From 04cfc577b8e2ff0ab5713a5a8c54e728e6a087d4 Mon Sep 17 00:00:00 2001
From: Laura Montemayor <lmontemayor@gitlab.com>
Date: Thu, 16 Oct 2025 15:37:32 +0200
Subject: [PATCH] Add RulesConverter to convert expression nodes into JSON

---
 lib/gitlab/ci/inputs/rules_converter.rb       |  56 +++++++++
 .../gitlab/ci/inputs/rules_converter_spec.rb  | 108 ++++++++++++++++++
 2 files changed, 164 insertions(+)
 create mode 100644 lib/gitlab/ci/inputs/rules_converter.rb
 create mode 100644 spec/lib/gitlab/ci/inputs/rules_converter_spec.rb

diff --git a/lib/gitlab/ci/inputs/rules_converter.rb b/lib/gitlab/ci/inputs/rules_converter.rb
new file mode 100644
index 00000000000000..447c2bf7b9c5f2
--- /dev/null
+++ b/lib/gitlab/ci/inputs/rules_converter.rb
@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    module Inputs
+      ##
+      #
+      # Converts parsed expression AST nodes JSON format with operator, field, value, and children.
+      #
+      class RulesConverter
+        def convert(node)
+          return unless node
+
+          case node
+          when Gitlab::Ci::Pipeline::Expression::Lexeme::Equals
+            {
+              'operator' => 'equals',
+              'field' => extract_input_name(node.left),
+              'value' => extract_value(node.right)
+            }
+          when Gitlab::Ci::Pipeline::Expression::Lexeme::NotEquals
+            {
+              'operator' => 'not_equals',
+              'field' => extract_input_name(node.left),
+              'value' => extract_value(node.right)
+            }
+          when Gitlab::Ci::Pipeline::Expression::Lexeme::And
+            {
+              'operator' => 'AND',
+              'children' => [convert(node.left), convert(node.right)].compact
+            }
+          when Gitlab::Ci::Pipeline::Expression::Lexeme::Or
+            {
+              'operator' => 'OR',
+              'children' => [convert(node.left), convert(node.right)].compact
+            }
+          end
+        end
+
+        private
+
+        def extract_input_name(node)
+          return unless node.is_a?(Gitlab::Ci::Pipeline::Expression::Lexeme::Input)
+
+          node.value
+        end
+
+        def extract_value(node)
+          return unless node.is_a?(Gitlab::Ci::Pipeline::Expression::Lexeme::String)
+
+          node.evaluate
+        end
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/ci/inputs/rules_converter_spec.rb b/spec/lib/gitlab/ci/inputs/rules_converter_spec.rb
new file mode 100644
index 00000000000000..fa4450c33584b8
--- /dev/null
+++ b/spec/lib/gitlab/ci/inputs/rules_converter_spec.rb
@@ -0,0 +1,108 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Ci::Inputs::RulesConverter, feature_category: :pipeline_composition do
+  let(:converter) { described_class.new }
+
+  describe '#convert' do
+    context 'with nil node' do
+      it 'returns nil' do
+        expect(converter.convert(nil)).to be_nil
+      end
+    end
+
+    context 'with equals operator' do
+      it 'converts to equals structure' do
+        statement = Gitlab::Ci::Pipeline::Expression::Statement.new('$[[ inputs.env ]] == "prod"')
+        node = statement.parse_tree
+
+        result = converter.convert(node)
+
+        expect(result).to eq(
+          'operator' => 'equals',
+          'field' => 'env',
+          'value' => 'prod'
+        )
+      end
+    end
+
+    context 'with not_equals operator' do
+      it 'converts to not_equals structure' do
+        statement = Gitlab::Ci::Pipeline::Expression::Statement.new('$[[ inputs.env ]] != "dev"')
+        node = statement.parse_tree
+
+        result = converter.convert(node)
+
+        expect(result).to eq(
+          'operator' => 'not_equals',
+          'field' => 'env',
+          'value' => 'dev'
+        )
+      end
+    end
+
+    context 'with AND operator' do
+      it 'converts to AND structure with children' do
+        statement = Gitlab::Ci::Pipeline::Expression::Statement.new(
+          '$[[ inputs.env ]] == "prod" && $[[ inputs.region ]] == "us"'
+        )
+        node = statement.parse_tree
+
+        result = converter.convert(node)
+
+        expect(result).to eq(
+          'operator' => 'AND',
+          'children' => [
+            { 'operator' => 'equals', 'field' => 'env', 'value' => 'prod' },
+            { 'operator' => 'equals', 'field' => 'region', 'value' => 'us' }
+          ]
+        )
+      end
+    end
+
+    context 'with OR operator' do
+      it 'converts to OR structure with children' do
+        statement = Gitlab::Ci::Pipeline::Expression::Statement.new(
+          '$[[ inputs.env ]] == "prod" || $[[ inputs.env ]] == "staging"'
+        )
+        node = statement.parse_tree
+
+        result = converter.convert(node)
+
+        expect(result).to eq(
+          'operator' => 'OR',
+          'children' => [
+            { 'operator' => 'equals', 'field' => 'env', 'value' => 'prod' },
+            { 'operator' => 'equals', 'field' => 'env', 'value' => 'staging' }
+          ]
+        )
+      end
+    end
+
+    context 'with nested operators' do
+      it 'converts nested AND/OR correctly' do
+        statement = Gitlab::Ci::Pipeline::Expression::Statement.new(
+          '($[[ inputs.env ]] == "prod" && $[[ inputs.region ]] == "us") || $[[ inputs.env ]] == "dev"'
+        )
+        node = statement.parse_tree
+
+        result = converter.convert(node)
+
+        expect(result).to eq(
+          'operator' => 'OR',
+          'children' => [
+            {
+              'operator' => 'AND',
+              'children' => [
+                { 'operator' => 'equals', 'field' => 'env', 'value' => 'prod' },
+                { 'operator' => 'equals', 'field' => 'region', 'value' => 'us' }
+              ]
+            },
+            { 'operator' => 'equals', 'field' => 'env', 'value' => 'dev' }
+          ]
+        )
+      end
+    end
+  end
+end
-- 
GitLab