hostname-service/auth/handlers.go

// Copyright 2024 Florian Beisel
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package auth

import (
	"database/sql"
	"log"
	"net/http"

	"git.beisel.it/florian/hostname-service/db"
	"git.beisel.it/florian/hostname-service/models"
	"golang.org/x/crypto/bcrypt"

	"github.com/gin-gonic/gin"
)

// LoginHandler godoc
//
// @Summary		User login
// @Description	Authenticate user and return JWT token
// @Tags			Authentication
// @Accept			json
// @Produce		json
// @Param			loginCredentials	body		models.LoginCredentials	true	"Login Credentials"
// @Success		200					{object}	models.TokenResponse	"Successfully authenticated, JWT token returned"
// @Failure		400					{object}	models.ErrorResponse	"Invalid request body"
// @Failure		401					{object}	models.ErrorResponse	"Invalid login credentials"
// @Failure		500					{object}	models.ErrorResponse	"Internal server error"
// @Router			/login [post]
func LoginHandler(c *gin.Context) {
	var creds models.LoginCredentials

	// Bind JSON to creds
	if err := c.BindJSON(&creds); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid request body"})
		return
	}

	// Fetch user from the database
	var storedCreds models.User
	err := db.DB.QueryRow("SELECT username, password FROM users WHERE username = ?", creds.Username).Scan(&storedCreds.Username, &storedCreds.Password)
	if err != nil {
		if err == sql.ErrNoRows {
			// User not found
			c.JSON(http.StatusUnauthorized, gin.H{"error": "Invalid login credentials"})
			return
		}
		// Other errors
		c.JSON(http.StatusInternalServerError, gin.H{"error": "Internal server error"})
		return
	}

	// Compare provided password with stored hashed password
	if err := bcrypt.CompareHashAndPassword([]byte(storedCreds.Password), []byte(creds.Password)); err != nil {
		// Password does not match
		c.JSON(http.StatusUnauthorized, gin.H{"error": "Invalid login credentials"})
		return
	}

	// If password matches, generate a JWT token
	token, err := GenerateToken(storedCreds.Username)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to generate token"})
		log.Printf("Error generating token %v", err)
		return
	}

	// Send the token in the response
	c.JSON(http.StatusOK, gin.H{"token": token})
}