orion/docs/architecture/url-routing/overview.md

# Wizamart Multi-Tenant URL Routing Guide

## Quick Answer

**How do customers access a vendor's shop in Wizamart?**

There are three ways depending on the deployment mode:

**⚠️ Important:** This guide describes **customer-facing shop routes**. For vendor dashboard/management routes, see [Vendor Frontend Architecture](../../frontend/vendor/architecture.md). The shop uses `/vendors/{code}/shop/*` (plural) in path-based mode, while the vendor dashboard uses `/vendor/{code}/*` (singular).

### 1. **SUBDOMAIN MODE** (Production - Recommended)
```
https://VENDOR_SUBDOMAIN.platform.com/shop/products

Example:
https://acme.wizamart.com/shop/products
https://techpro.wizamart.com/shop/categories/electronics
```

### 2. **CUSTOM DOMAIN MODE** (Production - Premium)
```
https://VENDOR_CUSTOM_DOMAIN/shop/products

Example:
https://store.acmecorp.com/shop/products
https://shop.techpro.io/shop/cart
```

### 3. **PATH-BASED MODE** (Development Only)
```
http://localhost:PORT/vendors/VENDOR_CODE/shop/products

Example:
http://localhost:8000/vendors/acme/shop/products
http://localhost:8000/vendors/techpro/shop/checkout
```

---

## Three Deployment Modes Explained

### 1. SUBDOMAIN MODE (Production - Recommended)

**URL Pattern:** `https://VENDOR_SUBDOMAIN.platform.com/shop/...`

**Example:**
- Vendor subdomain: `acme`
- Platform domain: `wizamart.com`
- Customer Shop URL: `https://acme.wizamart.com/shop/products`
- Product Detail: `https://acme.wizamart.com/shop/products/123`

**How It Works:**
1. Customer visits `https://acme.wizamart.com/shop/products`
2. `vendor_context_middleware` detects subdomain `"acme"`
3. Queries: `SELECT * FROM vendors WHERE subdomain = 'acme'`
4. Finds Vendor with ID=1 (ACME Store)
5. Sets `request.state.vendor = Vendor(ACME Store)`
6. `context_middleware` detects it's a SHOP request
7. `theme_context_middleware` loads ACME's theme
8. Routes to `shop_pages.py` → `shop_products_page()`
9. Renders template with ACME's colors, logo, and products

**Advantages:**
- Single SSL certificate for all vendors (*.wizamart.com)
- Easy to manage DNS (just add subdomains)
- Customers don't need to bring their own domain

---

### 2. CUSTOM DOMAIN MODE (Production - Premium)

**URL Pattern:** `https://CUSTOM_DOMAIN/shop/...`

**Example:**
- Vendor name: "ACME Store"
- Custom domain: `store.acme-corp.com`
- Customer Shop URL: `https://store.acme-corp.com/shop/products`

**Database Setup:**
```sql
-- vendors table
id | name        | subdomain
1  | ACME Store  | acme

-- vendor_domains table (links custom domains to vendors)
id | vendor_id | domain              | is_active | is_verified
1  | 1         | store.acme-corp.com | true      | true
```

**How It Works:**
1. Customer visits `https://store.acme-corp.com/shop/products`
2. `vendor_context_middleware` detects custom domain (not *.wizamart.com, not localhost)
3. Normalizes domain to `"store.acme-corp.com"`
4. Queries: `SELECT * FROM vendor_domains WHERE domain = 'store.acme-corp.com'`
5. Finds `VendorDomain` with `vendor_id = 1`
6. Joins to get `Vendor(ACME Store)`
7. Rest is same as subdomain mode...

**Advantages:**
- Professional branding with vendor's own domain
- Better for premium vendors
- Vendor controls the domain

**Considerations:**
- Each vendor needs their own SSL certificate
- Vendor must own and configure the domain

---

### 3. PATH-BASED MODE (Development Only)

**URL Pattern:** `http://localhost:PORT/vendors/VENDOR_CODE/shop/...`

**Example:**
- Development: `http://localhost:8000/vendors/acme/shop/products`
- With port: `http://localhost:8000/vendors/acme/shop/products/123`

**How It Works:**
1. Developer visits `http://localhost:8000/vendors/acme/shop/products`
2. `vendor_context_middleware` detects path-based routing pattern `/vendors/acme/...`
3. Extracts vendor code `"acme"` from the path
4. Looks up Vendor: `SELECT * FROM vendors WHERE subdomain = 'acme'`
5. Sets `request.state.vendor = Vendor(acme)`
6. Routes to shop pages

**Advantages:**
- Perfect for local development
- No need to configure DNS/domains
- Test multiple vendors easily without domain setup

**Limitations:**
- Only for development (not production-ready)
- All vendors share same localhost address

---

## Complete Route Examples

### Subdomain/Custom Domain (PRODUCTION)
```
https://acme.wizamart.com/shop/                        → Homepage
https://acme.wizamart.com/shop/products                → Product Catalog
https://acme.wizamart.com/shop/products/123            → Product Detail
https://acme.wizamart.com/shop/categories/electronics  → Category Page
https://acme.wizamart.com/shop/cart                    → Shopping Cart
https://acme.wizamart.com/shop/checkout                → Checkout
https://acme.wizamart.com/shop/search?q=laptop         → Search Results
https://acme.wizamart.com/shop/account/login           → Customer Login
https://acme.wizamart.com/shop/account/dashboard       → Account Dashboard (Auth Required)
https://acme.wizamart.com/shop/account/orders          → Order History (Auth Required)
https://acme.wizamart.com/shop/account/profile         → Profile (Auth Required)
```

### Path-Based (DEVELOPMENT)
```
http://localhost:8000/vendors/acme/shop/                → Homepage
http://localhost:8000/vendors/acme/shop/products        → Products
http://localhost:8000/vendors/acme/shop/products/123    → Product Detail
http://localhost:8000/vendors/acme/shop/cart            → Cart
http://localhost:8000/vendors/acme/shop/checkout        → Checkout
http://localhost:8000/vendors/acme/shop/account/login   → Login
```

### API Endpoints (Same for All Modes)
```
GET  /api/v1/public/vendors/1/products              → Get vendor products
GET  /api/v1/public/vendors/1/products/123          → Get product details
POST /api/v1/public/vendors/1/products/{id}/reviews → Add product review
```

---

## How Vendor Isolation Works

### Multi-Layer Enforcement

**Layer 1: URL Routing**
- Vendor is detected from subdomain, custom domain, or path
- Each vendor gets their own request context

**Layer 2: Middleware**
- `request.state.vendor` is set to the detected Vendor object
- All downstream code can access the vendor

**Layer 3: Database Queries**
- All queries must include `WHERE vendor_id = ?`
- Product queries: `SELECT * FROM products WHERE vendor_id = 1`
- Order queries: `SELECT * FROM orders WHERE vendor_id = 1`

**Layer 4: API Authorization**
- Endpoints verify the vendor matches the request vendor
- Customers can only see their own vendor's products

### Example: No Cross-Vendor Leakage
```python
# Customer on acme.wizamart.com tries to access TechPro's products
# They make API call to /api/v1/public/vendors/2/products

# Backend checks:
vendor = get_vendor_from_request(request)  # Returns Vendor(id=1, name="ACME")
if vendor.id != requested_vendor_id:       # if 1 != 2
    raise UnauthorizedShopAccessException()
```

---

## Request Lifecycle: Complete Flow

### Scenario: Customer visits `https://acme.wizamart.com/shop/products`

```
┌─────────────────────────────────────────────────────────────────┐
│ 1. REQUEST ARRIVES                                              │
└─────────────────────────────────────────────────────────────────┘
   method: GET
   host: acme.wizamart.com
   path: /shop/products

┌─────────────────────────────────────────────────────────────────┐
│ 2. MIDDLEWARE CHAIN                                             │
└─────────────────────────────────────────────────────────────────┘

   A) vendor_context_middleware
      ├─ Detects host: "acme.wizamart.com"
      ├─ Extracts subdomain: "acme"
      ├─ Queries: SELECT * FROM vendors WHERE subdomain = 'acme'
      └─ Sets: request.state.vendor = Vendor(ACME Store)

   B) context_middleware
      ├─ Checks path: "/shop/products"
      ├─ Has request.state.vendor? YES
      └─ Sets: request.state.context_type = RequestContext.SHOP

   C) theme_context_middleware
      ├─ Queries: SELECT * FROM vendor_themes WHERE vendor_id = 1
      └─ Sets: request.state.theme = {...ACME's theme...}

┌─────────────────────────────────────────────────────────────────┐
│ 3. ROUTE MATCHING                                               │
└─────────────────────────────────────────────────────────────────┘
   Path: /shop/products
   Matches: @router.get("/shop/products")
   Handler: shop_products_page(request)

┌─────────────────────────────────────────────────────────────────┐
│ 4. HANDLER EXECUTES                                             │
└─────────────────────────────────────────────────────────────────┘
   @router.get("/shop/products", response_class=HTMLResponse)
   async def shop_products_page(request: Request):
       return templates.TemplateResponse(
           "shop/products.html",
           {"request": request}
       )

┌─────────────────────────────────────────────────────────────────┐
│ 5. TEMPLATE RENDERS                                             │
└─────────────────────────────────────────────────────────────────┘
   Template accesses:
   ├─ request.state.vendor.name → "ACME Store"
   ├─ request.state.theme.colors.primary → "#FF6B6B"
   ├─ request.state.theme.branding.logo → "acme-logo.png"
   └─ Products will load via JavaScript API call

┌─────────────────────────────────────────────────────────────────┐
│ 6. JAVASCRIPT LOADS PRODUCTS (Client-Side)                     │
└─────────────────────────────────────────────────────────────────┘
   fetch(`/api/v1/public/vendors/1/products`)
   .then(data => renderProducts(data.products, {theme}))

┌─────────────────────────────────────────────────────────────────┐
│ 7. RESPONSE SENT                                                │
└─────────────────────────────────────────────────────────────────┘
   HTML with ACME's colors, logo, and products
```

---

## Theme Integration

Each vendor's shop is fully branded with their custom theme:

```python
# Theme loaded for https://acme.wizamart.com
request.state.theme = {
    "theme_name": "modern",
    "colors": {
        "primary": "#FF6B6B",
        "secondary": "#FF8787",
        "accent": "#FF5252",
        "background": "#ffffff",
        "text": "#1f2937"
    },
    "branding": {
        "logo": "acme-logo.png",
        "favicon": "acme-favicon.ico",
        "banner": "acme-banner.jpg"
    },
    "fonts": {
        "heading": "Poppins, sans-serif",
        "body": "Inter, sans-serif"
    }
}
```

In Jinja2 template:
```html
<style>
  :root {
    --color-primary: {{ request.state.theme.colors.primary }};
    --color-secondary: {{ request.state.theme.colors.secondary }};
  }
</style>

<img src="{{ request.state.theme.branding.logo }}" alt="{{ request.state.vendor.name }}" />
<h1 style="font-family: {{ request.state.theme.fonts.heading }}">
  Welcome to {{ request.state.vendor.name }}
</h1>
```

---

## Key Points for Understanding

### 1. Customer Perspective
- Customers just visit a URL (like any normal e-commerce site)
- They have no awareness it's a multi-tenant platform
- Each store looks completely separate and branded

### 2. Vendor Perspective
- Vendors can use a subdomain (free/standard): `acme.wizamart.com`
- Or their own custom domain (premium): `store.acme-corp.com`
- Both routes go to the exact same backend code

### 3. Developer Perspective
- The middleware layer detects which vendor is being accessed
- All business logic remains vendor-unaware
- Database queries automatically filtered by vendor
- No risk of data leakage because of multi-layer isolation

### 4. Tech Stack
- **Frontend:** Jinja2 templates + Alpine.js + Tailwind CSS
- **Backend:** FastAPI + SQLAlchemy
- **Auth:** JWT with vendor-scoped cookies
- **Database:** All tables have `vendor_id` foreign key

---

## Path-Based Routing Implementation

**Current Solution: Double Router Mounting**

The application handles path-based routing by registering shop routes **twice** with different prefixes:

```python
# In main.py
app.include_router(shop_pages.router, prefix="/shop")
app.include_router(shop_pages.router, prefix="/vendors/{vendor_code}/shop")
```

**How This Works:**

1. **For Subdomain/Custom Domain Mode:**
   - URL: `https://acme.wizamart.com/shop/products`
   - Matches: First router with `/shop` prefix
   - Route: `@router.get("/products")` → Full path: `/shop/products`

2. **For Path-Based Development Mode:**
   - URL: `http://localhost:8000/vendors/acme/shop/products`
   - Matches: Second router with `/vendors/{vendor_code}/shop` prefix
   - Route: `@router.get("/products")` → Full path: `/vendors/{vendor_code}/shop/products`
   - Bonus: `vendor_code` available as path parameter!

**Benefits:**
- ✅ No middleware complexity or path manipulation
- ✅ FastAPI native routing
- ✅ Explicit and maintainable
- ✅ Vendor code accessible via path parameter when needed
- ✅ Both deployment modes supported cleanly

---

## Authentication in Multi-Tenant Shop

Customer authentication uses vendor-scoped cookies:

```python
# Login sets cookie scoped to vendor's shop
Set-Cookie: customer_token=eyJ...; Path=/shop; HttpOnly; SameSite=Lax

# This prevents:
# - Tokens leaking across vendors
# - Cross-site request forgery
# - Cookie scope confusion in multi-tenant setup
```

---

## Summary Table

| Mode | URL | Use Case | SSL | DNS |
|------|-----|----------|-----|-----|
| Subdomain | `vendor.platform.com/shop` | Production (standard) | *.platform.com | Add subdomains |
| Custom Domain | `vendor-domain.com/shop` | Production (premium) | Per vendor | Vendor configures |
| Path-Based | `localhost:8000/vendors/v/shop` | Development only | None | None |

---

## Next Steps

1. **For Production:** Use subdomain or custom domain mode
2. **For Development:** Use path-based mode locally
3. **For Deployment:** Configure DNS for subdomains or custom domains
4. **For Testing:** Create test vendors with different themes
5. **For Scaling:** Consider CDN for vendor-specific assets

---

Generated: November 7, 2025
Wizamart Version: Current Development