From c16110d0b57a37ad6aeb986ef22848b1ca2275c0 Mon Sep 17 00:00:00 2001
From: Mehrdad Shirvani <mehrdadsh0901@gmail.com>
Date: Mon, 2 Jun 2025 10:35:28 +0330
Subject: [PATCH] vault backup: 2025-06-02 10:35:28

---
 .../Session07/Session07 Additional Info.md    | 785 ++++++++++++++++++
 .../Session07/Session07 Backend.md            | 527 ++++++++++++
 .../Session07/Session07 Frontend.md           | 304 +++++++
 .../Session07/Session07.md                    |  82 --
 4 files changed, 1616 insertions(+), 82 deletions(-)
 create mode 100644 02_ProjectOrientedSessions/Session07/Session07 Additional Info.md
 create mode 100644 02_ProjectOrientedSessions/Session07/Session07 Backend.md
 create mode 100644 02_ProjectOrientedSessions/Session07/Session07 Frontend.md
 delete mode 100644 02_ProjectOrientedSessions/Session07/Session07.md

diff --git a/02_ProjectOrientedSessions/Session07/Session07 Additional Info.md b/02_ProjectOrientedSessions/Session07/Session07 Additional Info.md
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+
+# AUTHENTICATION METHODS FOR ASP.NET CORE WEB API
+
+### 1. **JWT (JSON Web Token) Authentication**
+
+**Most common for SPAs (like your React frontend)**
+
+- ✅ **Stateless**: No session stored on the server.
+    
+- 🔐 **Token structure**: Header + Payload (including roles) + Signature.
+    
+- 🎯 Good for: SPAs, mobile apps, APIs.
+    
+- 📦 Libraries: `Microsoft.AspNetCore.Authentication.JwtBearer`.
+    
+
+**Setup Highlights:**
+
+- Client sends credentials → API generates token with user roles → Client stores token → Client sends token in `Authorization` header (`Bearer <token>`).
+    
+- Server verifies signature and extracts user identity and roles from the token.
+    
+
+**Role support**:
+
+- You embed roles inside the JWT (`"roles": ["Admin", "User"]`).
+    
+- Use `[Authorize(Roles = "Admin")]`.
+    
+
+---
+
+### 2. **Cookie-Based Authentication**
+
+**Traditional approach for server-rendered apps (not ideal for APIs)**
+
+- 🛑 **Not recommended for APIs** due to CSRF vulnerability and session overhead.
+    
+- 🗂 Stores session identifier in browser cookie.
+    
+- Useful when using ASP.NET Core MVC or Razor Pages (not Web API).
+    
+
+---
+
+### 3. **OAuth2 + OpenID Connect (OIDC)**
+
+**Best for federated login, single sign-on (SSO), or external providers**
+
+- 🔗 Integrates with Identity Providers (IDPs) like:
+    
+    - Azure AD
+        
+    - Google, Facebook, GitHub
+        
+    - Auth0, Okta, Duende IdentityServer
+        
+- 📦 Library: `Microsoft.AspNetCore.Authentication.OpenIdConnect`
+    
+- Uses **access tokens** (JWT) issued by an authority.
+    
+
+**Role support**:
+
+- Roles/claims provided by the Identity Provider.
+    
+- You map these claims to roles in the API.
+    
+- `[Authorize(Roles = "Admin")]` still works.
+    
+
+---
+
+### 4. **API Key Authentication**
+
+**Lightweight alternative (not ideal for user-based roles)**
+
+- Client includes a static API key in headers or query string.
+    
+- 🔐 No user context → ❌ no role-based support unless you map API keys to roles in a custom way.
+    
+- 🔧 Implemented manually in middleware or filters.
+    
+
+---
+
+### 5. **Basic Authentication**
+
+- User provides `username:password` in Base64 via `Authorization` header.
+    
+- ❌ Insecure unless used with HTTPS.
+    
+- ⚠️ Rarely used anymore — not good for role-based systems or production apps.
+    
+
+---
+
+### 6. **ASP.NET Core Identity**
+
+**Full-featured user management system (often combined with JWT)**
+
+- ✅ Provides login, registration, role management, password hashing, etc.
+    
+- 🎯 Good choice if you want to **own the user system** and **manage roles** yourself.
+    
+- Can be used with:
+    
+    - JWT tokens (custom token generation)
+        
+    - Cookie auth (not for APIs)
+        
+- 🔧 Use `UserManager`, `RoleManager`.
+    
+
+**Example**: Use Identity for creating users and roles, then issue JWTs on login.
+
+---
+
+
+## Summary Table
+
+|Method|Stateless|Token-Based|Role Support|Ideal For|
+|---|---|---|---|---|
+|JWT Authentication|✅|✅|✅|APIs, SPAs (React, etc.)|
+|Cookie Authentication|❌|❌|✅|Server-side apps only|
+|OAuth2 + OpenID Connect|✅|✅|✅|External login, SSO, enterprise|
+|API Key|✅|❌|❌ (manual)|Simple apps, service-to-service|
+|Basic Auth|✅|❌|❌ (manual)|Very basic use, not recommended|
+|ASP.NET Core Identity|❌|Optional|✅|User/Role management|
+
+---
+
+# Web Security and JWT Terms
+
+
+### 🧨 **CSP (Content Security Policy)**
+
+**Definition:**  
+A **browser security mechanism** that helps prevent **XSS attacks** by controlling which sources the browser can load content from.
+
+**Example Usage:**  
+It can prevent JavaScript from running unless it's from a trusted source.
+
+**Example CSP header:**
+
+```http
+Content-Security-Policy: default-src 'self'; script-src 'self' https://trustedscripts.example.com
+```
+
+---
+
+### 💥 **XSS (Cross-Site Scripting)**
+
+**Definition:**  
+A vulnerability where an attacker **injects malicious JavaScript** into a web page that gets executed in a user’s browser.
+
+**Why It Matters for JWT:**  
+If you store JWTs in `localStorage`, and your app is vulnerable to XSS, the attacker can steal the token and impersonate the user.
+
+**Prevention:**
+
+- Never trust user input (sanitize!)
+    
+- Use **CSP headers**
+    
+- Avoid inline scripts
+    
+- Use frameworks that auto-escape HTML (like React, Razor)
+    
+
+---
+
+### 📦 **Payload (in JWT)**
+
+**Definition:**  
+The **middle part** of a JWT. It contains the **claims** (user data, permissions, roles, etc.) in a **Base64-encoded JSON** format.
+
+**Example:**
+
+```json
+{
+  "sub": "1234567890",
+  "name": "John Doe",
+  "role": "Admin",
+  "exp": 1716850984
+}
+```
+
+⚠️ **Note:** Payload is **not encrypted**, just encoded — anyone can read it, but not modify it without invalidating the signature.
+
+---
+
+### ✍️ **Signature (in JWT)**
+
+**Definition:**  
+The **third part** of the token. It's a cryptographic hash (HMAC or RSA/ECDSA) of the header and payload, signed with a **secret** or private key.
+
+**Purpose:**  
+To verify that the token **hasn’t been tampered with**.
+
+**Structure:**
+
+```
+JWT = base64(header) + '.' + base64(payload) + '.' + signature
+```
+
+Only the server (with the secret key) can validate the signature.
+
+---
+
+### 🦠 **CSRF (Cross-Site Request Forgery)**
+
+**Definition:**  
+A vulnerability where an attacker tricks a user’s **browser** (with a valid session/cookie) into making an unwanted request to your site **without the user’s knowledge**.
+
+**Example:**  
+If you're logged in and visit a malicious site, that site may submit a POST request using your cookies to perform actions on your behalf.
+
+**Why It Matters:**
+
+- If you store JWTs in **HttpOnly cookies**, you must guard against CSRF.
+    
+
+**Defense:**
+
+- Use `SameSite=Strict` cookies
+    
+- Use anti-CSRF tokens
+    
+- Prefer `Authorization` header with tokens (doesn’t auto-send like cookies)
+    
+
+---
+
+### 🧠 **Session Overhead**
+
+**Definition:**  
+The **memory and server resource cost** of maintaining a session for each logged-in user on the server.
+
+**Why It Matters:**
+
+- Traditional **cookie-based auth** stores session info on the server.
+    
+- With JWT, the session is **stateless** (no server memory), reducing overhead and scaling better.
+    
+
+---
+
+## 🔑 **Authentication Ecosystem Concepts**
+
+---
+
+### 🌐 **Federated Login**
+
+**Definition:**  
+Users log in to your application using **another trusted identity provider** (IdP), such as:
+
+- Google
+    
+- Facebook
+    
+- Microsoft
+    
+- GitHub
+    
+
+You delegate authentication to the third party and just receive user info (often as a JWT or OpenID Connect token).
+
+**Protocol Examples:**
+
+- OAuth2
+    
+- OpenID Connect
+    
+
+---
+
+### 🔁 **SSO (Single Sign-On)**
+
+**Definition:**  
+A user logs in **once** and gains access to **multiple systems or applications** without logging in again.
+
+**Common in Enterprises**:
+
+- Logging into one dashboard gives you access to HR system, email, file storage, etc.
+    
+
+**How It Works:**
+
+- A **central identity provider (IdP)** issues tokens
+    
+- Applications **trust the token** and skip login
+    
+- Often uses **OAuth2**, **OpenID Connect**, or **SAML**
+    
+
+---
+
+## 🔄 Summary Table
+
+|Term|Meaning|
+|---|---|
+|**CSP**|Restricts sources of scripts/styles to prevent XSS|
+|**XSS**|Injected JavaScript that steals data like JWT tokens|
+|**JWT Payload**|JSON with user claims (readable but not secure on its own)|
+|**JWT Signature**|Proves the token is untampered (signed by server)|
+|**CSRF**|Unauthorized actions using authenticated user's browser/session|
+|**Session Overhead**|Cost of storing user sessions in memory on the server|
+|**Federated Login**|Login using a third-party identity provider (e.g., Google)|
+|**SSO**|One login grants access to multiple trusted systems|
+
+
+# ASP.NET Identity vs JWT Authentication
+
+---
+
+### ✅ **What is ASP.NET Identity?**
+
+**ASP.NET Identity** is a full **membership system** that:
+
+- Manages users, roles, passwords, claims, tokens, and external logins.
+    
+- Stores user data in a **database** (usually using Entity Framework).
+    
+- Works well with **cookie-based authentication** by default.
+    
+- Handles login, logout, registration, password hashing, email confirmation, two-factor auth, etc.
+    
+
+**Default storage:** SQL Server (via Entity Framework)
+
+---
+
+### 🔑 **How Authentication Works in ASP.NET Identity (Cookie-Based)**
+
+1. **Login request**: The user submits a form with username/password.
+    
+2. **Server validates** the credentials using ASP.NET Identity.
+    
+3. If valid, the server issues a **cookie** (with a session token).
+    
+4. The browser stores this **authentication cookie**.
+    
+5. For future requests, the browser **automatically sends the cookie**.
+    
+6. The server validates the cookie (and reads the user session from memory or database).
+    
+
+✅ **Stateful**  
+❌ Doesn't scale well for large APIs unless you add external session storage (like Redis).
+
+---
+
+### 🔐 What is JWT Authentication?
+
+JWT Authentication is:
+
+- **Stateless**.
+    
+- Based on tokens — not sessions.
+    
+- Works well for APIs and SPAs/mobile apps.
+    
+
+#### Flow:
+
+1. **User logs in**, and if credentials are valid...
+    
+2. Server **creates a JWT** containing user info (e.g., roles).
+    
+3. Server **signs the token** and sends it to the client.
+    
+4. Client stores it (e.g., in localStorage or cookies).
+    
+5. On every request, the client sends the JWT in the `Authorization` header.
+    
+6. Server **verifies the JWT signature** using a secret or key.
+    
+7. If valid → allow access (no server-side session needed).
+    
+
+✅ **Stateless**  
+✅ Scales easily  
+✅ Good for distributed APIs
+
+---
+
+### 📊 Comparison Table
+
+|Feature|ASP.NET Identity (Cookie)|JWT Authentication (Token-Based)|
+|---|---|---|
+|**Stateful/Stateless**|Stateful|Stateless|
+|**Storage**|Cookie on client, session on server|Token on client only|
+|**Default Transport**|Cookie (auto-sent by browser)|Authorization header (manual send)|
+|**Built-in Support**|ASP.NET Identity (UI + EF Core)|ASP.NET Core + Manual JWT setup|
+|**Scalability**|Limited (server stores session)|High (no session to manage)|
+|**Security**|Cookie CSRF risk|XSS risk if stored in JS-accessible storage|
+|**Use Case**|Web apps with UI (MVC, Razor)|APIs, SPAs, mobile apps|
+|**External login support**|Built-in|Needs integration|
+|**Token expiration**|Server-controlled session|Token has expiration embedded|
+
+---
+
+### 🚨 Statelessness — What Does It Mean?
+
+- **Stateful Authentication**: Server **stores a session** (usually in memory or a database) for each user. The client just stores a cookie with a session ID.
+    
+    - When user logs in, server keeps a record of that.
+        
+    - Logout → delete session.
+        
+- **Stateless Authentication** (JWT):
+    
+    - Server **does not remember anything**.
+        
+    - JWT has all info about the user in itself (claims, roles, expiry).
+        
+    - Logout = just delete token on client side (server has no "memory").
+        
+
+⚠️ **You can't "force logout" someone server-side in pure JWT unless you blacklist tokens manually** (or rotate secrets).
+
+---
+
+### 💡 Can You Use ASP.NET Identity with JWT?
+
+Yes — ASP.NET Identity can be configured to:
+
+- Authenticate user credentials
+    
+- Then issue a **JWT** instead of using a cookie
+    
+- This way, you get:
+    
+    - ASP.NET Identity’s user management
+        
+    - JWT’s **stateless** API authentication
+        
+
+This is often used in **hybrid apps**:
+
+- Use Identity for registration/login
+    
+- Use JWT for frontend and mobile API calls
+    
+
+
+# What does `null!` mean?
+
+It's a **null-forgiving operator**.
+
+When you write:
+
+```csharp
+string? maybeNull = null;
+string definitelyNotNull = null!;  // ← This tells the compiler: “Trust me, it’s not null.”
+```
+
+You're telling the compiler:
+
+> _“I know this is technically null, but treat it as non-null and don’t warn me.”_
+
+---
+
+### 🧩 Why is this needed?
+
+C# 8 introduced **nullable reference types**, where the compiler gives warnings if you assign or use `null` where it's not safe.
+
+For example:
+
+```csharp
+string name = null; // Warning: assigning null to non-nullable reference
+```
+
+To silence the warning, you can use `null!`:
+
+```csharp
+string name = null!; // No warning
+```
+
+But this is **your responsibility**: the compiler **assumes you're guaranteeing** that it won’t cause a `NullReferenceException`.
+
+---
+
+### ⚠️ When to use `null!`?
+
+Use it **sparingly and carefully**, only when:
+
+- You know an object **will be initialized later**.
+    
+- You’re working with **ORMs like EF Core** where properties are set **after construction**.
+    
+- You're dealing with **dependency injection** and the value is assigned **automatically later**.
+    
+
+#### Example:
+
+```csharp
+public class Account
+{
+    public string PhoneNumber { get; set; } = null!; // EF will populate it
+}
+```
+
+---
+
+### ✅ Summary
+
+|Expression|Meaning|
+|---|---|
+|`null!`|"This is null, but treat it as if it's non-null (trust me)."|
+|Use case|Avoiding compiler warnings for nullable reference types|
+|Risk|Can lead to runtime `NullReferenceException` if used incorrectly|
+
+---
+
+Let me know if you want help turning on/off nullable reference types or dealing with EF Core model warnings.
+
+
+# What is a JWT Generator?
+
+A **JWT Generator** is a class or service in your backend that:
+
+1. **Generates** a signed JWT (JSON Web Token) when a user logs in.
+    
+2. **Encodes** the user's identity, roles, and other claims.
+    
+3. **Signs** the token with a secret or private key so it can be validated later.
+    
+
+---
+
+## 🔧 Structure of a JWT
+
+A JWT has 3 parts:
+
+```plaintext
+xxxxx.yyyyy.zzzzz
+```
+
+1. **Header** (Base64-encoded JSON):
+    
+    ```json
+    {
+      "alg": "HS256",
+      "typ": "JWT"
+    }
+    ```
+    
+2. **Payload** (Base64-encoded JSON):  
+    Contains user data and claims (e.g., user ID, role, expiry).
+    
+    ```json
+    {
+      "sub": "userId123",
+      "phone": "0930xxx",
+      "role": "Admin",
+      "exp": 1717502800
+    }
+    ```
+    
+3. **Signature**:  
+    HMACSHA256(header + "." + payload, secret key)
+    
+
+---
+
+## ✅ What Goes into the Payload?
+
+Include things you want to check _without querying the DB every time_:
+
+- `sub` (Subject – usually user ID)
+    
+- `phone` or username
+    
+- `role` (e.g., "Admin", "User")
+    
+- `exp` (expiration timestamp)
+    
+- Any custom claim, like `companyId`, `verified`, etc.
+    
+
+---
+
+## 🔐 Signature
+
+The **signature ensures** that the token hasn't been tampered with. If the signature doesn't match (due to modification or incorrect secret), the token is invalid.
+
+---
+
+## 🧱 Example: JWT Generator in ASP.NET Core
+
+```csharp
+public interface IJwtGenerator
+{
+    string GenerateToken(Account account);
+}
+```
+
+```csharp
+public class JwtGenerator : IJwtGenerator
+{
+    private readonly IConfiguration _config;
+
+    public JwtGenerator(IConfiguration config)
+    {
+        _config = config;
+    }
+
+    public string GenerateToken(Account account)
+    {
+        var claims = new[]
+        {
+            new Claim(JwtRegisteredClaimNames.Sub, account.Id.ToString()),
+            new Claim(JwtRegisteredClaimNames.PhoneNumber, account.PhoneNumber),
+            new Claim(ClaimTypes.Role, account.Role),
+        };
+
+        var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_config["Jwt:Key"]!));
+        var creds = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);
+
+        var token = new JwtSecurityToken(
+            issuer: _config["Jwt:Issuer"],
+            audience: _config["Jwt:Audience"],
+            claims: claims,
+            expires: DateTime.UtcNow.AddHours(2),
+            signingCredentials: creds
+        );
+
+        return new JwtSecurityTokenHandler().WriteToken(token);
+    }
+}
+```
+
+---
+
+## 🛠 Configuration in `appsettings.json`
+
+```json
+"Jwt": {
+  "Key": "YourSuperSecureSecretKey123!",
+  "Issuer": "YourAppName",
+  "Audience": "YourFrontendApp"
+}
+```
+
+---
+
+## 🧪 Token Validation
+
+When the frontend sends this token on requests (via `Authorization: Bearer <token>` header), ASP.NET Core automatically validates:
+
+- Signature (using the same secret)
+    
+- Expiry (`exp`)
+    
+- Audience, Issuer
+    
+- Claims (like role)
+    
+
+This is done via `JwtBearer` middleware.
+
+---
+
+## 🔐 Roles in the Token?
+
+Yes, you can (and should) include user roles. The backend will **automatically enforce** `[Authorize(Roles = "Admin")]` using that claim.
+
+But:
+
+- Don't rely **only** on frontend logic — always **protect endpoints** on the backend too.
+    
+- Frontend can use roles to **hide UI elements**, but not for enforcing access.
+    
+
+---
+
+## 🤔 Should You Encrypt the Token?
+
+No, standard practice is:
+
+- Don't encrypt JWTs — they’re just base64-encoded.
+    
+- **Don’t put sensitive data** inside.
+    
+- Sign them to prevent tampering.
+    
+- Secure the token in frontend (e.g., HttpOnly cookies or `localStorage` with care).
+    
+
+---
+
+## ✅ Summary of Responsibilities
+
+|Responsibility|Backend (JWT Generator)|Frontend|
+|---|---|---|
+|Token generation|✅|❌|
+|Storing token|❌|✅ (localStorage / cookie)|
+|Sending token|❌|✅ (Authorization header)|
+|Token validation|✅ (`JwtBearer`)|❌|
+|Role enforcement|✅ (`[Authorize]`)|✅ (UI-level only)|
+
+
+
+---
+
+# How multiple roles in JWT claims work
+
+- The JWT claims are basically a list of key-value pairs.
+    
+- For roles, the key is usually `"role"` or `ClaimTypes.Role`.
+    
+- You add **multiple claims with the same key** — one for each role.
+    
+
+**Example:**
+
+```json
+{
+  "sub": "1234567890",
+  "phone_number": "123456789",
+  "role": "Admin",
+  "role": "Editor",
+  "role": "User",
+  "exp": 1711600000
+}
+```
+
+- When the token is created, it contains multiple `"role"` entries.
+    
+- On the backend, ASP.NET Core `ClaimsPrincipal` reads all of them, so `[Authorize(Roles="Admin,Editor")]` works by checking if **any** of the roles match.
+    
+
+---
+
+### How frontend handles multiple roles in the JWT
+
+1. The frontend receives the JWT (usually after login).
+    
+2. It **decodes** the JWT payload (using a library like `jwt-decode`).
+    
+3. It extracts the roles as an **array of strings**.
+    
+
+Example in React using `jwt-decode`:
+
+```js
+import jwtDecode from 'jwt-decode';
+
+const token = localStorage.getItem('token');
+const decoded = jwtDecode(token);
+const roles = decoded.role; // roles is usually an array if multiple roles exist
+
+console.log(roles); // ["Admin", "Editor", "User"]
+```
+
+4. The frontend can then use these roles to:
+    
+    - Conditionally render UI components or routes.
+        
+    - Show/hide buttons, pages, or features.
+        
+
+---
+
+### Important security note for frontend roles
+
+- The frontend can **only do UI-level checks** based on roles.
+    
+- **Never trust frontend role checks to secure data or APIs.**
+    
+- The backend must always verify the token and roles via `[Authorize]` attributes or middleware.
+    
+
+---
+
+### Summary
+
+|Step|How it works|
+|---|---|
+|JWT creation|Multiple `"role"` claims added to token|
+|Backend authorization|Validates token and checks if user has required roles|
+|Frontend decoding|Extracts `role` claim(s) as array of strings|
+|Frontend UI control|Shows or hides content based on roles|
diff --git a/02_ProjectOrientedSessions/Session07/Session07 Backend.md b/02_ProjectOrientedSessions/Session07/Session07 Backend.md
new file mode 100644
index 0000000..ecccd94
--- /dev/null
+++ b/02_ProjectOrientedSessions/Session07/Session07 Backend.md	
@@ -0,0 +1,527 @@
+
+# Add a field in Database
+- [ ] Add `User` field in `Roles` table
+
+# Branching
+ - [ ] Create the feature/authentication branch based on develop
+
+# Adjusting Account and Configurations 
+
+- [ ] Add navigation property for `AccountRoles` in Account
+```c#
+public virtual ICollection<AccountRole> AccountRoles { get; set; }
+```
+
+- [ ] Add navigation properties for Account and Role in `AccountRole`
+```C#
+public virtual Role Role { get; set; }
+public virtual Account Account{ get; set; }
+```
+
+- [ ] Update the entity configuration to reflect relationship mappings:
+```c#
+builder.HasOne<Account>(ar => ar.Account)
+    .WithMany(a => a.AccountRoles)
+    .HasForeignKey(ar => ar.AccountId)
+    .OnDelete(DeleteBehavior.Restrict);
+
+builder.HasOne<Role>(ar => ar.Role)
+    .WithMany()
+    .HasForeignKey(ar => ar.RoleId)
+    .OnDelete(DeleteBehavior.Restrict);
+```
+
+# Creating DTOs
+📂 Suggested Folder: ApplicationLayer/DTOs/[RelatedFolder]
+## AccountDto
+- [ ] Create `AccountDto` to expose relevant account information:
+```c#
+public class AccountDto
+{
+    public long Id { get; set; }
+    public required string PhoneNumber { get; set; }
+    public required string Password { set; get; }
+    public string? Email { get; set; }
+    public long? PersonId { get; set; }
+    public List<string> Roles { get; set; }
+}
+```
+## AuthResponseDto
+- [ ] Define a DTO for authentication responses:
+```c#
+public class AuthResponseDto
+{
+    public long Id { get; set; }
+    public string Token { get; set; } = null!;
+    public string PhoneNumber { get; set; } = null!;
+    public List<string> Roles { get; set; }
+}
+```
+- [ ] Define a DTO for login requests:
+```c#
+public class LoginRequestDto
+{
+    public string PhoneNumber { get; set; } = null!;
+    public string Password { get; set; } = null!;
+}
+```
+## RegisterRequestDto
+- [ ] Define a DTO for registration with validation attributes:
+```c#
+public class RegisterRequestDto
+{
+    [Required(ErrorMessage = "Phone number is required.")]
+    [Phone(ErrorMessage = "Phone number format is invalid.")]
+    public required string PhoneNumber { get; set; }
+
+    [Required(ErrorMessage = "Password is required.")]
+    [MinLength(6, ErrorMessage = "Password must be at least 6 characters long.")]
+    public required string Password { get; set; }
+
+    [Compare("Password", ErrorMessage = "Passwords do not match.")]
+    public required string ConfirmPassword { get; set; }
+}
+```
+
+
+### 🔹 **1. What do the annotations like `[Required]`, `[Phone]`, `[MinLength]`, `[Compare]` on the DTO do?**
+
+These are **Data Annotations** from `System.ComponentModel.DataAnnotations`.
+
+They’re used by:
+
+- The ASP.NET Core `[ApiController]` attribute
+    
+- **Model binding & automatic validation**
+    
+
+**What happens:**  
+If your controller is marked with `[ApiController]`, ASP.NET Core will **automatically validate** the DTO against these annotations **before entering your action method**.
+
+Example:
+
+```csharp
+[ApiController]
+public class AuthController : ControllerBase
+```
+
+Then this:
+
+```csharp
+[HttpPost("register")]
+public async Task<IActionResult> Register(RegisterRequestDto dto)
+```
+
+If `dto.PhoneNumber` is missing, it **won’t even run your logic**, and will return a `400 Bad Request` with validation errors.
+
+
+> “Why are these here if my frontend is separate?”
+
+✅ **Answer**: They're still useful:
+
+- For **security and safety**: you _must_ validate on the backend — never trust the frontend.
+    
+- For **auto validation** before hitting your logic — saving you boilerplate checks.
+    
+- You can use them for **Swagger/OpenAPI documentation** as well.
+    
+
+Frontend validation is for **user experience**, not security.
+
+---
+
+### 🔹 **2. Where should password requirements be checked? Frontend or backend?**
+
+✅ **Both.**
+
+- **Frontend**: show real-time UX feedback (“Password must be 6+ characters”).
+    
+- **Backend**: enforce security.
+    
+
+**Backend is the source of truth.**  
+Frontend can be bypassed (e.g., Postman).
+
+In the backend, you can either:
+
+- Use annotations like `[MinLength(6)]`
+    
+- Or do manual checks:
+    
+
+```csharp
+if (dto.Password.Length < 6)
+    return BadRequest("Password must be at least 6 characters long.");
+```
+
+---
+
+### 🔹 **3. Should confirm password be in the backend?**
+
+✅ **Yes — if you're doing password comparison in backend.**
+
+- `[Compare("Password")]` will validate if `ConfirmPassword` matches.
+    
+- Otherwise, you’ll need to check manually.
+    
+
+You **can skip sending ConfirmPassword to backend** and just validate in frontend if you’re confident your frontend handles it.
+
+But again: if someone sends malformed input manually (e.g., via Postman), backend should defend.
+
+💡 **Best practice:**
+
+- Validate `ConfirmPassword` in frontend (UX)
+    
+- Do one last check in backend, or use `[Compare]` for auto-validation
+    
+
+---
+
+### 🔹 **4. Is it OK to send plain password in request? Or should we hash it on frontend?**
+
+**✅ YES — it is OK and standard to send raw password in the login/signup request.**
+
+Why?
+
+- Passwords are sent over **HTTPS**, which encrypts the entire request.
+    
+- Hashing on frontend is _not_ secure, because:
+    
+    - Your algorithm/salt would be exposed
+        
+    - It defeats the purpose of salting and hashing correctly
+        
+    - You lose control over security management
+        
+
+### 🔹 **5. Error Response from Automatic Model Validation**
+
+If your DTO looks like this:
+
+```csharp
+public class RegisterRequestDto
+{
+    [Required(ErrorMessage = "Phone number is required.")]
+    [Phone(ErrorMessage = "Phone number format is invalid.")]
+    public string PhoneNumber { get; set; }
+
+    [Required(ErrorMessage = "Password is required.")]
+    [MinLength(6, ErrorMessage = "Password must be at least 6 characters long.")]
+    public string Password { get; set; }
+
+    [Compare("Password", ErrorMessage = "Passwords do not match.")]
+    public string ConfirmPassword { get; set; }
+}
+```
+
+And the frontend sends this:
+
+```json
+{
+  "phoneNumber": "",
+  "password": "123",
+  "confirmPassword": "abc"
+}
+```
+
+#### The backend will automatically return:
+
+```json
+{
+  "type": "https://tools.ietf.org/html/rfc7231#section-6.5.1",
+  "title": "One or more validation errors occurred.",
+  "status": 400,
+  "errors": {
+    "PhoneNumber": [
+      "Phone number is required."
+    ],
+    "Password": [
+      "Password must be at least 6 characters long."
+    ],
+    "ConfirmPassword": [
+      "Passwords do not match."
+    ]
+  }
+}
+```
+
+This is thanks to `[ApiController]` on your controller class. The framework uses the **ModelState** and returns errors in a structured way.
+
+---
+
+
+
+## Adding Mappings
+- [ ] Update `MappingProfile` with the following mappings:
+
+```c#
+CreateMap<Account, AccountDto>()
+    .ForMember(dest => dest.Roles, opt => opt.MapFrom(src => src.AccountRoles.Select(x=>x.Role.Title)));
+CreateMap<AccountDto, Account>() 
+.ForMember(dest => dest.AccountRoles, opt => opt.Ignore());
+```
+
+# Add Password Hasher Utility
+- [ ] Create a password hashing utility class
+📂 Suggested Folder: ApplicationLayer/Utils/`PasswordHasher.cs`
+```c#
+public static class PasswordHasher
+{
+    public static string HashPassword(string password)
+    {
+        byte[] salt = RandomNumberGenerator.GetBytes(16);
+
+        var pbkdf2 = new Rfc2898DeriveBytes(password, salt, 100000, HashAlgorithmName.SHA256);
+        byte[] hash = pbkdf2.GetBytes(32);
+
+        byte[] hashBytes = new byte[48];
+        Array.Copy(salt, 0, hashBytes, 0, 16);
+        Array.Copy(hash, 0, hashBytes, 16, 32);
+
+        return Convert.ToBase64String(hashBytes);
+    }
+
+    public static bool VerifyPassword(string password, string hashedPassword)
+    {
+        byte[] hashBytes = Convert.FromBase64String(hashedPassword);
+
+        byte[] salt = new byte[16];
+        Array.Copy(hashBytes, 0, salt, 0, 16);
+
+        var pbkdf2 = new Rfc2898DeriveBytes(password, salt, 100000, HashAlgorithmName.SHA256);
+        byte[] hash = pbkdf2.GetBytes(32);
+
+        for (int i = 0; i < 32; i++)
+        {
+            if (hashBytes[i + 16] != hash[i])
+                return false;
+        }
+
+        return true;
+    }
+}
+```
+
+
+# Modifying Account Repository 
+
+- [ ] Add the following methods in **`IAccountRepository`** 
+
+```c#
+Task<Account> GetByPhoneNumberAsync(string phoneNumber);
+Task AddAccountRoleAsync(AccountRole accountRole);
+```
+
+- [ ] Implement the methods in **`AccountRepository`**
+```c#
+ public async Task AddAccountRoleAsync(AccountRole accountRole)
+ {
+     await DbContext.AccountRoles.AddAsync(accountRole);
+ }
+ 
+ public async Task<Account> GetByPhoneNumberAsync(string phoneNumber)
+ {
+     var user = await DbContext.Accounts.Include(x => x.AccountRoles).ThenInclude(x => x.Role).FirstOrDefaultAsync(x => x.PhoneNumber == phoneNumber);
+     return user;
+ }
+```
+
+# Creating Service
+## Fix `Result.cs` Error Method
+- [ ] Update the `Error` method to include error messages:
+```c#
+public static Result<T> Error(T data, string errorMessage) => new() { Status = ResultStatus.Error, Data = data, ErrorMessage = errorMessage };
+```
+
+## Creating `IAuthService.cs` and `AuthService.cs`
+- [ ] Define the `IAuthService` interface
+```c#
+public interface IAuthService
+{
+    Task<Result<AuthResponseDto>> RegisterAsync(RegisterRequestDto request);
+    Task<Result<AuthResponseDto>> LoginAsync(LoginRequestDto request);
+}
+```
+
+- [ ] Implement the interface in `AuthService.cs`
+
+Use this project as a reference: 
+https://github.com/MehrdadShirvani/AlibabaClone-Backend/blob/develop/AlibabaClone.Application/Services/AuthService.cs
+
+## Register `IAuthService` in Service in `Program.cs`
+
+- [ ] Add to `Program.cs`
+```c# 
+//...
+builder.Services.AddScoped<IAuthService, AuthService>();
+//...
+```
+
+
+# Adding JWT
+
+## Installing Required NuGet Packages
+Install these packages in the **`WebApi` (Presentation Layer)** project:
+```
+Microsoft.AspNetCore.Authentication.JwtBearer
+Microsoft.IdentityModel.Tokens
+System.IdentityModel.Tokens.Jwt
+```
+
+## Create JWT Configuration Classes
+
+- [ ] Add JWT section to `appsettings.json`
+```xaml
+"Jwt": {
+	"Key": "[supersecretkeyyoustoresecurely]",
+	"Issuer": "[Issuer]",
+	"Audience": "MyAppUsers",
+	"ExpiryMinutes": 60
+}
+```
+
+- [ ] Create  `JwtSettings` and add the following method
+📂 Suggested Folder: WebAPI/Authentication
+```c#
+public class JwtSettings
+{
+    public string Key { get; set; } = null!;
+    public string Issuer { get; set; } = null!;
+    public string Audience { get; set; } = null!;
+    public int ExpiryMinutes { get; set; }
+}
+```
+
+- [ ] Create  `IJwtGenerator` and add the following method
+📂 Suggested Folder: WebAPI/Authentication
+```c#
+string GenerateToken(AuthResponseDto authResponseDto);
+```
+
+
+- [ ] Create  `JwtGenerator`, implementing `IJwtGenerator`
+📂 Suggested Folder: WebAPI/Authentication
+
+use this project as a reference
+https://github.com/MehrdadShirvani/AlibabaClone-Backend/blob/develop/AlibabaClone.Application/Services/AuthService.cs
+
+
+## Configuring Jwt in Program.cs
+- [ ] Register `JwtGenerator` service
+```c#
+builder.Services.AddScoped<IJwtGenerator, JwtGenerator>();
+```
+- [ ] Bind `JwtSettings` from configuration
+```c#
+builder.Services.Configure<JwtSettings>(builder.Configuration.GetSection("Jwt"));
+```
+- [ ] Configure JWT authentication
+```c#
+var jwtSettings = builder.Configuration.GetSection("Jwt").Get<JwtSettings>();
+builder.Services.AddAuthentication("Bearer")
+    .AddJwtBearer("Bearer", options =>
+    {
+        options.TokenValidationParameters = new TokenValidationParameters
+        {
+            ValidateIssuer = true,
+            ValidIssuer = jwtSettings.Issuer,
+
+            ValidateAudience = true,
+            ValidAudience = jwtSettings.Audience,
+
+            ValidateIssuerSigningKey = true,
+            IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(jwtSettings.Key)),
+
+            ValidateLifetime = true,
+            ClockSkew = TimeSpan.Zero
+        };
+    });
+
+builder.Services.AddAuthorization();
+
+```
+
+- [ ] Add `app.UseAuthentication` before `app.UseAuthorization`
+```c#
+app.UseAuthentication();
+app.UseAuthorization();
+```
+# Add ApiControllers
+
+- [ ] Create `AuthController`
+📂 Suggested Folder: WebApi/Controllers/`AuthController.cs`
+
+- [ ] Add Class and Constructor
+```c#
+private readonly IAuthService _authService;
+private readonly IJwtGenerator _jwtGenerator;
+
+public AuthController(IAuthService authService, IJwtGenerator jwtGenerator)
+{
+    _authService = authService;
+    _jwtGenerator = jwtGenerator;
+}
+```
+- [ ] Add Register Method
+```c#
+public async Task<IActionResult> Register(RegisterRequestDto request)
+{
+    var result = await _authService.RegisterAsync(request);
+
+    if (!result.IsSuccess)
+        return BadRequest(result.ErrorMessage);
+
+    var token = _jwtGenerator.GenerateToken(result.Data);
+    var response = new AuthResponseDto
+    {
+        PhoneNumber = result.Data.PhoneNumber,
+        Roles = result.Data.Roles,
+        Token = token
+    };
+
+    return Ok(response);
+}
+```
+- [ ] Add Login Method
+
+```c#
+ [HttpPost("login")]
+ public async Task<IActionResult> Login(LoginRequestDto request)
+ {
+     var result = await _authService.LoginAsync(request);
+
+     if (!result.IsSuccess)
+         return Unauthorized(result.ErrorMessage);
+
+     var token = _jwtGenerator.GenerateToken(result.Data);
+     var response = new AuthResponseDto
+     {
+         PhoneNumber = result.Data.PhoneNumber,
+         Roles = result.Data.Roles,
+         Token = token
+     };
+
+     return Ok(response);
+ }
+```
+
+- [ ] Create AccountController
+📂 Suggested Folder: WebApi/Controllers/AccountController.cs
+```c#
+public class AccountController : ControllerBase
+{
+    [Authorize(Roles = "User")]
+    [HttpGet("profile")]
+    public IActionResult GetProfile()
+    {
+        return Ok("Hi there, hello");
+    }
+}
+```
+
+# Merge
+- [ ] Create a PR and merge the current branch with develop
+
+
+
diff --git a/02_ProjectOrientedSessions/Session07/Session07 Frontend.md b/02_ProjectOrientedSessions/Session07/Session07 Frontend.md
new file mode 100644
index 0000000..8c7553f
--- /dev/null
+++ b/02_ProjectOrientedSessions/Session07/Session07 Frontend.md	
@@ -0,0 +1,304 @@
+
+
+
+Great — now we’re connecting both ends of your application. Let’s walk through **how authentication and authorization flow works on the frontend side (React)** when using **JWT-based authentication with a backend API**.
+
+---
+
+## 🔁 Overall Frontend Authentication Flow (React + JWT)
+
+1. **User logs in**:
+    
+    - They submit credentials (username/password) via a login form.
+        
+    - Frontend sends a POST request to `/api/auth/login`.
+        
+    - Backend validates and responds with a **JWT** (and optionally a **refresh token**).
+        
+2. **Frontend stores the token**:
+    
+    - This is usually saved in:
+        
+        - `localStorage` ✅ simple, persistent
+            
+        - or an **HttpOnly cookie** ✅ safer, but needs server support
+            
+3. **Frontend sends the token on future API calls**:
+    
+    - Automatically attaches the token as a header:
+        
+        ```js
+        Authorization: Bearer <token>
+        ```
+        
+4. **Frontend restricts access to protected pages**:
+    
+    - You read the token from storage.
+        
+    - Decode it to extract role/claims.
+        
+    - Use React Router + `PrivateRoute` (or similar) to guard access.
+        
+
+---
+
+## 🧱 How to Restrict Pages in React (Role-Based Routing)
+
+### ✅ Step 1: Decode and Check the Token
+
+```bash
+npm install jwt-decode
+```
+
+```js
+import jwtDecode from "jwt-decode";
+
+function getUserFromToken() {
+  const token = localStorage.getItem("token");
+  if (!token) return null;
+
+  try {
+    const decoded = jwtDecode(token);
+    return decoded; // contains roles, exp, username, etc.
+  } catch {
+    return null;
+  }
+}
+```
+
+---
+
+### ✅ Step 2: Create a Protected Route Component
+
+```jsx
+import { Navigate } from "react-router-dom";
+
+function PrivateRoute({ children, requiredRole }) {
+  const user = getUserFromToken();
+
+  if (!user) return <Navigate to="/login" />;
+  if (requiredRole && !user.role?.includes(requiredRole)) {
+    return <Navigate to="/unauthorized" />;
+  }
+
+  return children;
+}
+```
+
+---
+
+### ✅ Step 3: Use It in Routing
+
+```jsx
+<Route
+  path="/admin-dashboard"
+  element={
+    <PrivateRoute requiredRole="Admin">
+      <AdminDashboard />
+    </PrivateRoute>
+  }
+/>
+```
+
+---
+
+## 🛡️ Where to Store the JWT?
+
+|Method|Persistent?|Secure?|Notes|
+|---|---|---|---|
+|`localStorage`|✅ Yes|❌ No (accessible to JS)|Good for simple apps|
+|`sessionStorage`|❌ No (clears on tab close)|❌ No||
+|`HttpOnly cookie`|✅ Yes|✅ Yes|Needs backend to set cookie|
+
+> 🔐 **If your app is vulnerable to XSS, use `HttpOnly` cookies instead of localStorage**.
+
+---
+
+## 🧷 Automatically Adding JWT to Requests
+
+You can use **Axios interceptors**:
+
+```js
+// axios.js
+import axios from "axios";
+
+const api = axios.create({
+  baseURL: "http://your-api-url.com/api",
+});
+
+api.interceptors.request.use(config => {
+  const token = localStorage.getItem("token");
+  if (token) {
+    config.headers.Authorization = `Bearer ${token}`;
+  }
+  return config;
+});
+
+export default api;
+```
+
+Then use `api.get(...)` or `api.post(...)` in your services.
+
+---
+
+## 🧠 Summary
+
+|Task|Solution|
+|---|---|
+|Protect route to logged-in users|Use custom `<PrivateRoute />` with token check|
+|Check if user has a role|Decode token and inspect `role` claim|
+|Send token with API requests|Use Axios interceptors|
+|Save token|LocalStorage (easy) or HttpOnly cookie (secure)|
+|Keep user logged in|Token stays in localStorage or cookie|
+|Handle logout|Clear the token from storage|
+
+---
+
+Let me know if you want:
+
+- A sample React project with protected routes and JWT integration
+    
+- How to implement auto-logout when token expires
+    
+- How to use **refresh tokens**
+    
+
+Happy to walk you through any of it!
+
+That flow is **excellent** and matches exactly how modern applications with **JWT-based authentication** typically work. You're thinking about both UX (popup forms) and proper backend coordination — that's a solid start.
+
+---
+
+## ✅ Your Flow — Reviewed & Annotated:
+
+### **1. Account Sign-Up (Register)**
+
+> **Frontend (React)**: Sign-up modal with:
+
+- Phone number
+    
+- Password (+ confirm password)
+    
+- Basic validations (empty fields, password length, etc.)
+    
+
+> **Backend (ASP.NET Core API)**:
+
+- Validate: Check if phone already exists
+    
+- Validate password strength (you can set rules)
+    
+- Hash the password securely (use `PasswordHasher<T>` or Identity's helper)
+    
+- Store the user in DB (with phone number as username or unique field)
+    
+- Return success/failure
+    
+
+✅ **Note**: Use `[ApiController]`, `[FromBody]`, and model validation on the backend for clean error reporting.
+
+---
+
+### **2. Login Page (Popup)**
+
+> **Frontend (React)**:
+
+- Login modal with:
+    
+    - Phone number
+        
+    - Password
+        
+
+> **Backend**:
+
+- Validate credentials
+    
+- If valid, generate:
+    
+    - **JWT** (access token) — includes user ID and roles
+        
+    - (Optional) Refresh token
+        
+- Return the JWT token to the frontend
+    
+
+✅ **Token Payload Example**:
+
+```json
+{
+  "sub": "user_id_here",
+  "phone": "09xxxxxxxxx",
+  "role": "Customer",
+  "exp": 1234567890
+}
+```
+
+✅ You’ll send this token to the frontend in the response.
+
+---
+
+### **3. Store the Token + Access Protected Page**
+
+> **Frontend**:
+
+- Store the token (in `localStorage` for now)
+    
+- Use Axios to attach it on every request
+    
+- Use a `PrivateRoute` component to guard protected pages
+    
+- Access `/profile` page (protected by `[Authorize]` in backend)
+    
+
+> **Backend**:
+
+- Secure `/profile` with `[Authorize(Roles = "Customer")]` or similar
+    
+- Parse token from `Authorization: Bearer <token>` header
+    
+- Allow or reject based on claims
+    
+
+---
+
+## 🛠️ What You'll Need
+
+### Frontend:
+
+- `react-router-dom`
+    
+- `axios`
+    
+- `jwt-decode`
+    
+- Modals (e.g., using Tailwind or a component lib)
+    
+
+### Backend:
+
+- ASP.NET Core API (you already have it)
+    
+- JWT configuration in `Program.cs`
+    
+- Custom authentication controller (`/api/auth/register`, `/api/auth/login`)
+    
+- Role support
+    
+- Token generation utility
+    
+
+---
+
+## 🚀 Ready to Begin?
+
+Let's start with **Step 1**: Sign-up flow
+
+Would you like to begin with:
+
+1. **Backend first** — setting up `/api/auth/register` endpoint and phone+password validation
+    
+2. **Frontend first** — creating the sign-up modal form in React
+    
+
+Let me know your preference and we’ll go step by step.
\ No newline at end of file
diff --git a/02_ProjectOrientedSessions/Session07/Session07.md b/02_ProjectOrientedSessions/Session07/Session07.md
deleted file mode 100644
index 87c908a..0000000
--- a/02_ProjectOrientedSessions/Session07/Session07.md
+++ /dev/null
@@ -1,82 +0,0 @@
-
-
-### 🔹 1. **User Sign-Up Flow**
-
-- React modal (SignUpModal component)
-    
-- Fields: `PhoneNumber`, `Password`, `ConfirmPassword`
-    
-- Frontend validation (empty fields, password length match, etc.)
-    
-- Send request to `/api/auth/register` (POST)
-    
-- Backend controller:
-    
-    - Check if user with phone exists
-        
-    - Validate password (min length, maybe complexity rules)
-        
-    - Hash password
-        
-    - Store new user in DB
-        
-    - Return success/failure
-        
-
-✅ **Backend helper**: Use `PasswordHasher<TUser>` to hash passwords securely  
-✅ **Phone number** can act as username or unique field
-
----
-
-### 🔹 2. **User Login Flow**
-
-- React modal (LoginModal component)
-    
-- Fields: `PhoneNumber`, `Password`
-    
-- Submit to `/api/auth/login` (POST)
-    
-- Backend checks:
-    
-    - Find user by phone
-        
-    - Verify password (using PasswordHasher)
-        
-    - Generate **JWT**
-        
-    - Return token (and optionally refresh token)
-        
-
-✅ Token should include claims like user ID and role  
-✅ Sign token with your secret key
-
----
-
-### 🔹 3. **Store Token + Access Protected Page**
-
-- Save token to `localStorage` or `cookie`
-    
-- Attach it to future API requests using Axios interceptor
-    
-- Use `jwt-decode` to extract roles and validate access in frontend
-    
-- Restrict `/profile` page using custom React `PrivateRoute`
-    
-
-Backend: Secure `/api/profile` with `[Authorize]` (or `[Authorize(Roles = "X")]`)
-
----
-
-## 🛠 Technologies to Use
-
-|Area|Tool|
-|---|---|
-|Frontend|React, Axios, React Router, jwt-decode|
-|Backend|ASP.NET Core API, EF Core, JWT Bearer Auth|
-|Security|PasswordHasher, Authorization attributes, Token signing key|
-
----
-
-
-# Mention adding User Role in Database
-# Becareful not to put Jwt inside another thing in the appsettings 
\ No newline at end of file