"""UME alarm normalize / upsert / notification apply."""
from __future__ import annotations

import hashlib
import json
import re
import threading
import time
from datetime import datetime
from typing import Any

from sqlalchemy import func
from sqlalchemy.dialects.postgresql import insert as pg_insert
from sqlalchemy.exc import IntegrityError
from sqlalchemy.orm import Session

from .config import settings
from .models import UmeAlarmCurrent
from .ume_raw import dumps_ume_raw
from .ume_sync_common import _lookup_host_name, _pick, _s, _utc_now_naive

def _alarm_key(alarm: dict[str, Any]) -> str:
    key = _s(_pick(alarm, "alarmKey", "alarm-key","alarmkey","id"))
    if key:
        # Keep full upstream key; use a stable digest only for pathological ultra-long keys.
        if len(key) > 512:
            return "sha256:" + hashlib.sha256(key.encode("utf-8", errors="ignore")).hexdigest()
        return key
    parts = [
        _s(_pick(alarm, "objectName", "object-name")),
        _s(_pick(alarm, "eventType", "event-type")),
        _s(_pick(alarm, "timeCreated", "time-created")),
        _s(_pick(alarm, "nativeProbableCause", "native-probable-cause")),
    ]
    merged = "|".join(x for x in parts if x)
    raw = merged or f"fallback-{_utc_now_naive().timestamp()}"
    if len(raw) > 512:
        return "sha256:" + hashlib.sha256(raw.encode("utf-8", errors="ignore")).hexdigest()
    return raw


def _derive_ne_id_from_alarm(alarm: dict[str, Any]) -> str:
    ne_id = _s(_pick(alarm, "ne-id", "neId", "ne_id"))
    if ne_id:
        return ne_id

    def _uuid_like(s: str) -> bool:
        return bool(
            re.fullmatch(
                r"[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}",
                str(s or "").strip(),
            )
        )

    # Prefer UUID net_id in objectName, e.g. "... ME{33a3e8f4-a76e-40fd-a0ba-045371a5f234} ..."
    object_name = _s(_pick(alarm, "objectName", "object-name"))
    if object_name:
        m_obj = re.search(r"ME\{([^}]+)\}", object_name, flags=re.IGNORECASE)
        if m_obj:
            candidate = _s(m_obj.group(1))
            if _uuid_like(candidate):
                return candidate

    alarm_key = _s(_pick(alarm, "alarmKey", "alarm-key", "alarmkey"))
    if not alarm_key:
        return ""

    # If alarmkey contains ME{...}, only accept it when it looks like a UUID.
    m0 = re.search(r"ME\{([^}]+)\}", alarm_key, flags=re.IGNORECASE)
    if m0:
        candidate = _s(m0.group(1))
        if _uuid_like(candidate):
            return candidate

    # Common UME formats observed:
    # 1) "<net_id>#<suffix>"
    # 2) "<net_id>, <x>, <y>"
    # 3) "<net_id> <x> <y>"
    if "#" in alarm_key:
        candidate = _s(alarm_key.split("#", 1)[0])
        return candidate if _uuid_like(candidate) else ""
    if "," in alarm_key:
        candidate = _s(alarm_key.split(",", 1)[0])
        return candidate if _uuid_like(candidate) else ""
    parts = [p for p in alarm_key.split() if p]
    if len(parts) >= 2 and ":" not in parts[0]:
        candidate = _s(parts[0])
        return candidate if _uuid_like(candidate) else ""
    return ""


def _normalize_yang_key(key: str) -> str:
    raw = str(key or "").strip()
    if not raw:
        return ""
    if ":" in raw:
        return raw.rsplit(":", 1)[-1]
    return raw


def normalize_yang_alarm(raw: dict[str, Any]) -> dict[str, Any]:
    """Flatten YANG namespace-prefixed keys (e.g. zte-alarms:alarmkey) for _pick()."""
    out: dict[str, Any] = {}
    for k, v in raw.items():
        nk = _normalize_yang_key(str(k))
        if not nk:
            continue
        if nk in out and out[nk] not in (None, ""):
            continue
        out[nk] = v
    return out


def _is_alarm_cleared(alarm: dict[str, Any]) -> bool:
    val = _pick(alarm, "isCleared", "is-cleared")
    if isinstance(val, bool):
        return val
    text = _s(val).lower()
    return text in {"true", "1", "yes"}


_cleared_tombstone_lock = threading.Lock()
_cleared_tombstones: dict[str, float] = {}


def _mark_alarm_cleared_tombstone(alarm_key: str) -> None:
    key = str(alarm_key or "").strip()
    if not key:
        return
    ttl_s = max(60, int(getattr(settings, "ume_alarm_cleared_tombstone_s", 300) or 300))
    expires = time.time() + ttl_s
    with _cleared_tombstone_lock:
        _cleared_tombstones[key] = expires
        now = time.time()
        # Always sweep expired keys; hard-cap with oldest-first eviction.
        stale = [k for k, exp in _cleared_tombstones.items() if exp <= now]
        for k in stale:
            _cleared_tombstones.pop(k, None)
        max_keys = 50000
        if len(_cleared_tombstones) > max_keys:
            overflow = len(_cleared_tombstones) - max_keys
            oldest = sorted(_cleared_tombstones.items(), key=lambda kv: kv[1])[:overflow]
            for k, _ in oldest:
                _cleared_tombstones.pop(k, None)


def _is_alarm_cleared_tombstone(alarm_key: str) -> bool:
    key = str(alarm_key or "").strip()
    if not key:
        return False
    now = time.time()
    with _cleared_tombstone_lock:
        exp = _cleared_tombstones.get(key)
        if exp is None:
            return False
        if exp <= now:
            _cleared_tombstones.pop(key, None)
            return False
        return True


def notification_id_from_norm(norm: dict[str, Any]) -> str:
    return _s(_pick(norm, "notificationId", "notification-id"))


def _alarm_row_from_norm(key: str, norm: dict[str, Any], *, touch_ts: datetime, first_seen_at: datetime) -> dict[str, Any]:
    return {
        "alarm_key": key,
        "ne_id": _s(_derive_ne_id_from_alarm(norm)),
        "host_name": "",
        "object_name": _s(_pick(norm, "objectName", "object-name")),
        "event_type": _s(_pick(norm, "eventType", "event-type")),
        "native_probable_cause": _s(_pick(norm, "nativeProbableCause", "native-probable-cause")),
        "perceived_severity": _s(_pick(norm, "perceivedSeverity", "perceived-severity")),
        "is_cleared": _s(_pick(norm, "isCleared", "is-cleared")),
        "time_created": _s(_pick(norm, "timeCreated", "time-created")),
        "root_cause_alarm_indication": _s(
            _pick(norm, "rootCauseAlarmIndication", "root-cause-alarm-indication")
        ),
        "notification_id": notification_id_from_norm(norm),
        "first_seen_at": first_seen_at,
        "last_seen_at": touch_ts,
        "raw_json": dumps_ume_raw(norm),
    }


def _apply_row_to_model(db: Session, existing: UmeAlarmCurrent, norm: dict[str, Any], *, touch_ts: datetime) -> None:
    existing.ne_id = _s(_derive_ne_id_from_alarm(norm))
    existing.object_name = _s(_pick(norm, "objectName", "object-name"))
    existing.event_type = _s(_pick(norm, "eventType", "event-type"))
    existing.native_probable_cause = _s(_pick(norm, "nativeProbableCause", "native-probable-cause"))
    existing.perceived_severity = _s(_pick(norm, "perceivedSeverity", "perceived-severity"))
    existing.is_cleared = _s(_pick(norm, "isCleared", "is-cleared"))
    existing.time_created = _s(_pick(norm, "timeCreated", "time-created"))
    existing.root_cause_alarm_indication = _s(
        _pick(norm, "rootCauseAlarmIndication", "root-cause-alarm-indication")
    )
    existing.notification_id = notification_id_from_norm(norm)
    prev_seen = existing.last_seen_at
    if prev_seen is None or touch_ts >= prev_seen:
        existing.last_seen_at = touch_ts
    existing.raw_json = dumps_ume_raw(norm)


def _upsert_alarm_current(db: Session, key: str, norm: dict[str, Any], *, touch_ts: datetime) -> tuple[str, bool]:
    bind = db.get_bind()
    dialect = str(getattr(getattr(bind, "dialect", None), "name", "") or "").lower()
    existing = db.get(UmeAlarmCurrent, key)
    if existing is not None:
        _apply_row_to_model(db, existing, norm, touch_ts=touch_ts)
        existing.host_name = _lookup_host_name(db, existing.ne_id)
        return "updated", True

    if dialect == "postgresql":
        row = _alarm_row_from_norm(key, norm, touch_ts=touch_ts, first_seen_at=touch_ts)
        row["host_name"] = _lookup_host_name(db, row["ne_id"])
        ins = pg_insert(UmeAlarmCurrent).values(**row)
        excluded = ins.excluded
        stmt = ins.on_conflict_do_update(
            index_elements=[UmeAlarmCurrent.alarm_key],
            set_={
                "ne_id": excluded.ne_id,
                "host_name": excluded.host_name,
                "object_name": excluded.object_name,
                "event_type": excluded.event_type,
                "native_probable_cause": excluded.native_probable_cause,
                "perceived_severity": excluded.perceived_severity,
                "is_cleared": excluded.is_cleared,
                "time_created": excluded.time_created,
                "root_cause_alarm_indication": excluded.root_cause_alarm_indication,
                "notification_id": excluded.notification_id,
                "last_seen_at": func.greatest(UmeAlarmCurrent.last_seen_at, excluded.last_seen_at),
                "raw_json": excluded.raw_json,
            },
        )
        db.execute(stmt)
        return "inserted", True

    try:
        with db.begin_nested():
            model = UmeAlarmCurrent(alarm_key=key, first_seen_at=touch_ts)
            db.add(model)
            db.flush()
        _apply_row_to_model(db, model, norm, touch_ts=touch_ts)
        model.host_name = _lookup_host_name(db, model.ne_id)
        return "inserted", True
    except IntegrityError:
        existing = db.get(UmeAlarmCurrent, key)
        if existing is None:
            return "skipped", False
        _apply_row_to_model(db, existing, norm, touch_ts=touch_ts)
        existing.host_name = _lookup_host_name(db, existing.ne_id)
        return "updated", True


def extract_alarm_from_notification(payload: dict[str, Any]) -> dict[str, Any] | None:
    """Parse alarm-notification from a WS/REST notification envelope."""
    if not isinstance(payload, dict):
        return None

    def _find_alarm_notification(node: Any) -> dict[str, Any] | None:
        if isinstance(node, dict):
            for k, v in node.items():
                key = str(k).lower()
                if key in {"alarm-notification", "alarm_notification"} and isinstance(v, dict):
                    return normalize_yang_alarm(v)
                found = _find_alarm_notification(v)
                if found is not None:
                    return found
        elif isinstance(node, list):
            for item in node:
                found = _find_alarm_notification(item)
                if found is not None:
                    return found
        return None

    direct = _find_alarm_notification(payload)
    if direct is not None:
        return direct
    return normalize_yang_alarm(payload) if payload else None


def apply_alarm_to_current(
    db: Session,
    alarm: dict[str, Any],
    *,
    touch_ts: datetime,
    source: str = "",
) -> tuple[str, bool]:
    """
    Apply one alarm to ume_alarms_current.
    Returns (action, changed) where action is inserted|updated|deleted|skipped.
    """
    norm = normalize_yang_alarm(alarm) if alarm else {}
    if not norm:
        return "skipped", False

    if _is_alarm_cleared(norm):
        key = _alarm_key(norm)
        if not key:
            return "skipped", False
        existing = db.get(UmeAlarmCurrent, key)
        if existing is None:
            _mark_alarm_cleared_tombstone(key)
            return "deleted", False
        db.delete(existing)
        _mark_alarm_cleared_tombstone(key)
        return "deleted", True

    key = _alarm_key(norm)
    if not key:
        return "skipped", False
    if str(source or "").strip().lower() == "rest" and _is_alarm_cleared_tombstone(key):
        return "skipped", False

    return _upsert_alarm_current(db, key, norm, touch_ts=touch_ts)