# Compute the number of words, lines and characters in a file or entered on
# the keyboard.  The behaviour of the program varies with the number of 
# command line parameters (beyond the name of the .py file):
# 
# No command line parameters: Input is read from the keyboard (use ctrl-d to
#   indicate the end of input) and the results are printed on the screen
#
# One command line parameter: Input is read from a file and the results
#   are printed on the screen
#
# Two command line parameters: Input is read from a file and the results are
#   saved in a file
#
# Three or more command line parameters: An error message is displayed
#
import sys

# Read from the keyboard and write to the screen
if len(sys.argv) == 1:
  inf = sys.stdin
  outf = sys.stdout

# Read from a file and write to the screen
elif len(sys.argv) == 2:
  inf = open(sys.argv[1], "r")
  outf = sys.stdout

# Read from a file and write to a file
elif len(sys.argv) == 3:
  inf = open(sys.argv[1], "r")
  outf = open(sys.argv[2], "w")

# Too many command line parameters were provided
else:
  print("You must start this program with at nost 2 command line parameters beyond the name of the .py file.")
  print("")
  print(sys.argv[0], "<inputfile> <outputfile>")
  quit()


# Count the words, lines and characters in the input file
num_lines = 0
num_chars = 0
num_words = 0

line = inf.readline()
while line != "":
  num_lines = num_lines + 1
  num_chars = num_chars + len(line)
  # Use split to generate a list of words, then compute the length of the
  # list to get the number of words
  num_words = num_words + len(line.split())

  # Read the next line from the file
  line = inf.readline()

# Save the number of words, lines and characters in the output file
outf.write("Lines: " + str(num_lines) + "\n")
outf.write("Words: " + str(num_words) + "\n")
outf.write("Chars: " + str(num_chars) + "\n")

# Close the files
inf.close()
outf.close()