module IOStreams
  module Record
    # Example, implied header from first record:
    #   IOStreams.record_writer do |stream|
    #     stream << {name: 'Jack', address: 'Somewhere', zipcode: 12345}
    #     stream << {name: 'Joe', address: 'Lost', zipcode: 32443, age: 23}
    #   end
    #
    # Output:
    #   name, add
    #
    class Writer
      # Write a record as a Hash at a time to a file or stream.
      def self.open(file_name_or_io, delimiter: $/, encoding: UTF8_ENCODING, strip_non_printable: false, **args)
        if file_name_or_io.is_a?(String)
          IOStreams.line_writer(file_name_or_io,
                                delimiter:           delimiter,
                                encoding:            encoding,
                                strip_non_printable: strip_non_printable) do |io|
            yield new(io, file_name: file_name_or_io, **args)
          end
        else
          yield new(file_name_or_io, **args)
        end
      end

      # Create a Tabular writer that takes individual
      # Parse a delimited data source.
      #
      # Parameters
      #   delimited: [#<<]
      #     Anything that accepts a line / record at a time when #<< is called on it.
      #
      #   format: [Symbol]
      #     :csv, :hash, :array, :json, :psv, :fixed
      #
      #   For all other parameters, see Tabular::Header.new
      #
      #     columns: nil, allowed_columns: nil, required_columns: nil, skip_unknown: true)
      def initialize(delimited, columns: nil, **args)
        @tabular   = IOStreams::Tabular.new(columns: columns, **args)
        @delimited = delimited

        # Render header line when `columns` is supplied.
        delimited << @tabular.render(columns) if columns && @tabular.requires_header?
      end

      def <<(hash)
        raise(ArgumentError, 'Must supply a Hash') unless hash.is_a?(Hash)
        if tabular.requires_header?
          columns                = hash.keys
          tabular.header.columns = columns
          delimited << tabular.render(columns)
        end
        delimited << tabular.render(hash)
      end

      private

      attr_reader :tabular, :delimited, :cleanse_header
    end
  end
end