"""APScheduler background scheduler for upstream checks and daily tasks."""
from __future__ import annotations

import json
import logging
from datetime import datetime, timezone
from typing import Any

from apscheduler.executors.pool import ThreadPoolExecutor
from apscheduler.schedulers.background import BackgroundScheduler
from apscheduler.triggers.cron import CronTrigger
from sqlalchemy.orm import Session

from app.database import SessionLocal
from app.models.upstream import Upstream
from app.models.snapshot import UpstreamRateSnapshot
from app.services.auth_config import normalize_auth_config
from app.services.upstream_client import UpstreamClient, build_snapshot
from app.services.snapshot_service import diff_snapshots, prune_snapshots
from app.services import webhook_service
from app.services import website_sync
from app.config import get_settings
from app.routers.external_api_logs import clean_expired_logs

logger = logging.getLogger(__name__)

_scheduler = BackgroundScheduler(timezone="UTC", executors={"default": ThreadPoolExecutor(max_workers=1)})


def get_scheduler() -> BackgroundScheduler:
    return _scheduler


def _persist_auth_config_update(upstream: Upstream, updated_config: dict[str, Any]) -> None:
    config_json = json.dumps(
        normalize_auth_config(upstream.auth_type, updated_config),
        ensure_ascii=False,
    )
    updated_at = datetime.now(timezone.utc)
    db = SessionLocal()
    try:
        row = db.query(Upstream).filter(Upstream.id == upstream.id).first()
        if row:
            row.auth_config_json = config_json
            row.updated_at = updated_at
            db.commit()
            upstream.auth_config_json = row.auth_config_json
            upstream.updated_at = updated_at
    finally:
        db.close()


def _check_upstream(upstream_id: int) -> None:
    """Full upstream check executed by scheduler (runs in thread).

    Phase 1 — upstream API call + snapshot write (single transaction).
    Phase 2 — webhook/website sync (separate sessions, so a notification
              failure never rolls back the snapshot).
    """
    settings = get_settings()
    # ── Phase 1: upstream check + DB write ──────────────────────────
    db: Session = SessionLocal()
    try:
        upstream = db.query(Upstream).filter(Upstream.id == upstream_id).first()
        if not upstream or not upstream.enabled:
            _remove_job(upstream_id)
            return

        auth_config = json.loads(upstream.auth_config_json or "{}")
        was_unhealthy = upstream.last_status == "unhealthy"
        balance_alert_triggered = False
        snapshot = None
        changes = None

        with UpstreamClient(
            base_url=upstream.base_url,
            api_prefix=upstream.api_prefix,
            auth_type=upstream.auth_type,
            auth_config=auth_config,
            timeout=float(upstream.timeout_seconds),
            on_auth_config_update=lambda updated: _persist_auth_config_update(upstream, updated),
            target_id=upstream.id,
            target_name=upstream.name,
        ) as client:
            try:
                client.ensure_authenticated()
                groups = client.get_available_groups(upstream.groups_endpoint)
                raw_rates = client.get_group_rates(upstream.rate_endpoint)
                snapshot = build_snapshot(
                    upstream.id, upstream.base_url, upstream.api_prefix, groups, raw_rates
                )
                # ── Balance fetch (inside with block, client still open) ──
                balance: Optional[float] = None
                if upstream.balance_endpoint and upstream.balance_response_path:
                    try:
                        raw_balance = client.get_balance(upstream.balance_endpoint, upstream.balance_response_path)
                        if raw_balance is not None:
                            divisor = upstream.balance_divisor or 1.0
                            balance = raw_balance / divisor
                    except Exception as exc:
                        logger.warning("upstream %s balance fetch failed: %s", upstream.name, exc)
                if balance is not None:
                    upstream.balance = balance
                    upstream.balance_updated_at = datetime.now(timezone.utc)
                    # ── 余额告警阈值检查 ──
                    threshold = upstream.balance_alert_threshold
                    if threshold is not None and threshold > 0:
                        if balance < threshold and not upstream.balance_alert_notified:
                            upstream.balance_alert_notified = True
                            balance_alert_triggered = True
                        elif balance >= threshold and upstream.balance_alert_notified:
                            upstream.balance_alert_notified = False
            except Exception as exc:
                # failure path
                upstream.consecutive_failures = (upstream.consecutive_failures or 0) + 1
                upstream.last_error = str(exc)
                upstream.last_checked_at = datetime.now(timezone.utc)
                threshold = settings.unhealthy_threshold
                became_unhealthy = (
                    upstream.consecutive_failures >= threshold
                    and upstream.last_status != "unhealthy"
                )
                if became_unhealthy:
                    upstream.last_status = "unhealthy"
                db.commit()
                logger.warning("upstream %s check failed: %s", upstream.name, exc)
                # Phase 2: notify unhealthy in a fresh session
                if became_unhealthy:
                    _notify_status(upstream.id, upstream.name, upstream.base_url,
                                   "upstream_unhealthy", str(exc))
                return

        # success path (client auto-closed by `with`)

        prev_snapshot_row = (
            db.query(UpstreamRateSnapshot)
            .filter(UpstreamRateSnapshot.upstream_id == upstream_id)
            .order_by(UpstreamRateSnapshot.captured_at.desc())
            .first()
        )
        previous = json.loads(prev_snapshot_row.snapshot_json) if prev_snapshot_row else None
        changes = diff_snapshots(previous, snapshot)

        # save new snapshot
        new_row = UpstreamRateSnapshot(
            upstream_id=upstream_id,
            snapshot_json=json.dumps(snapshot, ensure_ascii=False),
            captured_at=datetime.now(timezone.utc),
        )
        db.add(new_row)
        prune_snapshots(db, upstream_id, settings.snapshot_retention_count)

        # update upstream status
        upstream.last_status = "healthy"
        upstream.last_checked_at = datetime.now(timezone.utc)
        upstream.last_error = None
        upstream.consecutive_failures = 0
        db.commit()

        logger.info(
            "upstream %s: %d rate change(s)" if changes else "upstream %s: no changes",
            upstream.name, len(changes) if changes else 0,
        )

    finally:
        db.close()

    # ── Phase 2: key sync (independent session) ───────────────────
    if snapshot:
        captured_at = snapshot.get("captured_at")
        if isinstance(captured_at, str):
            from datetime import datetime as dt
            try:
                captured_at = dt.fromisoformat(captured_at)
            except Exception:
                captured_at = datetime.now(timezone.utc)
        elif captured_at is None:
            captured_at = datetime.now(timezone.utc)
        _sync_upstream_keys(upstream_id, snapshot, captured_at)

    # ── Phase 3: notifications (independent sessions) ──────────────
    if was_unhealthy:
        _notify_status(upstream_id, upstream.name, upstream.base_url, "upstream_recovered")

    if changes:
        _notify_rate_changed(upstream_id, upstream.name, upstream.base_url, changes)
        _sync_website_bindings(upstream_id, changes)
        _sync_account_priorities(upstream_id)

    if balance_alert_triggered:
        _notify_balance_low(
            upstream_id, upstream.name, upstream.base_url,
            upstream.balance, upstream.balance_alert_threshold,
        )


def _notify_status(
    upstream_id: int,
    upstream_name: str,
    base_url: str,
    event: str,
    error: str = "",
) -> None:
    db = SessionLocal()
    try:
        webhook_service.send_status_event(db, upstream_id, upstream_name, base_url, event, error)
    except Exception:
        logger.exception("status webhook failed for upstream %s", upstream_name)
    finally:
        db.close()


def _notify_rate_changed(
    upstream_id: int,
    upstream_name: str,
    base_url: str,
    changes: list[dict[str, Any]],
) -> None:
    db = SessionLocal()
    try:
        webhook_service.send_rate_changed(db, upstream_id, upstream_name, base_url, changes)
    except Exception:
        logger.exception("rate webhook failed for upstream %s", upstream_name)
    finally:
        db.close()


def _notify_balance_low(
    upstream_id: int,
    upstream_name: str,
    base_url: str,
    balance: float,
    threshold: float,
) -> None:
    db = SessionLocal()
    try:
        webhook_service.send_balance_low(db, upstream_id, upstream_name, base_url, balance, threshold)
    except Exception:
        logger.exception("balance low webhook failed for upstream %s", upstream_name)
    finally:
        db.close()


def _sync_upstream_keys(upstream_id: int, snapshot: dict[str, Any], captured_at: datetime) -> None:
    """上游检测成功后同步 SmartUp Key 状态（远端删除/分组删除）。

    委托给 website_sync.reconcile_upstream_keys 实现核心逻辑。
    """
    db = SessionLocal()
    try:
        active_group_ids = set(snapshot.get("groups", {}).keys())

        # 获取倒数第二个快照作为 previous snapshot
        prev_active_group_ids: set[str] | None = None
        from app.models.snapshot import UpstreamRateSnapshot
        snapshots = (
            db.query(UpstreamRateSnapshot)
            .filter(UpstreamRateSnapshot.upstream_id == upstream_id)
            .order_by(UpstreamRateSnapshot.captured_at.desc())
            .limit(2)
            .all()
        )
        if len(snapshots) >= 2:
            prev_snapshot = snapshots[1]
            try:
                prev_data = json.loads(prev_snapshot.snapshot_json or "{}")
                prev_groups = prev_data.get("groups") or {}
                if isinstance(prev_groups, dict):
                    prev_active_group_ids = set(prev_groups.keys())
            except Exception:
                pass

        # 用 UpstreamClient 查询远端活跃 Key ID 集合
        remote_key_ids: set[str] | None = None
        try:
            upstream = db.query(Upstream).filter(Upstream.id == upstream_id).first()
            if upstream:
                auth_config = json.loads(upstream.auth_config_json or "{}")
                with UpstreamClient(
                    base_url=upstream.base_url,
                    api_prefix=upstream.api_prefix,
                    auth_type=upstream.auth_type,
                    auth_config=auth_config,
                    timeout=float(upstream.timeout_seconds),
                    on_auth_config_update=lambda updated: _persist_auth_config_update(upstream, updated),
                    target_id=upstream.id,
                    target_name=upstream.name,
                ) as client:
                    client.ensure_authenticated()
                    remote_key_ids = website_sync._fetch_remote_managed_key_ids(db, client, upstream_id)
        except Exception as exc:
            logger.warning("sync upstream keys list failed for %s: %s", upstream_id, exc)

        website_sync.reconcile_upstream_keys(db, upstream_id, active_group_ids, remote_key_ids, captured_at, prev_active_group_ids=prev_active_group_ids)
        db.commit()
    except Exception:
        logger.exception("key sync failed for upstream %s", upstream_id)
    finally:
        db.close()


def _sync_account_priorities(upstream_id: int) -> None:
    """倍率变更后自动更新已导入下游账号的 priority。"""
    db = SessionLocal()
    try:
        website_sync.sync_account_priorities_for_upstream(db, upstream_id)
    except Exception:
        logger.exception("account priority sync failed for upstream %s", upstream_id)
    finally:
        db.close()


def _sync_website_bindings(upstream_id: int, changes: list[dict[str, Any]]) -> None:
    db = SessionLocal()
    try:
        website_sync.sync_affected_bindings(db, upstream_id, changes)
    except Exception:
        logger.exception("website sync failed for upstream %s", upstream_id)
    finally:
        db.close()


def _remove_job(upstream_id: int) -> None:
    job_id = f"upstream_{upstream_id}"
    if _scheduler.get_job(job_id):
        _scheduler.remove_job(job_id)


def refresh_upstream(upstream_id: int, interval_seconds: int = 0, enabled: bool = True) -> None:
    """Add/update/remove a scheduler job for the given upstream."""
    job_id = f"upstream_{upstream_id}"
    if not enabled or interval_seconds <= 0:
        _remove_job(upstream_id)
        return
    _scheduler.add_job(
        _check_upstream,
        "interval",
        seconds=interval_seconds,
        id=job_id,
        args=[upstream_id],
        replace_existing=True,
        coalesce=True,
        max_instances=1,
        misfire_grace_time=60,
        jitter=30,
    )
    logger.info("scheduler job %s set to %ds interval", job_id, interval_seconds)


def start_scheduler() -> None:
    """Start scheduler and load all enabled upstreams."""
    _scheduler.start()
    db: Session = SessionLocal()
    try:
        upstreams = db.query(Upstream).filter(Upstream.enabled == True).all()
        for u in upstreams:
            refresh_upstream(u.id, u.check_interval_seconds, u.enabled)
        # Daily cleanup of expired external API logs
        _scheduler.add_job(
            _cleanup_external_logs,
            "interval",
            hours=24,
            id="cleanup_external_api_logs",
            replace_existing=True,
            coalesce=True,
            max_instances=1,
            misfire_grace_time=3600,
        )
        # Daily finance summary at 00:05 Asia/Shanghai
        _scheduler.add_job(
            _compute_finance_daily_summary,
            trigger=CronTrigger(timezone="Asia/Shanghai", hour=0, minute=5),
            id="finance_daily_summary",
            replace_existing=True,
            coalesce=True,
            max_instances=1,
            misfire_grace_time=3600,
        )
        logger.info("scheduler started with %d upstream job(s)", len(upstreams))
    finally:
        db.close()


def _cleanup_external_logs() -> None:
    """Delete external API logs older than the configured retention period."""
    db = SessionLocal()
    try:
        deleted = clean_expired_logs(db)
        if deleted:
            logger.info("cleaned %d expired external API log(s)", deleted)
    except Exception:
        logger.exception("failed to clean expired external API logs")
    finally:
        db.close()


def _compute_finance_daily_summary() -> None:
    """Compute and save finance daily summary for yesterday (Asia/Shanghai).

    Runs daily at 00:05 Asia/Shanghai. Delegates to save_summary_if_absent
    which handles the skip-if-exists logic and concurrent-save race.
    """
    from app.services.finance_service import yesterday_shanghai, save_summary_if_absent

    target = yesterday_shanghai()
    db = SessionLocal()
    try:
        saved = save_summary_if_absent(db, target)
        if saved:
            logger.info("finance daily summary for %s saved", target)
        else:
            logger.info("finance daily summary for %s already exists, skipping", target)
    except Exception:
        logger.exception("failed to compute finance daily summary for %s", target)
    finally:
        db.close()


def stop_scheduler() -> None:
    if _scheduler.running:
        _scheduler.shutdown(wait=True)