from param import *
from random import random

runs=10

def rv(p):
    """
    A uniform random variable with probability p.
    
    Return true with probability p
    """
    if random()<p:
        return 1
    else:
        return 0

def next_state(x,t,d):
    """
    Determine what happens during this time unit.
    
    Returns (x,t,r,e) where:
      x: next energy state
      t: next time unit
      r: number of offspring
      e: 1 if it was eaten, 0 otherwise
    """
    # always move one time step
    next_t = t+1
    # hope we're not eaten
    e = 0
    
    # look at possible decisions:
    if d<2:
        # forage
        r = 0
        if rv(m[d]):
            # eaten
            next_x = chop( x-cost, 0, xmax )
            e=1
        else:
            # not eaten
            if rv(p[d]):
                # found food
                next_x = chop( x+y[d]-cost, 0, xmax )
            else:
                # no food found
                next_x = chop( x-cost, 0, xmax )
    
    else:
        # try to reproduce (no predation here)
        if x < xrep: # can't reproduce
            r = 0
            next_x = chop(x-cost,0,xmax)
        elif x < xrep+c3: # limited reproduction
            r = x - xrep
            next_x = chop(xrep-cost,0,xmax)
        else: # full reproduction
            r = c3
            next_x = chop(x-cost-c3, 0, xmax)
    
    return (next_x,next_t,r,e)        

print "Loading data..."
dec = fromfile(decfile, Int, (xmax+1,tmax+1))

# open and prep the data file
data = open(montefile, 'w')
data.write("sim\tt\tx\td\tr\tterminal\n")

for i in range(runs):
    # set starting state
    x=4 # energy level
    t=0 # time
    r=0 # total reproduction
    terminal=0 # terminal condition
    
    print "Running simulation %i..." % (i)
    
    while t<=tmax and not terminal:
        d=dec[x,t]
        
        (next_x, next_t, new_r, e) = next_state(x,t,d)
        
        x = next_x # go to the new state
        t = next_t
        r = r + new_r # add in any new reproduction

        if e==1:
            # we were eaten
            terminal = 1
        if next_x==0:
            # starved to death
            terminal = 2
        
        # output a line to a file with the current state        
        data.write("%i\t%i\t%i\t%i\t%i\t%i\n" % (i,t,x,d,r,terminal))

data.close()