"""In-memory notification store used when Postgres is not configured.

Mirrors MockEventStore's role for BaseEventStore: keeps the feature usable in
local dev and in tests without a live database, and matches
DOCUMENT_REPOSITORY_BACKEND's existing Mock/Postgres split.
"""

from __future__ import annotations

from datetime import UTC, datetime

from app.infrastructure.perception.base_notification_store import BaseNotificationStore


class MockNotificationStore(BaseNotificationStore):
    """Dict-backed notification store. Data does not survive a process restart."""

    def __init__(self) -> None:
        """Start with an empty feed and no read receipts."""
        self._notifications: list[dict] = []
        self._next_id = 1
        # (notification_id, user_id) pairs — presence means read.
        self._reads: set[tuple[int, str]] = set()

    def create(
        self,
        *,
        event_id: str,
        kind: str,
        title: str,
        impact_level: str | None,
        summary: str | None,
    ) -> None:
        """Append a notification with an auto-incrementing id."""
        self._notifications.append({
            "id": self._next_id,
            "event_id": event_id,
            "kind": kind,
            "title": title,
            "impact_level": impact_level,
            "summary": summary,
            "created_at": datetime.now(UTC).isoformat(),
        })
        self._next_id += 1

    def list_for_user(self, user_id: str, limit: int = 20) -> list[dict]:
        """Return the newest `limit` notifications with this user's read state."""
        ordered = sorted(self._notifications, key=lambda n: n["id"], reverse=True)
        return [
            {**n, "read": (n["id"], user_id) in self._reads}
            for n in ordered[:limit]
        ]

    def unread_count(self, user_id: str) -> int:
        """Count notifications this user has not yet read."""
        return sum(1 for n in self._notifications if (n["id"], user_id) not in self._reads)

    def mark_all_read(self, user_id: str) -> int:
        """Add a read receipt for every currently-unread notification."""
        marked = 0
        for n in self._notifications:
            key = (n["id"], user_id)
            if key not in self._reads:
                self._reads.add(key)
                marked += 1
        return marked