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

# remember () for functions!!!

# 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()      # strip() removes leading and trailing whitespaces
# cases don't matter in this case

# 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: " )

print()

# convert reply into a list of numeric strings
numeric_strings = reply.split()

# build one-by-one the list of indices out of the numeric strings 
# build a list of integers from the list of numeric strings
indices = []    # list accumulator, starts with empty list

# for each numeric string in numeric_strings, convert to an int and put it into the list indices
# (use i for ints for range stuff, generally - just a convention)
for s in numeric_strings:
    index = int( s )      # s = numeric string --> int(s) --> convert to int version
    indices.append( index )     # remember, you don't have to assign indices = indices.append( index )
                                # append() will update the original list --> puts index at the end of list indices

# we must convert our numeric string into ints because indices will ONLY TAKE INTS!
# no strings nor floats as our positions/indices

# print the list of indices
print( "Indices:", indices )

print()

# build secret message (string) by peeking into code phrase using the
# indices one-by-one
message = ''    # string accumulator starts with empty string ('') as we build from scratch
                # '' indicates that our accumulator is a string, so we use + to build up a new string
                # we already know we want to produce a string, so to start our accumulator, we start
                # with ''

# if we know that we want to build a list, then the accumulator starts with []
# if we know that we want a running sum, then the accumulator starts with 0

# message = []

# we need to peak in the original message at the indices we said to look at
# for each index in the list indices, we look into the original message (code_phrase) at that index
for i in indices:
    ch = code_phrase[ i ]       # string indices ALWAYS USE BRACKETS [] NOT ()
    # print( i, ch )
    message = message + ch      # each time through, take the current message and then glue on the next
                                # character at the end of the current message using + --> update it
    # message.append(ch)        # if message is a list, but the problem says to give back a string

    # don't append() for strings!!! only concatenate for strings
    # append() is ONLY for lists
    # CANNOT + with a list

# string subscripting allows use of one int or a range of things using : inside []
# s = computer
#     01234567
# s[3] = 'p'
# s[0] = 'c'
# s[5] = 't'
# s[9] = not valid--> error (out of range)

# print secret message
print( "Secret message:", message )