# File_IO_Demo_Read_File.py
#
# Description: Reading the content of a file in various ways.
#
# Author: Anne Lavergne
# Last modified date: March 2024

def read_1_line_at_a_time(anInputFile):
    '''Reading (and printing) a line at a time
        from file "anInputFile".'''

    print("\nDemo 1 - Reading a line at a time from anInputFile.")

    # Opening a file for reading
    fileR = open(anInputFile, 'r')

    # Read its first line -> a string
    firstLine = fileR.readline()
    print("First line: ", firstLine)
    print(f"Data type of first line is '{type(firstLine)}'.")

    # Read its second line - file object "fileR" keeps track of
    # where it currently is in the file
    secondLine = fileR.readline()
    print("\nSecond line: " , secondLine)
    
    # Close the file
    fileR.close( )

    return

def read_1_line_using_for_loop(anInputFile):
    '''Reading (and printing) a line at a time
       from file "anInputFile" using a for loop.'''

    print("\nDemo 2 - Reading a line at a time from a file using a for loop.")
    
    # Opening a file for reading
    fileR = open(anInputFile, 'r')
    
    # Read a line at a time using a for loop
    for line in fileR:
        print(f"\nThe line read from the file is '{line}'.")
        print(f"Data type of first line is '{type(line)}'.")
        strippedLine = line.strip()
        print(f"The line once stripped is '{strippedLine}'.")

    # Close the file
    fileR.close( )
    
    return

def read_all_lines_into_a_list_v1(anInputFile):
    '''Reading (and printing) all lines from file
       "anInputFile" into a list.'''

    print("\nDemo 3 - Reading all lines from a file into a list - v1.")

    # Opening a file for reading
    fileR = open(anInputFile, 'r')

    # Read all lines from a file into a list
    myList1 = list(fileR)
    print("\nFirst list: ", myList1)
    print(f"Data type of the lines is '{type(myList1)}'.")

    # Close the file
    fileR.close( )

    return

def read_all_lines_into_a_list_v2(anInputFile):
    '''Reading (and printing) all lines from file
       "anInputFile" into a list.'''

    print("\nDemo 4 - Reading all lines from a file into a list - v2.")

    # Opening a file for reading
    fileR = open(anInputFile, 'r')
    
    # Read all lines from a file into a list
    myList2 = fileR.readlines( )
    print("\nSecond list: ", myList2)
    print(f"Data type of the lines is '{type(myList2)}'.")    
    # Close the file
    fileR.close( )

    
# *** Main part of program

# Ask user to enter a filename ('words_7_a.txt')
theInputFile = input("Please, enter a filename: ")

# Demo 1 - Reading (and printing) a line at a time from a file
##read_1_line_at_a_time(theInputFile)

# Demo 2 - Reading a line at a time from a file into a string
read_1_line_using_for_loop(theInputFile)

### Demo 3 - Reading all lines from a file into a list - v1
##read_all_lines_into_a_list_v1(theInputFile)
##
### Demo 4 - Reading all lines from a file into a list - v2
##read_all_lines_into_a_list_v2(theInputFile)