# Author:  James Tam
# Version: March 9, 2011

import random


# CONSTANTS
SIZE = 4
FIELD = " "
FOREST = "^"
WATER = "W"
BURNT = "F"
ERROR = "!"

'''
   @ generateElemement
   @ a random number argument (precondition 1<=number<=100)
   @ returns a string of length one (an element to populate
     world
   @* 50% are empty fields
   @* 30% are forests
   @* The remaining 20% consist of water
'''
def generateElement(randomNumber):
    element = ERROR
    if ((randomNumber >= 1) and (randomNumber <= 50)):
        element = FIELD
    elif ((randomNumber >= 51) and (randomNumber <= 80)):
        element = FOREST
    elif ((randomNumber >= 81) and (randomNumber <= 100)):
        element = WATER
    else:
        element = ERROR
    return(element)


'''
   @ initialize()
   @ no parameters
   @ returns a fully initialized randomly generated world

'''
def initialize():
    world = []
    r = -1
    c = -1
    randomNumber = -1
    newElement = ERROR

    for r in range (0,SIZE,1):
        world.append([])  # Add in new empty row
        for c in range (0,SIZE,1):
            randomNumber = random.randrange(1,101)
            element = generateElement(randomNumber)
            world[r].append(element) # Add new element to row end
    return(world)

'''
   @ display()
   @ argument: 2D list of char(length 1 string), simulated game
     world
   @ return value: none
   @ 
   @ Shows the current state of the world
   
'''
def display(world):
   r = -1
   c = -1
   for r in range (0,SIZE,1):
      for c in range (0,SIZE,1):
         print(world[r][c], end="")
      print()
   print()

'''
   @ forestFire()
   @ argument: 2D list of char(length 1 string), simulated game
     world
   @ return value: none
   @
   @ Simulates a massive forest fire, all the forests have been
     burnt down.
'''
def forestFire(world):
   r = -1
   c = -1
   for r in range (0,SIZE,1):
      for c in range (0,SIZE,1):
          if(world[r][c] == FOREST):
              world[r][c] = BURNT

# MAIN EXECUTION POINT
def start():
    world = initialize()
    print("Initial world")
    display(world)
    input("Hit enter to continue")
    print("Post fire world")
    forestFire(world)
    display(world)

start()