import base64
import json
import sqlite3

from edge.events import Event, EventType, Severity


class OfflineQueue:
    def __init__(self, db_path: str, client):
        self.client = client
        self.db = sqlite3.connect(db_path)
        self.db.execute(
            "CREATE TABLE IF NOT EXISTS queue ("
            "id INTEGER PRIMARY KEY AUTOINCREMENT, payload TEXT, snaps TEXT)"
        )
        self.db.commit()

    def _rehydrate(self, payload: dict, snaps: list[bytes]) -> tuple[Event, list[bytes]]:
        e = Event(EventType(payload["event_type"]), Severity(payload["severity"]),
                  payload["camera_id"], payload["track_id"], payload["zone_id"],
                  payload["occurred_at"], payload["duration_s"], payload["metrics"],
                  tuple(payload["spatial"]) if payload.get("spatial") else None)
        return e, snaps

    def enqueue(self, event: Event, snapshots: list[bytes]) -> None:
        payload = event.to_payload("")  # device_id는 client가 다시 채움
        payload["event_type"] = event.event_type.value
        payload["severity"] = event.severity.value
        payload["spatial"] = list(event.spatial) if event.spatial else None
        snaps = [base64.b64encode(s).decode() for s in snapshots]
        self.db.execute("INSERT INTO queue (payload, snaps) VALUES (?, ?)",
                        (json.dumps(payload), json.dumps(snaps)))
        self.db.commit()

    def try_send(self, event: Event, snapshots: list[bytes]) -> bool:
        if self.client.send(event, snapshots):
            return True
        self.enqueue(event, snapshots)
        return False

    def flush(self) -> int:
        rows = self.db.execute("SELECT id, payload, snaps FROM queue ORDER BY id").fetchall()
        sent = 0
        for rid, payload_json, snaps_json in rows:
            payload = json.loads(payload_json)
            snaps = [base64.b64decode(s) for s in json.loads(snaps_json)]
            event, snapshots = self._rehydrate(payload, snaps)
            if self.client.send(event, snapshots):
                self.db.execute("DELETE FROM queue WHERE id = ?", (rid,))
                self.db.commit()
                sent += 1
            else:
                break  # 여전히 오프라인 — 순서 보존
        return sent

    def pending(self) -> int:
        return self.db.execute("SELECT COUNT(*) FROM queue").fetchone()[0]