package main

import "sort"

type User struct {
	Id    int
	Focus map[int]bool
	Twis  []Twi
}

type Twi struct {
	sortId int
	TwiId int

}

type Twitter struct {
	TwisCount int
	UsersTable map[int]*User
}


/** Initialize your data structure here. */
func Constructor() Twitter {
	return Twitter{
		0,
		make(map[int]*User),
	}
}


/** Compose a new tweet. */
func (this *Twitter) PostTweet(userId int, tweetId int)  {
	// 用户首次发推，自动给用户注册
	if _ , ok := this.UsersTable[userId] ; !ok {
		this.UsersTable[userId] = &User{
			Id:    userId,
			Focus: make(map[int]bool),
			Twis:  make([]Twi, 0, 0),
		}
	}
	u := this.UsersTable[userId]
	u.Twis = append(u.Twis, Twi{this.TwisCount,tweetId} )
	this.TwisCount ++
}


/** Retrieve the 10 most recent tweet ids in the user's news feed. Each item in the news feed must be posted by users who the user followed or by the user herself. Tweets must be ordered from most recent to least recent. */
func (this *Twitter) GetNewsFeed(userId int) []int {
	u, ok := this.UsersTable[userId]
	if !ok {
		return []int{}
	}
	res := make([]Twi, 0, 0)
	res = append(res, u.Twis...)
	for id , ok1 := range u.Focus  {
		fu, ok2 := this.UsersTable[id]
		if ok1 && ok2 {
			res = append(res, fu.Twis...)
		}
	}
	sort.Slice(res, func(i, j int) bool {
		return res[i].sortId > res[j].sortId
	})
	messages := make([]int, 0,0)
	for i := 0 ; i < min(len(res), 10) ; i ++ {
		messages = append(messages, res[i].TwiId)
	}
	return messages
}


/** Follower follows a followee. If the operation is invalid, it should be a no-op. */
func (this *Twitter) Follow(followerId int, followeeId int)  {
	if _ , ok := this.UsersTable[followerId] ; !ok {
		this.UsersTable[followerId] = &User{
			Id:    followerId,
			Focus: make(map[int]bool),
			Twis:  make([]Twi,0 ,0),
		}
	}
	_ , hasFollow := this.UsersTable[followerId].Focus[followeeId]
	if !hasFollow {
		this.UsersTable[followerId].Focus[followeeId] = true
	}
}


/** Follower unfollows a followee. If the operation is invalid, it should be a no-op. */
func (this *Twitter) Unfollow(followerId int, followeeId int)  {
	if _, ok := this.UsersTable[followerId] ; !ok {
		return
	}
	// 必须是已经关注过的
	if _ , ok := this.UsersTable[followerId].Focus[followeeId] ; ok {
		delete(this.UsersTable[followerId].Focus, followeeId)
	}
}

func min(a, b int) int {
	if a < b{
		return a
	}
	return b
}



/**
 * Your Twitter object will be instantiated and called as such:
 * obj := Constructor();
 * obj.PostTweet(userId,tweetId);
 * param_2 := obj.GetNewsFeed(userId);
 * obj.Follow(followerId,followeeId);
 * obj.Unfollow(followerId,followeeId);
 */