"""History sync background task.

Periodically copies new records from the fail2ban sqlite database into the
BanGUI application archive table to prevent gaps when fail2ban purges old rows.
"""

from __future__ import annotations

import datetime
from typing import TYPE_CHECKING

import structlog

from app.repositories import fail2ban_db_repo
from app.utils.fail2ban_db_utils import get_fail2ban_db_path

if TYPE_CHECKING:  # pragma: no cover
    from fastapi import FastAPI

log: structlog.stdlib.BoundLogger = structlog.get_logger()

#: Stable APScheduler job id.
JOB_ID: str = "history_sync"

#: Interval in seconds between sync runs.
HISTORY_SYNC_INTERVAL: int = 300

#: Backfill window when archive is empty (seconds).
BACKFILL_WINDOW: int = 7 * 86400


async def _get_last_archive_ts(db) -> int | None:
    async with db.execute("SELECT MAX(timeofban) FROM history_archive") as cur:
        row = await cur.fetchone()
    if row is None or row[0] is None:
        return None
    return int(row[0])


async def _run_sync(app: FastAPI) -> None:
    db = app.state.db
    socket_path: str = app.state.settings.fail2ban_socket

    try:
        last_ts = await _get_last_archive_ts(db)
        now_ts = int(datetime.datetime.now(datetime.UTC).timestamp())

        if last_ts is None:
            last_ts = now_ts - BACKFILL_WINDOW
            log.info("history_sync_backfill", window_seconds=BACKFILL_WINDOW)

        per_page = 500
        next_since = last_ts
        total_synced = 0

        while True:
            fail2ban_db_path = await get_fail2ban_db_path(socket_path)
            rows, total = await fail2ban_db_repo.get_history_page(
                db_path=fail2ban_db_path,
                since=next_since,
                page=1,
                page_size=per_page,
            )

            if not rows:
                break

            from app.repositories.history_archive_repo import archive_ban_event

            for row in rows:
                await archive_ban_event(
                    db=db,
                    jail=row.jail,
                    ip=row.ip,
                    timeofban=row.timeofban,
                    bancount=row.bancount,
                    data=row.data,
                    action="ban",
                )
                total_synced += 1

            # Continue where we left off by max timeofban + 1.
            max_time = max(row.timeofban for row in rows)
            next_since = max_time + 1

            if len(rows) < per_page:
                break

        log.info("history_sync_complete", synced=total_synced)

    except Exception:
        log.exception("history_sync_failed")


def register(app: FastAPI) -> None:
    """Register the history sync periodic job.

    Should be called after scheduler startup, from the lifespan handler.
    """
    app.state.scheduler.add_job(
        _run_sync,
        trigger="interval",
        seconds=HISTORY_SYNC_INTERVAL,
        kwargs={"app": app},
        id=JOB_ID,
        replace_existing=True,
        next_run_time=datetime.datetime.now(tz=datetime.UTC),
    )
    log.info("history_sync_scheduled", interval_seconds=HISTORY_SYNC_INTERVAL)