from __future__ import annotations

import time

from asgiref.sync import sync_to_async
from django.conf import settings

from core.events.manticore import get_event_ledger_backend
from core.models import ConversationEvent
from core.observability.tracing import ensure_trace_id
from core.util import logs

log = logs.get_logger("event-ledger")


def event_ledger_enabled() -> bool:
    return bool(
        getattr(settings, "EVENT_LEDGER_DUAL_WRITE", False)
        or getattr(settings, "EVENT_PRIMARY_WRITE_PATH", False)
    )


def event_ledger_status() -> dict:
    return {
        "event_ledger_dual_write": bool(
            getattr(settings, "EVENT_LEDGER_DUAL_WRITE", False)
        ),
        "event_primary_write_path": bool(
            getattr(settings, "EVENT_PRIMARY_WRITE_PATH", False)
        ),
    }


def _normalize_direction(value: str) -> str:
    direction = str(value or "system").strip().lower()
    if direction not in {"in", "out", "system"}:
        return "system"
    return direction


def _safe_ts(value: int | None) -> int:
    if value is None:
        return int(time.time() * 1000)
    try:
        parsed = int(value)
    except Exception:
        return int(time.time() * 1000)
    if parsed <= 0:
        return int(time.time() * 1000)
    return parsed


def append_event_sync(
    *,
    user,
    session,
    event_type: str,
    direction: str,
    actor_identifier: str = "",
    origin_transport: str = "",
    origin_message_id: str = "",
    origin_chat_id: str = "",
    payload: dict | None = None,
    raw_payload: dict | None = None,
    trace_id: str = "",
    ts: int | None = None,
):
    if not event_ledger_enabled():
        return None

    normalized_type = str(event_type or "").strip().lower()
    if not normalized_type:
        raise ValueError("event_type is required")

    candidates = {str(choice[0]) for choice in ConversationEvent.EVENT_TYPE_CHOICES}
    if normalized_type not in candidates:
        raise ValueError(f"unsupported event_type: {normalized_type}")

    normalized_direction = _normalize_direction(direction)
    normalized_trace = ensure_trace_id(trace_id, payload or {})

    safe_ts = _safe_ts(ts)
    transport = str(origin_transport or "").strip().lower()
    message_id = str(origin_message_id or "").strip()
    actor_identifier = str(actor_identifier or "").strip()
    origin_chat_id = str(origin_chat_id or "").strip()
    payload = dict(payload or {})
    raw_payload = dict(raw_payload or {})

    dual_write = bool(getattr(settings, "EVENT_LEDGER_DUAL_WRITE", False))
    primary_write = bool(getattr(settings, "EVENT_PRIMARY_WRITE_PATH", False))
    write_django = dual_write and not primary_write

    row = None
    if write_django:
        dedup_row = None
        if transport and message_id:
            dedup_row = (
                ConversationEvent.objects.filter(
                    user=user,
                    session=session,
                    event_type=normalized_type,
                    origin_transport=transport,
                    origin_message_id=message_id,
                )
                .order_by("-created_at")
                .first()
            )
        if dedup_row is not None:
            row = dedup_row
        else:
            row = ConversationEvent.objects.create(
                user=user,
                session=session,
                ts=safe_ts,
                event_type=normalized_type,
                direction=normalized_direction,
                actor_identifier=actor_identifier,
                origin_transport=transport,
                origin_message_id=message_id,
                origin_chat_id=origin_chat_id,
                payload=payload,
                raw_payload=raw_payload,
                trace_id=normalized_trace,
            )

    try:
        get_event_ledger_backend().upsert_event(
            user_id=int(user.id),
            person_id=str(session.identifier.person_id),
            session_id=str(session.id),
            event_type=normalized_type,
            direction=normalized_direction,
            ts=safe_ts,
            actor_identifier=actor_identifier,
            origin_transport=transport,
            origin_message_id=message_id,
            origin_chat_id=origin_chat_id,
            payload=payload,
            raw_payload=raw_payload,
            trace_id=normalized_trace,
        )
    except Exception as exc:
        if primary_write:
            raise
        log.warning(
            "Event ledger manticore dual-write failed session=%s event_type=%s err=%s",
            getattr(session, "id", "-"),
            normalized_type,
            exc,
        )

    return row


async def append_event(**kwargs):
    return await sync_to_async(append_event_sync, thread_sensitive=True)(**kwargs)