from __future__ import annotations

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

from sqlalchemy.orm import Session

from .config import settings
from .models import (
    UmeAlarmBatch,
    UmeAlarmCurrent,
    UmeAlarmHistory,
    UmeInventoryEquipmentHolder,
    UmeInventoryNE,
    UmeSyncJob,
)
from .ume_client import UMEClient


def _s(v: Any) -> str:
    if v is None:
        return ""
    text = str(v).strip()
    if text.lower() == "nan":
        return ""
    return text


def _utc_now_naive() -> datetime:
    return datetime.now(timezone.utc).replace(tzinfo=None)


def _pick(d: dict[str, Any], *keys: str) -> Any:
    for key in keys:
        if key in d:
            return d.get(key)
    return None


def _alarm_key(alarm: dict[str, Any]) -> str:
    key = _s(_pick(alarm, "alarmKey", "alarm-key","alarmkey","id"))
    if key:
        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)
    return merged or f"fallback-{datetime.utcnow().timestamp()}"


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

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

    # Common UME formats observed:
    # 1) "<net_id>#<suffix>"
    # 2) "<net_id>, <x>, <y>"
    if "#" in alarm_key:
        return _s(alarm_key.split("#", 1)[0])
    if "," in alarm_key:
        return _s(alarm_key.split(",", 1)[0])
    return ""


def _build_sync_job(domain: str, trigger_mode: str) -> UmeSyncJob:
    return UmeSyncJob(
        domain=domain,
        status="running",
        trigger_mode=trigger_mode,
        started_at=_utc_now_naive(),
    )


def sync_inventory_full(db: Session, client: UMEClient, *, trigger_mode: str = "manual") -> UmeSyncJob:
    job = _build_sync_job("inventory", trigger_mode)
    db.add(job)
    db.flush()
    pulled = inserted = updated = 0
    try:
        ne_rows, _ = client.get_network_elements()
        now = _utc_now_naive()
        pulled = len(ne_rows)
        for row in ne_rows:
            ne_id = _s(_pick(row, "ne-id", "ne_id", "id"))
            if not ne_id:
                continue
            existing = db.get(UmeInventoryNE, ne_id)
            if existing is None:
                existing = UmeInventoryNE(
                    ne_id=ne_id,
                    first_seen_at=now,
                )
                db.add(existing)
                inserted += 1
            else:
                updated += 1
            existing.ne_name = _s(_pick(row, "name", "ne-name"))
            existing.user_label = _s(_pick(row, "user-label", "user_label"))
            existing.ip_address = _s(_pick(row, "ip-Address", "ip-address", "ip"))
            existing.ne_type = _s(_pick(row, "type", "ne-type"))
            existing.device_level = _s(_pick(row, "device-level"))
            existing.host_name = _s(_pick(row, "host-name"))
            existing.location = _s(_pick(row, "location"))
            existing.hardware_version = _s(_pick(row, "hardware-version"))
            existing.loopback = _s(_pick(row, "loopback"))
            existing.consistent_state = _s(_pick(row, "consistent-state"))
            existing.interface_version = _s(_pick(row, "interface-version"))
            existing.mac = _s(_pick(row, "mac"))
            existing.admin_status = _s(_pick(row, "admin-status"))
            existing.address_type = _s(_pick(row, "address-type"))
            existing.connection_status = _s(_pick(row, "connection-status"))
            existing.maintain_status = _s(_pick(row, "maintain-status"))
            existing.net_mask = _s(_pick(row, "net-mask"))
            existing.create_time = _s(_pick(row, "create-time"))
            existing.creator = _s(_pick(row, "creator"))
            existing.vendor = _s(_pick(row, "vendor-name")) or "ZTE"
            existing.last_seen_at = now
            existing.raw_json = json.dumps(row, ensure_ascii=False, default=str)

        # Optional: holders may not exist in current UME deployment; keep best-effort.
        # This pass keeps schema warm for later detailed holder endpoint integration.
        holder_payload: list[dict[str, Any]] = []
        for ne in ne_rows:
            holders = _pick(ne, "equipment-holder", "equipment-holders")
            if isinstance(holders, list):
                for h in holders:
                    if isinstance(h, dict):
                        h2 = dict(h)
                        if "ne-id" not in h2:
                            h2["ne-id"] = _pick(ne, "ne-id", "ne_id", "id")
                        holder_payload.append(h2)
        for h in holder_payload:
            ne_id = _s(_pick(h, "ne-id", "ne_id"))
            holder_name = _s(_pick(h, "name", "holder-name"))
            if not ne_id or not holder_name:
                continue
            existing_holder = (
                db.query(UmeInventoryEquipmentHolder)
                .filter(
                    UmeInventoryEquipmentHolder.ne_id == ne_id,
                    UmeInventoryEquipmentHolder.holder_name == holder_name,
                )
                .one_or_none()
            )
            if existing_holder is None:
                existing_holder = UmeInventoryEquipmentHolder(
                    ne_id=ne_id,
                    holder_name=holder_name,
                    first_seen_at=now,
                )
                db.add(existing_holder)
            existing_holder.holder_type = _s(_pick(h, "type", "holder-type"))
            existing_holder.holder_state = _s(_pick(h, "state", "holder-state"))
            existing_holder.last_seen_at = now
            existing_holder.raw_json = json.dumps(h, ensure_ascii=False, default=str)

        job.status = "done"
    except Exception as exc:
        job.status = "failed"
        job.error_message = str(exc)[:1024]
    finally:
        job.pulled_count = int(pulled)
        job.inserted_count = int(inserted)
        job.updated_count = int(updated)
        job.ended_at = _utc_now_naive()
        db.commit()
        db.refresh(job)
    return job


def _sync_alarms_common(
    db: Session,
    client: UMEClient,
    *,
    is_uncleared: bool,
    trigger_mode: str,
) -> tuple[UmeSyncJob, UmeAlarmBatch]:
    domain = "alarms_history" if is_uncleared else "alarms_current"
    job = _build_sync_job(domain, trigger_mode)
    db.add(job)
    batch = UmeAlarmBatch(
        kind="history" if is_uncleared else "current",
        status="running",
        started_at=_utc_now_naive(),
    )
    db.add(batch)
    db.flush()
    now = _utc_now_naive()
    pulled = inserted = updated = 0
    paging_mode = "offset"
    paging_note = ""
    try:
        limit_max = int(getattr(settings, "ume_limit_max", 5000) or 5000)
        limit_max = max(1, limit_max)
        page_size = int(getattr(settings, "ume_page_size", 1000) or 1000)
        page_size = max(1, min(page_size, limit_max))
        max_pages = int(getattr(settings, "ume_max_pages", 2000) or 2000)
        max_pages = max(1, min(max_pages, 20000))
        offset = 0
        page_no = 0

        def upsert_alarm(alarm: dict[str, Any]) -> None:
            nonlocal inserted, updated
            key = _alarm_key(alarm)
            if is_uncleared:
                existing = db.get(UmeAlarmHistory, key)
                if existing is None:
                    existing = UmeAlarmHistory(alarm_key=key, first_seen_at=now)
                    db.add(existing)
                    inserted += 1
                else:
                    updated += 1
            else:
                existing = db.get(UmeAlarmCurrent, key)
                if existing is None:
                    existing = UmeAlarmCurrent(alarm_key=key, first_seen_at=now)
                    db.add(existing)
                    inserted += 1
                else:
                    updated += 1
            existing.ne_id = _derive_ne_id_from_alarm(alarm)
            existing.ne_name = _s(_pick(alarm, "ne-name", "neName", "ne_name"))
            existing.user_label = _s(_pick(alarm, "user-label", "userLabel", "user_label"))
            existing.object_name = _s(_pick(alarm, "objectName", "object-name"))
            existing.event_type = _s(_pick(alarm, "eventType", "event-type"))
            existing.native_probable_cause = _s(_pick(alarm, "nativeProbableCause", "native-probable-cause"))
            existing.perceived_severity = _s(_pick(alarm, "perceivedSeverity", "perceived-severity"))
            existing.is_cleared = _s(_pick(alarm, "isCleared", "is-cleared"))
            existing.time_created = _s(_pick(alarm, "timeCreated", "time-created"))
            existing.root_cause_alarm_indication = _s(
                _pick(alarm, "rootCauseAlarmIndication", "root-cause-alarm-indication")
            )
            existing.last_seen_at = now
            existing.raw_json = json.dumps(alarm, ensure_ascii=False, default=str)

        def is_offset_unsupported_error(exc: Exception) -> bool:
            msg = str(exc or "")
            if "ume_request_failed:400" not in msg:
                return False
            low = msg.lower()
            return ("offset" in low) or ("unknown" in low and "param" in low) or ("illegal" in low and "param" in low)

        # Try offset pagination first (best-effort). If server rejects offset, fall back to single-page.
        try:
            while True:
                page_no += 1
                if page_no > max_pages:
                    raise RuntimeError(f"ume_alarms_pagination_exceeded:max_pages={max_pages}")
                rows, _ = client.get_alarms(is_uncleared=is_uncleared, limit=page_size, offset=offset)
                pulled += len(rows)
                for alarm in rows:
                    upsert_alarm(alarm)
                if len(rows) < page_size:
                    break
                offset += page_size
        except Exception as exc:
            if is_offset_unsupported_error(exc):
                paging_mode = "limit_only"
                paging_note = str(exc)[:200]
                limit_only_size = int(getattr(settings, "ume_limit_only_page_size", limit_max) or limit_max)
                limit_only_size = max(1, min(limit_only_size, limit_max))
                # Re-run as single page without offset param.
                pulled = inserted = updated = 0
                rows, _ = client.get_alarms(is_uncleared=is_uncleared, limit=limit_only_size, offset=None)
                pulled = len(rows)
                for alarm in rows:
                    upsert_alarm(alarm)
            else:
                raise

        if not is_uncleared:
            expiry = now - timedelta(hours=48)
            (
                db.query(UmeAlarmCurrent)
                .filter(UmeAlarmCurrent.last_seen_at < expiry)
                .delete(synchronize_session=False)
            )

        batch.total_rows = int(pulled)
        batch.success_rows = int(inserted + updated)
        batch.failed_rows = max(0, int(pulled) - int(inserted + updated))
        batch.status = "done"
        batch.ended_at = _utc_now_naive()
        batch.raw_json = json.dumps(
            {"pulled": pulled, "inserted": inserted, "updated": updated, "paging_mode": paging_mode},
            ensure_ascii=False,
        )

        job.status = "done"
    except Exception as exc:
        msg = str(exc)[:1024]
        batch.status = "failed"
        batch.error_message = msg
        batch.ended_at = _utc_now_naive()
        job.status = "failed"
        job.error_message = msg
    finally:
        job.pulled_count = int(pulled)
        job.inserted_count = int(inserted)
        job.updated_count = int(updated)
        job.ended_at = _utc_now_naive()
        job.details_json = json.dumps(
            {
                "batch_id": batch.batch_id,
                "kind": batch.kind,
                "status": batch.status,
                "paging_mode": paging_mode,
                "paging_note": paging_note,
            },
            ensure_ascii=False,
        )
        db.commit()
        db.refresh(job)
        db.refresh(batch)
    return job, batch


def sync_alarms_current(db: Session, client: UMEClient, *, trigger_mode: str = "manual") -> tuple[UmeSyncJob, UmeAlarmBatch]:
    return _sync_alarms_common(db, client, is_uncleared=False, trigger_mode=trigger_mode)


def sync_alarms_history_full(
    db: Session, client: UMEClient, *, trigger_mode: str = "manual"
) -> tuple[UmeSyncJob, UmeAlarmBatch]:
    return _sync_alarms_common(db, client, is_uncleared=True, trigger_mode=trigger_mode)