1 files changed, 153 insertions, 0 deletions
diff --git a/user/validate.go b/user/validate.go
new file mode 100644
index 0000000..b51757f
--- /dev/null
+++ b/user/validate.go
@@ -0,0 +1,153 @@
+/* OpenBills-server - Server for libre billing software OpenBills-web
+ * Copyright (C) 2022  Vidhu Kant Sharma <vidhukant@vidhukant.xyz>
+
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package user
+
+import (
+	"context"
+	"strings"
+	"net/mail"
+	"net/http"
+	"log"
+	"github.com/gin-gonic/gin"
+	"go.mongodb.org/mongo-driver/mongo"
+	"go.mongodb.org/mongo-driver/bson"
+	"errors"
+)
+
+var (
+	errUsernameTaken = errors.New("username is taken")
+	errUsernameTooShort = errors.New("username is too short")
+	errUsernameInvalid = errors.New("invalid username")
+	errEmailTaken = errors.New("email is taken")
+	errEmailInvalid = errors.New("email is invalid")
+	errPasswordTooShort = errors.New("password is too short")
+)
+
+func isUsernameTaken(username string) error {
+	var x User
+	err := db.FindOne(context.TODO(), bson.M{"UserName": username}).Decode(&x)
+	if err != nil {
+		if err == mongo.ErrNoDocuments {
+			return nil
+		} else {
+			return err
+		}
+	} else {
+		return errUsernameTaken
+	}
+	return nil
+}
+
+func isEmailTaken(email string) error {
+	var x User
+	err := db.FindOne(context.TODO(), bson.M{"Email": email}).Decode(&x)
+	if err != nil {
+		if err == mongo.ErrNoDocuments {
+			return nil
+		} else {
+			return err
+		}
+	} else {
+		return errEmailTaken
+	}
+	return nil
+}
+
+func validateUsername(username string) error {
+	username = strings.Trim(username, " ")
+
+	if len(username) < 2 {
+		return errUsernameTooShort
+	}
+
+	if strings.Contains(username, " ") {
+		return errUsernameInvalid
+	}
+
+	return isUsernameTaken(username)
+}
+
+func validateEmail(email string) error {
+	email = strings.Trim(email, " ")
+
+	// verify if string is valid email
+	_, err := mail.ParseAddress(email)
+	if err != nil {
+		return errEmailInvalid
+	}
+
+	return isEmailTaken(email)
+}
+
+func validatePassword(password string) error {
+	// TODO: load password length from config
+	if len(password) < 12 {
+		return errPasswordTooShort
+	}
+
+	return nil
+}
+
+func validateMiddleware() gin.HandlerFunc {
+	return func(ctx *gin.Context) {
+		var u User
+		ctx.BindJSON(&u)
+
+		// validate username
+		isUsernameValid := validateUsername(u.UserName)
+		switch isUsernameValid {
+		case nil:
+			break;
+		case errUsernameTooShort, errUsernameInvalid:
+			ctx.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"error": isUsernameValid.Error()})
+		case errUsernameTaken:
+			ctx.AbortWithStatusJSON(http.StatusConflict, gin.H{"error": isUsernameValid.Error()})
+		default:
+		    log.Printf("Error while creating new user '%s': %s", u.UserName, isUsernameValid.Error())
+		    ctx.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"error": "internal server error (cannot create user)"})
+		}
+
+		// validate email
+		isEmailValid := validateEmail(u.Email)
+		switch isEmailValid {
+		case nil:
+			break;
+		case errEmailInvalid:
+			ctx.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"error": isEmailValid.Error()})
+		case errEmailTaken:
+			ctx.AbortWithStatusJSON(http.StatusConflict, gin.H{"error": isEmailValid.Error()})
+		default:
+		    log.Printf("Error while creating new user '%s': %s", u.UserName, isEmailValid.Error())
+		    ctx.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"error": "internal server error (cannot create user)"})
+		}
+
+		// validate password
+		isPasswordValid := validatePassword(u.Password)
+		switch isPasswordValid {
+		case nil:
+			break;
+		case errPasswordTooShort:
+			ctx.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"error": isPasswordValid.Error()})
+		default:
+		    ctx.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"error": "internal server error (cannot create user)"})
+		    log.Printf("Error while creating new user '%s': %s", u.UserName, isPasswordValid.Error())
+		}
+
+		ctx.Set("user", u)
+	}
+}