main.go

package main

import (
	"log"
	"os"

	"github.com/gin-gonic/gin"
	"github.com/joho/godotenv"
	"github.com/line/line-bot-sdk-go/v7/linebot"
)

func main() {

	err := godotenv.Load()
	if err != nil {
		log.Fatal("Error loading .env file")
	}

	bot, err := linebot.New(os.Getenv("CHANNEL_SECRET"), os.Getenv("CHANNEL_TOKEN"))
	if err != nil {
		log.Fatal(err)
	}

	router := gin.Default()

	router.POST("/callback", func(c *gin.Context) {
		events, err := bot.ParseRequest(c.Request)
		if err != nil {
			if err == linebot.ErrInvalidSignature {
				c.Writer.WriteHeader(400)
			} else {
				c.Writer.WriteHeader(500)
			}
			return
		}

		for _, event := range events {
			if event.Type == linebot.EventTypeMessage {
				switch message := event.Message.(type) {
				case *linebot.TextMessage:
					result := CmdHandler(message.Text)
					if _, err = bot.ReplyMessage(event.ReplyToken, result).Do(); err != nil {
						log.Print(err)
					}

				default:
					const usage = "Try 'help' for more information"
					if _, err = bot.ReplyMessage(event.ReplyToken, linebot.NewTextMessage(usage)).Do(); err != nil {
						log.Print(err)
					}
				}
			}
		}
	})

	port := os.Getenv("PORT")
	if len(port) == 0 {
		port = "8080"
	}
	router.Run(":" + port)
}