"""Functions to keep track and alter inventory."""


def create_inventory(items):
    """Create a dict that tracks the amount (count) of each element on the `items` list.

    :param items: list - list of items to create an inventory from.
    :return: dict - the inventory dictionary.
    """
    inventory: dict = {}
    for item in items:
        inventory[item] = items.count(item)
    return inventory


def add_items(inventory, items):
    """Add or increment items in inventory using elements from the items `list`.

    :param inventory: dict - dictionary of existing inventory.
    :param items: list - list of items to update the inventory with.
    :return: dict - the inventory updated with the new items.
    """
    # inventory is empty, create new one and return inventory
    if inventory == {}:
        return create_inventory(items)
    # increment items that already exists in inventory
    for item in inventory:
        inventory[item] += items.count(item)
    # add new items that doesnt exist in inventory
    # the new items can only be added after incrementing items that already
    # exists in inventory to avoid adding the new items again
    for item in items:
        if item not in inventory:
            inventory[item] = items.count(item)
    return inventory


def decrement_items(inventory, items):
    """Decrement items in inventory using elements from the `items` list.

    :param inventory: dict - inventory dictionary.
    :param items: list - list of items to decrement from the inventory.
    :return: dict - updated inventory with items decremented.
    """
    for item in inventory:
        if item in items:
            inventory[item] -= items.count(item)
            if inventory[item] < 0:
                inventory[item] = 0
    return inventory


def remove_item(inventory, item):
    """Remove item from inventory if it matches `item` string.

    :param inventory: dict - inventory dictionary.
    :param item: str - item to remove from the inventory.
    :return: dict - updated inventory with item removed. Current inventory if item does not match.
    """
    if item in inventory:
        inventory.pop(item)
    return inventory


def list_inventory(inventory):
    """Create a list containing only available (item_name, item_count > 0) pairs in inventory.

    :param inventory: dict - an inventory dictionary.
    :return: list of tuples - list of key, value pairs from the inventory dictionary.
    """
    inventory_list: list[tuple] = []
    # conventional
    # for item in inventory:
    #     if inventory[item] > 0:
    #         inventory_list.append((item, inventory[item]))
    # using list comprehension
    inventory_list = [
        (item, inventory[item]) for item in inventory if inventory[item] > 0
    ]
    return inventory_list