#---------------------------------
#           Q3: Xshift           #
#---------------------------------

#-----------------------------------------
# Parametes:    plaintext (str)
#               key: (shiftString,shifts)
# Return:       ciphertext (str)
# Description:  Encryption using Xshift Cipher
#-----------------------------------------
def e_xshift(plaintext, key):
    # your code here

    modified_key = utilities.shift_string(key[0],int(key[1]),'l')
    ciphertext = ''

    for char in plaintext:
        if char in modified_key:
            index_key = key[0].index(char)
            ciphertext += modified_key[index_key]

        else:
            ciphertext+=char

    return ciphertext

#-----------------------------------------
# Parametes:    ciphertext (str)
#               key: (shiftString,shifts)
# Return:       plaintext (str)
# Description:  Decryption using Xshift Cipher
#-----------------------------------------
def d_xshift(ciphertext, key):
    # your code here

    modified_key = utilities.shift_string(key[0],int(key[1]),'l')
    plaintext = ''

    for char in ciphertext:
        if char in modified_key:
            index_modifed_key = modified_key.index(char)
            plaintext += key[0][index_modifed_key]

        else:
            plaintext+=char

    return plaintext