Added signin route in backend

backend/src/services/user.service.js

@@ -1,6 +1,7 @@
-import { SALT } from "../config/veriables.js";
-import { createUser } from "../repositories/user.repo.js";
+import { JWT_PRIVATE, SALT } from "../config/veriables.js";
+import { createUser, findUserByEmail } from "../repositories/user.repo.js";
 import bcrypt from "bcrypt";
+import jwt from "jsonwebtoken";
 
 export async function signupService(username, email, password) {
   try {
@@ -24,3 +25,35 @@ export async function signupService(username, email, password) {
     }
   }
 }
+
+export async function signinService(email, password) {
+  try{
+    if (email.trim() == "" || password.trim() == "") {
+      throw {
+        statusCode: 400,
+        message: "All fields are required",
+      };
+    }
+
+    const user = await findUserByEmail(email);
+    if (!user){
+      throw {
+        statusCode : 404,
+        message : "User not found."
+      }
+    }
+    if (!bcrypt.compareSync(password, user?.password)){
+      throw {
+        statusCode : 401,
+        message : "Password isn't correct."
+      }
+    }
+
+    const token = jwt.sign({id : user._id}, JWT_PRIVATE);
+    const {password:pass, ...userData} = user._doc;
+    return {token, userData};
+  }
+  catch(err){
+    throw err;
+  }
+}