module Capistrano
  class CLI
    module Help
      LINE_PADDING = 7
      MIN_MAX_LEN  = 30
      HEADER_LEN   = 60

      def self.included(base) #:nodoc:
        base.send :alias_method, :execute_requested_actions_without_help, :execute_requested_actions
        base.send :alias_method, :execute_requested_actions, :execute_requested_actions_with_help
      end

      def execute_requested_actions_with_help(config)
        if options[:tasks]
          task_list(config)
        elsif options[:explain]
          explain_task(config, options[:explain])
        else
          execute_requested_actions_without_help(config)
        end
      end

      def task_list(config) #:nodoc:
        tasks = config.task_list(:all)

        if tasks.empty?
          warn "There are no tasks available. Please specify a recipe file to load."
        else
          all_tasks_length = tasks.length
          if options[:verbose].to_i < 1
            tasks = tasks.reject { |t| t.description.empty? || t.description =~ /^\[internal\]/ }
          end

          tasks = tasks.sort_by { |task| task.fully_qualified_name }

          longest = tasks.map { |task| task.fully_qualified_name.length }.max
          max_length = output_columns - longest - LINE_PADDING
          max_length = MIN_MAX_LEN if max_length < MIN_MAX_LEN

          tasks.each do |task|
            puts "cap %-#{longest}s # %s" % [task.fully_qualified_name, task.brief_description(max_length)]
          end

          if all_tasks_length > tasks.length
            puts
            puts "Some tasks were not listed, either because they have no description,"
            puts "or because they are only used internally by other tasks. To see all"
            puts "tasks, type `#{File.basename($0)} -Tv'."
          end

          puts
          puts "Extended help may be available for these tasks."
          puts "Type `#{File.basename($0)} -e taskname' to view it."
        end
      end

      def explain_task(config, name) #:nodoc:
        task = config.find_task(name)
        if task.nil?
          warn "The task `#{name}' does not exist."
        else
          puts "-" * HEADER_LEN
          puts "cap #{name}"
          puts "-" * HEADER_LEN

          if task.description.empty?
            puts "There is no description for this task."
          else
            puts format_text(task.description)
          end

          puts
        end
      end

      def long_help #:nodoc:
        help_text = File.read(File.join(File.dirname(__FILE__), "help.txt"))
        self.class.ui.page_at = self.class.ui.output_rows - 2
        self.class.ui.say format_text(help_text)
      end

      def format_text(text) #:nodoc:
        formatted = ""
        text.each_line do |line|
          indentation = line[/^\s+/] || ""
          indentation_size = indentation.split(//).inject(0) { |c,s| c + (s[0] == ?\t ? 8 : 1) }
          lines = line.strip.gsub(/(.{1,#{output_columns - indentation_size}})(?:\s+|\Z)/, "\\1\n").split(/\n/)
          if lines.empty?
            formatted << "\n"
          else
            formatted << lines.map { |l| "#{indentation}#{l}\n" }.join
          end
        end
        formatted
      end

      def output_columns #:nodoc:
        @output_columns ||= self.class.ui.output_cols > 80 ? 80 : self.class.ui.output_cols
      end
    end
  end
end