import turtle
# Always put imports at the top

# We put the core logic into a function, so that in the future if we want to use one of the other functions
# (eg the get_number function), we can simply import it from this file and use it.
# If we left everything outside a function, the code would be run when trying to import one of the other functions
def run():
    print('**************************************')
    print('Welcome to DumbCAD 1.01')

    # \n adds a new line (there is one put in automatically at the end of a print statement)
    print('A Simple Programme to Draw A Regular Polygon\n')

    # Move repeated logic out into another more general function so we can reuse code in the future
    num_sides = get_number(minimum=3, maximum=20, prompt='Please enter number of sides (between 3 and 20):')
    side_length = get_number(minimum=1, maximum=100, prompt='Please enter the length for each side:')

    polygon_name = get_polyname(num_sides)

    # calculate internal angle of polygon
    internal_angle = (num_sides - 2) * 180 / num_sides

    print(
        f'Okay, a {num_sides} sided polygon is called a {polygon_name} and it has an internal angles of {internal_angle} degrees.')
    print(f'Lets draw a regular {polygon_name} with {side_length} long sides.')

    draw_polygon(num_sides=num_sides, side_length=side_length, internal_angle=internal_angle, polygon_name=polygon_name)


# A function that will keep asking until a number is supplied between min and max
# A default value for prompt is used if not supplied
def get_number(minimum, maximum, prompt='Please enter a number:'):
    # Check whether function was supplied with sane min and max values, quit if not
    if not int(minimum) or not int(maximum) or minimum > maximum:
        raise ValueError('Please supply valid min and max integers')

    # Loop infinitely until we reach return clause which exits function
    while True:

        # This block catches any errors and jumps to the 'except Exception' line below
        try:
            value = int(input(prompt + ' '))

            #  Only finish if we have a valid value
            if minimum <= value <= maximum:
                return value
            else:
                print(f"Error - number not between {minimum} and {maximum}")
        except Exception as e:
            print(e)


# returns polygone name for supplied number of sides in range 3-20
def get_polyname(sides):
    # dictionary of names "polynames"
    polynames = {
        3: "Triangle",
        4: "Square",
        5: "Pentagon",
        6: "Hexagon",
        7: "Heptagon",
        8: "Octagon",
        9: "Nonagon",
        10: "Decagon",
        11: "Hendecagon",
        12: "Dodecagon",
        13: "Triskaidecagon",
        14: "Tetradecagon",
        15: "Pendedecagon",
        16: "Hexdecagon",
        17: "Heptdecagon",
        18: "Octdecagon",
        19: "Enneadecagon",
        20: "Icosagon",
    }

    return polynames[sides]

# Holds the logic to draw a polygon using turtle
def draw_polygon(num_sides, side_length, internal_angle, polygon_name):
    turtle.screensize(4000, 4000)
    turtle.hideturtle()
    turtle.speed(speed=1)
    turtle.bgcolor("grey")
    turtle.pen(pencolor="blue", pensize=5)

    for i in range(num_sides):
        turtle.forward(side_length)
        turtle.left(180 - internal_angle)

    turtle.penup()
    label_length = len(polygon_name)
    turtle.goto(-label_length * 9 + label_length / 2, -60)  # start position for text
    turtle.write(polygon_name, font=("Verdana", 25, "normal"))

    # Wont close the screen until you click
    turtle.Screen().exitonclick()


# This will run the run() function only if we launched this script directly
# Eg: it will not use the run() function if this file has been loaded as an import in another script
if __name__ == '__main__':
    run()