from random import randrange

class Character():
    def __init__ (self, health, attack, defense):
        self.health = health
        self.base_attack = attack
        self.base_defense = defense
        self.defending = False
        self.exp = 0
        self.inventory = {}

    def inflict (self, damage):
        calculated_damage = damage - self.base_defense
        if self.defending:
            calculated_damage = calculated_damage // 2
        if calculated_damage < 0:
            calculated_damage = 0
        self.health -= calculated_damage
        return calculated_damage

    def give_item (self, item, quantity):
        original_quantity = self.inventory.get(item, 0)
        self.inventory.update({item: original_quantity + quantity})

    def attack (self, other_character):
        self.defending = False
        return other_character.inflict(self.base_attack)

    def defend (self):
        self.defending = True

    def use_item (self, item):
        self.defending = False
        quantity = self.inventory.get(item, 0)
        if quantity == 0:
            return "you do not have the item"
        self.inventory.update({item: quantity - 1})

        if item == "potion":
            self.health += 20
            return "you were healed 20 hp"

        return "it had a mysterious effect"

    def has_item (self, item):
        quantity = self.inventory.get(item, 0)
        return quantity > 0

player = Character(100, 10, 6)
player.give_item("potion", 3)

enemies_defeated = 0

while player.health > 0:
    player_level = player.exp // 10 + 1
    enemy = Character(player_level * 10 + randrange(10*player_level, 20*player_level),
                        player_level * 10 + randrange(2*player_level, 10*player_level),
                        player_level + randrange(player_level, 2*player_level))
    if randrange(1, 10) > 4:
        enemy.give_item("potion", randrange(1, 5))

    print("A wild beast appears!")
    while enemy.health > 0:
        action = None
        while action is None:
            user_input = input("Action? Attack, Defend, Item: ").strip().lower()
            if user_input == "attack" or user_input == "defend":
                action = user_input
            elif user_input == "item":
                print ("You have the following items:")
                for item in player.inventory:
                    print (item, ": ", player.inventory[item])
                print ("Type the item name to use it")
            elif player.has_item(user_input):
                action = user_input
            else:
                print ("Invalid command")

        if action == "attack":
            actual_damage = player.attack(enemy)
            print("You did ", actual_damage, " damage to the beast")
        elif action == "defend":
            player.defend();
            print("You defend")
        else:
            print ("You use the ", action, " and ", player.use_item(action))

        if enemy.health > 0:
            enemy_action = randrange(1, 100)
            if enemy_action < 50:
                print ("The beast attacks and deals ", enemy.attack(player), " damage")
                print ("You have ", player.health, " health")
                if player.health <= 0:
                    break
            elif enemy_action < 90:
                enemy.defend()
                print ("The beast defends")
            else:
                if enemy.has_item("potion"):
                    enemy.use_item("potion")
                    print ("The beast uses a potion")
                else:
                    print ("The beast ponders the meaning of life")

    if player.health > 0:
        enemies_defeated += 1
        print ("The beast was slain!")
        if enemy.has_item("potion"):
            player.give_item("potion", enemy.inventory["potion"])
            print ("You receive ", enemy.inventory["potion"], " potions")
        player.exp += 7
        print ("You receive 7exp")
        new_player_level = player.exp // 10 + 1
        if new_player_level > player_level:
            print ("You reached level ", new_player_level)
            player.health += 100
            player.base_attack += 5
            player.base_defense += 3
    else:
        print ("You were slain")
        print ("You had defeated ", enemies_defeated, " beasts")