package auth

import (
	"fmt"
	"net/http"
	"time"

	"github.com/dgrijalva/jwt-go"
	"github.com/gin-gonic/gin"
)

const (
	CtxRequestHeaderUserId        = "user_id"
	ctxRequestHeaderAuthorization = "Authorization"
	ctxRequestCookieAuthorization = "ak"
	ctxRequestTokenExpired        = "expired"
)

func Auth(authKey string) gin.HandlerFunc {
	return func(ctx *gin.Context) {
		var (
			err error
			tk  = ctx.Request.Header.Get(ctxRequestHeaderAuthorization)
		)

		if tk == "" {
			tk, err = ctx.Cookie(ctxRequestCookieAuthorization)
			if err != nil {
				ctx.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"msg": "auth failed"})
				return
			}

			tk = "Bearer " + tk
		}

		if len(tk) < 8 {
			ctx.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"msg": "auth failed"})
			return
		}

		token, err := jwt.Parse(tk[7:], func(token *jwt.Token) (interface{}, error) {
			if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
				return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
			}

			return []byte(authKey), nil
		})

		if err != nil || !token.Valid {
			ctx.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"msg": "auth failed"})
			return
		}

		mapClaims := token.Claims.(jwt.MapClaims)
		expired := int64(mapClaims[ctxRequestTokenExpired].(float64))
		if expired < time.Now().Unix() {
			// Only cookie is blank value, check token expired
			if _, err := ctx.Cookie(ctxRequestCookieAuthorization); err != nil {
				ctx.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"msg": "auth failed, token timeout"})
				return
			}
		}

		ctx.Set(CtxRequestHeaderUserId, int(mapClaims[CtxRequestHeaderUserId].(float64)))
	}
}