"""
https://gist.github.com/riceissa/1ead1b9881ffbb48793565ce69d7dbdd
"""


# "New Cards" tab
NEW_STEPS = [15, 25, 35]  # in minutes
GRADUATING_INTERVAL = 15  # in days
EASY_INTERVAL = 4  # in days
STARTING_EASE = 2.50  # in percent

# "Reviews" tab
EASY_BONUS = 1.30
INTERVAL_MODIFIER = 1
MAXIMUM_INTERVAL = 36500  # in days

# "Lapses" tab
LAPSES_STEPS = [20]  # in minutes
NEW_INTERVAL = 0.70
MINIMUM_INTERVAL = 2  # in days

class Card:
    def __init__(self):
        self.status = 'learning'  # can be 'learning', 'learned', or 'relearning'
        self.steps_index = 0
        self.ease_factor = STARTING_EASE
        self.interval = None

        self.history = []

    def __repr__(self):
        return "Card[%s; steps_idx=%s; ease=%s; interval=%s]" % (self.status,
                                                                 self.steps_index,
                                                                 self.ease_factor,
                                                                 str(self.interval))


    def choice(self, button: str):
        '''button is one of "wrong", "hard", "good", or "easy"
        returns a result in days'''
        self.history.append(button)

        if self.status == 'learning':
            # for learning cards, there is no "hard" response possible
            if button == "wrong":
                self.steps_index = 0
                return self.minutes_to_days(NEW_STEPS[self.steps_index])
            elif button == "good":
                self.steps_index += 1
                if self.steps_index < len(NEW_STEPS):
                    return self.minutes_to_days(NEW_STEPS[self.steps_index])
                else:
                    # we have graduated!
                    self.status = 'learned'
                    self.interval = GRADUATING_INTERVAL
                    return self.interval
            elif button == "easy":
                self.status = 'learned'
                self.interval = EASY_INTERVAL
                return EASY_INTERVAL
            else:
                # raise ValueError("you can't press this button / we don't know how to deal with this case")
                return
        elif self.status == 'learned':
            if button == "wrong":
                self.status = 'relearning'
                self.steps_index = 0
                self.ease_factor = max(1.30, self.ease_factor - 0.20)
                # the anki manual says "the current interval is multiplied by the
                # value of new interval", but I have no idea what the "new
                # interval" is
                return self.minutes_to_days(LAPSES_STEPS[0])
            elif button == "hard":
                self.ease_factor = max(1.30, self.ease_factor - 0.15)
                self.interval = self.interval * 1.2 * INTERVAL_MODIFIER
                return min(MAXIMUM_INTERVAL, self.interval)
            elif button == "good":
                self.interval = (self.interval * self.ease_factor
                                 * INTERVAL_MODIFIER)
                return min(MAXIMUM_INTERVAL, self.interval)
            elif button == "easy":
                self.ease_factor += 0.15
                self.interval = (self.interval * self.ease_factor
                                 * INTERVAL_MODIFIER * EASY_BONUS)
                return min(MAXIMUM_INTERVAL, self.interval)
            else:
                # raise ValueError("you can't press this button / we don't know how to deal with this case")
                return
        elif self.status == 'relearning':
            if button == "wrong":
                self.steps_index = 0
                return self.minutes_to_days(LAPSES_STEPS[0])
            elif button == "good":
                self.steps_index += 1
                if self.steps_index < len(LAPSES_STEPS):
                    return self.minutes_to_days(LAPSES_STEPS[self.steps_index])
                else:
                    # we have re-graduated!
                    self.status = 'learned'
                    self.interval = max(MINIMUM_INTERVAL, self.interval * NEW_INTERVAL)
                    return self.interval
            else:
                # raise ValueError("you can't press this button / we don't know how to deal with this case")
                return


    def minutes_to_days(self, minutes):
        return minutes / (60 * 24)



    @property
    def prompt(self):
        c = Card()
        wrong_ivl = [c.choice(b) for b in self.history + ["wrong"]][-1]
        c = Card()
        hard_ivl = [c.choice(b) for b in self.history + ["hard"]][-1]
        c = Card()
        good_ivl = [c.choice(b) for b in self.history + ["good"]][-1]
        c = Card()
        easy_ivl = [c.choice(b) for b in self.history + ["easy"]][-1]
        def prompt_pp(ivl, s: str):
            if ivl:
                if ivl <= 1:
                    return f'{s} {ivl * 1440}m'
                else:
                    return f'{s} {round(ivl, 2)}d'
        s = " | ".join(filter(None,
        [
            prompt_pp(wrong_ivl, "wrong"),
            prompt_pp(hard_ivl, "hard"),
            prompt_pp(good_ivl, "good"),
            prompt_pp(easy_ivl, "easy")
         ]))

        return s




# python
# >>> from anki_algorithm import *
# >>> a = Card()
# >>> a.prompt
# >>> a.choice("good")
# >>> a.choice("good")
# >>> a.prompt