# Name:
# Date: 
# Class: 
# Pledge:  
# Description:

#This function reads in the first 3 lines of the infile
#and writes those 3 lines out to the outfile
#Parameters: infile (fileObject that you're reading from),
#            outfile(fileObject that you're writing to)
#Returns: None
def process_header(infile, outfile):
    pass # remove this line (including the 'pass') when starting to write this function.

#This function reads in the body of a PPM file, one line at a time
#Each line is split apart and put into 3 1-D lists (red, green, and blue)
#red, green, and blue will be parallel lists, such that red[0], green[0], and blue[0] will
#all refer to the rgb values for the 1st pixel in the line
#Hint: Recall that the split function for strings allows you to either specify exactly
#how many variables to create, or if you don't know, you can return the result into
#a single variable, which will be a list of strings
#Example:   s = "5,4,2,5,6,7"
#           values = s.split(',') #values is now equal to ['5','4','2','5','6','7']
#           
#
#Process each line individiually.
#Call the appropriate modification functions on the correct color lists
#Write out the modified lists to the outfile
#
#Parameters: infile (fileObject that you're reading from),
#            outfile(fileObject that you're writing to),
#            modification (string explaining which modifications the use wants)
#Returns: None
def process_body(infile, outfile, modification):
    pass # remove this line (including the 'pass') when starting to write this function.

    
    # Algorithm:  (You can remove all these comments when you're done.)
    # Loop over the infile object 1 line at a time
    # strip off whitespace from the end of line
    # split the line into a list of strings
    # create 3 empty lists, one for red, one for blue, and one for green
    #
    # loop over the list of strings
    # for each rgb triple in the list, put the red value into the red list,
    # green into green list, and blue into blue list
    #
    # SAVE THIS PART UNTIL YOU GET THE OUTPUT FILE WORKING
    # once the entire line has been put into lists, call the appropriate filters
    # on the correct lists depending on the modification
    # For example, if modification is the negate red option, your code
    # should call the negate function and pass in the red list
    #
    # 
    # create a new string variable that is empty
    # Write a loop that iterates over each index in red list
    # Use string concatentation to put together the red, green, and blue values
    # in the appropriate order, with spaces in between, into the new string you created
    # add an endline character to the end of the new string
    # write this new string to the outfile
    # Hint: print out this string, if you haven't done any modifications
    # it should be the exact same string as the original line from the infile
    


#This file takes in a list and negates each value in the list
#To negate a value, subtract 255 and take the absolute value of the result
#Parameters: lst, a 1-D list of integers
#Returns: a list with the modified values (negatives of the original values)
def negate(lst):
    pass # remove this line (including the 'pass') when starting to write this function.

#This file takes in a list and flattens each value in the list
#To flatten a value, set it equal to zero 
#Parameters: lst, a 1-D list of integers
#Returns: a list of the same length as (lst) with all zeros
def flatten(lst):
    pass # remove this line (including the 'pass') when starting to write this function.

#This file takes in three 1-D lists, and returns 3 lists that contain the average 
#of the original values at each index
#To calculate the new value for each list, we need to take the average of the values
#and replace the value with the average in all 3 lists (these values must be integers)
#Example: red[0] = 30, green[0] = 100, blue[0] = 74, average = (30 + 100 + 74) / 3 = 68
#so we set red[0] = 68, green[0] = 68 and blue[0] = 68.
#Hint: Use parallel lists
#Parameters: red, green, blue (3 1-D lists with the same number of elements in them)
#Returns: the updated lists, red, green, blue
def grey_scale(red, green, blue):
    #Add your code here to correctly modify all 3 lists
    return red, green, blue

#This file takes in a list and reverses the order of the list
#Parameters: lst, a 1-D list of integers
#Returns: the original list in reverse order
def flip_horizontal(lst):
    pass # remove this line (including the 'pass') when starting to write this function.

#This function takes in a filename and modification and outputs the correct
#output file name
#The output file name should retain the name of the input file, but also
#include your last name and first name and the modification made to the file
#Example: makeOutputFileName("BCLC.ppm", '3') returns "BCLC_welsh_catie_negate_green.ppm"
#Parameters: filename (a string that includes a 3 character extension),
#            mod (the selected menu option)
def makeOutputFileName(filename, mod):
    outputFileName = ''
    
    return outputFileName
    
# the main function is mostly written for you.
# Add an input validation loop where specified to ensure
# valid input from the user
def main():

    #get input from the user
    inputFileName = input("What file would you like to modify? ")
    print("Here are the options for modifications: \n\
          (1) Negate red \n\
          (2) Negate blue\n\
          (3) Negate green\n\
          (4) Negate all\n\
          (5) Remove red\n\
          (6) Remove blue\n\
          (7) Remove green\n\
          (8) Flip horizontally\n\
          (9) Grey scale\n")

    mod = input("What modification would you like to do? ")
    #add input validation loop here to ensure valid input from the user       
            
    #open the file 
    infile = open(inputFileName, 'r')

    #get the correct output file name, and open the file in write mode
    outputFileName = makeOutputFileName(inputFileName, mod)
    outfile = open(outputFileName, 'w')

    #process the entire file
    process_header(infile, outfile)
    process_body(infile, outfile, mod)

    #close both files, and let user know what the updated file is called
    infile.close()
    outfile.close()
    print("Your modified file has been created. It is called", outputFileName)

#Uncomment this line once you are ready to test the full program
#main()