from linked_list import LinkedList


class LRUCache:
    # Initializes an LRU cache with the capacity size
    def __init__(self, capacity):
        self.cache_capacity = capacity
        self.cache_map = {}
        self.cache_list = LinkedList()

    # Returns the value of the key, or -1 if the key does not exist.
    def get(self, key):
        found_itr = None
        if key in self.cache_map:
            found_itr = self.cache_map[key]
        else:
            return -1

        list_iterator = found_itr
        self.cache_list.move_to_head(found_itr)

        return list_iterator.pair[1]

    # Adds a new key-value pair or updates an existing key with a new value
    def set(self, key, value):
        if key in self.cache_map:
            found_iter = self.cache_map[key]
            list_iterator = found_iter
            self.cache_list.move_to_head(found_iter)
            list_iterator.pair[1] = value
            return

        if len(self.cache_map) == self.cache_capacity:
            key_tmp = self.cache_list.get_tail().pair[0]
            self.cache_list.remove_tail()
            del self.cache_map[key_tmp]

        self.cache_list.insert_at_head([key, value])
        self.cache_map[key] = self.cache_list.get_head()

    def print(self):
        print("Cache current size: ", self.cache_list.size,
                ", ", end="")
        print("Cache contents: {", end="")
        node = self.cache_list.get_head()
        while node:
            print("{", str(node.pair[0]), ",", str(node.pair[1]),
                    "}", end="")
            node = node.next
            if node:
                print(", ", end="")
        print("}")
        print("-"*100, "\n")


def main():
    # Creating a cache of size 2
    cache_capacity = 2
    cache = LRUCache(cache_capacity)
    print("Initial state of cache")
    print("Cache capacity: " + str(cache_capacity))
    cache.print()

    keys = [10, 10, 15, 20, 15, 25, 5]
    values = ["20", "get", "25", "40", "get", "85", "5"]

    for i in range(len(keys)):
        if values[i] == "get":
            print("Getting by Key: ", keys[i])
            print("Cached value returned: ", cache.get(keys[i]))
        else:
            print("Setting cache: Key: ", keys[i], ", Value: ", values[i])
            cache.set(keys[i], int(values[i]))
        cache.print()


if __name__ == '__main__':
    main()