package service

import (
	"sync"
	"time"
)

// RateLimiter 内存速率限制器
type RateLimiter struct {
	mu       sync.Mutex
	records  map[string][]time.Time
	limits   map[string]int // key -> 每分钟最大请求数
	cooldown map[string]time.Duration
}

func NewRateLimiter() *RateLimiter {
	return &RateLimiter{
		records:  make(map[string][]time.Time),
		limits:   make(map[string]int),
		cooldown: make(map[string]time.Duration),
	}
}

// SetLimit 设置某类请求的每分钟限制
func (r *RateLimiter) SetLimit(key string, perMinute int) {
	r.mu.Lock()
	defer r.mu.Unlock()
	r.limits[key] = perMinute
}

// Allow 检查是否允许请求
func (r *RateLimiter) Allow(key string) bool {
	r.mu.Lock()
	defer r.mu.Unlock()

	limit, ok := r.limits[key]
	if !ok {
		return true
	}

	now := time.Now()
	windowStart := now.Add(-1 * time.Minute)

	// 清理过期记录
	records := r.records[key]
	valid := records[:0]
	for _, t := range records {
		if t.After(windowStart) {
			valid = append(valid, t)
		}
	}

	if len(valid) >= limit {
		r.records[key] = valid
		return false
	}

	valid = append(valid, now)
	r.records[key] = valid
	return true
}

// 速率限制类型常量
const (
	RateLogin    = "login"
	RateRegister = "register"
	RatePost     = "post"
	RateComment  = "comment"
)

// DefaultRateLimiter 创建默认速率限制器
func DefaultRateLimiter() *RateLimiter {
	rl := NewRateLimiter()
	rl.SetLimit(RateLogin, 20)     // 登录 20/分钟
	rl.SetLimit(RateRegister, 10)  // 注册 10/分钟
	rl.SetLimit(RatePost, 10)      // 发帖 10/分钟
	rl.SetLimit(RateComment, 30)   // 评论 30/分钟
	return rl
}