"""
Sofiia Supervisor — State Backend

Supports:
  - redis: production (requires redis-py)
  - memory: in-process dict (testing / single-instance dev)

Redis schema:
  run:{run_id}         → JSON (RunRecord without events)
  run:{run_id}:events  → Redis list of JSON RunEvent
  TTL: RUN_TTL_SEC (default 24h)
"""

from __future__ import annotations

import json
import logging
from abc import ABC, abstractmethod
from typing import List, Optional

from .config import settings
from .models import RunEvent, RunRecord, RunStatus

logger = logging.getLogger(__name__)


class StateBackend(ABC):
    @abstractmethod
    async def save_run(self, run: RunRecord) -> None: ...

    @abstractmethod
    async def get_run(self, run_id: str) -> Optional[RunRecord]: ...

    @abstractmethod
    async def append_event(self, run_id: str, event: RunEvent) -> None: ...

    @abstractmethod
    async def get_events(self, run_id: str) -> List[RunEvent]: ...

    @abstractmethod
    async def cancel_run(self, run_id: str) -> bool: ...


# ─── In-memory backend (testing/dev) ─────────────────────────────────────────

class MemoryStateBackend(StateBackend):
    def __init__(self):
        self._runs: dict[str, RunRecord] = {}
        self._events: dict[str, list[RunEvent]] = {}

    async def save_run(self, run: RunRecord) -> None:
        self._runs[run.run_id] = run

    async def get_run(self, run_id: str) -> Optional[RunRecord]:
        return self._runs.get(run_id)

    async def append_event(self, run_id: str, event: RunEvent) -> None:
        self._events.setdefault(run_id, []).append(event)

    async def get_events(self, run_id: str) -> List[RunEvent]:
        return list(self._events.get(run_id, []))

    async def cancel_run(self, run_id: str) -> bool:
        run = self._runs.get(run_id)
        if not run:
            return False
        if run.status in (RunStatus.SUCCEEDED, RunStatus.FAILED, RunStatus.CANCELLED):
            return False
        run.status = RunStatus.CANCELLED
        return True


# ─── Redis backend (production) ──────────────────────────────────────────────

class RedisStateBackend(StateBackend):
    def __init__(self):
        self._redis = None

    async def _client(self):
        if self._redis is None:
            try:
                import redis.asyncio as aioredis
                self._redis = await aioredis.from_url(
                    settings.REDIS_URL,
                    decode_responses=True,
                )
            except Exception as e:
                logger.error(f"Redis connection error: {e}")
                raise
        return self._redis

    def _run_key(self, run_id: str) -> str:
        return f"run:{run_id}"

    def _events_key(self, run_id: str) -> str:
        return f"run:{run_id}:events"

    async def save_run(self, run: RunRecord) -> None:
        r = await self._client()
        # Store run without events (events stored separately in list)
        data = run.model_dump(exclude={"events"})
        await r.setex(
            self._run_key(run.run_id),
            settings.RUN_TTL_SEC,
            json.dumps(data, default=str),
        )

    async def get_run(self, run_id: str) -> Optional[RunRecord]:
        r = await self._client()
        raw = await r.get(self._run_key(run_id))
        if not raw:
            return None
        try:
            data = json.loads(raw)
            events = await self.get_events(run_id)
            data["events"] = [e.model_dump() for e in events]
            return RunRecord(**data)
        except Exception as e:
            logger.error(f"Deserialise run {run_id}: {e}")
            return None

    async def append_event(self, run_id: str, event: RunEvent) -> None:
        r = await self._client()
        key = self._events_key(run_id)
        await r.rpush(key, json.dumps(event.model_dump(), default=str))
        await r.expire(key, settings.RUN_TTL_SEC)

    async def get_events(self, run_id: str) -> List[RunEvent]:
        r = await self._client()
        raw_list = await r.lrange(self._events_key(run_id), 0, -1)
        events = []
        for raw in raw_list:
            try:
                events.append(RunEvent(**json.loads(raw)))
            except Exception:
                pass
        return events

    async def cancel_run(self, run_id: str) -> bool:
        run = await self.get_run(run_id)
        if not run:
            return False
        if run.status in (RunStatus.SUCCEEDED, RunStatus.FAILED, RunStatus.CANCELLED):
            return False
        run.status = RunStatus.CANCELLED
        await self.save_run(run)
        return True


# ─── Factory ─────────────────────────────────────────────────────────────────

def create_state_backend() -> StateBackend:
    if settings.STATE_BACKEND == "redis":
        logger.info("Using Redis state backend")
        return RedisStateBackend()
    logger.info("Using in-memory state backend")
    return MemoryStateBackend()