Added Email Auth himanshusharma89#27

Author: puruganda

lib/services/auth_service.dart

@@ -1,7 +1,11 @@
 import 'package:google_sign_in/google_sign_in.dart';
 import 'package:firebase_auth/firebase_auth.dart';
+import 'package:retro_shopping/helpers/constants.dart';
+import 'package:flutter/material.dart';
 
 class AuthenticationService {
+  final FirebaseAuth _auth = FirebaseAuth.instance;
+
   static Future<String> signInWithGoogle() async {
     final GoogleSignInAccount googleSignInAccount =
         await GoogleSignIn().signIn();
@@ -27,4 +31,102 @@ class AuthenticationService {
   static Future<void> signOutGoogle() async {
     await GoogleSignIn().signOut();
   }
+
+  String userEmailValidation(String value, String errorMessage) {
+    if (value.isEmpty) {
+      return 'Required';
+    } else if (errorMessage != null) {
+      if (!errorMessage.contains('Password') ||
+          errorMessage.contains('Invalid Request')) {
+        return errorMessage;
+      }
+      return null;
+    }
+    return null;
+  }
+
+  String userPasswordValidation(String value, String errorMessage) {
+    if (value.isEmpty) {
+      return 'Required';
+    } else if (errorMessage != null) {
+      if (errorMessage.contains('Password') ||
+          errorMessage.contains('Invalid Request')) {
+        return errorMessage;
+      }
+      return null;
+    }
+    return null;
+  }
+
+  String userConfirmPasswordValidation(
+      String value, String password, String confirmPassword) {
+    if (value.isEmpty) {
+      return 'Required';
+    } else if (password != confirmPassword) {
+      return 'Passwords Do Not Match';
+    }
+    return null;
+  }
+
+  Future<String> userSignUp(String errorText, BuildContext context,
+      String email, String password) async {
+    String errorTemp = errorText;
+    try {
+      final UserCredential newUser = await _auth.createUserWithEmailAndPassword(
+          email: email, password: password);
+      if (newUser != null) {
+        Navigator.of(context)
+            .pushReplacementNamed(RouteConstant.DASHBOARD_SCREEN);
+      }
+    } catch (e) {
+      if (e.toString().contains('invalid-email')) {
+        errorTemp = 'Invalid Email';
+      } else if (e.toString().contains('email-already-in-use')) {
+        errorTemp = 'User Already Exists';
+      } else if (e.toString().contains('weak-password')) {
+        errorTemp = 'Password Too Short';
+      } else {
+        errorTemp = 'Invalid Request';
+      }
+      return errorTemp;
+    }
+    return null;
+  }
+
+  Future<String> userLogin(String errorText, BuildContext context, String email,
+      String password) async {
+    String errorTemp = errorText;
+    try {
+      final UserCredential existingUser = await _auth
+          .signInWithEmailAndPassword(email: email, password: password);
+      if (existingUser != null) {
+        Navigator.of(context).pushReplacementNamed(
+          RouteConstant.DASHBOARD_SCREEN,
+        );
+      }
+    } catch (e) {
+      if (e.toString().contains('invalid-email')) {
+        errorTemp = 'Invalid Email';
+      } else if (e.toString().contains('user-not-found')) {
+        errorTemp = 'User Not Found';
+      } else if (e.toString().contains('wrong-password')) {
+        errorTemp = 'Incorrect Password';
+      } else {
+        errorTemp = 'Invalid Request';
+      }
+      return errorTemp;
+    }
+    return null;
+  }
+
+  Future<void> userSignOut(BuildContext context) async {
+    final User user = _auth.currentUser;
+    if (user != null) {
+      await _auth.signOut();
+      Navigator.of(context).pushNamedAndRemoveUntil(
+        RouteConstant.LOGIN_SCREEN,
+        (Route<dynamic> route) => false,
+      );
+    }
+  }
 }