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 54

def initialize
  @use_mimemagic = false
end

Instance Attribute Details

#use_mimemagic ⇒ Object 



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# File 'lib/aspera/preview/file_types.rb', line 52

def use_mimemagic
  @use_mimemagic
end

Instance Method Details

#conversion_type(filepath, mimetype) ⇒ Object

Returns file type, one of enum CONVERSION_TYPES.

Parameters:

  • filepath (String) —

    full path to file

  • mimetype (String) —

    provided by node API

Returns:

  • file type, one of enum CONVERSION_TYPES

Raises:

  • (RuntimeError) —

    if no conversion type found



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# File 'lib/aspera/preview/file_types.rb', line 90

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 = mime_to_type(mimetype) if !mimetype.nil?
  # 2- else, from computed mime type (if available)
  if conversion_type.nil? && @use_mimemagic
    detected_mime = file_to_mime(filepath)
    if !detected_mime.nil?
      conversion_type = mime_to_type(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
  mime_by_ext = MIME::Types.of(File.basename(filepath)).first
  conversion_type = mime_to_type(mime_by_ext.to_s) if conversion_type.nil? && !mime_by_ext.nil?
  raise "no conversion type found for #{File.basename(filepath)}" if conversion_type.nil?
  Log.log.trace1{"conversion_type(#{File.basename(filepath)}): #{conversion_type.class.name} [#{conversion_type}]"}
  return conversion_type
end

#file_to_mime(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 69

def file_to_mime(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 mime_to_type(detected_mime).nil?
    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

#mime_to_type(mimetype) ⇒ Object

Returns file type, one of enum CONVERSION_TYPES.

Parameters:

  • mimetype (String) —

    mime type

Returns:

  • file type, one of enum CONVERSION_TYPES



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# File 'lib/aspera/preview/file_types.rb', line 60

def mime_to_type(mimetype)
  return SUPPORTED_MIME_TYPES[mimetype] if SUPPORTED_MIME_TYPES.key?(mimetype)
  return :office if mimetype.start_with?('application/vnd.')
  return :video if mimetype.start_with?('video/')
  return :image if mimetype.start_with?('image/')
  return nil
end