from linked_list import LinkedList
from print_list import print_list_with_forward_arrow

def reverse(head):
    # initialize prev and next pointer to None
    prev, next = None, None
    # set current pointer to the head node
    curr = head
    # while the current pointer is not None
    while curr is not None:
        # set the next pointer to the next node in the list
        next = curr.next
        # reverse the current node's pointer to point to the previous node
        curr.next = prev
        # set the previous pointer to the current node
        prev = curr
        # move the current pointer to the next node
        curr = next
    # set the head pointer to the last node, which is the new first node after reversal
    head = prev
    # return the new head pointer
    return head


def main():

    input = (
        [1, 2, 3, 4, 5],
        [1, 2, 3, 4, 5, 6],
        [3, 2, 1],
        [10],
        [1, 2],
    )

    for i in range(len(input)):
        input_linked_list = LinkedList()
        input_linked_list.create_linked_list(input[i])
        print(i+1, ".\tInput linked list: ", sep="", end="")
        print_list_with_forward_arrow(input_linked_list.head)
        print("\n\tReversed linked list: ", end="")
        print_list_with_forward_arrow(reverse(input_linked_list.head))
        print("\n", "-"*100)


if __name__ == "__main__":
    main()