(champ_value(1), constant(1))) }
+    end
+
+    context 'when two rows are added' do
+      let(:top_operator_name) { Logic::And.name }
+      let(:rows) do
+        [
+          { targeted_champ: champ_value(1).to_json, operator_name: Logic::Eq.name, value: '2' },
+          { targeted_champ: champ_value(3).to_json, operator_name: Logic::GreaterThan.name, value: '4' }
+        ]
+      end
+
+      let(:expected) do
+        ds_and([
+          ds_eq(champ_value(1), constant(2)),
+          greater_than(champ_value(3), constant(4))
+        ])
+      end
+      it { is_expected.to eq(expected) }
+    end
+
+    context 'when 3 rows are added' do
+      let(:top_operator_name) { Logic::Or.name }
+      let(:rows) do
+        [
+          { targeted_champ: champ_value(1).to_json, operator_name: Logic::Eq.name, value: '2' },
+          { targeted_champ: champ_value(3).to_json, operator_name: Logic::GreaterThan.name, value: '4' },
+          { targeted_champ: champ_value(5).to_json, operator_name: Logic::LessThan.name, value: '6' }
+        ]
+      end
+
+      let(:expected) do
+        ds_or([
+          ds_eq(champ_value(1), constant(2)),
+          greater_than(champ_value(3), constant(4)),
+          less_than(champ_value(5), constant(6))
+        ])
+      end
+      it { is_expected.to eq(expected) }
+    end
+  end
+end