package main

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"io/ioutil"
	"net/http"
	"time"

	"github.com/shirou/gopsutil/disk"
)

// SendGroupType .
type SendGroupType struct {
	MsgType string   `json:"msgtype"`
	Text    TextType `json:"text"`
	At      AtType   `json:"at"`
	IsAtAll bool     `json:"isAtAll"`
}

// TextType .
type TextType struct {
	Content string `json:"content"`
}

// AtType .
type AtType struct {
	AtMobiles []string `json:"atMobiles"`
}

// SendGroupResp .
type SendGroupResp struct {
	ErrMsg  string `json:"errmsg"`
	ErrCode int    `json:"errcode"`
}

const (
	token       = "your token"
	allensPhone = "your dingtalk phone"

	b = 1024
	k = b * 1024
	g = k * 1024
)

func main() {
	diskInfo, _ := disk.Usage("/")
	if diskInfo.Free/g <= 3 {
		SendDingRobot("告警： 当前您的服务器 [ XXX ] 硬盘内存剩余已不足 3 G", []string{
			allensPhone,
		})
	}
}

// SendDingRobot Send text messages to ding robot
func SendDingRobot(msg string, phone []string) error {
	t := TextType{
		Content: msg,
	}
	a := AtType{
		AtMobiles: phone,
	}
	g := SendGroupType{
		MsgType: "text",
		Text:    t,
		At:      a,
		IsAtAll: true,
	}

	err := sendGroup(g)
	if err != nil {
		return fmt.Errorf("send ding Group err:[%s]", err.Error())
	}
	return nil
}

// SendGroup 发送消息到钉钉群机器人
func sendGroup(sendGroup SendGroupType) error {

	client := &http.Client{
		Timeout: time.Duration(15) * time.Second,
	}

	reqData, err := json.Marshal(sendGroup)
	if err != nil {
		return err
	}

	reader := bytes.NewReader(reqData)
	resp, err := client.Post("https://oapi.dingtalk.com/robot/send?access_token="+token, "application/json;charset=UTF-8", reader)
	if err != nil {
		return err
	}

	defer resp.Body.Close()

	data, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return err
	}

	var respData SendGroupResp
	err = json.Unmarshal(data, &respData)
	if err != nil {
		return err
	}

	if respData.ErrCode != 0 {
		return errors.New(respData.ErrMsg)
	}
	return nil
}

scp diskMonitor myservice:~/monitor/disk

crontab -e