require 'attached/processor/base'
require 'attached/processor/error'

module Attached
  module Processor
    class Image < Base


      attr_reader :path
      attr_reader :extension

      attr_reader :width
      attr_reader :height
      attr_reader :quality
      attr_reader :operation


      # Create a processor.
      #
      # Parameters:
      #
      # * file       - The file to be processed.
      # * options    - The options to be applied to the processing.
      # * attachment - The attachment the processor is being run for.

      def initialize(file, options = {}, attachment = nil)
        super

        @path      = self.file.path

        @size      = options[:size]
        @quality   = options[:quality]
        @extension = options[:extension]

        @width, @height, @operation = @size.match(/(\d*)x?(\d*)(.*)/)[1..3] if @size

        @width     ||= options[:width]
        @height    ||= options[:height]
        @operation ||= options[:operation]

        if @operation
          case @operation.intern
          when :decrease then @operation = '>'
          when :increase then @operation = '<'
          when :default  then @operation = '#'
          end
        end

        @operation ||= '#'
        @extension ||= self.attachment.extension

        @width     = Integer(self.width)  if self.width
        @height    = Integer(self.height) if self.height
      end


      # Redirect output path.

      def redirect
        ">/dev/null 2>&1" if File.exist?("/dev/null")
      end


      # Helper function for calling processors.
      #
      # Usage:
      #
      #   self.process

      def process

        result = Tempfile.new(["", self.extension])
        result.binmode

        begin

          parameters = []

          parameters << self.path

          if width and height
            case operation
            when '#' then parameters << "-resize #{width}x#{height}^ -gravity center -extent #{width}x#{height}"
            when '<' then parameters << "-resize #{width}x#{height}\\<"
            when '>' then parameters << "-resize #{width}x#{height}\\>"
            else          parameters << "-resize #{width}x#{height}"
            end
          end

          parameters << "-quality #{quality}" if quality

          parameters << result.path

          parameters = parameters.join(" ").squeeze(" ")

          `convert #{parameters} #{redirect}`

          raise Errno::ENOENT if $?.exitstatus == 127

        rescue Errno::ENOENT
          raise "command 'convert' not found: ensure ImageMagick is installed"
        end

        unless $?.exitstatus == 0
          raise Attached::Processor::Error, "must be an image file"
        end

        return result

      end

    end
  end
end