office_translator/core/redis.py

"""
Centralized Redis client for the application.
Single shared async and sync clients; REDIS_URL from environment.
Used by: rate limiting, tier quota, storage tracker, auth blocklist, admin sessions, health check.
"""
from __future__ import annotations

import os
import logging

logger = logging.getLogger(__name__)

_async_client = None
_sync_client = None
# Sentinel: False = no REDIS_URL or connection failed; None = not yet tried
_async_attempted = None
_sync_attempted = None


def get_redis_url() -> str:
    """Return REDIS_URL from environment (empty if not set)."""
    return (os.getenv("REDIS_URL") or "").strip()


def get_async_redis():
    """
    Return shared async Redis client or None.
    Uses REDIS_URL from env. Lazy init; on failure returns None (graceful degradation).
    """
    global _async_client, _async_attempted
    if _async_attempted is not None:
        return _async_client if _async_client is not None else None
    url = get_redis_url()
    if not url:
        _async_attempted = True
        return None
    try:
        import redis.asyncio as redis

        _async_client = redis.Redis.from_url(url, decode_responses=True)
        logger.info("Redis async client connected (shared)")
        _async_attempted = True
        return _async_client
    except Exception as e:
        logger.warning("Redis async connection failed: %s", e)
        _async_client = None
        _async_attempted = True
        return None


def get_sync_redis():
    """
    Return shared sync Redis client or None.
    Uses REDIS_URL from env. Lazy init; on failure returns None.
    Used by health check, admin sessions, auth blocklist.
    """
    global _sync_client, _sync_attempted
    if _sync_attempted is not None:
        return _sync_client if _sync_client is not None else None
    url = get_redis_url()
    if not url:
        _sync_attempted = True
        return None
    try:
        import redis

        _sync_client = redis.Redis.from_url(
            url, decode_responses=True, socket_connect_timeout=5
        )
        _sync_client.ping()
        logger.info("Redis sync client connected (shared)")
        _sync_attempted = True
        return _sync_client
    except Exception as e:
        logger.warning("Redis sync connection failed: %s", e)
        _sync_client = None
        _sync_attempted = True
        return None


def ping_sync() -> tuple[bool, str]:
    """
    Ping Redis (sync). Returns (success, error_message).
    Use for health/readiness checks.
    """
    client = get_sync_redis()
    if not client:
        return False, "not_configured"
    try:
        client.ping()
        return True, ""
    except Exception as e:
        return False, str(e)


# ---------------------------------------------------------------------------
# Translation job status cache (for GET /api/v1/translations/{id})
# Key: translation:job:{job_id}, value: JSON, TTL e.g. 2h
# ---------------------------------------------------------------------------

JOB_STATUS_KEY_PREFIX = "translation:job"
JOB_STATUS_TTL = 2 * 3600  # 2 hours


async def set_job_status_async(job_id: str, data: dict, ttl: int = JOB_STATUS_TTL) -> bool:
    """Store job status in Redis for multi-instance progress polling. Returns True if stored."""
    client = get_async_redis()
    if not client:
        return False
    try:
        import json

        key = f"{JOB_STATUS_KEY_PREFIX}:{job_id}"
        await client.set(key, json.dumps(data), ex=ttl)
        return True
    except Exception as e:
        logger.warning("Redis set_job_status_async failed for %s: %s", job_id, e)
        return False


async def get_job_status_async(job_id: str) -> dict | None:
    """Retrieve job status from Redis. Returns None if not found or Redis unavailable."""
    client = get_async_redis()
    if not client:
        return None
    try:
        import json

        key = f"{JOB_STATUS_KEY_PREFIX}:{job_id}"
        data = await client.get(key)
        return json.loads(data) if data else None
    except Exception as e:
        logger.warning("Redis get_job_status_async failed for %s: %s", job_id, e)
        return None


async def delete_job_status_async(job_id: str) -> bool:
    """Remove a job's status key from Redis (user deleted it from history).

    Best-effort like the other job-status helpers: never raises, returns
    True when the key was deleted, False when Redis is unavailable or the
    key did not exist.
    """
    client = get_async_redis()
    if not client:
        return False
    try:
        key = f"{JOB_STATUS_KEY_PREFIX}:{job_id}"
        return bool(await client.delete(key))
    except Exception as e:
        logger.warning("Redis delete_job_status_async failed for %s: %s", job_id, e)
        return False