package main

import (
	"database/sql"
	"github.com/gin-gonic/gin"
	_ "github.com/go-sql-driver/mysql"
	"log"
	"net/http"
)

var DB *sql.DB

func init() {
	db, err := sql.Open("mysql", "root:mashibing@tcp(192.168.177.131:3307)/saga?charset=utf8mb4&parseTime=True&loc=Local")
	if err != nil {
		log.Fatalln(err)
	}
	DB = db
}

type Req struct {
	Quantity int    `json:"quantity"`
	Id       int    `json:"id"`
	TxId     string `json:"tx_id"`
}

func main() {
	r := gin.Default()

	r.POST("/deduct", func(c *gin.Context) {
		// 解析请求数据
		req := &Req{}
		if err := c.BindJSON(req); err != nil {
			log.Fatalln(err)
		}
		// 执行 扣减库存
		query := "update storages set inventory = inventory-? where id = ?"
		if _, err := DB.Exec(query, req.Quantity, req.Id); err != nil {
			c.JSON(http.StatusOK, gin.H{"dtm_result": "FAILURE", "message": "deduct inventory failed"})
			return
		}
		// 判定库存是否为负数，负数失败
		inventory := 0
		query = "select inventory from storages where id=?"
		if err := DB.QueryRow(query, req.Id).Scan(&inventory); err != nil {
			log.Fatalln(err)
		}
		if inventory < 0 {
			c.JSON(http.StatusOK, gin.H{"dtm_result": "FAILURE", "message": "inventory is not enough"})
			return
		}

		c.JSON(http.StatusOK, gin.H{"dtm_result": "SUCCESS"})

	})
	r.POST("/deduct-compensate", func(c *gin.Context) {
		req := &Req{}
		if err := c.BindJSON(req); err != nil {
			log.Fatalln(err)
		}

		// 执行 扣减库存的补偿操作
		query := "update storages set inventory = inventory+? where id = ?"
		if _, err := DB.Exec(query, req.Quantity, req.Id); err != nil {
			c.JSON(http.StatusOK, gin.H{"dtm_result": "FAILURE", "message": "compensate inventory failed"})
			return
		}

		c.JSON(http.StatusOK, gin.H{"dtm_result": "SUCCESS"})
	})

	r.Run(":8082")
}