package middleware

import (
    "gugegin/tools"
    "net/http"
    "time"

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

//Nonce 存放随机字符串，防止重复访问
var Nonce = make(map[string]string)

//Ban 存放封禁用户，向该用户发出通知
var Ban = make(map[string]string)

// IsLegitimate 检查是否合法用户,根据接收到的时间戳判断访问时间是否是5分支之内，根据nonce判断是否同一请求重复访问
// IsLegitimate 检查1 时间戳 检查2 nonce 检查3 token
func IsLegitimate() gin.HandlerFunc {
    return func(c *gin.Context) {
        // 检查时间戳
        timestamp := c.GetHeader("timestamp")
        if tools.TimeDifference(timestamp) >= 5 { //请求超过5分钟
            c.JSON(http.StatusUnauthorized, gin.H{
                "message": "请求超时",
            })
            c.Abort()
            return
        }
        // 检查随机字符串
        receiveNonce := c.GetHeader("nonce")
        for _, v := range Nonce {
            if v == receiveNonce {
                c.JSON(http.StatusUnauthorized, gin.H{
                    "message": "重复请求",
                })
                c.Abort()
                return
            } else {
                Nonce[receiveNonce] = receiveNonce
            }
        }
        // 检查token
        token := c.GetHeader("token")
        if !CheckToken(token) {
            c.JSON(http.StatusUnauthorized, gin.H{
                "message": "访问未授权",
            })
            c.Abort()
            return
        }
        //检查是否封号
        uid := c.GetHeader("uid")
        if uid == "" {
            c.JSON(http.StatusUnauthorized, gin.H{
                "message": "非法用户",
            })
            c.Abort()
            return
        } else {
            for _, v := range Ban {
                if uid == v {
                    c.JSON(http.StatusUnauthorized, gin.H{
                        "message": "该账号已被系统管理员封禁",
                    })
                    c.Abort()
                    return
                }
            }
        }
        c.Next()
    }
}

// RegularCleaning 定时清理随机数map，避免占用太多内存,每隔 5 小时执行一次
func RegularCleaning() {
    time.AfterFunc(5*time.Hour, RegularCleaning)
    for k, v := range Nonce {
        if tools.TimeDifference(v) >= 60*5 {
            delete(Nonce, k)
        }
    }
}