class RubyXL::ContentTypes

def self.xlsx_path
  ROOT.join('[Content_Types].xml')
end

def before_write_xml
  content_types_by_ext = {}
  # Collect all extensions and corresponding content types

  root.rels_hash.each_pair { |klass, objects|
    objects.each { |obj|
      next unless klass.const_defined?(:CONTENT_TYPE)
      ext = obj.xlsx_path.extname[1..-1]
      next if ext.nil?
      content_types_by_ext[ext] ||= []
      content_types_by_ext[ext] << klass::CONTENT_TYPE 
    }
  }
  self.defaults = [ RubyXL::ContentTypeDefault.new(:extension => 'xml', :content_type => 'application/xml') ]
  # Determine which content types are used most often, and add them to the list of defaults

  content_types_by_ext.each_pair { |ext, content_types_arr|
    next if ext.nil? || defaults.any? { |d| d.extension == ext } 
    counter = {}  # Count the number of occurrences of a given +content_type+.

    content_types_arr.each { |ct| counter[ct] = (counter[ct] || 0) + 1 }
    most_used_content_type = counter.to_a.max_by{ |pair| pair.last }.first
    defaults << RubyXL::ContentTypeDefault.new(:extension => ext,
                                               :content_type => most_used_content_type)
  }
  self.overrides = []
  # Add overrides for the files with known extensions but different content types.

  root.rels_hash.each_pair { |klass, objects|
    objects.each { |obj|
      next unless defined?(klass::CONTENT_TYPE)
      ext = obj.xlsx_path.extname[1..-1]
      next if ext.nil?
      next if defaults.any? { |d| (d.content_type == klass::CONTENT_TYPE) && (d.extension == ext) }
      overrides << RubyXL::ContentTypeOverride.new(:part_name => obj.xlsx_path,
                                                   :content_type => klass::CONTENT_TYPE)
    }
  }
  true
end

def xlsx_path
  self.class.xlsx_path
end