import * as fs from 'fs';
import * as path from 'path';
import {
  IgApiClient,
  IgClientError, IgExactUserNotFoundError,
  IgLoginRequiredError,
  IgNetworkError,
  ReelsMediaFeedResponseItem, UserFeedResponseUser
} from 'instagram-private-api';
import { RequestError } from 'request-promise/errors';
import { SocksProxyAgent } from 'socks-proxy-agent';

import { getLogger } from './loggers';
import QQBot, { Message } from './koishi';
import { BigNumOps } from './utils';
import Webshot from './webshot';

const parseLink = (link: string): {userName?: string, storyId?: string} => {
  let match =
    /instagram\.com\/stories\/([^\/?#]+)\/(\d+)/.exec(link);
  if (match) return {userName: ScreenNameNormalizer.normalize(match[1]).split(':')[0], storyId: match[2]};
  match =
    /instagram\.com\/([^\/?#]+)/.exec(link) ||
    /^([^\/?#]+)$/.exec(link);
  if (match) return {userName: ScreenNameNormalizer.normalize(match[1]).split(':')[0]};
  return;
};

const linkBuilder = (config: ReturnType<typeof parseLink>): string => {
  if (!config.userName) return;
  if (!config.storyId) return `https://www.instagram.com/${config.userName}/`;
  return `https://www.instagram.com/stories/${config.userName}/${config.storyId}/`;
};

export {linkBuilder, parseLink};

interface IWorkerOption {
  sessionLockfile: string;
  credentials: [string, string];
  proxyUrl: string;
  lock: ILock;
  lockfile: string;
  webshotCookiesLockfile: string;
  bot: QQBot;
  workInterval: number;
  webshotDelay: number;
  mode: number;
  wsUrl: string;
}

export class SessionManager {
  private ig: IgApiClient;
  private username: string;
  private password: string;
  private lockfile: string;
  
  constructor(client: IgApiClient, file: string, credentials: [string, string]) {
    this.ig = client;
    this.lockfile = file;
    [this.username, this.password] = credentials;
  }

  public init = () => {
    this.ig.state.generateDevice(this.username);
    this.ig.request.end$.subscribe(() => { this.save(); });
    const filePath = path.resolve(this.lockfile);
    if (fs.existsSync(filePath)) {
      try {
        const serialized = JSON.parse(fs.readFileSync(filePath, 'utf8')) as {[key: string]: any};
        return this.ig.state.deserialize(serialized).then(() => { 
          logger.info(`successfully loaded client session cookies for user ${this.username}`);
        });
      } catch (err) {
        logger.error(`failed to load client session cookies from file ${this.lockfile}: `, err);
        return Promise.resolve();
      }
    } else return this.login();
  };

  public login = () =>
    this.ig.simulate.preLoginFlow()
      .then(() => this.ig.account.login(this.username, this.password))
      .then(() => new Promise(resolve => {
        logger.info(`successfully logged in as ${this.username}`);
        process.nextTick(() => resolve(this.ig.simulate.postLoginFlow()));
      }));

  public save = () =>
    this.ig.state.serialize()
      .then((serialized: {[key: string]: any}) => {
        delete serialized.constants;
        return fs.writeFileSync(path.resolve(this.lockfile), JSON.stringify(serialized, null, 2), 'utf-8');
      });
}

export class ScreenNameNormalizer {

  // tslint:disable-next-line: variable-name
  public static _queryUser: (username: string) => Promise<string>;

  public static normalize = (username: string) => `${username.toLowerCase().replace(/^@/, '')}:`;

  public static async normalizeLive(username: string) {
    if (this._queryUser) {
      return await this._queryUser(username)
        .catch((err: IgClientError) => {
          if (!(err instanceof IgExactUserNotFoundError)) {
            logger.warn(`error looking up user: ${err.message}`);
            return `${username}:`;
          }
          return null;
        });
    }
    return this.normalize(username);
  }
}

export let sendAllStories = (segmentId: string, receiver: IChat): void => {
  throw Error();
};

export type MediaItem = ReelsMediaFeedResponseItem;

const logger = getLogger('instagram');
const maxTrials = 3;
const retryInterval = 1500;
const ordinal = (n: number) => {
  switch ((Math.trunc(n / 10) % 10 === 1) ? 0 : n % 10) {
    case 1:
      return `${n}st`;
    case 2:
      return `${n}nd`;
    case 3:
      return `${n}rd`;
    default:
      return `${n}th`;
  }
};
const retryOnError = <T, U>(
  doWork: () => Promise<T>,
  onRetry: (error, count: number, terminate: (defaultValue: U) => void) => void
) => new Promise<T | U>(resolve => {
  const retry = (reason, count: number) => {
    setTimeout(() => {
      let terminate = false;
      onRetry(reason, count, defaultValue => { terminate = true; resolve(defaultValue); });
      if (!terminate) doWork().then(resolve).catch(error => retry(error, count + 1));
    }, retryInterval);
  };
  doWork().then(resolve).catch(error => retry(error, 1));
});

export default class {

  private client: IgApiClient;
  private lock: ILock;
  private lockfile: string;
  private workInterval: number;
  private bot: QQBot;
  private webshotDelay: number;
  private webshot: Webshot;
  private mode: number;
  private wsUrl: string;

  public session: SessionManager;

  constructor(opt: IWorkerOption) {
    this.client = new IgApiClient();
    if (opt.proxyUrl) {
      try {
        const url = new URL(opt.proxyUrl);
        if (!/^socks(?:4a?|5h?)?:$/.test(url.protocol)) throw Error();
        if (!url.port) url.port = '1080';
        this.client.request.defaults.agent = new SocksProxyAgent({
          hostname: url.hostname,
          port: url.port,
          userId: url.username,
          password: url.password,
        });
      } catch (e) {
        logger.warn(`invalid socks proxy url: ${opt.proxyUrl}, ignoring`);
      }
    }
    this.session = new SessionManager(this.client, opt.sessionLockfile, opt.credentials);
    this.lockfile = opt.lockfile;
    this.lock = opt.lock;
    this.workInterval = opt.workInterval;
    this.bot = opt.bot;
    this.webshotDelay = opt.webshotDelay;
    this.mode = opt.mode;
    this.wsUrl = opt.wsUrl;

    ScreenNameNormalizer._queryUser = this.queryUser;
    sendAllStories = (rawUserName, receiver) => {
      const sender = this.sendStories(`instagram stories for ${rawUserName}`, receiver);
      this.queryUser(rawUserName)
        .then(userNameId => {
          const [userName, userId] = userNameId.split(':');
          if (userName in this.cache && Object.keys(this.cache[userName].stories).length > 0) {
            return Promise.resolve(
              Object.values(this.cache[userName].stories)
                .map(story => ({...story, user: this.cache[userName].user}))
                .sort((i1, i2) => BigNumOps.compare(i2.pk, i1.pk))
            );
          }
          return this.client.feed.reelsMedia({userIds: [userId]}).items()
            .then(storyItems => {
              storyItems = storyItems.map(story => ({...story, user: this.cache[userName].user}));
              storyItems.forEach(item => {
                if (!(item.pk in this.cache[userName].stories)) {
                  this.cache[userName].stories[item.pk] = item;
                }
              });
              if (storyItems.length === 0) this.bot.sendTo(receiver, `当前用户 (@${userName}) 没有可用的推特故事。`);
              return storyItems;
            });
        })
        .then(storyItems => this.workOnMedia(storyItems, sender))
        .catch((error: IgClientError & Partial<RequestError>) => {
          if (error instanceof IgNetworkError) {
            logger.warn(`error on fetching stories for ${rawUserName}: ${JSON.stringify(error.cause)}`);
            this.bot.sendTo(receiver, `获取 Fleets 时出现错误：原因： ${error.cause}`);
          } else if (error instanceof IgLoginRequiredError) {
            logger.warn('login required, logging in again...');
            this.session.login().then(() => sendAllStories(rawUserName, receiver));
          } else {
            logger.error(`unhandled error on fetching media for ${rawUserName}: ${error}`);
            this.bot.sendTo(receiver, `获取 Fleets 时发生未知错误： ${error}`); 
          }
        });
    };
  }

  public launch = () => {
    this.webshot = new Webshot(
      this.wsUrl,
      this.mode,
      () => {
        setTimeout(this.workForAll, this.workInterval * 1000);
        setTimeout(() => {
          this.work();
          setInterval(this.workForAll, this.workInterval * 10000);
        }, this.workInterval * 1200);
      }
    );
  };

  public queryUser = (rawUserName: string) => {
    const username = ScreenNameNormalizer.normalize(rawUserName).split(':')[0];
    if (username in this.cache) {
      return Promise.resolve(`${username}:${this.cache[username].user.pk}`);
    }
    return this.client.user.searchExact(username)
      .then(user => {
        this.cache[user.username] = {user, stories: {}};
        return `${user.username}:${user.pk}`;
      });
  };

  private workOnMedia = (
    mediaItems: MediaItem[],
    sendMedia: (msg: string, text: string, author: string) => void
  ) => this.webshot(mediaItems, sendMedia, this.webshotDelay);

  private sendStories = (source?: string, ...to: IChat[]) => (msg: string, text: string, author: string) => {
    to.forEach(subscriber => {
      logger.info(`pushing data${source ? ` of ${Message.ellipseBase64(source)}` : ''} to ${JSON.stringify(subscriber)}`);
      retryOnError(
        () => this.bot.sendTo(subscriber, msg),
        (_, count, terminate: (doNothing: Promise<void>) => void) => {
          if (count <= maxTrials) {
            logger.warn(`retry sending to ${subscriber.chatID} for the ${ordinal(count)} time...`);
          } else {
            logger.warn(`${count - 1} consecutive failures while sending` +
            'message chain, trying plain text instead...');
            terminate(this.bot.sendTo(subscriber, author + text));
          }
        });
    });
  };

  private cache: {
    [userName: string]: {
      user: UserFeedResponseUser & ReelsMediaFeedResponseItem['user'],
      stories: {[storyId: string]: MediaItem},
    },
  } = {};

  private workForAll = () => {
    const idToUserMap: {[id: number]: UserFeedResponseUser} = {};
    Promise.all(Object.entries(this.lock.threads).map(entry => {
      const id = entry[1].id;
      const userName = parseLink(entry[0]).userName;
      logger.debug(`preparing to add user @${userName} to next pull task...`);
      if (userName in this.cache) return Promise.resolve(idToUserMap[id] = this.cache[userName].user);
      return this.client.user.info(id).then(user => {
        logger.debug(`initialized cache item for user ${user.full_name} (@${userName})`);
        this.cache[userName] = {user, stories: {}};
        return idToUserMap[id] = user as UserFeedResponseUser;
      });
    }))
      .then(() => {
        logger.debug(`pulling stories for users: ${Object.values(idToUserMap).map(user => user.username)}`);
        this.client.feed.reelsMedia({
          userIds: Object.keys(idToUserMap),
        }).items()
          .then(storyItems => storyItems.forEach(item => {
            if (!(item.pk in this.cache[idToUserMap[item.user.pk].username].stories)) {
              this.cache[idToUserMap[item.user.pk].username].stories[item.pk] = item;
            }
          }))
          .catch((error: IgClientError & Partial<RequestError>) => {
            if (error instanceof IgNetworkError) {
              logger.warn(`error on fetching stories for all: ${JSON.stringify(error.cause)}`);
            } else if (error instanceof IgLoginRequiredError) {
              logger.warn('login required, logging in again...');
              this.session.login().then(this.workForAll);
            } else {
              logger.error(`unhandled error on fetching media for all: ${error}`);
            }
          });
      });
  };

  public work = () => {
    const lock = this.lock;
    logger.debug(`current cache: ${JSON.stringify(this.cache)}`);
    if (this.workInterval < 1) this.workInterval = 1;
    if (lock.feed.length === 0) {
      setTimeout(this.work, this.workInterval * 1000);
      return;
    }
    if (lock.workon >= lock.feed.length) lock.workon = 0;
    if (!lock.threads[lock.feed[lock.workon]] ||
      !lock.threads[lock.feed[lock.workon]].subscribers ||
      lock.threads[lock.feed[lock.workon]].subscribers.length === 0) {
      logger.warn(`nobody subscribes thread ${lock.feed[lock.workon]}, removing from feed`);
      delete lock.threads[lock.feed[lock.workon]];
      lock.feed.splice(lock.workon, 1);
      fs.writeFileSync(path.resolve(this.lockfile), JSON.stringify(lock));
      this.work();
      return;
    }

    const currentFeed = lock.feed[lock.workon];
    logger.debug(`searching for new items from ${currentFeed} in cache`);

    const promise = new Promise<MediaItem[]>(resolve => {
      const match = /https:\/\/www\.instagram\.com\/([^\/]+)/.exec(currentFeed);
      if (match) {
        const cachedFeed = this.cache[match[1]];
        if (!cachedFeed) {
          setTimeout(this.work, this.workInterval * 1000);
          resolve([]);
        }
        const newer = (item: MediaItem) =>
          BigNumOps.compare(item.pk, lock.threads[currentFeed].offset) > 0;
        resolve(Object.values(cachedFeed.stories)
          .filter(newer)
          .map(story => ({...story, user: cachedFeed.user}))
          .sort((i1, i2) => BigNumOps.compare(i2.pk, i1.pk))
        );
      }
    });

    promise.then((mediaItems: MediaItem[]) => {
      const currentThread = lock.threads[currentFeed];

      const updateDate = () => currentThread.updatedAt = new Date().toString();
      if (!mediaItems || mediaItems.length === 0) { updateDate(); return; }

      const topOfFeed = mediaItems[0].pk;
      const updateOffset = () => currentThread.offset = topOfFeed;

      if (currentThread.offset === '-1') { updateOffset(); return; }
      if (currentThread.offset === '0') mediaItems.splice(1);

      return this.workOnMedia(mediaItems, this.sendStories(`thread ${currentFeed}`, ...currentThread.subscribers))
        .then(updateDate).then(updateOffset);
    })
      .then(() => {
        lock.workon++;
        let timeout = this.workInterval * 1000 / lock.feed.length;
        if (timeout < 1000) timeout = 1000;
        fs.writeFileSync(path.resolve(this.lockfile), JSON.stringify(lock));
        setTimeout(() => {
          this.work();
        }, timeout);
      });
  };
}