import time, os, binascii
import hexView as view

def readb(fn):
    file = open(fn, 'rb')
    b = file.read()
    file.close()
    return b
        
def writeb(fn, b):
    file = open(fn, 'wb')
    file.write(b)
    file.close()

def read(fn):
    file = open(fn, 'rb')
    t = file.read().decode('utf8')
    file.close()
    return t

def write(fn, t):
    file = open(fn, 'wb')
    file.write(t.encode('utf8'))
    file.close()

def lenb(i):
    length = 0
    while i > 0:
        i = i >> 8
        length += 1
    return length

def xorb(a, b):
    alen = len(a)
    blen = len(b)
    a = int.from_bytes(a, byteorder='big')
    b = int.from_bytes(b, byteorder='big')
    r = a ^ b
    if alen > blen:
        return r.to_bytes(alen, byteorder='big')
    else:
        return r.to_bytes(blen, byteorder='big')

def xorfile(datfn, keyfn, outfn):
    if os.path.getsize(keyfn) < os.path.getsize(datfn):
            print('Key file is of insufficent size at', os.path.getsize(keyfn), 'bytes')
            return
    
    dat = open(datfn, 'rb')
    key = open(keyfn, 'rb')
    out = open(outfn, 'wb')
    
    while True:
        datbytes = dat.read(CHUNK_SIZE)
        keybytes = key.read(CHUNK_SIZE)
        if len(datbytes) == 0:
            break
        out.write(xorb(datbytes, keybytes))

    dat.close()
    key.close()
    out.close()

def genkey(keyfn, length):
    writeb(keyfn, os.urandom(length))

def printfile(datfn):
    for line in view.hex_viewer(datfn):
        print(line)

CHUNK_SIZE = 16

while True and __name__ == '__main__':
    mode = input('''Please choose an option:
X: Encrypt/Decrypt file (xor)
I: File info
G: Generate key
S: Show file
Option> ''').upper()
    print('\n')

    if mode == 'X':
        print('Xor file\n')
        datfn = input('Enter data filename: ')
        keyfn = input('Enter key filename: ')
        outfn = input('Output filename: ')
        if os.path.getsize(keyfn) < os.path.getsize(datfn):
            print('Key file is of insufficent size at', os.path.getsize(keyfn), 'bytes')
        else:
            print('Xor file...')
            start = time.time()
            xorfile(datfn, keyfn, outfn)
            duration = round(time.time()-start, 4)
            print(f'File xor ({duration} sec)')
            
    if mode == 'I':
        print('File information')
        fn = input('Enter filename: ')
        print('File length is', os.path.getsize(fn), 'bytes')
        
    if mode == 'G':
        print('Generate key\n')
        keyfn = input('Enter key filename: ')
        length = int(input('Enter key length: '))
        print('Generating key...')
        start = time.time()
        genkey(keyfn, length)
        duration = round(time.time()-start, 4)
        print(f'Key generated ({duration} sec)')
    if mode == 'S':
        print('Show file')
        datfn = input('Enter data filename: ')
        print('\n')
        printfile(datfn)
    print('\n')