orion/app/api/deps.py

# app/api/deps.py
"""
Authentication dependencies for FastAPI routes.

This module provides authentication dependencies for all three contexts in the
multi-tenant application, implementing dual token storage with proper isolation:

ADMIN ROUTES (/admin/*):
- Cookie: admin_token (path=/admin) OR Authorization header
- Role: admin only
- Blocks: vendors, customers

VENDOR ROUTES (/vendor/*):
- Cookie: vendor_token (path=/vendor) OR Authorization header
- Role: vendor only
- Blocks: admins, customers

CUSTOMER/SHOP ROUTES (/shop/account/*):
- Cookie: customer_token (path=/shop) OR Authorization header
- Role: customer only
- Blocks: admins, vendors
- Note: Public shop pages (/shop/products, etc.) don't require auth

This dual authentication approach supports:
- HTML pages: Use cookies (automatic browser behavior)
- API calls: Use Authorization headers (explicit JavaScript control)

The cookie path restrictions prevent cross-context cookie leakage:
- admin_token is NEVER sent to /vendor/* or /shop/*
- vendor_token is NEVER sent to /admin/* or /shop/*
- customer_token is NEVER sent to /admin/* or /vendor/*
"""

import logging
from datetime import UTC

from fastapi import Cookie, Depends, Request
from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
from sqlalchemy.orm import Session

from app.core.database import get_db
from app.exceptions import (
    AdminRequiredException,
    InsufficientPermissionsException,
    InsufficientVendorPermissionsException,
    InvalidTokenException,
    UnauthorizedVendorAccessException,
    VendorAccessDeniedException,
    VendorNotFoundException,
    VendorOwnerOnlyException,
)
from app.services.vendor_service import vendor_service
from middleware.auth import AuthManager
from middleware.rate_limiter import RateLimiter
from models.database.user import User
from models.database.vendor import Vendor

# Initialize dependencies
security = HTTPBearer(auto_error=False)  # auto_error=False prevents automatic 403
auth_manager = AuthManager()
rate_limiter = RateLimiter()
logger = logging.getLogger(__name__)


# ============================================================================
# HELPER FUNCTIONS
# ============================================================================


def _get_token_from_request(
    credentials: HTTPAuthorizationCredentials | None,
    cookie_value: str | None,
    cookie_name: str,
    request_path: str,
) -> tuple[str | None, str | None]:
    """
    Extract token from Authorization header or cookie.

    Priority:
    1. Authorization header (for API calls from JavaScript)
    2. Cookie (for browser page navigation)

    Args:
        credentials: Optional Bearer token from Authorization header
        cookie_value: Optional token from cookie
        cookie_name: Name of the cookie (for logging)
        request_path: Request URL path (for logging)

    Returns:
        Tuple of (token, source) where source is "header" or "cookie"
    """
    if credentials:
        logger.debug(f"Token found in Authorization header for {request_path}")
        return credentials.credentials, "header"
    if cookie_value:
        logger.debug(f"Token found in {cookie_name} cookie for {request_path}")
        return cookie_value, "cookie"

    return None, None


def _validate_user_token(token: str, db: Session) -> User:
    """
    Validate JWT token and return user.

    Args:
        token: JWT token string
        db: Database session

    Returns:
        User: Authenticated user object

    Raises:
        InvalidTokenException: If token is invalid
    """
    mock_credentials = HTTPAuthorizationCredentials(scheme="Bearer", credentials=token)
    return auth_manager.get_current_user(db, mock_credentials)


# ============================================================================
# ADMIN AUTHENTICATION
# ============================================================================


def get_current_admin_from_cookie_or_header(
    request: Request,
    credentials: HTTPAuthorizationCredentials | None = Depends(security),
    admin_token: str | None = Cookie(None),
    db: Session = Depends(get_db),
) -> User:
    """
    Get current admin user from admin_token cookie or Authorization header.

    Used for admin HTML pages (/admin/*) that need cookie-based auth.

    Priority:
    1. Authorization header (API calls)
    2. admin_token cookie (page navigation)

    Args:
        request: FastAPI request
        credentials: Optional Bearer token from header
        admin_token: Optional token from admin_token cookie
        db: Database session

    Returns:
        User: Authenticated admin user

    Raises:
        InvalidTokenException: If no token or invalid token
        AdminRequiredException: If user is not admin
    """
    token, source = _get_token_from_request(
        credentials, admin_token, "admin_token", str(request.url.path)
    )

    if not token:
        logger.warning(f"Admin auth failed: No token for {request.url.path}")
        raise InvalidTokenException("Admin authentication required")

    # Validate token and get user
    user = _validate_user_token(token, db)

    # Verify user is admin
    if user.role != "admin":
        logger.warning(
            f"Non-admin user {user.username} attempted admin route: {request.url.path}"
        )
        raise AdminRequiredException("Admin privileges required")

    return user


def get_current_admin_api(
    credentials: HTTPAuthorizationCredentials = Depends(security),
    db: Session = Depends(get_db),
) -> User:
    """
    Get current admin user from Authorization header ONLY.

    Used for admin API endpoints that should not accept cookies.
    This prevents CSRF attacks on API endpoints.

    Args:
        credentials: Bearer token from Authorization header
        db: Database session

    Returns:
        User: Authenticated admin user

    Raises:
        InvalidTokenException: If no token or invalid token
        AdminRequiredException: If user is not admin
    """
    if not credentials:
        raise InvalidTokenException("Authorization header required for API calls")

    user = _validate_user_token(credentials.credentials, db)

    if user.role != "admin":
        logger.warning(f"Non-admin user {user.username} attempted admin API")
        raise AdminRequiredException("Admin privileges required")

    return user


# ============================================================================
# VENDOR AUTHENTICATION
# ============================================================================


def get_current_vendor_from_cookie_or_header(
    request: Request,
    credentials: HTTPAuthorizationCredentials | None = Depends(security),
    vendor_token: str | None = Cookie(None),
    db: Session = Depends(get_db),
) -> User:
    """
    Get current vendor user from vendor_token cookie or Authorization header.

    Used for vendor HTML pages (/vendor/*) that need cookie-based auth.

    Priority:
    1. Authorization header (API calls)
    2. vendor_token cookie (page navigation)

    Args:
        request: FastAPI request
        credentials: Optional Bearer token from header
        vendor_token: Optional token from vendor_token cookie
        db: Database session

    Returns:
        User: Authenticated vendor user

    Raises:
        InvalidTokenException: If no token or invalid token
        InsufficientPermissionsException: If user is not vendor or is admin
    """
    token, source = _get_token_from_request(
        credentials, vendor_token, "vendor_token", str(request.url.path)
    )

    if not token:
        logger.warning(f"Vendor auth failed: No token for {request.url.path}")
        raise InvalidTokenException("Vendor authentication required")

    # Validate token and get user
    user = _validate_user_token(token, db)

    # CRITICAL: Block admins from vendor routes
    if user.role == "admin":
        logger.warning(
            f"Admin user {user.username} attempted vendor route: {request.url.path}"
        )
        raise InsufficientPermissionsException(
            "Vendor access only - admins cannot use vendor portal"
        )

    # Verify user is vendor
    if user.role != "vendor":
        logger.warning(
            f"Non-vendor user {user.username} attempted vendor route: {request.url.path}"
        )
        raise InsufficientPermissionsException("Vendor privileges required")

    return user


def get_current_vendor_api(
    credentials: HTTPAuthorizationCredentials = Depends(security),
    db: Session = Depends(get_db),
) -> User:
    """
    Get current vendor user from Authorization header ONLY.

    Used for vendor API endpoints that should not accept cookies.
    Validates that:
    1. Token contains vendor context (token_vendor_id)
    2. User still has access to the vendor specified in the token

    Args:
        credentials: Bearer token from Authorization header
        db: Database session

    Returns:
        User: Authenticated vendor user (with token_vendor_id, token_vendor_code, token_vendor_role)

    Raises:
        InvalidTokenException: If no token, invalid token, or missing vendor context
        InsufficientPermissionsException: If user is not vendor or lost access to vendor
    """
    if not credentials:
        raise InvalidTokenException("Authorization header required for API calls")

    user = _validate_user_token(credentials.credentials, db)

    # Block admins from vendor API
    if user.role == "admin":
        logger.warning(f"Admin user {user.username} attempted vendor API")
        raise InsufficientPermissionsException("Vendor access only")

    if user.role != "vendor":
        logger.warning(f"Non-vendor user {user.username} attempted vendor API")
        raise InsufficientPermissionsException("Vendor privileges required")

    # Require vendor context in token
    if not hasattr(user, "token_vendor_id"):
        raise InvalidTokenException("Token missing vendor information. Please login again.")

    vendor_id = user.token_vendor_id

    # Verify user still has access to this vendor
    if not user.is_member_of(vendor_id):
        logger.warning(
            f"User {user.username} lost access to vendor_id={vendor_id}"
        )
        raise InsufficientPermissionsException(
            "Access to vendor has been revoked. Please login again."
        )

    logger.debug(
        f"Vendor API access: user={user.username}, vendor_id={vendor_id}, "
        f"vendor_code={getattr(user, 'token_vendor_code', 'N/A')}"
    )

    return user


# ============================================================================
# CUSTOMER AUTHENTICATION (SHOP)
# ============================================================================


def _validate_customer_token(token: str, request: Request, db: Session):
    """
    Validate customer JWT token and return Customer object.

    Validates:
    1. Token signature and expiration
    2. Token type is "customer"
    3. Customer exists and is active
    4. Token vendor_id matches request vendor (URL-based)

    Args:
        token: JWT token string
        request: FastAPI request (for vendor context)
        db: Database session

    Returns:
        Customer: Authenticated customer object

    Raises:
        InvalidTokenException: If token is invalid or expired
        UnauthorizedVendorAccessException: If vendor mismatch
    """
    from datetime import datetime

    from jose import JWTError, jwt

    from models.database.customer import Customer

    # Decode and validate customer JWT token
    try:
        payload = jwt.decode(
            token, auth_manager.secret_key, algorithms=[auth_manager.algorithm]
        )

        # Verify this is a customer token
        token_type = payload.get("type")
        if token_type != "customer":
            logger.warning(f"Invalid token type for customer route: {token_type}")
            raise InvalidTokenException("Customer authentication required")

        # Get customer ID from token
        customer_id: str = payload.get("sub")
        if customer_id is None:
            logger.warning("Token missing 'sub' (customer_id)")
            raise InvalidTokenException("Invalid token")

        # Verify token hasn't expired
        exp = payload.get("exp")
        if exp and datetime.fromtimestamp(exp, tz=UTC) < datetime.now(UTC):
            logger.warning(f"Expired customer token for customer_id={customer_id}")
            raise InvalidTokenException("Token has expired")

        # Get vendor_id from token for validation
        token_vendor_id = payload.get("vendor_id")

    except JWTError as e:
        logger.warning(f"JWT decode error: {str(e)}")
        raise InvalidTokenException("Could not validate credentials")

    # Load customer from database
    customer = db.query(Customer).filter(Customer.id == int(customer_id)).first()

    if not customer:
        logger.warning(f"Customer not found: {customer_id}")
        raise InvalidTokenException("Customer not found")

    if not customer.is_active:
        logger.warning(f"Inactive customer attempted access: {customer.email}")
        raise InvalidTokenException("Customer account is inactive")

    # Validate vendor context matches token
    # This prevents using a customer token from vendor A on vendor B's shop
    request_vendor = getattr(request.state, "vendor", None)
    if request_vendor and token_vendor_id:
        if request_vendor.id != token_vendor_id:
            logger.warning(
                f"Customer {customer.email} token vendor mismatch: "
                f"token={token_vendor_id}, request={request_vendor.id}"
            )
            raise UnauthorizedVendorAccessException(
                vendor_code=request_vendor.vendor_code,
                user_id=customer.id,
            )

    logger.debug(f"Customer authenticated: {customer.email} (ID: {customer.id})")

    return customer


def get_current_customer_from_cookie_or_header(
    request: Request,
    credentials: HTTPAuthorizationCredentials | None = Depends(security),
    customer_token: str | None = Cookie(None),
    db: Session = Depends(get_db),
):
    """
    Get current customer from customer_token cookie or Authorization header.

    Used for shop account HTML pages (/shop/account/*) that need cookie-based auth.
    Note: Public shop pages (/shop/products, etc.) don't use this dependency.

    Validates that token vendor_id matches request vendor (URL-based detection).

    Priority:
    1. Authorization header (API calls)
    2. customer_token cookie (page navigation)

    Args:
        request: FastAPI request
        credentials: Optional Bearer token from header
        customer_token: Optional token from customer_token cookie
        db: Database session

    Returns:
        Customer: Authenticated customer object

    Raises:
        InvalidTokenException: If no token or invalid token
        UnauthorizedVendorAccessException: If vendor mismatch
    """
    token, source = _get_token_from_request(
        credentials, customer_token, "customer_token", str(request.url.path)
    )

    if not token:
        logger.warning(f"Customer auth failed: No token for {request.url.path}")
        raise InvalidTokenException("Customer authentication required")

    return _validate_customer_token(token, request, db)


def get_current_customer_api(
    request: Request,
    credentials: HTTPAuthorizationCredentials = Depends(security),
    db: Session = Depends(get_db),
):
    """
    Get current customer from Authorization header ONLY.

    Used for shop API endpoints that should not accept cookies.
    Validates that token vendor_id matches request vendor (URL-based detection).

    Args:
        request: FastAPI request (for vendor context)
        credentials: Bearer token from Authorization header
        db: Database session

    Returns:
        Customer: Authenticated customer object

    Raises:
        InvalidTokenException: If no token or invalid token
        UnauthorizedVendorAccessException: If vendor mismatch
    """
    if not credentials:
        raise InvalidTokenException("Authorization header required for API calls")

    return _validate_customer_token(credentials.credentials, request, db)


# ============================================================================
# GENERIC AUTHENTICATION (for mixed-use endpoints)
# ============================================================================


def get_current_user(
    credentials: HTTPAuthorizationCredentials = Depends(security),
    db: Session = Depends(get_db),
) -> User:
    """
    Get current authenticated user from Authorization header only.

    Generic authentication without role checking.
    Used for endpoints accessible to any authenticated user.

    Args:
        credentials: Bearer token from Authorization header
        db: Database session

    Returns:
        User: Authenticated user (any role)

    Raises:
        InvalidTokenException: If no token or invalid token
    """
    if not credentials:
        raise InvalidTokenException("Authorization header required")

    return _validate_user_token(credentials.credentials, db)


# ============================================================================
# VENDOR OWNERSHIP VERIFICATION
# ============================================================================


def get_user_vendor(
    vendor_code: str,
    current_user: User = Depends(get_current_vendor_from_cookie_or_header),
    db: Session = Depends(get_db),
) -> Vendor:
    """
    Get vendor and verify user ownership/membership.

    Ensures the current user has access to the specified vendor.
    - Vendor owners can access their own vendor
    - Team members can access their vendor
    - Admins are BLOCKED (use admin routes instead)

    Args:
        vendor_code: Vendor code to look up
        current_user: Current authenticated vendor user
        db: Database session

    Returns:
        Vendor: Vendor object if user has access

    Raises:
        VendorNotFoundException: If vendor doesn't exist
        UnauthorizedVendorAccessException: If user doesn't have access
    """
    from sqlalchemy.orm import joinedload

    vendor = (
        db.query(Vendor)
        .options(joinedload(Vendor.company))
        .filter(Vendor.vendor_code == vendor_code.upper())
        .first()
    )

    if not vendor:
        raise VendorNotFoundException(vendor_code)

    # Check if user owns this vendor (via company ownership)
    if vendor.company and vendor.company.owner_user_id == current_user.id:
        return vendor

    # Check if user is team member
    # TODO: Add team member check when VendorUser relationship is set up

    # User doesn't have access to this vendor
    raise UnauthorizedVendorAccessException(vendor_code, current_user.id)


# ============================================================================
# PERMISSIONS CHECKING
# ============================================================================


def require_vendor_permission(permission: str):
    """
    Dependency factory to require a specific vendor permission.

    Uses token_vendor_id from JWT token (authenticated vendor API pattern).
    The vendor object is loaded and stored in request.state.vendor for endpoint use.

    Usage:
        @router.get("/products")
        def list_products(
            request: Request,
            user: User = Depends(require_vendor_permission(VendorPermissions.PRODUCTS_VIEW.value))
        ):
            vendor = request.state.vendor  # Vendor is set by this dependency
            ...
    """

    def permission_checker(
        request: Request,
        db: Session = Depends(get_db),
        current_user: User = Depends(get_current_vendor_from_cookie_or_header),
    ) -> User:
        # Get vendor ID from JWT token
        if not hasattr(current_user, "token_vendor_id"):
            raise InvalidTokenException("Token missing vendor information. Please login again.")

        vendor_id = current_user.token_vendor_id

        # Load vendor from database (raises VendorNotFoundException if not found)
        vendor = vendor_service.get_vendor_by_id(db, vendor_id)

        # Store vendor in request state for endpoint use
        request.state.vendor = vendor

        # Check if user has permission
        if not current_user.has_vendor_permission(vendor.id, permission):
            raise InsufficientVendorPermissionsException(
                required_permission=permission,
                vendor_code=vendor.vendor_code,
            )

        return current_user

    return permission_checker


def require_vendor_owner(
    request: Request,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_vendor_from_cookie_or_header),
) -> User:
    """
    Dependency to require vendor owner role.

    Uses token_vendor_id from JWT token (authenticated vendor API pattern).
    The vendor object is loaded and stored in request.state.vendor for endpoint use.

    Usage:
        @router.delete("/team/{user_id}")
        def remove_team_member(
            request: Request,
            user: User = Depends(require_vendor_owner)
        ):
            vendor = request.state.vendor  # Vendor is set by this dependency
            ...
    """
    # Get vendor ID from JWT token
    if not hasattr(current_user, "token_vendor_id"):
        raise InvalidTokenException("Token missing vendor information. Please login again.")

    vendor_id = current_user.token_vendor_id

    # Load vendor from database (raises VendorNotFoundException if not found)
    vendor = vendor_service.get_vendor_by_id(db, vendor_id)

    # Store vendor in request state for endpoint use
    request.state.vendor = vendor

    if not current_user.is_owner_of(vendor.id):
        raise VendorOwnerOnlyException(
            operation="team management",
            vendor_code=vendor.vendor_code,
        )

    return current_user


def require_any_vendor_permission(*permissions: str):
    """
    Dependency factory to require ANY of the specified permissions.

    Uses token_vendor_id from JWT token (authenticated vendor API pattern).
    The vendor object is loaded and stored in request.state.vendor for endpoint use.

    Usage:
        @router.get("/dashboard")
        def dashboard(
            request: Request,
            user: User = Depends(require_any_vendor_permission(
                VendorPermissions.DASHBOARD_VIEW.value,
                VendorPermissions.REPORTS_VIEW.value
            ))
        ):
            vendor = request.state.vendor  # Vendor is set by this dependency
            ...
    """

    def permission_checker(
        request: Request,
        db: Session = Depends(get_db),
        current_user: User = Depends(get_current_vendor_from_cookie_or_header),
    ) -> User:
        # Get vendor ID from JWT token
        if not hasattr(current_user, "token_vendor_id"):
            raise InvalidTokenException("Token missing vendor information. Please login again.")

        vendor_id = current_user.token_vendor_id

        # Load vendor from database (raises VendorNotFoundException if not found)
        vendor = vendor_service.get_vendor_by_id(db, vendor_id)

        # Store vendor in request state for endpoint use
        request.state.vendor = vendor

        # Check if user has ANY of the required permissions
        has_permission = any(
            current_user.has_vendor_permission(vendor.id, perm) for perm in permissions
        )

        if not has_permission:
            raise InsufficientVendorPermissionsException(
                required_permission=f"Any of: {', '.join(permissions)}",
                vendor_code=vendor.vendor_code,
            )

        return current_user

    return permission_checker


def require_all_vendor_permissions(*permissions: str):
    """
    Dependency factory to require ALL of the specified permissions.

    Uses token_vendor_id from JWT token (authenticated vendor API pattern).
    The vendor object is loaded and stored in request.state.vendor for endpoint use.

    Usage:
        @router.post("/products/bulk-delete")
        def bulk_delete_products(
            request: Request,
            user: User = Depends(require_all_vendor_permissions(
                VendorPermissions.PRODUCTS_VIEW.value,
                VendorPermissions.PRODUCTS_DELETE.value
            ))
        ):
            vendor = request.state.vendor  # Vendor is set by this dependency
            ...
    """

    def permission_checker(
        request: Request,
        db: Session = Depends(get_db),
        current_user: User = Depends(get_current_vendor_from_cookie_or_header),
    ) -> User:
        # Get vendor ID from JWT token
        if not hasattr(current_user, "token_vendor_id"):
            raise InvalidTokenException("Token missing vendor information. Please login again.")

        vendor_id = current_user.token_vendor_id

        # Load vendor from database (raises VendorNotFoundException if not found)
        vendor = vendor_service.get_vendor_by_id(db, vendor_id)

        # Store vendor in request state for endpoint use
        request.state.vendor = vendor

        # Check if user has ALL required permissions
        missing_permissions = [
            perm
            for perm in permissions
            if not current_user.has_vendor_permission(vendor.id, perm)
        ]

        if missing_permissions:
            raise InsufficientVendorPermissionsException(
                required_permission=f"All of: {', '.join(permissions)}",
                vendor_code=vendor.vendor_code,
            )

        return current_user

    return permission_checker


def get_user_permissions(
    request: Request,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_vendor_from_cookie_or_header),
) -> list:
    """
    Get all permissions for current user in current vendor.

    Uses token_vendor_id from JWT token (authenticated vendor API pattern).
    Also sets request.state.vendor for endpoint use.

    Returns empty list if no vendor context in token.
    """
    # Get vendor ID from JWT token
    if not hasattr(current_user, "token_vendor_id"):
        return []

    vendor_id = current_user.token_vendor_id

    # Load vendor from database
    vendor = vendor_service.get_vendor_by_id(db, vendor_id)

    # Store vendor in request state for endpoint use
    request.state.vendor = vendor

    # If owner, return all permissions
    if current_user.is_owner_of(vendor.id):
        from app.core.permissions import VendorPermissions

        return [p.value for p in VendorPermissions]

    # Get permissions from vendor membership
    for vm in current_user.vendor_memberships:
        if vm.vendor_id == vendor.id and vm.is_active:
            return vm.get_all_permissions()

    return []


# ============================================================================
# OPTIONAL AUTHENTICATION (For Login Page Redirects)
# ============================================================================


def get_current_admin_optional(
    request: Request,
    credentials: HTTPAuthorizationCredentials | None = Depends(security),
    admin_token: str | None = Cookie(None),
    db: Session = Depends(get_db),
) -> User | None:
    """
    Get current admin user from admin_token cookie or Authorization header.

    Returns None instead of raising exceptions if not authenticated.
    Used for login pages to check if user is already authenticated.

    Priority:
    1. Authorization header (API calls)
    2. admin_token cookie (page navigation)

    Args:
        request: FastAPI request
        credentials: Optional Bearer token from header
        admin_token: Optional token from admin_token cookie
        db: Database session

    Returns:
        User: Authenticated admin user if valid token exists
        None: If no token, invalid token, or user is not admin
    """
    token, source = _get_token_from_request(
        credentials, admin_token, "admin_token", str(request.url.path)
    )

    if not token:
        return None

    try:
        # Validate token and get user
        user = _validate_user_token(token, db)

        # Verify user is admin
        if user.role == "admin":
            return user
    except Exception:
        # Invalid token or other error
        pass

    return None


def get_current_vendor_optional(
    request: Request,
    credentials: HTTPAuthorizationCredentials | None = Depends(security),
    vendor_token: str | None = Cookie(None),
    db: Session = Depends(get_db),
) -> User | None:
    """
    Get current vendor user from vendor_token cookie or Authorization header.

    Returns None instead of raising exceptions if not authenticated.
    Used for login pages to check if user is already authenticated.

    Priority:
    1. Authorization header (API calls)
    2. vendor_token cookie (page navigation)

    Args:
        request: FastAPI request
        credentials: Optional Bearer token from header
        vendor_token: Optional token from vendor_token cookie
        db: Database session

    Returns:
        User: Authenticated vendor user if valid token exists
        None: If no token, invalid token, or user is not vendor
    """
    token, source = _get_token_from_request(
        credentials, vendor_token, "vendor_token", str(request.url.path)
    )

    if not token:
        return None

    try:
        # Validate token and get user
        user = _validate_user_token(token, db)

        # Verify user is vendor
        if user.role == "vendor":
            return user
    except Exception:
        # Invalid token or other error
        pass

    return None


def get_current_customer_optional(
    request: Request,
    credentials: HTTPAuthorizationCredentials | None = Depends(security),
    customer_token: str | None = Cookie(None),
    db: Session = Depends(get_db),
):
    """
    Get current customer from customer_token cookie or Authorization header.

    Returns None instead of raising exceptions if not authenticated.
    Used for login pages to check if user is already authenticated.

    Priority:
    1. Authorization header (API calls)
    2. customer_token cookie (page navigation)

    Args:
        request: FastAPI request
        credentials: Optional Bearer token from header
        customer_token: Optional token from customer_token cookie
        db: Database session

    Returns:
        Customer: Authenticated customer if valid token exists
        None: If no token, invalid token, or vendor mismatch
    """
    token, source = _get_token_from_request(
        credentials, customer_token, "customer_token", str(request.url.path)
    )

    if not token:
        return None

    try:
        # Validate customer token (includes vendor validation)
        return _validate_customer_token(token, request, db)
    except Exception:
        # Invalid token, vendor mismatch, or other error
        return None