#Future Value
#It is difficult to make a budget that spans several years,
#because prices are not stable. If your company needs 200 pencils
#per year, you cannot simply use this year's price as the cost of
#pencils two years from now. Because of inflation the cost is likely
#to be higher than it is today. 
#
#Write a program to gauge the expected cost of an item in a specified
#number of years. The program asks for the cost of the item,
#the number of years from now that the item will be purchased,
# and the rate of inflation. The program then outputs the estimated
#cost of the item after the specified period. 

#Have the user enter the inflation rate as a percentage, like 5.6 (%).
#Your program should then convert the percent to a fraction, like 0.056,
#and should use a loop to estimate the price adjusted for inflation.

from graphics import *

def main():
    print("This program calculates the expected price of an item")
    price = eval(input("Please, input the today's price of an item: "))
    years = eval(input("Please, input the number of years from now that the item will be purchased: "))
    inflation = eval(input("Please, input the inflation rate: "))

    starting_price = price # preserving the starting price

    # calculating the price in ... years
    inflation = inflation/100.0
    for i in range(years):
        price=price+price*inflation
        #print("price = ", price)
    
    phrase = "The starting price is $"+str(starting_price)+",\n In "+\
             str(years)+" years the price will be $"+str(round(price,2))
    print(phrase)

    print("\n \t Now let's do it in graphics!")

    window = GraphWin('Predicting item\'s price.',800,600)
    window.setBackground("white")

    
    #Displaying the result in the graphics window
    PriceText = Text(Point(400,450),phrase)
    PriceText.draw(window)

    # let's draw the scale consisting of five marks(you may skip this part till drawing bars):
    print("calculations:")
    diff = price-starting_price # calculating the difference in starting price and final price
    scale=diff/4.# dividing by four, since we'll have 5 marks;
    print("difference = ",diff)
    print("scale = ",scale)
    
    l1='$'+str(round(starting_price,2)) # converting numerical mark to string
    print("label 1=",l1)

    label2=starting_price+scale
    l2='$'+str(round(label2,2)) # converting numerical mark to string, rounding off to two decimal places
    print("label 2=",l2)
  
    label3=starting_price+2*scale
    l3='$'+str(round(label3,2)) # converting numerical mark to string, rounding off to two decimal places
    print("label 3=",l3)

    label4=starting_price+3*scale
    l4='$'+str(round(label4,2)) # converting numerical mark to string, rounding off to two decimal places
    print("label 4=",l4)

    label5=starting_price+4*scale
    l5='$'+str(round(label5,2)) # converting numerical mark to string, rounding off to two decimal places
    print("label 5",l5)

    # displaying labels and lines
    Text(Point(40,30), l5).draw(window)
    Line(Point(70,30),Point(580,30)).draw(window)
    Text(Point(40,80), l4).draw(window)
    Line(Point(70,80),Point(580,80)).draw(window)
    Text(Point(40,130),l3).draw(window)
    Line(Point(70,130),Point(580,130)).draw(window)
    Text(Point(40,180),l2).draw(window)
    Line(Point(70,180),Point(580,180)).draw(window)
    Text(Point(40,230),l1).draw(window)
    Line(Point(70,230),Point(580,230)).draw(window)
    
    # draw bars for successive years

    price = starting_price # re-assigning price to initial one
    
    # need variable pixels to find the bar height
    pixels=(50.)/scale # calculating how many pixels should be used to 1$
    print("pixels=" ,pixels)

    bar_width = 40  
    for i in range(years): 
        price = price + price*inflation # calculating price in a year
        print("price=", price)
        # draw bar for this value
        x = i * bar_width + 180 # x-coordinate of the bottom left
        #corner of the bar
        height=(price-starting_price)*pixels # calculating the height of the
        # bar so that it corresponds to the difference between
        # previous year's price and current year's price
        print("height=",height)

        bar=Rectangle(Point(x,230),Point(x+bar_width,230-height))
        bar.setFill('green')
        bar.setWidth(1)
        bar.draw(window)

        # putting label under the bar with the corresponind price
        T = Text(Point(x+bar_width/2,260),str(round(price,1)))
        T.draw(window)
        
    T = Text(Point(400,500),"Click on EXIt button to terminate the program.")
    T.draw(window) # drawing the text

    # Building exit button - rectangle + text
    exitButton = Rectangle(Point(680,520),Point(770,570))
    exitButton.setFill("green")
    exitText = Text(Point(725,545),"EXIT")
    exitText.setSize(22)
    exitButton.draw(window)
    exitText.draw(window)
    
    while True:
        x = window.getMouse() # waiting for a mouse click
        if 680<=x.getX()<=770 and 520 <= x.getY() <= 570:
            break
    
    window.close()

main()