module PowerStencil
  module Engine

    module BuildHandling

      include Climatic::Utils::SafeExec

      attr_reader :last_build_report

      def build(entities_to_build, fail_on_error: false, parallelized: false)
        logger.debug 'Starting build process...'
        raise PowerStencil::Error, 'Parallel builds are not yet supported !' if parallelized

        build_target_seed =  entities_to_build.map(&:as_path).map do |entity_full_name|
          entity_full_name.tr '/', '_'
        end .join '_'
        build_target_path = project.build_run_path build_target_seed

        @last_build_report = {}

        entities_to_build.each do |entity_to_build|
          begin
            entity_build_report = []
            unless entity_to_build.buildable?
              msg = "Entity '#{entity_to_build.as_path}' is not buildable !"
              entity_build_report << msg
              raise PowerStencil::Error, msg
            end
            build_entity_target_path = if config[:'target-path']
                                         specified_target_path = File.expand_path config[:'target-path']
                                         if File.exists? specified_target_path
                                           raise PowerStencil::Error, "Specified target path '#{specified_target_path}' already exists ! Aborting..."
                                         end
                                         specified_target_path
                                       else
                                         File.join build_target_path, entity_to_build.as_path.tr('/', '_')
                                       end

            build_entity entity_to_build, build_entity_target_path

            entity_build_report << 'Ok'
          rescue SyntaxError, StandardError => e
            entity_build_report << e.message
            if fail_on_error
              raise e
            else
              logger.debug PowerStencil::Error.report_error e
            end
          ensure
            last_build_report[entity_to_build.as_path] = entity_build_report
          end
        end
      end

      def generate_build_files(entity_to_build, target_path)
        logger.info "Rendering '#{entity_to_build.as_path}' templates in '#{target_path}'"
        render_source entity_to_build.templates_path, target_path, main_entry_point: entity_to_build.as_path
        logger.info "Detemplatized files generated in '#{target_path}'"
        manage_build_links target_path
      end

      def post_build_hook(entity_to_build, files_path)
        case entity_to_build.type
        when :simple_exec
          script_to_execute = File.expand_path File.join(files_path, entity_to_build.post_process.process)
          exec_options = {message: "Running '#{script_to_execute}'"}
          exec_options[:show_output] = true if config[:verbose]
          process_report = safely_exec_command "'#{script_to_execute}'", exec_options
          unless process_report.exit_status.exitstatus == 0
            raise PowerStencil::Error, "Process `#{process_report.command}` failed and returned exit code '#{process_report.exit_status.exitstatus}'"
          end
          process_report
        end
      end


      private

      def manage_build_links(last_build_path)
        if PowerStencil::Utils::Os.windows?
          logger.info 'Cannot create link to last build folder under Windows !'
          return
        end
        last_build_link_path = project.last_build_stable_link_path
        previous_build_link_path = project.previous_build_stable_link_path
        current_last_build_link_target_path = (File.symlink? last_build_link_path) ? File.readlink(last_build_link_path) : nil

        safely_remove_link previous_build_link_path
        unless current_last_build_link_target_path.nil?
          File.symlink current_last_build_link_target_path, previous_build_link_path unless File.exists? previous_build_link_path
        end

        safely_remove_link last_build_link_path
        File.symlink last_build_path, last_build_link_path unless File.exists? last_build_link_path

        if config[:'tag-build']
          build_tag_path = File.join project.build_root_path, config[:'tag-build']
          safely_remove_link build_tag_path
          File.symlink last_build_path, build_tag_path unless File.exists? build_tag_path
        end
      end


      def safely_remove_link(link)
        if File.exists? link
          if File.symlink? link
            File.unlink link
          else
            logger.warn "Warning '#{link}' is not a symlink !!"
            return false
          end
        else
          logger.debug "No file/link to delete ('#{link}')"
        end
        true
      end


      def build_entity(entity_to_build, target_path)
        initial_directory = Dir.pwd
        target_plugin_name =  entity_to_build.buildable_by.to_s

        # Files generation
        if target_plugin_name.empty?
          generate_build_files entity_to_build, target_path
        else
          target_plugin = project.plugins[target_plugin_name]
          raise PowerStencil::Error, "Could not find plugin '#{target_plugin_name}' !" if target_plugin.nil?
          if target_plugin.capabilities[:generate_build_files]
            target_plugin.generate_build_files entity_to_build, target_path
          else
            logger.info 'Falling back to PowerStencil core build files generation process...'
            generate_build_files entity_to_build, target_path
          end
        end

        # Post processing executed from generated directory (#11)
        Dir.chdir target_path

        # Post generation action
        if target_plugin_name.empty?
          post_build_hook entity_to_build, target_path
        else
          target_plugin = project.plugins[target_plugin_name]
          raise PowerStencil::Error, "Could not find plugin '#{target_plugin_name}' !" if target_plugin.nil?
          raise PowerStencil::Error, "Plugin '#{target_plugin_name}' has no post build capability !" unless target_plugin.capabilities[:post_build]
          target_plugin.post_build_hook entity_to_build, target_path
        end

      ensure
        Dir.chdir initial_directory
      end

    end

  end
end