设计一个在线聊天系统

约束和限制

• 假设我们聚焦在以下的工作流

  • 只是输入Text进行对话

  • Users

    • Add a User
    • Remove a User
    • Update a user
    • Add to a user’s friends list
      • Add friend request
        • Approve friend request
        • Reject friend request
      • Remove from a user’s friends list

  • Create a group chat

    • 邀请朋友到一个 group chat
    • 发送一个消息到一个 group chat

  • 私人 1-1 chat

    • 邀请一个朋友到一个 Private Chat
    • 发送一个消息到一个 Private Chat

  • 不需要担心初始化的扩展问题

编码实现

from abc import ABCMeta

class UserService(object):
	def __init__(self):
		self.users_by_id = {}

	def add_user(self, user_id, name, pass_hash): #...
	def remove_user(self, user_id): #...
	def add_friend_request(self, from_user_id, to_user_id): #...
	def approve_friend_request(self, from_user_id, to_user_id): #...
	def reject_friend_request(self, from_user_id, to_user_id): #...


class User(object):
	def __init__(self, user_id, name, pass_hash):
		self.user_id = user_id
		self.name = name
		self.pass_hash = pass_hash
		self.friends_by_id = {}
		self.friend_ids_to_private_chats = {}
		self.group_chats_by_id = {}
		self.received_friend_requests_by_friend_id = {}
		self.sent_friend_requests_by_friend_id = {}

	def message_user(self, friend_id, message): #...
	def message_group(self, group_id, message): #...
	def send_friend_request(self, friend_id): #...
	def receive_friend_request(self, friend_id): #...
	def approve_friend_request(self, friend_id): #...
	def reject_friend_request(self, friend_id): #...


class Chat(metaclass=ABCMeta):

	def __init__(self, chat_id):
		self.chat_id = chat_id
		self.users = []
		self.message = []

class PrivateChat(Chat):
	
	def __init__(self, first_user, second_user):
		super(PrivateChat, self).__init__()
		self.users.append(first_user)
		self.users.append(second_user)


class GroupChat(Chat):
	def add_user(self, user): #...
	def remove_user(self, user): #...

class Message(object):
	
	def __init__(self, message_id, message, timestamp):
		self.message_id = message_id
		self.message = message
		self.timestamp = timestamp

class AddRequest(object):
	
	def __init__(self, message_id, message, timestamp):
		self.message_id = message_id
		self.message = message
		self.timestamp = timestamp

class RequestStatus(Enum):

	UNREAD = 0
	READ = 1
	ACCEPTED = 2
	REJETED = 3