# AreaCalculator_1.py
#
# This program allows us to compute the area of
# a triangle, a circle, a rectangle, a square and an ellipse.
#
# Anne Lavergne:
# Created June 2015 - Modified March 2017
#
# Liaqat Ali:
# Modified July 2018
#
# Demonstrating "Incremental Development"
# 1) We write a header comment block
# 2) We copy and paste the low-level algorithm into our empty program.
#    The steps of this algorithm become our comments.
# 3) We start incrementally implementing the steps of this algorithm: (Step 4)
#    In this version of our AreaCalculator, we implement the first few steps of our algorithm, namely
#     - Print menu
#       - Print description of program
#       - Print menu displaying selection of shapes
#     - Get selection from user (+ validate input)
#        - Print input instruction to user and read user input
#        - Validate input
# 4) We make sure our partial program executes (it has no syntax/runtime errors). (Step 5)
# 5) Then, we create test plans for it and test it (make sure it has no semantic errors). (Step 5)

# Set variables
exitProgram  = 'X'
       
def printMenu( ) :
    """
       Print description of program and menu displaying selection of shapes.
       Parameters: none.
       Returned value: none.
    """
    print("Welcome to my Area Calculator.\n")
    print("""This AreaCalculator allows us to compute the area of:\n
      \t* a triangle\tEnter T
      \t* a circle\tEnter C
      \t* a rectangle\tEnter R
      \t* a square\tEnter S
      \t* an ellipse\tEnter E
      \t* to exit\t\tEnter X""")
    return


def getSelection() :
    """
       Print input instruction to user, read user input (selection) then validate user input.
       Parameter: "notASelectionCode" - a letter indicating that the user has entered an invalid input.
       Returned value: "selectedShape" - either contains a valid selection or the value of parameter "notASelectionCode".
    """
    # Print input instruction to user and read user input
    selectedShape = input("\nPlease, enter your selection: ")
    # Validate input
    # Transform the user's input into an upper case letter in case
    # the user has entered a lower case letter as an selection
    selectedShape = selectedShape.upper( )
    return selectedShape

# Main part of the program - top level (of execution)
# Print description of program and menu displaying selection of shapes
printMenu( )

# Get selection from user (+ validate input)
selectedShape = getSelection( )

# As long as the user enters a valid selection ...
while selectedShape != exitProgram : 
    # If "triangle" is selected?
    if selectedShape == "T":
        print("triangle")
    # If "circle" is selected?
    elif selectedShape == "C":
        print("circle")
    # If "rectangle" is selected?
    elif selectedShape == "R":
        print("rectangle")
    # If "square" is selected?
    elif selectedShape == "S":
        print("square")
    # If "ellipse" is selected?
    elif selectedShape == "E" :
        print("elipse")
    elif len(selectedShape) == 0 :
        print("You have not entered anything. Please, try again!")
    # Has the user entered valid input (1 letter either T, C, R, S or E)
    elif not (selectedShape in ["T", "C", "R", "S", "E"] ) :  
        print("You have not entered valid input. Please, try again!")
    selectedShape = getSelection( )

# For testing purposes:
# print("Exiting Main: selectedShape = ", selectedShape)
print("---")


# NOT YET IMPLEMENTED
# Based on selection selected by user, get appropriate input from user (validate input)
    # If "triangle" is selected, then ask for the base and height
    # If "circle" is selected, then ask for the radius
    # If "rectangle" is selected, then ask for the width and height
    # If "square" is selected, then ask for one side
    # If "elipse" is selected, then ask for both radii
    # Validate input
    
# Compute desired area
    # If "triangle" is selected, then compute area = 0.5 ( base * height )
    # If "circle" is selected, then compute area = pi * radius squared
    # If "rectangle" is selected, then compute area = width * height
    # If "square" is selected, then compute area = side squared
    # If "elipse" is selected, then compute area = pi * radius1 * radius2
    
# Display result
    # Print the shape, the input data and the area