require "csv"

csv_opts = {
  :col_sep => ";",
  :skip_lines => /^(Notes|The |;)/,
  :headers => true,
  :converters => :all,
}

sales_by_date = {}

rows = CSV.foreach(ARGV[0], csv_opts)

rows.each do |row|
  d = Date.parse(row["Date"])
  if sales_by_date[d]
    sales_by_date[d][:count] += row["quantity"]
    sales_by_date[d][:total] += row["revenue EUR"]
  else
    sales_by_date[d] = {:count => row["quantity"], :total => row["revenue EUR"]}
  end
end

sales_by_date.each do |row|
  p row
end