cognito_user_pool.go

import (
	"encoding/json"
	"fmt"
	"sync"
)

const poolFileName = "pool.json"

func main() {
	data, err := ioutil.ReadFile(poolFileName)
	if err != nil {
		panic(err)
	}
	poolMap := make(map[UserPoolID]UserMap)
	err = json.Unmarshal(data, &poolMap)
	if err != nil {
		panic(err)
	}
	userPool = UserPool{
		poolMap: poolMap,
		mutex:   &sync.Mutex{},
	}

	...
}

type User struct {
	UUID          string   `json:"uuid"`
	Password      string   `json:"password"`
	Username      Username `json:"username"`
	Email         string   `json:"email"`
	EmailVerified bool     `json:"email_verified"`
}

type Username string

type UserMap map[Username]*User

type UserPoolID string

type UserPool struct {
	poolMap map[UserPoolID]UserMap
	mutex   *sync.Mutex
}

func (pool UserPool) GetUser(userPoolID UserPoolID, username Username) (*User, bool) {
	pool.mutex.Lock()
	defer pool.mutex.Unlock()
	return pool.getUser(userPoolID, username)
}

func (pool UserPool) getUser(userPoolID UserPoolID, username Username) (*User, bool) {
	uMap, ok := pool.poolMap[userPoolID]
	if !ok {
		return nil, false
	}
	u, ok := uMap[username]
	if !ok {
		return nil, false
	}
	return u, true
}

func (pool UserPool) CreateUser(userPoolID UserPoolID, user User) error {
	pool.mutex.Lock()
	defer pool.mutex.Unlock()
	
	uMap, ok := pool.poolMap[userPoolID]
	if !ok {
		uMap = make(UserMap)
		pool.poolMap[userPoolID] = uMap
	}
	if _, ok := uMap[user.Username]; ok {
		return fmt.Errorf("already exist")
	}
	uMap[user.Username] = &user
	return pool.updateFile()
}

func (pool UserPool) updateFile() error {
	file, err := os.Create(poolFileName)
	if err != nil {
		return err
	}
	defer file.Close()
	content, err := json.Marshal(pool.poolMap)
	if err != nil {
		return err
	}
	_, err = file.Write(content)
	return err
}

func (pool UserPool) DeleteUser(userPoolID UserPoolID, username Username) error {
	pool.mutex.Lock()
	defer pool.mutex.Unlock()
	
	if _, exist := pool.getUser(userPoolID, username); exist {
		delete(pool.poolMap[userPoolID], username)
	}
	return pool.updateFile()
}