module Ci
  class CreatePipelineService < BaseService
    attr_reader :pipeline

    def execute(source, ignore_skip_ci: false, save_on_errors: true, trigger_request: nil, schedule: nil)
      @pipeline = Ci::Pipeline.new(
        source: source,
        project: project,
        ref: ref,
        sha: sha,
        before_sha: before_sha,
        tag: tag?,
        trigger_requests: Array(trigger_request),
        user: current_user,
        pipeline_schedule: schedule
      )

      result = validate(current_user,
                        ignore_skip_ci: ignore_skip_ci,
                        save_on_errors: save_on_errors)

      return result if result

      begin
        Ci::Pipeline.transaction do
          pipeline.save!

          yield(pipeline) if block_given?

          Ci::CreatePipelineStagesService
            .new(project, current_user)
            .execute(pipeline)
        end
      rescue ActiveRecord::RecordInvalid => e
        return error("Failed to persist the pipeline: #{e}")
      end

      update_merge_requests_head_pipeline

      cancel_pending_pipelines if project.auto_cancel_pending_pipelines?

      pipeline_created_counter.increment(source: source)

      pipeline.tap(&:process!)
    end

    private

    def validate(triggering_user, ignore_skip_ci:, save_on_errors:)
      unless project.builds_enabled?
        return error('Pipeline is disabled')
      end

      unless allowed_to_trigger_pipeline?(triggering_user)
        if can?(triggering_user, :create_pipeline, project)
          return error("Insufficient permissions for protected ref '#{ref}'")
        else
          return error('Insufficient permissions to create a new pipeline')
        end
      end

      unless branch? || tag?
        return error('Reference not found')
      end

      unless commit
        return error('Commit not found')
      end

      unless pipeline.config_processor
        unless pipeline.ci_yaml_file
          return error("Missing #{pipeline.ci_yaml_file_path} file")
        end
        return error(pipeline.yaml_errors, save: save_on_errors)
      end

      if !ignore_skip_ci && skip_ci?
        pipeline.skip if save_on_errors
        return pipeline
      end

      unless pipeline.has_stage_seeds?
        return error('No stages / jobs for this pipeline.')
      end
    end

    def allowed_to_trigger_pipeline?(triggering_user)
      if triggering_user
        allowed_to_create?(triggering_user)
      else # legacy triggers don't have a corresponding user
        !project.protected_for?(ref)
      end
    end

    def allowed_to_create?(triggering_user)
      access = Gitlab::UserAccess.new(triggering_user, project: project)

      can?(triggering_user, :create_pipeline, project) &&
        if branch?
          access.can_update_branch?(ref)
        elsif tag?
          access.can_create_tag?(ref)
        else
          true # Allow it for now and we'll reject when we check ref existence
        end
    end

    def update_merge_requests_head_pipeline
      return unless pipeline.latest?

      MergeRequest.where(source_project: @pipeline.project, source_branch: @pipeline.ref)
        .update_all(head_pipeline_id: @pipeline.id)
    end

    def skip_ci?
      return false unless pipeline.git_commit_message
      pipeline.git_commit_message =~ /\[(ci[ _-]skip|skip[ _-]ci)\]/i
    end

    def cancel_pending_pipelines
      Gitlab::OptimisticLocking.retry_lock(auto_cancelable_pipelines) do |cancelables|
        cancelables.find_each do |cancelable|
          cancelable.auto_cancel_running(pipeline)
        end
      end
    end

    def auto_cancelable_pipelines
      project.pipelines
        .where(ref: pipeline.ref)
        .where.not(id: pipeline.id)
        .where.not(sha: project.repository.sha_from_ref(pipeline.ref))
        .created_or_pending
    end

    def commit
      @commit ||= project.commit(origin_sha || origin_ref)
    end

    def sha
      commit.try(:id)
    end

    def before_sha
      params[:checkout_sha] || params[:before] || Gitlab::Git::BLANK_SHA
    end

    def origin_sha
      params[:checkout_sha] || params[:after]
    end

    def origin_ref
      params[:ref]
    end

    def branch?
      return @is_branch if defined?(@is_branch)

      @is_branch =
        project.repository.ref_exists?(Gitlab::Git::BRANCH_REF_PREFIX + ref)
    end

    def tag?
      return @is_tag if defined?(@is_tag)

      @is_tag =
        project.repository.ref_exists?(Gitlab::Git::TAG_REF_PREFIX + ref)
    end

    def ref
      @ref ||= Gitlab::Git.ref_name(origin_ref)
    end

    def valid_sha?
      origin_sha && origin_sha != Gitlab::Git::BLANK_SHA
    end

    def error(message, save: false)
      pipeline.tap do
        pipeline.errors.add(:base, message)

        if save
          pipeline.drop
          update_merge_requests_head_pipeline
        end
      end
    end

    def pipeline_created_counter
      @pipeline_created_counter ||= Gitlab::Metrics.counter(:pipelines_created_total, "Counter of pipelines created")
    end
  end
end