#!/usr/bin/python2


import datetime
import time


HEAL_SECONDS = 2


class Health(object):
    def __init__(self, initial=10):
        self.hearts = initial
        if initial < 10:
            self.lasthealing = datetime.datetime.utcnow()
        else:
            self.lasthealing = None

    def monitor(self):
        if self.hearts < 10:
            if self.lasthealing:
                # calculate how much time has passed, how much there is to heal
                # then update the time info
                now = datetime.datetime.utcnow()
                spendtime = now - self.lasthealing
                healing = spendtime.seconds / HEAL_SECONDS
                maxhealing = 10 - self.hearts
                realhealing = min(healing, maxhealing)
                for _ in xrange(realhealing):
                    print "+1 heart :D"
                self.hearts += realhealing
                if self.hearts < 10:
                    healupdate = healing * HEAL_SECONDS
                    self.lasthealing += datetime.timedelta(seconds=healupdate)
                else:
                    self.lasthealing = None
            else:
                # apparently we just lost some hearts
                self.lasthealing = datetime.datetime.utcnow()
            if self.hearts < 1:
                # we check this in the end so that healings that occured
                # previously are properly accounted for
                print "You are dead"
        else:
            self.lasthealing = None

    def __iadd__(self, amount):
        self.monitor()
        self.hearts += amount
        print "+{} hearts! :D".format(amount)
        self.monitor()
        return self

    def __isub__(self, amount):
        self.monitor()
        self.hearts -= amount
        print "-{} hearts! :'(".format(amount)
        self.monitor()
        return self

    @property
    def dead(self):
        return self.hearts < 1


def main():
    me = Health()
    me.monitor()
    me -= 2
    assert(me.hearts == 8)
    time.sleep(2)
    me.monitor()
    assert(me.hearts == 9)
    time.sleep(4)
    me.monitor()
    assert(me.hearts == 10)
    me -= 6
    time.sleep(4)
    me -= 5
    assert(me.hearts == 1)
    me -= 1


if __name__ == '__main__':
    main()