Added auth service

FrontEnd/lib/services/auth_service.dart

+import 'package:firebase_auth/firebase_auth.dart';
+import 'package:flutter/material.dart';
+import 'package:govimithura/models/auth_model.dart';
+import 'package:govimithura/models/error_model.dart';
+
+class AuthService {
+  static final FirebaseAuth _auth = FirebaseAuth.instance;
+
+  Future<bool> login(AuthModel authModel) async {
+    try {
+      UserCredential userCred = await _auth
+          .signInWithEmailAndPassword(
+              email: authModel.email, password: authModel.password)
+          .then((value) => value);
+
+      return userCred.user?.uid != null;
+    } on FirebaseAuthException catch (e) {
+      if (e.code == 'user-not-found') {
+        ErrorModel.errorMessage = 'No user found for this email.';
+      } else if (e.code == 'wrong-password') {
+        ErrorModel.errorMessage = 'Wrong password provided for this user.';
+      } else {
+        ErrorModel.errorMessage = e.message ?? '';
+      }
+    } on Exception catch (e) {
+      ErrorModel.errorMessage = e.toString();
+    }
+    return false;
+  }
+
+  Future<AuthModel?> register(AuthModel authModel) async {
+    try {
+      await _auth
+          .createUserWithEmailAndPassword(
+              email: authModel.email, password: authModel.password)
+          .then((value) => {
+                debugPrint("User registered ${value.user!.uid}"),
+                authModel.uid = value.user!.uid,
+              });
+      return authModel;
+    } on FirebaseAuthException catch (e) {
+      if (e.code == 'email-already-in-use') {
+        ErrorModel.errorMessage = 'The account already exists for this email.';
+      } else if (e.code == 'invalid-email') {
+        ErrorModel.errorMessage = 'Invalid email address.';
+      } else {
+        ErrorModel.errorMessage = e.message ?? '';
+      }
+      return null;
+    } on Exception catch (e) {
+      ErrorModel.errorMessage = e.toString();
+      return null;
+    }
+  }
+
+  bool isLoggedIn() {
+    _auth.userChanges().listen((User? user) {
+      if (user == null) {
+        debugPrint('User is currently signed out!');
+      } else {
+        debugPrint('User is signed in!');
+      }
+    });
+    return _auth.currentUser != null;
+  }
+
+  Future<void> signOut() async {
+    await _auth.signOut();
+  }
+
+  static Future<void>? forgetPassword(String email) async {
+    try {
+      return await _auth.sendPasswordResetEmail(email: email);
+    } on FirebaseAuthException catch (e) {
+      ErrorModel.errorMessage = e.message ?? '';
+      return;
+    } on Exception catch (e) {
+      ErrorModel.errorMessage = e.toString();
+      return;
+    }
+  }
+}