module Flucti
  module Utilities
    module UserInterface
      extend self
      
      def terminal_width
        @terminal_width ||= begin
          # Avoid error messages on Windows
          result = RUBY_PLATFORM =~ /mswin/ ? "" : `stty size 2>/dev/null`
          (result.split[1] || 80).to_i
        end
      end
      
      def puts_title(title, io=$stdout)
        generic_puts_title(io, title, "=", 3)
      end

      def puts_subtitle(title, io=$stdout)
        generic_puts_title(io, title, "-", 6)
      end

      def puts_long(message, io=$stdout)
        io.puts(adjust_to_terminal(message))
      end

      def puts_list(entries, *args, &block)
        Utilities::ListDisplayer.new(*args, &block).display(entries)
      end

      def qcommand(task_name)
        quote(command(task_name))
      end

      def quote(str)
        %(`#{str}')
      end
      alias q :quote

      def confirm(message)
        puts_title("/!\\ Warning")
        puts_long(message)
        puts "(You now have 10 seconds to cancel by pressing CTRL+C.)"
        puts

        if ENV['FORCE']
          puts "$FORCE set, proceeding forcefully."
        else
          # 10 second countdown to cancel
          begin
            10.downto(0) { |left| print(left, " "); sleep 1 }
          rescue Interrupt
            puts "\nAction cancelled."
            exit 0
          end
        end
      end

    private

      POINT_START_FORMAT = '^ *[*$!] +'.freeze

      def generic_puts_title(io, title, line_block, left_padding)
        io.puts "", "#{line_block * left_padding} #{title} ".ljust(terminal_width, line_block)
      end

      def strip_margin(str)
        str = str.to_s
        margin = str.scan(/^\s*/).sort.first
        str.gsub(/^#{Regexp.escape margin}/, '')
      end

      def adjust_to_terminal(str)
        str = strip_margin(str.to_s)
        
        result, paragraph = [], []
        process_current_paragraph = lambda do
          result << adjust_paragraph_to_terminal(paragraph.join("\n"), :auto) if paragraph.any?
          paragraph = []
        end
        tail = str[/\s+\z/] || ""
        str.split(/\n/).each do |line|
          case line
          when /^\s*$/
            process_current_paragraph[]
            result << nil
          when /^-/
            process_current_paragraph[]
            paragraph << line
            process_current_paragraph[]
          when /#{POINT_START_FORMAT}[^ ]/
            process_current_paragraph[]
            paragraph << line
          else
            paragraph << line
          end
        end
        process_current_paragraph[]
        result.join("\n") + tail
      end

      def adjust_paragraph_to_terminal(paragraph, margin=0)
        paragraph = paragraph.to_s
        if margin == :auto
          margin_top  = paragraph[/#{POINT_START_FORMAT}/]
          paragraph   = $' if $'
          margin      = margin_top ? margin_top.length : 0
          paragraph   = paragraph.gsub(/^\s{0,#{margin}}/, '')
        end
        tail = paragraph[/\s+\z/] || ""
        paragraph.
          split(/\n/).map { |line| line.strip }.join(" ").scan(/(.{1,#{terminal_width - margin}})(\s|$)/).
          map { |matches| (margin_top ? (old, margin_top = margin_top, nil; old) : " " * margin) + matches.first }.
          join("\n") + tail
      end
    end
  end
end