# flower.py
# Lillian Lee (LJL2@cornell.edu), Steve Marschner (srm@cs.cornell.edu)
# The idea to have an if-statement based on "he loves me",
# which was the inspiration for this demo,  is due to J. Kleinberg
# Feb 14, 2013

"""Module that when run, simulates the 'he loves me' flower ritual.

This demo was developed for the purposes of demonstrating if-statements
and conditional expressions; see the functions remove_petal(f), remove_petal1(f) and
remove_petal2(f). You can put any of these remove_petaling functions into
run_flower() and see what happens.

It also happens to demonstrate primitive versions of useful stuff
that we haven't talked about (yet): defining your own class of objects,
prompting a user for input, and doing something repeatedly via
while-loops.

A number of design choices were made in writing this code, simple
as it may seem, and several alternatives are possible."""
import random

class Flower(object):
    """An instance is a flower.  Flowers have two attributes.
    We describe these below by giving the 'class invariants' in
    comments. Programmers are assumed to write code that maintains
    the class invariants; they are constraints that are assumed
    to hold before and after code is executed.

     num_petals: the number of petals it has.  A non-negative int.

     loves_me_not: True if and only if the next petal
     to remove_petal corresponds to "he loves me" (vs. "he loves me not"),
     assuming there is at least one more petal.
     If there are no more petals, the value of loves_me_not
     is None."""

    MAX_PETALS = 5  # max number of petals a flower can have
                    # (chosen so that in-lecture demo wouldn't
                    # take too long)

   # METHODS
    def __init__(self):
        """Constructor: A new flower() with num_petals set
        to a random int in [1,MAX_PETALS], and he_loves_me
        set to True.

        Called by flower.Flower() or Flower(), depending on
        where the function call is made.
        """
        self.num_petals = random.randrange(1, Flower.MAX_PETALS+1)
        self.he_loves_me = True

    def __str__(self):
        """Returns: Readable, somewhat whimsical string representation
        of this flower.  The petals are shown as vertical bars.
        Sample outputs are:
            '||| he loves me'
            '|| he loves me not'
            'no more petals'

        This function uses string * .
        """
        if self.num_petals > 0:
            return ('|' * self.num_petals +
                    ' he loves me' +
                    ('' if self.he_loves_me else ' not'))
        else:
            return 'no more petals'


def remove_petal(f):
    """Remove a petal in the 'he loves me' ritual

    Prints out the appropriate 'he loves me' or 'he loves me not'
    message, and then removes a petal. An exclamation point is added
    to the printout if this was the last petal.

    This implementation uses if-statements with complex booleans.

    Precondition: f is a Flower object, and has at least one petal.
    Prints out a warning and exits if f is a Flower object without petals"""

    if f.num_petals == 0:
        print 'no more petals'
        return

    if f.he_loves_me and f.num_petals > 1:
        print "he loves me"
    elif f.he_loves_me and f.num_petals == 1:
        print "he loves me!"
    elif not f.he_loves_me and f.num_petals > 1:
        print "he loves me not"
    else:
        print "he loves me not!"

    # maintain class invariants (i.e., the constraints on attributes
    # given in the class docstring)
    f.num_petals = f.num_petals - 1
    f.he_loves_me = not f.he_loves_me if f.num_petals > 0 else None


def remove_petal1(f):
    """Remove a petal in the 'he loves me' ritual

    Prints out the appropriate 'he loves me' or 'he loves me not'
    message, and then removes a petal. An exclamation point is added
    to the printout if this was the last petal.

    This implementation uses nested if-statements.

    Precondition: f is a Flower object, and has at least one petal.
    Prints out a warning and exits if f is a Flower object without petals"""
    if f.num_petals == 0:
        print 'no more petals'
        return

    if f.he_loves_me:
        if f.num_petals > 1:
            print "he loves me"
        else:
            print "he loves me!"
    else:  # he doesn't love me
        if f.num_petals > 1:
            print "he loves me not"
        else:
            print "he loves me not!"

    # maintain class invariants on f.he_loves_me and f.num_petals
    f.num_petals = f.num_petals - 1
    f.he_loves_me = not f.he_loves_me if f.num_petals > 1 else None


def remove_petal2(f):
    """Remove a petal in the 'he loves me' ritual

    Prints out the appropriate 'he loves me' or 'he loves me not'
    message, and then removes a petal. An exclamation point is added
    to the printout if this was the last petal.

    This implementation uses if-statements and conditional expressions.

    Precondition: f is a Flower object, and has at least one petal.
    Prints out a warning and exits if f is a Flower object without petals"""
    if f.num_petals == 0:
        print 'no more petals'
        return

    if f.he_loves_me:
        print "he loves me" + ('' if f.num_petals > 1 else '!')
    else:
        print "he loves me not" + ('' if f.num_petals > 1 else '!')

    # maintain class invariants on f.he_loves_me and f.num_petals
    f.num_petals = f.num_petals - 1
    f.he_loves_me = not f.he_loves_me if f.num_petals > 0 else None


def test():
    """Some quick-and-dirty sanity-check code to see that
    things seem reasonable"""
    print "Running some sanity checks\n"

    f = Flower()
    print 'a new flower:', str(f)
    print '\nRemoving the petals with remove_petal()'
    while f.num_petals > 0:
        remove_petal(f)

    f = Flower()
    print '\na new flower:', str(f)
    print 'Removing the petals with remove_petal1()'
    while f.num_petals > 0:
        remove_petal1(f)

    f = Flower()
    print '\na new flower:', str(f)
    print 'Removing the petals with remove_petal2()'
    while f.num_petals > 0:
        remove_petal1(f)

    f.num_petals = 0
    print 'flower with no petals:', str(f)


def run_flower():
    """Simulate the 'he loves me' ritual with the user.

    Uses a while loop, where petals are remove_petaled until
    there are no more petals."""

    raw_input("\n\nPress 'return' to pick a flower")
    f = Flower()  # don't need flower.Flower() because inside flower.py

    print "New flower picked.  Let's see...\n"

    # invariant: if the flower had n petals when created,
    # then the flower still has petals 1 .. f.num_petals
    # and petals f.num_petals+1 .. n have been remove_petaled
    while f.num_petals > 0:
        raw_input('Press "return" to remove_petal a petal')
        remove_petal(f)

    print "\n\n"

if __name__ == '__main__':
    run_flower()