"""Text embedding client for the local embedding HTTP service."""

import logging
import os
import pickle
from datetime import timedelta
from typing import Any, List, Optional, Union

import numpy as np
import redis
import requests

logger = logging.getLogger(__name__)

from config.services_config import get_embedding_base_url

# Try to import REDIS_CONFIG, but allow import to fail
from config.env_config import REDIS_CONFIG

class TextEmbeddingEncoder:
    """
    Text embedding encoder using network service.
    """

    def __init__(self, service_url: Optional[str] = None):
        resolved_url = service_url or os.getenv("EMBEDDING_SERVICE_URL") or get_embedding_base_url()
        self.service_url = str(resolved_url).rstrip("/")
        self.endpoint = f"{self.service_url}/embed/text"
        self.expire_time = timedelta(days=REDIS_CONFIG.get("cache_expire_days", 180))
        self.cache_prefix = str(REDIS_CONFIG.get("embedding_cache_prefix", "embedding")).strip() or "embedding"
        logger.info("Creating TextEmbeddingEncoder instance with service URL: %s", self.service_url)

        try:
            self.redis_client = redis.Redis(
                host=REDIS_CONFIG.get("host", "localhost"),
                port=REDIS_CONFIG.get("port", 6479),
                password=REDIS_CONFIG.get("password"),
                decode_responses=False,
                socket_timeout=REDIS_CONFIG.get("socket_timeout", 1),
                socket_connect_timeout=REDIS_CONFIG.get("socket_connect_timeout", 1),
                retry_on_timeout=REDIS_CONFIG.get("retry_on_timeout", False),
                health_check_interval=10,
            )
            self.redis_client.ping()
            logger.info("Redis cache initialized for embeddings")
        except Exception as e:
            logger.warning("Failed to initialize Redis cache for embeddings: %s, continuing without cache", e)
            self.redis_client = None

    def _call_service(self, request_data: List[str], normalize_embeddings: bool = True) -> List[Any]:
        """
        Call the embedding service API.

        Args:
            request_data: List of texts

        Returns:
            List of embeddings (list[float]) or nulls (None), aligned to input order
        """
        try:
            response = requests.post(
                self.endpoint,
                params={"normalize": "true" if normalize_embeddings else "false"},
                json=request_data,
                timeout=60
            )
            response.raise_for_status()
            return response.json()
        except requests.exceptions.RequestException as e:
            logger.error(f"TextEmbeddingEncoder service request failed: {e}", exc_info=True)
            raise

    def encode(
        self,
        sentences: Union[str, List[str]],
        normalize_embeddings: bool = True,
        device: str = 'cpu',
        batch_size: int = 32
    ) -> np.ndarray:
        """
        Encode text into embeddings via network service with Redis caching.

        Args:
            sentences: Single string or list of strings to encode
            normalize_embeddings: Whether to request normalized embeddings from service
            device: Device parameter ignored for service compatibility
            batch_size: Batch size for processing (used for service requests)

        Returns:
            numpy array of dtype=object，元素均为有效 np.ndarray 向量。
            若任一输入无法生成向量，将直接抛出异常。
        """
        # Convert single string to list
        if isinstance(sentences, str):
            sentences = [sentences]

        # Check cache first
        uncached_indices: List[int] = []
        uncached_texts: List[str] = []
        
        embeddings: List[Optional[np.ndarray]] = [None] * len(sentences)

        for i, text in enumerate(sentences):
            cached = self._get_cached_embedding(text)
            if cached is not None:
                embeddings[i] = cached
            else:
                uncached_indices.append(i)
                uncached_texts.append(text)
        
        # Prepare request data for uncached texts (after cache check)
        request_data = list(uncached_texts)
        
        # If there are uncached texts, call service
        if uncached_texts:
            response_data = self._call_service(request_data, normalize_embeddings=normalize_embeddings)

            # Process response
            for i, text in enumerate(uncached_texts):
                original_idx = uncached_indices[i]
                if response_data and i < len(response_data):
                    embedding = response_data[i]
                else:
                    embedding = None

                if embedding is not None:
                    embedding_array = np.array(embedding, dtype=np.float32)
                    if self._is_valid_embedding(embedding_array):
                        embeddings[original_idx] = embedding_array
                        self._set_cached_embedding(text, embedding_array, normalize_embeddings)
                    else:
                        raise ValueError(
                            f"Invalid embedding returned from service for text index {original_idx}"
                        )
                else:
                    raise ValueError(f"No embedding found for text index {original_idx}: {text[:50]}...")
        
        # 返回 numpy 数组（dtype=object），元素均为有效 np.ndarray 向量
        return np.array(embeddings, dtype=object)
        
    def _is_valid_embedding(self, embedding: np.ndarray) -> bool:
        """
        Check if embedding is valid (not None, correct shape, no NaN/Inf).
        
        Args:
            embedding: Embedding array to validate
            
        Returns:
            True if valid, False otherwise
        """
        if embedding is None:
            return False
        if not isinstance(embedding, np.ndarray):
            return False
        if embedding.size == 0:
            return False
        # Check for NaN or Inf values
        if not np.isfinite(embedding).all():
            return False
        return True
    
    def _get_cached_embedding(
        self,
        query: str
    ) -> Optional[np.ndarray]:
        """Get embedding from cache if exists (with sliding expiration)"""
        if not self.redis_client:
            return None
            
        try:
            cache_key = f"{self.cache_prefix}:{query}"
            cached_data = self.redis_client.get(cache_key)
            if cached_data:
                embedding = pickle.loads(cached_data)
                # Validate cached embedding - if invalid, ignore cache and return None
                if self._is_valid_embedding(embedding):
                    logger.debug(f"Cache hit for embedding: {query}")
                    # Update expiration time on access (sliding expiration)
                    self.redis_client.expire(cache_key, self.expire_time)
                    return embedding
                else:
                    logger.warning(
                        f"Invalid embedding found in cache (contains NaN/Inf or invalid shape), "
                        f"ignoring cache for query: {query[:50]}..."
                    )
                    # Delete invalid cache entry
                    try:
                        self.redis_client.delete(cache_key)
                    except Exception as e:
                        logger.debug(f"Failed to delete invalid cache entry: {e}")
                    return None
            return None
        except Exception as e:
            logger.error(f"Error retrieving embedding from cache: {e}")
            return None
    
    def _set_cached_embedding(
        self,
        query: str,
        embedding: np.ndarray,
        normalize_embeddings: bool = True,
    ) -> bool:
        """Store embedding in cache"""
        if not self.redis_client:
            return False
            
        try:
            cache_key = f"{self.cache_prefix}:{query}"
            serialized_data = pickle.dumps(embedding)
            self.redis_client.setex(
                cache_key,
                self.expire_time,
                serialized_data
            )
            logger.debug(f"Successfully cached embedding for query: {query}")
            return True
        except (redis.exceptions.BusyLoadingError, redis.exceptions.ConnectionError, 
                redis.exceptions.TimeoutError, redis.exceptions.RedisError) as e:
            logger.warning(f"Redis error storing embedding in cache: {e}")
            return False
        except Exception as e:
            logger.error(f"Error storing embedding in cache: {e}")
            return False