348 lines
11 KiB
Python
348 lines
11 KiB
Python
# app/exceptions/error_renderer.py
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"""
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Error Page Renderer
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Renders context-aware error pages using Jinja2 templates.
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Handles fallback logic and context-specific customization.
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"""
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import logging
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from pathlib import Path
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from typing import Optional, Dict, Any
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from fastapi import Request
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from fastapi.responses import HTMLResponse
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from fastapi.templating import Jinja2Templates
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from middleware.context import RequestContext, get_request_context
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logger = logging.getLogger(__name__)
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class ErrorPageRenderer:
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"""Renders context-aware error pages using Jinja2 templates."""
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# Map status codes to friendly names
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STATUS_CODE_NAMES = {
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400: "Bad Request",
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401: "Unauthorized",
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403: "Forbidden",
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404: "Not Found",
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422: "Validation Error",
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429: "Too Many Requests",
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500: "Internal Server Error",
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502: "Bad Gateway",
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503: "Service Unavailable",
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}
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# Map status codes to user-friendly messages
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STATUS_CODE_MESSAGES = {
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400: "The request could not be processed due to invalid data.",
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401: "You need to be authenticated to access this resource.",
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403: "You don't have permission to access this resource.",
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404: "The page you're looking for doesn't exist or has been moved.",
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422: "The submitted data contains validation errors.",
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429: "Too many requests. Please slow down and try again later.",
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500: "Something went wrong on our end. We're working to fix it.",
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502: "Unable to reach the service. Please try again later.",
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503: "The service is temporarily unavailable. Please try again later.",
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}
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@staticmethod
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def get_templates_dir() -> Path:
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"""Get the templates directory path."""
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# Assuming templates are in app/templates/
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base_dir = Path(__file__).resolve().parent.parent
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return base_dir / "templates"
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@staticmethod
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def render_error_page(
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request: Request,
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status_code: int,
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error_code: str,
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message: str,
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details: Optional[Dict[str, Any]] = None,
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show_debug: bool = False,
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) -> HTMLResponse:
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"""
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Render appropriate error page based on request context.
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Template Selection Priority:
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1. Context-specific error page: {context}/errors/{status_code}.html
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2. Context-specific generic: {context}/errors/generic.html
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3. Fallback error page: fallback/{status_code}.html
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4. Fallback generic: fallback/generic.html
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Args:
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request: FastAPI request object
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status_code: HTTP status code
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error_code: Application error code
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message: Error message
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details: Additional error details
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show_debug: Whether to show debug information
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Returns:
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HTMLResponse with rendered error page
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"""
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# Get request context
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context_type = get_request_context(request)
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# Prepare template data
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template_data = ErrorPageRenderer._prepare_template_data(
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request=request,
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context_type=context_type,
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status_code=status_code,
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error_code=error_code,
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message=message,
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details=details,
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show_debug=show_debug,
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)
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# Find and render template
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templates_dir = ErrorPageRenderer.get_templates_dir()
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templates = Jinja2Templates(directory=str(templates_dir))
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# Try to find appropriate template
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template_path = ErrorPageRenderer._find_template(
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context_type=context_type,
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status_code=status_code,
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)
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logger.info(
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f"Rendering error page: {template_path} for {status_code} in {context_type.value} context",
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extra={
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"status_code": status_code,
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"error_code": error_code,
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"context": context_type.value,
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"template": template_path,
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}
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)
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try:
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# Render template
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return templates.TemplateResponse(
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template_path,
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{
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"request": request,
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**template_data,
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},
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status_code=status_code,
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)
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except Exception as e:
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logger.error(
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f"Failed to render error template {template_path}: {e}",
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exc_info=True
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)
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# Return basic HTML as absolute fallback
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return ErrorPageRenderer._render_basic_html_fallback(
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status_code=status_code,
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error_code=error_code,
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message=message,
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)
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@staticmethod
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def _find_template(
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context_type: RequestContext,
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status_code: int,
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) -> str:
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"""
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Find appropriate error template based on context and status code.
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Priority:
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1. {context}/errors/{status_code}.html
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2. {context}/errors/generic.html
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3. fallback/{status_code}.html
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4. fallback/generic.html
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"""
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templates_dir = ErrorPageRenderer.get_templates_dir()
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# Map context type to folder name
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context_folders = {
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RequestContext.ADMIN: "admin",
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RequestContext.VENDOR_DASHBOARD: "vendor",
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RequestContext.SHOP: "shop",
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RequestContext.API: "fallback", # API shouldn't get here, but just in case
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RequestContext.FALLBACK: "fallback",
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}
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context_folder = context_folders.get(context_type, "fallback")
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# Try context-specific status code template
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specific_template = f"{context_folder}/errors/{status_code}.html"
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if (templates_dir / specific_template).exists():
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return specific_template
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# Try context-specific generic template
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generic_template = f"{context_folder}/errors/generic.html"
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if (templates_dir / generic_template).exists():
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return generic_template
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# Try fallback status code template
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fallback_specific = f"fallback/{status_code}.html"
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if (templates_dir / fallback_specific).exists():
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return fallback_specific
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# Use fallback generic template (must exist)
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return "fallback/generic.html"
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@staticmethod
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def _prepare_template_data(
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request: Request,
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context_type: RequestContext,
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status_code: int,
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error_code: str,
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message: str,
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details: Optional[Dict[str, Any]],
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show_debug: bool,
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) -> Dict[str, Any]:
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"""Prepare data dictionary for error template."""
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# Get friendly status name
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status_name = ErrorPageRenderer.STATUS_CODE_NAMES.get(
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status_code, f"Error {status_code}"
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)
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# Get default user-friendly message
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default_message = ErrorPageRenderer.STATUS_CODE_MESSAGES.get(
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status_code, "An error occurred while processing your request."
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)
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# Use provided message or default
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user_message = message if message else default_message
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# Determine if we should show debug info
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# Only show to admins (we can check user role if available)
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display_debug = show_debug and ErrorPageRenderer._is_admin_user(request)
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# Get context-specific data
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context_data = ErrorPageRenderer._get_context_data(request, context_type)
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return {
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"status_code": status_code,
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"status_name": status_name,
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"error_code": error_code,
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"message": user_message,
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"details": details or {},
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"show_debug": display_debug,
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"context_type": context_type.value,
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"path": request.url.path,
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**context_data,
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}
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@staticmethod
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def _get_context_data(request: Request, context_type: RequestContext) -> Dict[str, Any]:
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"""Get context-specific data for error templates."""
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data = {}
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# Add vendor information if available (for shop context)
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if context_type == RequestContext.SHOP:
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vendor = getattr(request.state, "vendor", None)
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if vendor:
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# Pass minimal vendor info for templates
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data["vendor"] = {
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"id": vendor.id,
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"name": vendor.name,
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"subdomain": vendor.subdomain,
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"logo": getattr(vendor, "logo", None),
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}
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# Add theme information if available
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theme = getattr(request.state, "theme", None)
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if theme:
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# Theme can be a dict or object, handle both
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if isinstance(theme, dict):
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data["theme"] = theme
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else:
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# If it's an object, convert to dict
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data["theme"] = {
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"colors": getattr(theme, "colors", {}),
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"fonts": getattr(theme, "fonts", {}),
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"branding": getattr(theme, "branding", {}),
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"custom_css": getattr(theme, "custom_css", None),
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}
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return data
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@staticmethod
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def _is_admin_user(request: Request) -> bool:
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"""
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Check if current user is an admin (for debug info display).
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This is a placeholder - implement based on your auth system.
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"""
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# TODO: Implement actual admin check based on JWT/session
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# For now, check if we're in admin context
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context_type = get_request_context(request)
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return context_type == RequestContext.ADMIN
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@staticmethod
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def _render_basic_html_fallback(
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status_code: int,
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error_code: str,
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message: str,
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) -> HTMLResponse:
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"""
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Render a basic HTML error page as absolute fallback.
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Used when template rendering fails.
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"""
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html_content = f"""
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<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta charset="UTF-8">
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<meta name="viewport" content="width=device-width, initial-scale=1.0">
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<title>{status_code} - Error</title>
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<style>
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* {{
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margin: 0;
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padding: 0;
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box-sizing: border-box;
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}}
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body {{
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font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
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background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
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min-height: 100vh;
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display: flex;
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align-items: center;
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justify-content: center;
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color: white;
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padding: 2rem;
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}}
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.container {{
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text-align: center;
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max-width: 600px;
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}}
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h1 {{
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font-size: 6rem;
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font-weight: 700;
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margin-bottom: 1rem;
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text-shadow: 2px 2px 4px rgba(0,0,0,0.2);
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}}
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h2 {{
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font-size: 1.5rem;
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font-weight: 400;
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margin-bottom: 1rem;
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}}
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p {{
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font-size: 1.1rem;
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margin-bottom: 2rem;
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opacity: 0.9;
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}}
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.error-code {{
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font-size: 0.9rem;
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opacity: 0.7;
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font-family: 'Courier New', monospace;
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}}
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</style>
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</head>
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<body>
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<div class="container">
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<h1>{status_code}</h1>
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<h2>Error</h2>
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<p>{message}</p>
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<div class="error-code">Error Code: {error_code}</div>
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</div>
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</body>
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</html>
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"""
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return HTMLResponse(content=html_content, status_code=status_code)
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