1 files changed, 108 insertions, 0 deletions
diff --git a/lib/gitlab/ci/lint.rb b/lib/gitlab/ci/lint.rb
new file mode 100644
index 00000000000..86a9ebfa451
--- /dev/null
+++ b/lib/gitlab/ci/lint.rb
@@ -0,0 +1,108 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    class Lint
+      class Result
+        attr_reader :jobs, :errors, :warnings
+
+        def initialize(jobs:, errors:, warnings:)
+          @jobs = jobs
+          @errors = errors
+          @warnings = warnings
+        end
+
+        def valid?
+          @errors.empty?
+        end
+      end
+
+      def initialize(project:, current_user:)
+        @project = project
+        @current_user = current_user
+      end
+
+      def validate(content, dry_run: false)
+        if dry_run && Gitlab::Ci::Features.lint_creates_pipeline_with_dry_run?(@project)
+          simulate_pipeline_creation(content)
+        else
+          static_validation(content)
+        end
+      end
+
+      private
+
+      def simulate_pipeline_creation(content)
+        pipeline = ::Ci::CreatePipelineService
+          .new(@project, @current_user, ref: @project.default_branch)
+          .execute(:push, dry_run: true, content: content)
+
+        Result.new(
+          jobs: dry_run_convert_to_jobs(pipeline.stages),
+          errors: pipeline.error_messages.map(&:content),
+          warnings: pipeline.warning_messages(limit: ::Gitlab::Ci::Warnings::MAX_LIMIT).map(&:content)
+        )
+      end
+
+      def static_validation(content)
+        result = Gitlab::Ci::YamlProcessor.new(
+          content,
+          project: @project,
+          user: @current_user,
+          sha: @project.repository.commit.sha
+        ).execute
+
+        Result.new(
+          jobs: static_validation_convert_to_jobs(result),
+          errors: result.errors,
+          warnings: result.warnings.take(::Gitlab::Ci::Warnings::MAX_LIMIT) # rubocop: disable CodeReuse/ActiveRecord
+        )
+      end
+
+      def dry_run_convert_to_jobs(stages)
+        stages.reduce([]) do |jobs, stage|
+          jobs + stage.statuses.map do |job|
+            {
+              name: job.name,
+              stage: stage.name,
+              before_script: job.options[:before_script].to_a,
+              script: job.options[:script].to_a,
+              after_script: job.options[:after_script].to_a,
+              tag_list: (job.tag_list if job.is_a?(::Ci::Build)).to_a,
+              environment: job.options.dig(:environment, :name),
+              when: job.when,
+              allow_failure: job.allow_failure
+            }
+          end
+        end
+      end
+
+      def static_validation_convert_to_jobs(result)
+        jobs = []
+        return jobs unless result.valid?
+
+        result.stages.each do |stage_name|
+          result.builds.each do |job|
+            next unless job[:stage] == stage_name
+
+            jobs << {
+              name: job[:name],
+              stage: stage_name,
+              before_script: job.dig(:options, :before_script).to_a,
+              script: job.dig(:options, :script).to_a,
+              after_script: job.dig(:options, :after_script).to_a,
+              tag_list: job[:tag_list].to_a,
+              only: job[:only],
+              except: job[:except],
+              environment: job[:environment],
+              when: job[:when],
+              allow_failure: job[:allow_failure]
+            }
+          end
+        end
+
+        jobs
+      end
+    end
+  end
+end