package middleware

import (
	"time"

	"github.com/gin-gonic/gin"
)

// Limiter 限流器
type Limiter struct {
	limit      int                // 限制的请求数量
	duration   time.Duration      // 时间窗口
	timestamps map[string][]int64 // 请求的时间戳
}

// NewLimiter 创建限流器
func NewLimiter(limit int, duration time.Duration) *Limiter {
	return &Limiter{
		limit:      limit,
		duration:   duration,
		timestamps: make(map[string][]int64),
	}
}

// Middleware 限流中间件
func (l *Limiter) Middleware(c *gin.Context) {
	ip := c.ClientIP() // 获取客户端IP地址

	// 检查请求时间戳切片是否存在
	if _, ok := l.timestamps[ip]; !ok {
		l.timestamps[ip] = make([]int64, 0)
	}

	now := time.Now().Unix() // 当前时间戳

	// 移除过期的请求时间戳
	for i := 0; i < len(l.timestamps[ip]); i++ {
		if l.timestamps[ip][i] < now-int64(l.duration.Seconds()) {
			l.timestamps[ip] = append(l.timestamps[ip][:i], l.timestamps[ip][i+1:]...)
			i--
		}
	}

	// 检查请求数量是否超过限制
	if len(l.timestamps[ip]) >= l.limit {
		c.JSON(429, gin.H{
			"message": "Too Many Requests",
		})
		c.Abort()
		return
	}

	// 添加当前请求时间戳到切片
	l.timestamps[ip] = append(l.timestamps[ip], now)

	// 继续处理请求
	c.Next()
}