ksylvest/attached

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]
        @operation = case @operation
        when :decrease then '>'
        when :increase then '<'
        when :default  then '#'
        else @operation || '#'
        end
        @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
            parameters << case operation
            when '#' then "-resize #{width}x#{height}^ -gravity center -extent #{width}x#{height}"
            when '<' then "-resize #{width}x#{height}\\<"
            when '>' then "-resize #{width}x#{height}\\>"
            else          "-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