import random

# May 29, 2020
# Minor stylistic changes, functionality is the same

# Original version: March 9, 2011

SIZE = 4
NUM_RANDOM_VALUES = 10
EMPTY = " "
PERSON = "P"
PET = "T"
POOP = "O"
ERROR = "!"
CLEANED = "."

# @createElement(none)
# * Randomly generates an 'occupant' for a location in the world
# @returns(list element, string of length one)
def createElement():
    tempNum = random.randrange(NUM_RANDOM_VALUES)+1

    # 50% chance empty
    if ((tempNum >= 1) and (tempNum <= 5)):
        tempElement = EMPTY 

    # 20% of a person
    elif ((tempNum >= 6) and (tempNum <= 7)):
        tempElement = PERSON

    # 10% chance of pet
    elif (tempNum == 8):
        tempElement = PET

    # 20% chance of poop in that location (lots in this world)
    elif ((tempNum >= 9) and (tempNum <= 10)):
        tempElement = POOP

    # In case there's a bug in the random number genrator
    else:
        tempElement = ERROR

    return(tempElement)

# @ createWorld(none)
# Creates the SIZExSIZE world. Randomly populates it with the 
# return values from function createElement.
# returns(reference to the 2D list)
def createWorld():
    world = [] #  Create a variable that refers to a 1D list. 
    r = 0

    #  Outer 'r' loop traverses the rows. 
    # Each iteration of the outer loop creates a new 1D list.
    while (r < SIZE):  
        world.append([])  # Create new empty row
        c = 0
        # The inner 'c' loop traverses the columns of the newly 
        # created 1D list creating and initializing each element
        # to the value returned by createElement()
        while (c < SIZE):
            element = createElement()
            world[r].append(element)
            c = c + 1
        r = r + 1    
    return(world)

# @displayWorld(none)
# * Shows the elements of the world. All the elements in a row will
#   appear on the same line.
# @returns(nothing)
def display(world):
    print("OUR WORLD")
    print("========")
    r = 0
    while (r < SIZE): # Each iteration accesses a single row 
        c = 0
        while (c < SIZE):  # Each iteration accesses an element in a row
            print(world[r][c], end="")
            c = c + 1
        print()  # Done displaying row, move output to the next line
        r = r + 1 

# @getLocation(none)
# * Gets (row,column) of square to evaluate
# @return(integer,integer)


# Argument: any valid (row,column) coordinate
# Return: True when location contains a space, false otherwise
def isSpace(row,column,world):
    space = False
    if (world[row][column] == EMPTY):
        space = True
    return(space)

# Starting execution point for the program
def start():
    world = createWorld()
    display(world)
    row,column = getLocation()
    space = isSpace(row,column,world)
    print("Location: (%d/%d) contains space?" %(row,column), space)

start()