# week06_01_chap05_05.py

class Node:
    def __init__(self):
        self.data = None
        self.link = None


def print_nodes(start):
    current = start
    if current is None:  # 출력할 노드가 없으면
        return

    print(current.data, end=' ')
    while current.link is not start:  # !
        current = current.link  # 가르키는 대상 변경(증가)
        print(current.data, end=' ')
    print()


def insert_node(find_data, insert_data):
    global head, current, pre

    if head.data == find_data:
        node = Node()
        node.data = insert_data
        node.link = head
        last = head  # !
        while last.link is not head:  # !
            last = last.link  # !
        last.link = node  # !
        head = node
        return

    current = head
    while current.link is not head:  # !
        pre = current
        current = current.link
        if current.data == find_data:
            node = Node()
            node.data = insert_data
            node.link = current
            pre.link = node
            return

    node = Node()
    node.data = insert_data
    current.link = node
    node.link = head  # !


def delete_node(delete_data):
    global head, current, pre

    if head.data == delete_data:
        current = head
        head = head.link
        last = head  # !
        while last.link is not current:  # !
            last = last.link  # !
        last.link = head  # !
        del current
        return

    current = head
    while current.link is not head:  # !
        pre = current
        current = current.link
        if current.data == delete_data:
            pre.link = current.link
            del current
            return


def find_node(find_data):
    global head, current

    current = head
    if current.data == find_data:
        return current
    while current.link is not head:  # !
        current = current.link
        if current.data == find_data:
            return current

    return Node()  # 찾는 노드가 없음


head, current, pre = None, None, None
data_array = ["다현", "정연", "쯔위", "사나", "지효"]

if __name__ == "__main__":
    node = Node()
    node.data = data_array[0]
    node.link = node
    head = node

    for i in range(1, len(data_array)):
        pre = node
        node = Node()
        node.data = data_array[i]
        pre.link = node
        node.link = head  # 새로 맨 마지막에 추가된 노드는 맨 앞의 노드와 연결

    print_nodes(head)

    f_node = find_node("다현")
    print(f_node.data)

    delete_node("다현")
    print_nodes(head)

    f_node = find_node("다현")
    print(f_node.data)

    delete_node("쯔위")
    print_nodes(head)

    delete_node("이나")
    print_nodes(head)


    # insert_node("다현", "화사")
    # print_nodes(head)
    #
    # insert_node("사나", "솔라")
    # print_nodes(head)
    #
    # insert_node("이나", "문별")
    # print_nodes(head)