9-4

#! /usr/bin/env python3.2
# -*- coding: utf-8 -*-

# main.py
""" Task: Exercise 9.4
    Write a program to read through a mail log, and figure out who had the most
    messages in the file. The program looks for “From” lines and takes the
    second parameter on those lines as the person who sent the mail.
    The program creates a Python dictionary that maps the sender’s address to
    the total number of messages for that person.
    After all the data has been read the program looks through the dictionary
    using a maximum loop (see Section 5.7.2) to find who has the most messages
    and how many messages the person has.

    Enter a file name: mbox-short.txt
    cwen@iupui.edu 5

    Enter a file name: mbox.txt
    zqian@umich.edu 195
"""

''' Functions '''
def enterFileName():
    """
    The user has to enter a filename.
    Returns fileName
    """
    fileName = None
    while fileName == None:
        # Enter filename
        try:
            fileName = input("Enter the filename: ")
        except:
            print("Invalid input!")
            continue
    return fileName

''' Main '''
# Open file
fileName = enterFileName()
try:
    fhand = open(fileName)
except:
    print("File not found!")
    exit()

sender = dict()
for line in fhand:
    words = line.split()
    # print('Debug:', words)
    if len(words) >= 2 and words[0] == 'From':
        sender[words[1]] = sender.get(words[1], 0) + 1

# Print-out
for i in sender:
    if sender[i] == max(sender.values()):
        print(str(i) + " " + str(sender[i]))

# Close file
try:
    fhand.close()
except:
    exit()