Class: Aspera::Preview::FileTypes

Inherits:
Object
  • Object
show all
Includes:
Singleton
Defined in:
lib/aspera/preview/file_types.rb

Overview

function conversion_type returns one of the types: CONVERSION_TYPES

Constant Summary collapse

CONVERSION_TYPES =

values for conversion_type : input format

i[image office pdf plaintext video].freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ FileTypes

Returns a new instance of FileTypes.



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# File 'lib/aspera/preview/file_types.rb', line 278

def initialize
  @use_mimemagic = false
end

Instance Attribute Details

#use_mimemagic ⇒ Object 



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# File 'lib/aspera/preview/file_types.rb', line 276

def use_mimemagic
  @use_mimemagic
end

Instance Method Details

#conversion_type(filepath, mimetype) ⇒ Object

return file type, one of enum CONVERSION_TYPES

Parameters:

  • filepath (String) —

    full path to file

  • mimetype (String) —

    provided by node api



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# File 'lib/aspera/preview/file_types.rb', line 303

def conversion_type(filepath, mimetype)
  Log.log.debug{"conversion_type(#{filepath},m=#{mimetype},t=#{@use_mimemagic})"}
  # 1- get type from provided mime type, using local mapping
  conversion_type = SUPPORTED_MIME_TYPES[mimetype] if !mimetype.nil?
  # 2- else, from computed mime type (if available)
  if conversion_type.nil? && @use_mimemagic
    detected_mime = mime_from_file(filepath)
    if !detected_mime.nil?
      conversion_type = SUPPORTED_MIME_TYPES[detected_mime]
      if !mimetype.nil?
        if mimetype.eql?(detected_mime)
          Log.log.debug('matching mime type per magic number')
        else
          # NOTE: detected can be nil
          Log.log.debug{"non matching mime types: node=[#{mimetype}], magic=[#{detected_mime}]"}
        end
      end
    end
  end
  # 3- else, from extensions, using local mapping
  extension = File.extname(filepath.downcase)[1..-1]
  conversion_type = SUPPORTED_EXTENSIONS[extension] if conversion_type.nil?
  Log.log.debug{"conversion_type(#{extension}): #{conversion_type.class.name} [#{conversion_type}]"}
  return conversion_type
end

#mime_from_file(filepath) ⇒ Object

use mime magic to find mime type based on file content (magic numbers)



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# File 'lib/aspera/preview/file_types.rb', line 283

def mime_from_file(filepath)
  # moved here, as mimemagic can cause installation issues
  require 'mimemagic'
  require 'mimemagic/version'
  require 'mimemagic/overlay' if MimeMagic::VERSION.start_with?('0.3.')
  # check magic number inside file (empty string if not found)
  detected_mime = MimeMagic.by_magic(File.open(filepath)).to_s
  # check extension only
  if !SUPPORTED_MIME_TYPES.key?(detected_mime)
    Log.log.debug{"no conversion for #{detected_mime}, trying extension"}
    detected_mime = MimeMagic.by_extension(File.extname(filepath)).to_s
  end
  detected_mime = nil if detected_mime.empty?
  Log.log.debug{"mimemagic: #{detected_mime.class.name} [#{detected_mime}]"}
  return detected_mime
end