# coding: utf-8

module TTY
  class Screen
    class Size
      # Initialize terminal size detection
      #
      # @api public
      def initialize(options = {})
        @output  = options.fetch(:output) { $stderr }
        @verbose = options.fetch(:verbose) { false }
      end

      # Get terminal rows and columns
      #
      # @return [Array[Integer, Integer]]
      #   return rows & columns
      #
      # @api public
      def size
        size =   from_io_console
        size ||= from_readline
        size ||= from_tput
        size ||= from_stty
        size ||= from_env
        size ||= from_ansicon
        size ||  default_size
      end

      # Detect screen size by loading io/console lib
      #
      # @return [Array[Integer, Integer]]
      #
      # @api private
      def from_io_console
        return false if jruby?
        try_io_console { |size|
          size if nonzero_column?(size[1])
        }
      end

      # Attempts to load native console extension
      #
      # @return [Boolean, Array]
      #
      # @api private
      def try_io_console
        begin
          require 'io/console'

          begin
            if output.tty? && IO.method_defined?(:winsize)
              yield output.winsize
            else
              false
            end
          rescue Errno::EOPNOTSUPP
            false
          end
        rescue LoadError
          warn 'no native io/console support' if @verbose
          false
        end
      end

      # Detect screen size using Readline
      #
      # @api private
      def from_readline
        return unless defined?(Readline)
        size = Readline.get_screen_size
        size if nonzero_column?(size[1])
      rescue NotImplementedError
      end

      # Detect terminal size from tput utility
      #
      # @api private
      def from_tput
        return unless output.tty?
        lines = run_command('tput', 'lines').to_i
        cols  = run_command('tput', 'cols').to_i
        [lines, cols] if nonzero_column?(lines)
      rescue Errno::ENOENT
      end

      # Detect terminal size from stty utility
      #
      # @api private
      def from_stty
        return unless output.tty?
        size = run_command('stty', 'size').split.map(&:to_i)
        size if nonzero_column?(size[1])
      rescue Errno::ENOENT
      end

      # Detect terminal size from environment
      #
      # @api private
      def from_env
        return unless ENV['COLUMNS'] =~ /^\d+$/
        size = [(ENV['LINES'] || ENV['ROWS']).to_i, ENV['COLUMNS'].to_i]
        size if nonzero_column?(size[1])
      end

      # Detect terminal size on windows
      #
      # @api private
      def from_ansicon
        return unless ENV['ANSICON'] =~ /\((.*)x(.*)\)/
        size = [$2, $1].map(&:to_i)
        size if nonzero_column?(size[1])
      end

      # Default terminal size
      #
      # @api public
      def default_size
        [
          ENV['LINES'].to_i.nonzero? || 27,
          ENV['COLUMNS'].to_i.nonzero? || 80
        ]
      end

      private

      # Specifies an output stream object
      #
      # @api public
      attr_reader :output

      # Runs command in subprocess
      #
      # @api private
      def run_command(command, *args)
        `#{command} #{args.join(' ')} 2>/dev/null`
      end

      def nonzero_column?(column)
        column.to_i > 0
      end

      def jruby?
        RbConfig::CONFIG['ruby_install_name'] == 'jruby'
      end
    end # Size
  end # Screen
end # TTY