module Eco
  module Data
    module Files
      module Encoding
        include Eco::Language::AuxiliarLogger

        BOM_BYTES = [239, 187, 191].freeze

        def has_bom?(path)
          return false if !path || file_empty?(path)
          File.open(path, "rb") do |f|
            bytes = f.read(3)
            return bytes.unpack('C*') == BOM_BYTES
          end
        end

        def get_file_content_with_encoding(file, encoding: nil)
          encoding ||= scoped_encoding(file)

          unless !encoding || encoding == 'utf-8'
            msg = "File encoding: '#{encoding}'"
            log(:debug) { msg }
            puts msg
          end

          bom_enc = encoding && encoding.split('|')[0] == 'bom'
          if has_bom?(file) || bom_enc
            content  = remove_bom(File.read(file, encoding: 'utf-8'))
            encoding = 'utf-8'
          else
            content = File.read(file, encoding: encoding)
          end

          return unless content

          content = content.encode("utf-8") unless encoding.include?('utf-8')
          content
        end

        # Changes encoding from bom to utf8
        # https://stackoverflow.com/a/24916365/4352306
        def remove_bom(content)
          if content.bytes[0..2] == BOM_BYTES
            bom     = BOM_BYTES.pack('C*').force_encoding('utf-8').encode('utf-8')
            content = content.sub(bom, '')
            content.force_encoding('utf-8')
          end

          content
        end

        def encoding(path)
          has_bom?(path) ? "bom" : "utf-8"
        end

        # Gives the parameter as it should
        def scoped_encoding(path)
          unless file_exists?(path)
            log(:error) { "File does not exist: #{path}" }
            return nil
          end

          encoding ||= encoding(path)
          encoding   = "#{encoding}|utf-8" if encoding == "bom"
          encoding
        end

        def file_exists?(file)
          return false unless file

          File.exist?(file) || File.exist?(File.expand_path(file))
        end

        def file_empty?(path)
          return true unless File.file?(path)

          File.zero?(path)
        end
      end
    end
  end
end