# futval_graph3.py
#     Plots an investment 10 years into the future.
#     Illustrates use of a function to eliminate code duplication.

from graphics import *

def drawBar(window, year, height):
    # Draw a bar in window starting at year with given height
    bar = Rectangle(Point(year, 0), Point(year+1, height))
    bar.setFill("green")
    bar.setWidth(2)
    bar.draw(window)
    
def main():
    # Introduction
    print "This program plots the growth of a 10 year investment."

    # Get principal and interest rate
    principal = input("Enter the initial principal: ")
    apr = input("Enter the annualized interest rate: ")

    # Create a graphics window with labels on left edge
    win = GraphWin("Investment Growth Chart", 320, 240)
    win.setBackground("white")
    win.setCoords(-1.75,-200, 11.5, 10400)
    Text(Point(-1, 0), ' 0.0K').draw(win)
    Text(Point(-1, 2500), ' 2.5K').draw(win)
    Text(Point(-1, 5000), ' 5.0K').draw(win)
    Text(Point(-1, 7500), ' 7.5k').draw(win)
    Text(Point(-1, 10000), '10.0K').draw(win)

    # Draw bar for initial principal
    drawBar(win, 0, principal)
    
    # Draw a bar for each subsequent year
    for year in range(1, 11):
        principal = principal * (1 + apr)
        drawBar(win, year, principal)

    raw_input("Press <Enter> to quit.")
    win.close()

main()