How to build a maintenance mode page in Python

from datetime import datetime

class MaintenanceMode:
    """Mock a maintenance mode status page for a service."""
    
    def __init__(self, service_name: str, scheduled_end: str):
        self.service_name = service_name
        self.scheduled_end = datetime.fromisoformat(scheduled_end)
        self.affected_features = []
    
    def add_affected_feature(self, feature: str):
        self.affected_features.append(feature)
    
    def render_page(self) -> str:
        now = datetime.now()
        remaining = self.scheduled_end - now
        status = "restoring service" if remaining.total_seconds() > 0 else "service available"
        
        header = f"=== {self.service_name.upper()} — {status} ==="
        body = [
            header,
            f"Scheduled maintenance until: {self.scheduled_end:%Y-%m-%d %H:%M}",
            f"Estimated time remaining: {max(0, remaining.total_seconds() // 3600)}h {max(0, (remaining.total_seconds() // 60) % 60)}m",
            self._render_features(),
            "We appreciate your patience while we improve reliability.",
        ]
        return "\n".join(body)
    
    def _render_features(self) -> str:
        if not self.affected_features:
            return "All features available."
        return "Temporarily unavailable:\n- " + "\n- ".join(self.affected_features)

if __name__ == "__main__":
    page = MaintenanceMode("Weather API", "2024-12-31T23:59:00")
    page.add_affected_feature("Real-time forecasts")
    page.add_affected_feature("Historical data retrieval")
    print(page.render_page())