gem 'mime-types', '>= 1.16'
require 'mime/types'

module ChocolateDisco
  
  class << self
    
    @@supported_mime_types = nil
    
    # returns an array of supported mime types.
    def supported_mime_types
      @@supported_mime_types ||= Java::SupportedMimeTypes.constants.map { |const| eval("Java::SupportedMimeTypes::#{const}") }
    end # def supported_mime_types
    
    # returns whether or not the file is supported.
    # :path to specify the file. :mime to specify the mime.
    # :mimes to give an array of mimes.
    def supported?(opts = {})
      mimes = []
      mimes << opts[:mime] if opts[:mime].is_a?(String)
      mimes += opts[:mimes] if opts[:mimes].is_a?(Array)
      
      if opts[:path].is_a?(String) && File.exists?(opts[:path]) && !File.directory?(opts[:path]) && File.file?(opts[:path])
        begin
          mimes << MIME::Types.of(opts[:path]).map { |mime| mime.simplified }
        rescue NoMethodError # begin
          raise(NotImplementedError.new("MIME types of a file '#{opts[:path]}' could not be inferred."))
        end # rescue
      end # if opts[:path].is_a?(String) && File.exists?(opts[:path]) && !File.directory?(opts[:path]) && File.file?(opts[:path])
      
      mimes.flatten!
      mimes.compact!
      mimes.uniq!
      
      mimes.map { |mime| return true if supported_mime_types.include?(mime) }
      
      false
    end # def supported?(opts = {})
    
    # extracts text from path, returns string, empty string or nil.
    def extract(path, opts = {})
      
      if opts[:force_mime].is_a?(String)
        mimes = [opts[:force_mime]]
      else
        mimes = MIME::Types.of(path).map { |mime| mime.simplified }
      end
      
      raise(NotImplementedError.new("MIME (#{mimes.join(', ')}) for '#{path}' is not supported by chocolate_disco.")) unless supported?(:mimes => mimes)
      
      extractor = mimes.map { |mime| Java::TextExtractionFactory.getExtractor(mime) }[0]
      
      raise(RuntimeError.new('TextExtractionFactory failed to get an instance of TextExtractor, which is impossible.')) if extractor.nil?
      
      extractor.extractText(java.io.File.new(path))
    end # def extract
    
    alias :lets_party! :extract
    
  end # class << self
  
end # module ChocolateDisco