zhdk/madek

# -*- encoding : utf-8 -*-
module Exiftool

  class << self

    def extract_madek_subjective_metadata file, content_type
      group_tags = case content_type
                   when /image/ 
                     #NOTE - these two really don't bring much to the party,
                     #except broken character encodings.. # 'IPTC:', 'IPTC2']
                     ['XMP-madek', 'XMP-dc', 'XMP-photoshop', 'XMP-iptcCore', 
                       'XMP-xmpRights', 'XMP-expressionmedia', 'XMP-mediapro']
                   when /video/  # OPTIMIZE - some of these may move to Objective Metadata
                     ['QuickTime', 'Track', 'Composite', 'RIFF', 
                       'BMP', 'Flash', 'M2TS', 'AC3', 'H264' ] 
                   when /audio/ # OPTIMIZE - some of these may move to Objective Metadata
                     ['MPEG', 'ID3', 'Track', 'Composite', 
                       'ASF', 'FLAC', 'Vorbis' ] 
                   when /application/ # OPTIMIZE - some of these may move to Objective Metadata
                     ['FlashPix', 'PDF', 'XMP-', 'PostScript', 
                       'Photoshop', 'EXE', 'ZIP' ] 
                   when /text/
                     ['HTML' ]  # and inevitably more..
                   end
      Exiftool.parse_metadata(file, group_tags)
    end

    def filter_unwanted_fields meta_data_array, content_type

      ignore_fields = case content_type
                      when /image/
                        [/^XMP-photoshop:ICCProfileName$/,
                          /^XMP-photoshop:LegacyIPTCDigest$/, 
                          /^XMP-expressionmedia:(?!UserFields)/, 
                          /^XMP-mediapro:(?!UserFields)/]
                      when /video/
                        []
                      when /audio/
                        []
                      when /application/
                        []
                      when /text/
                        []
                      end

      meta_data_array.map do |l1|
        l1.map do |entry|
          key,value = entry
          if ignore_fields.find {|m| key =~ m}
            []
          else
            entry
          end
        end
      end

    end


    # parses the passed in file reference for the requested tag groups
    # returns an array of arrays of meta-data for the group tags requested

    #==== Depends on:
    # [external] exiftool meta-data manipulation perl library.

    def parse_metadata(file, tags = nil)
      result_set = []
      parse_hash = JSON.parse(`#{EXIFTOOL_PATH} -s "#{file}" -a -u -G1 -j`).first
      parse_hash.delete_if do |k,v| 
        v.is_a?(String) and (not v.valid_encoding? or v=~/^\(Binary data/)
      end
      tags.each do |tag_group|
        result_set << parse_hash.select {|k,v| k.include?(tag_group)}.sort
      end
      result_set
    end


    # ad-hoc method that generates a new exiftool config file, when it is
    # sensed that there are new keys/key_defs that should be saved in a file
    # using the XMP-madek metadata namespace.  
    # TODO refactor the use of exiftool, so that for each media file/entry it
    # is only called once, entrys' contents cached, and obj/subj meta-data
    # extracted as necessary  
    def generate_exiftool_config
      exiftool_keys = IoInterface.find("default") \
        .io_mappings.collect do |io_mapping| 
        "#{io_mapping.key_map.split(":").last} => {#{io_mapping.key_map_type == "Array" ? " List => 'Bag'" : nil} },"
      end

      skels = Dir.glob("#{METADATA_CONFIG_DIR}/ExifTool_config.skeleton.*")

      exif_conf = File.open(EXIFTOOL_CONFIG, 'w')
      exif_conf.puts IO.read(skels.first)
      exiftool_keys.sort.each do |k|
        exif_conf.puts "\t#{k}\n"
      end
      exif_conf.puts IO.read(skels.last)
      exif_conf.close
    end

  end

end