module Import
  # Feel free to add extra delimiters to this array.
  DELIMITERS = ["\t", '|', ","]
  
  def Import.import(klasses, params_data, args = {}, debug = false)
    args.merge!({:imported_at => Time.now.strftime("%Y-%m-%d %H:%M:%S")}) unless args.has_key?(:imported_at)
    klasses = [klasses] unless klasses.is_a?(Array)
    delim = auto_detect_delimiter(params_data.to_s)
    header_row = nil
    
    objects = []
    
    FCSV.parse(params_data, {:col_sep => delim, :row_sep => :auto}) do |row|
      next if row.join("") !~ /\w/ # Skip blank rows.
      
      header_row ||= row
      next if header_row.join("") === row.join("") # Skip over duplicate header rows.
      
      # Clean up the data, get rid of leading/trailing spaces.
      row.collect {|str| str.to_s.strip!}
      
      h = Hash[*header_row.zip(row).flatten]
      klasses.each do |c|
        style = c.recognize_hash_style(h, debug)
        objects << c.import(h, args) if style
      end
    end
    
    # Return an array of everything that was imported in this batch.
    objects
  end
  
  def Import.import_from_file(klasses, filename, debug = false)
    args = {}
    args[:date] = Date.strptime($1) if filename =~ /([0-9]{4}-[0-9]{2}-[0-9]{2})/
    import(klasses, File.read(filename), args, debug)
  end

  private
  
  def Import.import_if_valid_else_ignore
    begin
      yield
    rescue Exception => e
      puts e.inspect
      return nil
    end
  end
  
  # Guess the correct text file column delimiter. We look at the first row
  # of data and the most common character from the DELIMITERS array is
  # assumed to be the delimiter. You can add additional characters to the
  # DELIMITERS array but to avoid the risk of false positives it's probably
  # best not to add too many.
  def Import.auto_detect_delimiter(sample_text)
    sample_text = sample_text.split(/$/)[0] || ""
    delim = DELIMITERS[0]
    len = DELIMITERS.length
    DELIMITERS[1-len, len-1].each do |char|
      delim = char if sample_text.count(char) > sample_text.count(delim)
    end
    delim
  end
end