weather-alerts/app/models/state.py

"""State management models for alert deduplication and change detection."""

from dataclasses import dataclass, field
from datetime import datetime
from typing import Any, Optional


@dataclass
class SentAlertRecord:
    """Record of a sent alert for deduplication."""

    dedup_key: str
    alert_type: str
    sent_at: datetime
    forecast_hour: str

    def to_dict(self) -> dict[str, Any]:
        """Convert to dictionary for JSON serialization."""
        return {
            "dedup_key": self.dedup_key,
            "alert_type": self.alert_type,
            "sent_at": self.sent_at.isoformat(),
            "forecast_hour": self.forecast_hour,
        }

    @classmethod
    def from_dict(cls, data: dict[str, Any]) -> "SentAlertRecord":
        """Create from dictionary.

        Args:
            data: The serialized record dict.

        Returns:
            A SentAlertRecord instance.
        """
        return cls(
            dedup_key=data["dedup_key"],
            alert_type=data["alert_type"],
            sent_at=datetime.fromisoformat(data["sent_at"]),
            forecast_hour=data["forecast_hour"],
        )


@dataclass
class AlertSnapshot:
    """Snapshot of an alert for change detection between runs."""

    alert_type: str
    extreme_value: float
    threshold: float
    start_time: str
    end_time: str
    hour_count: int
    captured_at: datetime = field(default_factory=datetime.now)

    def to_dict(self) -> dict[str, Any]:
        """Convert to dictionary for JSON serialization."""
        return {
            "alert_type": self.alert_type,
            "extreme_value": self.extreme_value,
            "threshold": self.threshold,
            "start_time": self.start_time,
            "end_time": self.end_time,
            "hour_count": self.hour_count,
            "captured_at": self.captured_at.isoformat(),
        }

    @classmethod
    def from_dict(cls, data: dict[str, Any]) -> "AlertSnapshot":
        """Create from dictionary.

        Args:
            data: The serialized snapshot dict.

        Returns:
            An AlertSnapshot instance.
        """
        return cls(
            alert_type=data["alert_type"],
            extreme_value=data["extreme_value"],
            threshold=data["threshold"],
            start_time=data["start_time"],
            end_time=data["end_time"],
            hour_count=data["hour_count"],
            captured_at=datetime.fromisoformat(data["captured_at"]),
        )


@dataclass
class AlertState:
    """State container for tracking sent alerts and change detection."""

    sent_alerts: dict[str, SentAlertRecord] = field(default_factory=dict)
    last_updated: datetime = field(default_factory=datetime.now)
    previous_alert_snapshots: dict[str, AlertSnapshot] = field(default_factory=dict)
    last_ai_summary_sent: Optional[datetime] = None

    def is_duplicate(self, dedup_key: str) -> bool:
        """Check if an alert with this dedup key has already been sent.

        Args:
            dedup_key: The deduplication key to check.

        Returns:
            True if this alert has already been sent.
        """
        return dedup_key in self.sent_alerts

    def record_sent(self, dedup_key: str, alert_type: str, forecast_hour: str) -> None:
        """Record that an alert was sent.

        Args:
            dedup_key: The deduplication key.
            alert_type: The type of alert.
            forecast_hour: The forecast hour this alert was for.
        """
        self.sent_alerts[dedup_key] = SentAlertRecord(
            dedup_key=dedup_key,
            alert_type=alert_type,
            sent_at=datetime.now(),
            forecast_hour=forecast_hour,
        )
        self.last_updated = datetime.now()

    def purge_old_records(self, window_hours: int) -> int:
        """Remove records older than the deduplication window.

        Args:
            window_hours: Number of hours to retain records.

        Returns:
            Number of records purged.
        """
        cutoff = datetime.now()
        original_count = len(self.sent_alerts)

        self.sent_alerts = {
            key: record
            for key, record in self.sent_alerts.items()
            if (cutoff - record.sent_at).total_seconds() < (window_hours * 3600)
        }

        purged = original_count - len(self.sent_alerts)
        if purged > 0:
            self.last_updated = datetime.now()

        return purged

    def to_dict(self) -> dict[str, Any]:
        """Convert to dictionary for JSON serialization."""
        return {
            "sent_alerts": {
                key: record.to_dict() for key, record in self.sent_alerts.items()
            },
            "last_updated": self.last_updated.isoformat(),
            "previous_alert_snapshots": {
                key: snapshot.to_dict()
                for key, snapshot in self.previous_alert_snapshots.items()
            },
            "last_ai_summary_sent": (
                self.last_ai_summary_sent.isoformat()
                if self.last_ai_summary_sent
                else None
            ),
        }

    @classmethod
    def from_dict(cls, data: dict[str, Any]) -> "AlertState":
        """Create from dictionary.

        Args:
            data: The serialized state dict.

        Returns:
            An AlertState instance.
        """
        sent_alerts = {
            key: SentAlertRecord.from_dict(record_data)
            for key, record_data in data.get("sent_alerts", {}).items()
        }

        last_updated_str = data.get("last_updated")
        last_updated = (
            datetime.fromisoformat(last_updated_str)
            if last_updated_str
            else datetime.now()
        )

        previous_alert_snapshots = {
            key: AlertSnapshot.from_dict(snapshot_data)
            for key, snapshot_data in data.get("previous_alert_snapshots", {}).items()
        }

        last_ai_summary_str = data.get("last_ai_summary_sent")
        last_ai_summary_sent = (
            datetime.fromisoformat(last_ai_summary_str)
            if last_ai_summary_str
            else None
        )

        return cls(
            sent_alerts=sent_alerts,
            last_updated=last_updated,
            previous_alert_snapshots=previous_alert_snapshots,
            last_ai_summary_sent=last_ai_summary_sent,
        )