''' Purpose: get an input code phrase and list of indices. Determine the
             hidden message by using the indices to peek into the code phrase
'''

# get the code phrase that contains hidden message
reply = input( "Enter code phrase: " )

print()

# clean up reply to get code phrase with no leading or trailing whitespace
code_phrase = reply.strip() # doesn't change reply just stores stripped version of reply in code_phrase

# 'Clean up'
    # strip() function - get rid of leading and trailing whitespace

# print the code phrase
print( "Code phrase=", code_phrase )

print()

# get the list of indices (as string) for peeking into code phrase
reply = input( "Enter indices for looking into code phrase: " ) # ex. '1 2 3'

print()

# convert reply into a list of numeric strings
numeric_strings = reply.split() # ex. ['1','2','3']

print( numeric_strings )

# build one-by-one the list of indices out of the numeric strings 

# Convert list of numeric strings to list of integers (like slist to nlist in summing.py)
# You cannot CANNOT CANNOT call int(numeric_strings) - you can't call the int function on the list
# of numeric strings!

indices = [] # Initialize accumulator to empty list (we wanna build up a list of strings)

for ns in numeric_strings: # ns is the loop variable (for numeric string) in the numeric_strings list
    # convert each numeric string one by one ex. '1' becomes 1 stored in i
    i = int( ns )
    # add the integer version of ns to indices (list of integers)
    indices.append( i )

# print the list of indices
print( "Indices:", indices ) # ex. indices is [1,2,3] if numeric_strings was ['1','2','3']

print()

# STRING ACCUMULATOR EXAMPLE

# build secret message (string) by peeking into code phrase using the
# indices one-by-one
message = '' # accumulator

# Use the indices list and the code_phrase string and get the characters in code_phrase at those indices
# to create a secret message

# Each index in the indices list is adding a character to the message!

# What do we want to loop through? How are we going to determine the characters at the indices in our indices list?
# indices..... list................. characters...... subscripting.... hm....
# How can we use indices (list of numbers) and code_phrase (string we take characters from)?
# indices is the list of numbers while numeric_strings is the lsit of numeric strings

# WHY WE USE INDICES INSTEAD OF NUMERIC_STRINGS
    # You need the NUMBER (int) versions of numbers to subscript (to call code_phrase[i])
    # You don't want to do code_phrase['2'] you want to use code_phrase[2]
    # You can't use the numeric string as an index like code_phrase['2'] which is why
    # we use the list of integers indices we created from numeric_strings

for i in indices: # Get each index (number) from the list of indices (ex. [1,2,3])
    print( 'Loop variable', i )
    ch = code_phrase[i]  # Get character at code_phrase[i] where i will be a number index - subscripting!
    print( 'Character at index i:', ch )
    message = message + ch # string_accumulator = string_accumulator + modification (decoded character to add)
    print( 'Message so far:', message )
# print secret message
print( "Secret message:", message )

# computer
# 01234567

# indices is [3,6,5]
# p is at index 3
# e is at index 6
# t is at index 5
# 'pet' is the final message (string we built up)