data table wrapper

data_table.rb

class DataTable
  include Enumerable
  class Row
    def initialize(headers_index: headers_index, row: row)
      @headers_index = headers_index
      @row = row
    end

    def [](name)
      @row[@headers_index[name]]
    end

    def []=(name, value)
      @row[@headers_index[name]] = value
    end

    def values
      @row
    end

    def to_hash
      inverted_index = @headers_index.invert
      counter = 0
      ([email protected]).inject({}) { |a, idx|
        header = inverted_index[idx] || "missing"
        while a.has_key?(header)
          counter += 1
          header = "#{header}.#{counter}"
        end
        a[header] = @row[idx]
        a
      }
    end
  end

  attr_reader :headers

  def initialize(headers:[], rows:[])
    @rows = rows
    self.headers=headers
  end

  class Wrapper
    def initialize(table:)
      @table = table
    end

    [:sort_by, :map].each do |method|
      class_eval <<-EOM
        def #{method}(*args, &block)
          DataTable.new(headers: @table.headers, rows: @table.#{method}(*args, &block))
        end
      EOM
    end
  end

  def wrap
    Wrapper.new(table: self)
  end

  def <<(row)
    @rows << row
  end

  def [](idx)
    Row.new(headers_index: @headers_index, row: @rows[idx])
  end

  def length
    @rows.length
  end

  # def join(other)
    # lesser, greater = self.length  < other.length ? [self, other] : [other, self]
    # self.
    # self.select

  def headers=(headers)
    @headers = headers.dup
    reindex_headers
  end

  def reindex_headers
    @headers_index = Hash[@headers.each_with_index.map {|h,idx| [h, idx]}]
  end

  def each
    @rows.each do |row|
      yield(Row.new(headers_index: @headers_index, row: row))
    end
  end

  def output
    Output.aligned_table([headers] + @rows )
  end
end