package handler

import (
	"crypto/rand"
	"encoding/base64"
	"sync"
	"time"
)

type tokenInfo struct {
	createdAt time.Time
	expiresIn time.Duration
}

type authManager struct {
	tokens sync.Map
}

func newAuthManager() *authManager {
	am := &authManager{}
	// 启动token清理goroutine
	go am.cleanExpiredTokens()
	return am
}

func (am *authManager) generateToken() string {
	b := make([]byte, 32)
	rand.Read(b)
	return base64.URLEncoding.EncodeToString(b)
}

func (am *authManager) addToken(token string, expiry time.Duration) {
	am.tokens.Store(token, tokenInfo{
		createdAt: time.Now(),
		expiresIn: expiry,
	})
}

func (am *authManager) validateToken(token string) bool {
	if info, ok := am.tokens.Load(token); ok {
		tokenInfo := info.(tokenInfo)
		if time.Since(tokenInfo.createdAt) < tokenInfo.expiresIn {
			return true
		}
		am.tokens.Delete(token)
	}
	return false
}

func (am *authManager) cleanExpiredTokens() {
	ticker := time.NewTicker(time.Hour)
	for range ticker.C {
		am.tokens.Range(func(key, value interface{}) bool {
			token := key.(string)
			info := value.(tokenInfo)
			if time.Since(info.createdAt) >= info.expiresIn {
				am.tokens.Delete(token)
			}
			return true
		})
	}
}