# coding: utf-8

from argparse import ArgumentParser
from functions import readFile, countLetters


def checkArguments():
    args = ArgumentParser(description='Cryptanalyst')
    args.add_argument('-f', '--filename', help='Text to analyze')
    return args.parse_args()

def main():
    args = checkArguments()

    # Read file 
    dataFile = readFile(args.filename)

    # Get number of letters
    totalLetters = countLetters(dataFile)

    counts = []

    for i in range (0, 26):
        counts.append(0)

    # Count the number of letter in our text    
    letterToAscii = ord('a') # Get the ASCII code
    for i in dataFile:
        l = ord(i) - letterToAscii
        if l >= 0 and l <= 26:
            counts[l] += 1

    # We calculate the sum of all character in the text
    ic = 0
    for i in range(0, len(counts)):
        sum = (counts[i] * (counts[i] - 1))
        ic += sum / (totalLetters * (totalLetters - 1))
    print(f"Index of coincidence: {ic}")


if __name__ == "__main__":
    main()