class MimeMagic

def self.parse_database
  file = open_mime_database
  doc = Nokogiri::XML(file)
  extensions = {}
  types = {}
  magics = []
  (doc/'mime-info/mime-type').each do |mime|
    comments = Hash[*(mime/'comment').map {|comment| [comment['xml:lang'], comment.inner_text] }.flatten]
    type = mime['type']
    subclass = (mime/'sub-class-of').map{|x| x['type']}
    exts = (mime/'glob').map{|x| x['pattern'] =~ /^\*\.([^\[\]]+)$/ ? $1.downcase : nil }.compact
    (mime/'magic').each do |magic|
      priority = magic['priority'].to_i
      matches = get_matches(magic)
      magics << [priority, type, matches]
    end
    if !exts.empty?
      exts.each{|x|
        extensions[x] = type if !extensions.include?(x)
      }
      types[type] = [exts,subclass,comments[nil]]
    end
  end
  magics = magics.sort {|a,b| [-a[0],a[1]] <=> [-b[0],b[1]] }
  common_types = [
    "image/jpeg",                                                              # .jpg
    "image/png",                                                               # .png
    "image/gif",                                                               # .gif
    "image/tiff",                                                              # .tiff
    "image/bmp",                                                               # .bmp
    "image/vnd.adobe.photoshop",                                               # .psd
    "image/webp",                                                              # .webp
    "image/svg+xml",                                                           # .svg
    "video/x-msvideo",                                                         # .avi
    "video/x-ms-wmv",                                                          # .wmv
    "video/mp4",                                                               # .mp4, .m4v
    "video/quicktime",                                                         # .mov
    "video/mpeg",                                                              # .mpeg
    "video/ogg",                                                               # .ogv
    "video/webm",                                                              # .webm
    "video/x-matroska",                                                        # .mkv
    "video/x-flv",                                                             # .flv
    "audio/mpeg",                                                              # .mp3
    "audio/x-wav",                                                             # .wav
    "audio/aac",                                                               # .aac
    "audio/flac",                                                              # .flac
    "audio/mp4",                                                               # .m4a
    "audio/ogg",                                                               # .ogg
    "application/pdf",                                                         # .pdf
    "application/msword",                                                      # .doc
    "application/vnd.openxmlformats-officedocument.wordprocessingml.document", # .docx
    "application/vnd.ms-powerpoint",                                           # .pps
    "application/vnd.openxmlformats-officedocument.presentationml.slideshow",  # .ppsx
    "application/vnd.ms-excel",                                                # .pps
    "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",       # .ppsx
  ]
  common_magics = common_types.map do |common_type|
    magics.find { |_, type, _| type == common_type }
  end
  magics = (common_magics.compact + magics).uniq
  extensions.keys.sort.each do |key|
    EXTENSIONS[key] = extensions[key]
  end
  types.keys.sort.each do |key|
    exts = types[key][0]
    parents = types[key][1].sort
    comment = types[key][2]
    TYPES[key] = [exts, parents, comment]
  end
  magics.each do |priority, type, matches|
    MAGIC << [type, matches]
  end
end