require "open-uri"
require "stringio"
require "fileutils"

require File.join(File.dirname(__FILE__), '/image_temp_file')

module MiniMagick
  class MiniMagickError < RuntimeError; end

  VERSION = '1.2.4'

  class Image
    attr :path
    attr :tempfile
    attr :output

    # Class Methods
    # -------------
    class <<self
      def from_blob(blob, extension=nil)
        begin
          tempfile = ImageTempFile.new("minimagick#{extension}")
          tempfile.binmode
          tempfile.write(blob)
        ensure
          tempfile.close
        end
        
        return self.new(tempfile.path, tempfile)
      end

      # Use this if you don't want to overwrite the image file
      def from_file(image_path)
        File.open(image_path, "rb") do |f|
          self.from_blob(f.read, File.extname(image_path))
        end
      end
    end

    # Instance Methods
    # ----------------
    def cksum(input_path)
       run_command("cksum", @path.gsub(/\[\d+\]$/,"")).split(/\s/)[0]
    end

    def get_file_info(input_path)
      @image_hash = cksum(@path)
      @image_info_string = run_command("identify", "-format", "|s:%s|m:%m|h:%h|w:%w|%[EXIF:*]\n", @path)

      # save the hash of the file, so we can validate it again.

      mm=@image_info_string.match(/^\|s\:(\d+)\|m\:([^\|]*)\|h\:(\d+)\|w\:(\d+)\|(EXIF)?(.*)/)
      if mm
        @image_info = {}
        @image_info[:format] = mm[2];
        @image_info[:height] = mm[3];
        @image_info[:width] = mm[4];
        @image_info[:exif] = mm[5];
      end

    end


    def initialize(input_path, tempfile=nil)
      @path = input_path
      @tempfile = tempfile # ensures that the tempfile will stick around until this image is garbage collected.

      # Ensure that the file is an image
      # might as well collect some information here.
      #
      get_file_info(input_path)

    end

    # For reference see http://www.imagemagick.org/script/command-line-options.php#format
    def [](value)
      # Why do I go to the trouble of putting in newlines? Because otherwise animated gifs screw everything up
      case value.to_s
      when "format"
        if !(@image_info && @image_hash == cksum(@path))
	   get_file_info(@path)
	end
	@image_info[:format]

      when "height"
        if !(@image_info && @image_hash == cksum(@path))
	   get_file_info(@path)
	end
     	@image_info[:height]

      when "width"
        if !(@image_info && @image_hash == cksum(@path))
	   get_file_info(@path)
	end
        @image_info[:width]

      when "original_at"
        # Get the EXIF original capture as a Time object
        Time.local(*self["EXIF:DateTimeOriginal"].split(/:|\s+/)) rescue nil
      when /^EXIF\:/i
        run_command('identify', '-format', "\"%[#{value}]\"", @path).chop
      else
        run_command('identify', '-format', "\"#{value}\"", @path).split("\n")[0]
      end
    end

    # This is a 'special' command because it needs to change @path to reflect the new extension
    def format(format)
      run_command("mogrify", "-format", format, @path)
      @path = @path.sub(/(\.\w+)?$/, ".#{format}")
      
      raise "Unable to format to #{format}" unless File.exists?(@path)
    end

    # Writes the temporary image that we are using for processing to the output path
    def write(output_path)
      FileUtils.copy_file @path, output_path
      unless @image_info && @image_hash == cksum(@path)  # skip if we have the same file and we've read it
            run_command "identify", output_path # Verify that we have a good image
      end
    end

    # Give you raw data back
    def to_blob
      File.read @path
    end

    # If an unknown method is called then it is sent through the morgrify program
    # Look here to find all the commands (http://www.imagemagick.org/script/mogrify.php)
    def method_missing(symbol, *args)
      args.push(@path) # push the path onto the end
      run_command("mogrify", "-#{symbol}", *args)
      self
    end

    # You can use multiple commands together using this method
    def combine_options(&block)
      c = CommandBuilder.new
      block.call c
      run_command("mogrify", *c.args << @path)
    end

    # Check to see if we are running on win32 -- we need to escape things differently
    def windows?
      !(RUBY_PLATFORM =~ /win32/).nil?
    end

    # Outputs a carriage-return delimited format string for Unix and Windows
    def format_option(format)
      windows? ? "#{format}\\n" : "#{format}\\\\n"
    end

    def run_command(command, *args)
      args.collect! do |arg|
        arg = arg.to_s
        arg = %|"#{arg}"| unless arg[0] == ?- # values quoted because they can contain characters like '>', but don't quote switches          
        arg
      end

      @output = `#{command} #{args.join(' ')}`

      if $? != 0
        raise MiniMagickError, "ImageMagick command (#{command} #{args.join(' ')}) failed: Error Given #{$?}"
      else
        @output
      end
    end
  end

  class CommandBuilder
    attr :args

    def initialize
      @args = []
    end

    def method_missing(symbol, *args)
      @args << "-#{symbol}"
      @args += args
    end
    
    def +(value)
      @args << "+#{value}"
    end
  end
end