Helper Functions and Utilities

def abort(code: int, *args, **kwargs) -> NoReturn:
    """
    Raise HTTP exception with specified status code.
    
    Args:
        code: HTTP status code (400, 404, 500, etc.)
        *args: Additional arguments for exception
        **kwargs: Additional keyword arguments
        
    Raises:
        HTTPException: Always raises, never returns
    """

async def make_response(*args) -> Response:
    """
    Create response object from various input types.
    
    Args:
        *args: Response data (string, dict, tuple, Response, etc.)
        
    Returns:
        Response object
    """

def redirect(location: str, code: int = 302, Response=None) -> Response:
    """
    Create redirect response.
    
    Args:
        location: URL to redirect to
        code: HTTP redirect status code (301, 302, 303, 307, 308)
        Response: Custom response class (optional)
        
    Returns:
        Redirect response object
    """

def url_for(endpoint: str, **values) -> str:
    """
    Generate URL for endpoint with given parameters.
    
    Args:
        endpoint: Endpoint name (function name or 'blueprint.function_name')
        **values: URL parameters and query string arguments
        
    Returns:
        Generated URL string
        
    Example:
        url_for('user_profile', username='john', page=2)
        # Returns: '/user/john?page=2'
    """

async def send_file(
    filename_or_io,
    mimetype: str | None = None,
    as_attachment: bool = False,
    download_name: str | None = None,
    conditional: bool = True,
    etag: bool | str = True,
    last_modified: datetime | None = None,
    max_age: int | None = None,
    cache_timeout: int | None = None
) -> Response:
    """
    Send file as response with proper headers.
    
    Args:
        filename_or_io: File path or file-like object
        mimetype: MIME type (auto-detected if None)
        as_attachment: Force download vs inline display
        download_name: Filename for download
        conditional: Enable conditional requests (304 responses)
        etag: ETag value or True for auto-generation
        last_modified: Last modified datetime
        max_age: Cache max-age in seconds
        cache_timeout: Deprecated, use max_age
        
    Returns:
        File response with appropriate headers
    """

async def send_from_directory(
    directory: str, 
    filename: str, 
    **kwargs
) -> Response:
    """
    Send file from directory with path safety checks.
    
    Args:
        directory: Base directory path
        filename: Filename within directory (path traversal protected)
        **kwargs: Additional arguments for send_file()
        
    Returns:
        File response
        
    Raises:
        NotFound: If file doesn't exist or path is invalid
    """

async def flash(message: str, category: str = "message"):
    """
    Add flash message to session for next request.
    
    Args:
        message: Message text to display
        category: Message category ('message', 'error', 'warning', 'info')
    """

def get_flashed_messages(
    with_categories: bool = False, 
    category_filter: tuple = ()
) -> list:
    """
    Retrieve and clear flash messages from session.
    
    Args:
        with_categories: Return (category, message) tuples instead of just messages
        category_filter: Only return messages from specified categories
        
    Returns:
        List of messages or (category, message) tuples
    """

def jsonify(*args, **kwargs) -> Response:
    """
    Create JSON response from data.
    
    Args:
        *args: Positional arguments (single value becomes response)
        **kwargs: Keyword arguments (become JSON object)
        
    Returns:
        Response with JSON content and appropriate headers
        
    Examples:
        jsonify({'key': 'value'})  # JSON object
        jsonify([1, 2, 3])         # JSON array
        jsonify(key='value')       # JSON object from kwargs
    """

def dumps(obj, **kwargs) -> str:
    """
    Serialize object to JSON string using app's JSON encoder.
    
    Args:
        obj: Object to serialize
        **kwargs: Additional arguments for json.dumps()
        
    Returns:
        JSON string
    """

def dump(obj, fp, **kwargs):
    """
    Serialize object to JSON file using app's JSON encoder.
    
    Args:
        obj: Object to serialize
        fp: File-like object to write to
        **kwargs: Additional arguments for json.dump()
    """

def loads(s: str, **kwargs):
    """
    Deserialize JSON string using app's JSON decoder.
    
    Args:
        s: JSON string to deserialize
        **kwargs: Additional arguments for json.loads()
        
    Returns:
        Deserialized Python object
    """

def load(fp, **kwargs):
    """
    Deserialize JSON file using app's JSON decoder.
    
    Args:
        fp: File-like object to read from
        **kwargs: Additional arguments for json.load()
        
    Returns:
        Deserialized Python object
    """

async def make_push_promise(path: str):
    """
    Create HTTP/2 server push promise.
    
    Args:
        path: Resource path to push to client
        
    Note:
        Only works with HTTP/2 compatible servers
    """

def stream_with_context(func: Callable):
    """
    Decorator to stream response while preserving request context.
    
    Args:
        func: Generator function that yields response chunks
        
    Returns:
        Decorated function that maintains context during streaming
    """

def get_template_attribute(template_name: str, attribute: str):
    """
    Get attribute from template without rendering.
    
    Args:
        template_name: Template file name
        attribute: Attribute name to retrieve
        
    Returns:
        Template attribute value
    """

from quart import Quart, abort, make_response, redirect, url_for

app = Quart(__name__)

@app.route('/user/<int:user_id>')
async def user_profile(user_id):
    user = await get_user(user_id)
    if not user:
        abort(404)  # Raises 404 Not Found
    
    return f"User: {user.name}"

@app.route('/admin')
async def admin_area():
    if not current_user.is_admin:
        abort(403)  # Raises 403 Forbidden
    
    return "Admin Dashboard"

@app.route('/custom-response')
async def custom_response():
    # Create custom response
    response = await make_response("Custom content")
    response.status_code = 201
    response.headers['X-Custom'] = 'value'
    return response

@app.route('/login', methods=['POST'])
async def login():
    # Process login...
    if login_successful:
        return redirect(url_for('dashboard'))
    else:
        return redirect(url_for('login_form', error='invalid'))

@app.route('/old-url')
async def old_url():
    # Permanent redirect
    return redirect(url_for('new_url'), code=301)

from quart import Quart, send_file, send_from_directory

app = Quart(__name__)

@app.route('/download/<filename>')
async def download_file(filename):
    # Send file as download
    return await send_from_directory(
        'uploads', 
        filename,
        as_attachment=True,
        download_name=f"document_{filename}"
    )

@app.route('/image/<image_id>')
async def serve_image(image_id):
    # Serve image with caching
    image_path = f"/images/{image_id}.jpg"
    return await send_file(
        image_path,
        mimetype='image/jpeg',
        max_age=3600  # Cache for 1 hour
    )

@app.route('/report/pdf')
async def generate_report():
    # Generate PDF and send
    pdf_data = await generate_pdf_report()
    
    return await send_file(
        io.BytesIO(pdf_data),
        mimetype='application/pdf',
        as_attachment=True,
        download_name=f'report_{datetime.now().date()}.pdf'
    )

@app.route('/avatar/<username>')
async def user_avatar(username):
    # Serve user avatar with fallback
    avatar_path = f"/avatars/{username}.png"
    
    if os.path.exists(avatar_path):
        return await send_file(avatar_path, max_age=1800)
    else:
        # Send default avatar
        return await send_file("/static/default_avatar.png")

from quart import Quart, flash, get_flashed_messages, render_template, redirect, url_for

app = Quart(__name__)
app.secret_key = 'secret-key-for-sessions'

@app.route('/form', methods=['POST'])
async def process_form():
    form_data = await request.form
    
    try:
        # Process form data
        result = await process_user_data(form_data)
        
        await flash(f'Successfully processed {result.count} items!', 'success')
        await flash('Data has been saved to the database.', 'info')
        
    except ValidationError as e:
        await flash(f'Validation error: {e}', 'error')
    except Exception as e:
        await flash('An unexpected error occurred.', 'error')
    
    return redirect(url_for('show_form'))

@app.route('/form')
async def show_form():
    # Get flash messages for template
    messages = get_flashed_messages(with_categories=True)
    
    return await render_template('form.html', messages=messages)

@app.route('/admin/bulk-update', methods=['POST'])
async def bulk_update():
    try:
        updates = await perform_bulk_update()
        
        for category, count in updates.items():
            await flash(f'Updated {count} {category} records', 'success')
            
    except Exception as e:
        await flash('Bulk update failed', 'error')
        await flash(str(e), 'error')
    
    return redirect(url_for('admin_dashboard'))

# Template usage (form.html):
"""
{% for category, message in messages %}
    <div class="alert alert-{{ category }}">{{ message }}</div>
{% endfor %}
"""

from quart import Quart, jsonify, request
import json

app = Quart(__name__)

@app.route('/api/users')
async def api_users():
    users = await get_all_users()
    return jsonify({
        'users': users,
        'count': len(users),
        'status': 'success'
    })

@app.route('/api/user/<int:user_id>')
async def api_user(user_id):
    user = await get_user(user_id)
    if not user:
        return jsonify({'error': 'User not found'}), 404
    
    return jsonify(user.to_dict())

@app.route('/api/search')
async def api_search():
    query = request.args.get('q', '')
    results = await search_database(query)
    
    # Use jsonify with kwargs
    return jsonify(
        query=query,
        results=results,
        total=len(results),
        timestamp=datetime.now().isoformat()
    )

@app.route('/api/bulk-data')
async def bulk_data():
    # Large dataset
    data = await get_large_dataset()
    
    # Custom JSON encoding
    return jsonify(data), 200, {
        'Content-Type': 'application/json; charset=utf-8',
        'Cache-Control': 'max-age=300'
    }

# Custom JSON encoder for complex objects
class CustomJSONEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, datetime):
            return obj.isoformat()
        if isinstance(obj, Decimal):
            return float(obj)
        return super().default(obj)

app.json_encoder = CustomJSONEncoder

from quart import Quart, stream_with_context, make_push_promise, Response
import asyncio

app = Quart(__name__)

@app.route('/streaming-data')
async def streaming_data():
    @stream_with_context
    async def generate():
        for i in range(100):
            # Access request context during streaming
            user_id = request.args.get('user_id')
            data = await get_user_data(user_id, page=i)
            
            yield f"data: {json.dumps(data)}\n\n"
            await asyncio.sleep(0.1)
    
    return Response(generate(), mimetype='text/plain')

@app.route('/with-push-promise')
async def with_push_promise():
    # Push critical resources to client (HTTP/2)
    await make_push_promise('/static/critical.css')
    await make_push_promise('/static/critical.js')
    
    return await render_template('page.html')

@app.route('/template-data/<template_name>')
async def template_data(template_name):
    # Get template metadata without rendering
    try:
        title = get_template_attribute(f'{template_name}.html', 'title')
        description = get_template_attribute(f'{template_name}.html', 'description')
        
        return jsonify({
            'template': template_name,
            'title': title,
            'description': description
        })
    except Exception as e:
        return jsonify({'error': str(e)}), 404

@app.route('/server-sent-events')
async def server_sent_events():
    @stream_with_context
    async def event_stream():
        yield "data: Connected to event stream\n\n"
        
        while True:
            # Real-time data streaming
            event_data = await get_next_event()
            yield f"data: {json.dumps(event_data)}\n\n"
            
            await asyncio.sleep(1)
    
    return Response(
        event_stream(),
        mimetype='text/event-stream',
        headers={
            'Cache-Control': 'no-cache',
            'Connection': 'keep-alive'
        }
    )