class Csv
  def self.parse(handle, args={})
    # read a csv creating a hash with the first column as the primary identifier
    # assumes that the first line of the csv file is the header
    # uses header names as keys for the values for each primary identifier

    sep = args[:sep] || ',' # record separator
    key = args[:key] || 0   # which column is the key?

    # TODO: add support for taking a Proc as an argument for key

    # data is stored as a simple hash
    data = Hash.new

    # parse header
    header = handle.gets.strip.split(sep)
    header.delete_at(key)

    # read data
    handle.each do |line|
      line = line.strip.split(sep)
      datum = Hash.new
      primary = line.delete_at key
      header.zip(line).each do |k, d|
        if datum.has_key? k
          raise "Duplicate secondary key: #{k}! in #{handle.path}"
        end
        datum[k] = d
      end
      if data.has_key? primary
        raise "Duplicate primary key: #{primary}! in #{handle.path}"
      end
      data[primary] = datum
    end

    # return data as a simple Hash
    data
  end

end