import { App, Bot, segment, Session, sleep } from 'koishi';
import 'koishi-adapter-onebot';

import { parseCmd, view } from './command';
import { getLogger } from './loggers';

const logger = getLogger('qqbot');

interface IQQProps {
  access_token: string;
  host: string;
  port: number;
  bot_id: number;
  list(chat: IChat, args: string[], replyfn: (msg: string) => any): void;
  sub(chat: IChat, args: string[], replyfn: (msg: string) => any): void;
  unsub(chat: IChat, args: string[], replyfn: (msg: string) => any): void;
}

const cqUrlFix = (factory: segment.Factory<string | ArrayBuffer | Buffer>) =>
  (...args: Parameters<typeof factory>) => 
    factory(...args).replace(/(?<=\[CQ:.*)url=(?=(base64|file|https?):\/\/)/, 'file=');

export const Message = {
  Image: cqUrlFix(segment.image),
  Video: cqUrlFix(segment.video),
  Voice: cqUrlFix(segment.audio),
  ellipseBase64: (msg: string) => msg.replace(/(?<=\[CQ:.*base64:\/\/).*?(,|\])/g, '...$1'),
  separateAttachment: (msg: string) => {
    const attachments: string[] = [];
    const message = msg.replace(/\[CQ:(video|record),.*?\]/g, code => {
      attachments.push(code);
      return '';
    });
    return {message, attachments};
  },
};

export default class {

  private botInfo: IQQProps;
  private app: App;
  public bot: Bot;

  private messageQueues: {[key: string]: (() => Promise<void>)[]} = {};

  private next = (type: 'private' | 'group', id: string) => {
    const queue = this.messageQueues[`${type}:${id}`];
    if (queue && queue.length) {
      queue[0]().then(() => {
        queue.shift();
        if (!queue.length) delete this.messageQueues[`${type}:${id}`];
        else this.next(type, id);
      });
    }
  };

  private enqueue = (type: 'private' | 'group', id: string, resolver: () => Promise<void>) => {
    let wasEmpty = false;
    const queue = this.messageQueues[`${type}:${id}`] ||= (() => { wasEmpty = true; return []; })();
    queue.push(() => sleep(200).then(resolver));
    logger.debug(`no. of message currently queued for ${type}:${id}: ${queue.length}`);
    if (wasEmpty) this.next(type, id);
  };

  private getChat = async (session: Session): Promise<IChat> => {
    switch (session.subtype) {
      case 'private':
        if (session.groupId) { // temp message
          const friendList = await session.bot.getFriendList();
          if (!friendList.some(friendItem => friendItem.userId === session.userId)) {
            return {
              chatID: {
                qq: Number(session.userId),
                group: Number(session.groupId),
              },
              chatType: ChatType.Temp,
            };
          }
        }
        return { // already befriended
          chatID: Number(session.userId),
          chatType: ChatType.Private,
        };
      case 'group':
        return {
          chatID: Number(session.groupId),
          chatType: ChatType.Group,
        };
    }
  };

  private sendToGroup = (groupID: string, message: string) => new Promise<string>(resolve => {
    this.enqueue('group', groupID, () => this.bot.sendMessage(groupID, message).then(resolve));
  });

  private sendToUser = (userID: string, message: string) => new Promise<string>(resolve => {
    this.enqueue('private', userID, () => this.bot.sendPrivateMessage(userID, message).then(resolve));
  });

  public sendTo = (subscriber: IChat, messageChain: string) => Promise.all(
    (splitted => [splitted.message, ...splitted.attachments])(
      Message.separateAttachment(messageChain)
    ).map(msg => {
      switch (subscriber.chatType) {
        case 'group':
          return this.sendToGroup(subscriber.chatID.toString(), msg);
        case 'private':
          return this.sendToUser(subscriber.chatID.toString(), msg);
        case 'temp': // currently unable to open session, awaiting OneBot v12
          return this.sendToUser(subscriber.chatID.qq.toString(), msg);
      }
    }))
    .then(response => {
      if (response === undefined) return;
      logger.info(`pushing data to ${JSON.stringify(subscriber.chatID)} was successful, response: ${response}`);
    })
    .catch(reason => {
      reason = Message.ellipseBase64(reason);
      logger.error(`error pushing data to ${JSON.stringify(subscriber.chatID)}, reason: ${reason}`);
      throw Error(reason);
    });

  private initBot = () => {
    this.app = new App({
      type: 'onebot',
      server: `ws://${this.botInfo.host}:${this.botInfo.port}`,
      selfId: this.botInfo.bot_id.toString(),
      token: this.botInfo.access_token,
      axiosConfig: {
        maxContentLength: Infinity,
      },
      processMessage: msg => msg.trim(),
    });

    this.app.on('friend-request', async session => {
      const userString = `${session.username}(${session.userId})`;
      const groupString = `${session.groupName}(${session.groupId})`;
      logger.debug(`detected new friend request event: ${userString}`);
      return session.bot.getGroupList().then(groupList => {
        if (groupList.some(groupItem => groupItem.groupId === session.groupId)) {
          session.bot.handleFriendRequest(session.messageId, true);
          return logger.info(`accepted friend request from ${userString} (from group ${groupString})`);
        }
        logger.warn(`received friend request from ${userString} (from group ${groupString})`);
        logger.warn('please manually accept this friend request');
      });
    });

    this.app.on('group-request', async session => {
      const userString = `${session.username}(${session.userId})`;
      const groupString = `${session.groupName}(${session.groupId})`;
      logger.debug(`detected group invitation event: ${groupString}}`);
      return session.bot.getFriendList().then(friendList => {
        if (friendList.some(friendItem => friendItem.userId = session.userId)) {
          session.bot.handleGroupRequest(session.messageId, true);
          return logger.info(`accepted group invitation from ${userString} (friend)`);
        }
        logger.warn(`received group invitation from ${userString} (stranger)`);
        logger.warn('please manually accept this group invitation');
      });
    });

    this.app.middleware(async session => {
      const chat = await this.getChat(session);
      const cmdObj = parseCmd(session.content);
      const reply = async msg => session.sendQueued(msg);
      switch (cmdObj.cmd) {
        case 'igstory_view':
        case 'igstory_get':
          view(chat, cmdObj.args, reply);
          break;
        case 'igstory_sub':
        case 'igstory_subscribe':
          this.botInfo.sub(chat, cmdObj.args, reply);
          break;
        case 'igstory_unsub':
        case 'igstory_unsubscribe':
          this.botInfo.unsub(chat, cmdObj.args, reply);
          break;
        case 'ping':
        case 'igstory':
          this.botInfo.list(chat, cmdObj.args, reply);
          break;
        case 'help':
          if (cmdObj.args.length === 0) {
            reply(`Instagram 故事搬运机器人：
/igstory - 查询当前聊天中的 Instagram Stories 动态订阅
/igstory_subscribe〈链接|用户名〉- 订阅 Instagram Stories 搬运
/igstory_unsubscribe〈链接|用户名〉- 退订 Instagram Stories 媒体搬运
/igstory_view〈链接〉- 查看该用户所有 Stories
${chat.chatType === ChatType.Temp ?
    '\n（当前游客模式下无法使用订阅功能，请先添加本账号为好友。）' : ''
}`);
          }
      }
    }, true);
  };

  private listen = async (logMsg = 'connecting to bot provider...'): Promise<void> => {
    logger.warn(logMsg);
    try {
      await this.app.start();
    } catch (err) {
      logger.error(`error connecting to bot provider at ${this.app.options.server}, will retry in 2.5s...`);
      await sleep(2500);
      await this.listen('retry connecting...');
    }
  };

  public connect = async () => {
    this.initBot();
    await this.listen();
    this.bot = this.app.getBot('onebot');
  };

  constructor(opt: IQQProps) {
    logger.warn(`Initialized koishi on ${opt.host}:${opt.port} with access_token ${opt.access_token}`);
    this.botInfo = opt;
  }
}