import json

class Item:
    def __init__(self, id, description):
        self.id = id
        self.description = description

    def state(self):
        """Return a dictionary describing the item internals."""

        return {"id": self.id, "description": self.description}

    def __str__(self):
        return f"Item(id='{self.id}', description='{self.description}')"

    # this is so Items IN A SEQUENCE are printed nicely
    def __repr__(self):
        return str(self)

id2obj = {}     # the mapping dictionary,
inventory = []  # the inventory list

item1 = Item("axe1", "An Elven axe")
id2obj["axe1"] = item1
inventory.append(item1.id)

item2 = Item("book2", "A very old book with a cracked red cover")
id2obj["book2"] = item2
inventory.append(item2.id)

print(f"{inventory=}  # note the inventory is just strings")

# list what's in the inventory
# this shows how to use the 'id2obj' dictionary to *dereference* the 'id'
print("\nDescriptions of items in the inventory:")
for id in inventory:
    print("   ", id2obj[id].description)

# let's save the inventory list and the two items in a JSON file
# we create a single list with two elements, a list of 'state' dictionaries
# for each item and the inventory list itself
json_file = "save.json"
save_data = [[item1.state(), item2.state()], inventory]
with open(json_file, "w") as fd:
    fd.write(json.dumps(save_data))

print(f"\nJSON file '{json_file}' created.")

print("\n############ Saving and restoring data\n")

# now load the data back from JSON and recreate the Items, inventory and
# the id->object dictionary
with open(json_file) as fd:
    json_data = fd.read()

print(f"Restored {json_data=}")

# recreate the Items and the dictionary mapping id -> reference to object
(new_item_dicts, new_inventory) = json.loads(json_data)
print(f"\nRestored python data:\n    {new_item_dicts=}\n    {new_inventory=}")

# create the new Item instances, store in list, create the mapping dictionary
new_items = []
new_id2obj = {}
for item_dict in new_item_dicts:
    i = Item(**item_dict)
    new_items.append(i)
    new_id2obj[i.id] = i

print("\nRestored Items and mapping dictionary:")
print(f"    {new_items=}")
print(f"    {new_id2obj=}")

# print the descriptions of items in the new inventory using the new Items
# and the new mapping dictionary
print("\nNow print the recovered Items descriptions:")
for id in new_inventory:
    print("   ", new_id2obj[id].description)