Implement login resolver (#15)

* add sign_up_method to users table

* add session store

* implement login resolver

server/utils/authToken.go

@@ -0,0 +1,39 @@
+package utils
+
+import (
+	"time"
+
+	"github.com/golang-jwt/jwt"
+	"github.com/yauthdev/yauth/server/constants"
+	"github.com/yauthdev/yauth/server/enum"
+)
+
+type UserAuthInfo struct {
+	Email string `json:"email"`
+	ID    string `json:"id"`
+}
+
+type UserAuthClaim struct {
+	*jwt.StandardClaims
+	TokenType string `json:"token_type"`
+	UserAuthInfo
+}
+
+func CreateAuthToken(user UserAuthInfo, tokenType enum.TokenType) (string, error) {
+	t := jwt.New(jwt.GetSigningMethod(constants.JWT_TYPE))
+	expiryBound := time.Hour
+	if tokenType == enum.RefreshToken {
+		// expires in 90 days
+		expiryBound = time.Hour * 2160
+	}
+
+	t.Claims = &UserAuthClaim{
+		&jwt.StandardClaims{
+			ExpiresAt: time.Now().Add(expiryBound).Unix(),
+		},
+		tokenType.String(),
+		user,
+	}
+
+	return t.SignedString([]byte(constants.JWT_SECRET))
+}