"""
  Embedding service (FastAPI).
  
  API (simple list-in, list-out; aligned by index; failures -> null):
  - POST /embed/text   body: ["text1", "text2", ...] -> [[...], null, ...]
  - POST /embed/image  body: ["url_or_path1", ...]  -> [[...], null, ...]
  """
  

  import logging

  import threading
  from typing import Any, Dict, List, Optional
  
  import numpy as np
  from fastapi import FastAPI
  
  from embeddings.config import CONFIG
  from embeddings.bge_model import BgeTextModel
  from embeddings.clip_model import ClipImageModel

  from embeddings.clip_as_service_encoder import ClipAsServiceImageEncoder
  from embeddings.protocols import ImageEncoderProtocol

  logger = logging.getLogger(__name__)

  app = FastAPI(title="saas-search Embedding Service", version="1.0.0")

  # Models are loaded at startup, not lazily
  _text_model: Optional[BgeTextModel] = None

  _image_model: Optional[ImageEncoderProtocol] = None

  open_text_model = True

  open_image_model = True  # Enable image embedding when using clip-as-service

  
  _text_encode_lock = threading.Lock()
  _image_encode_lock = threading.Lock()
  
  

  @app.on_event("startup")
  def load_models():
      """Load models at service startup to avoid first-request latency."""
      global _text_model, _image_model

      logger.info("Loading embedding models at startup...")

      # Load text model

      if open_text_model:
          try:
              logger.info(f"Loading text model: {CONFIG.TEXT_MODEL_DIR}")
              _text_model = BgeTextModel(model_dir=CONFIG.TEXT_MODEL_DIR)
              logger.info("Text model loaded successfully")
          except Exception as e:
              logger.error(f"Failed to load text model: {e}", exc_info=True)
              raise
      

      # Load image model: clip-as-service (recommended) or local CN-CLIP

      # IMPORTANT: failures here should NOT prevent the whole service from starting.
      # If image model cannot be loaded, we keep `_image_model` as None and only
      # disable /embed/image while keeping /embed/text fully functional.

      if open_image_model:
          try:

              if CONFIG.USE_CLIP_AS_SERVICE:
                  logger.info(f"Loading image encoder via clip-as-service: {CONFIG.CLIP_AS_SERVICE_SERVER}")
                  _image_model = ClipAsServiceImageEncoder(
                      server=CONFIG.CLIP_AS_SERVICE_SERVER,
                      batch_size=CONFIG.IMAGE_BATCH_SIZE,
                  )
                  logger.info("Image model (clip-as-service) loaded successfully")
              else:
                  logger.info(f"Loading local image model: {CONFIG.IMAGE_MODEL_NAME} (device: {CONFIG.IMAGE_DEVICE})")
                  _image_model = ClipImageModel(
                      model_name=CONFIG.IMAGE_MODEL_NAME,
                      device=CONFIG.IMAGE_DEVICE,
                  )
                  logger.info("Image model (local CN-CLIP) loaded successfully")

          except Exception as e:

              logger.error(
                  "Failed to load image model; image embeddings will be disabled but text embeddings remain available: %s",
                  e,
                  exc_info=True,
              )
              _image_model = None

  
      logger.info("All embedding models loaded successfully, service ready")

  
  
  def _as_list(embedding: Optional[np.ndarray]) -> Optional[List[float]]:
      if embedding is None:
          return None
      if not isinstance(embedding, np.ndarray):
          embedding = np.array(embedding, dtype=np.float32)
      if embedding.ndim != 1:
          embedding = embedding.reshape(-1)
      return embedding.astype(np.float32).tolist()
  
  
  @app.get("/health")
  def health() -> Dict[str, Any]:

      """Health check endpoint. Returns status and model loading state."""
      return {
          "status": "ok",
          "text_model_loaded": _text_model is not None,
          "image_model_loaded": _image_model is not None,
      }

  
  
  @app.post("/embed/text")
  def embed_text(texts: List[str]) -> List[Optional[List[float]]]:

      if _text_model is None:
          raise RuntimeError("Text model not loaded")

      out: List[Optional[List[float]]] = [None] * len(texts)
  
      indexed_texts: List[tuple] = []
      for i, t in enumerate(texts):
          if t is None:
              continue
          if not isinstance(t, str):
              t = str(t)
          t = t.strip()
          if not t:
              continue
          indexed_texts.append((i, t))
  
      if not indexed_texts:
          return out
  
      batch_texts = [t for _, t in indexed_texts]
      try:
          with _text_encode_lock:

              embs = _text_model.encode_batch(

                  batch_texts, batch_size=int(CONFIG.TEXT_BATCH_SIZE), device=CONFIG.TEXT_DEVICE
              )
          for j, (idx, _t) in enumerate(indexed_texts):
              out[idx] = _as_list(embs[j])
      except Exception:
          # keep Nones
          pass
      return out
  
  
  @app.post("/embed/image")
  def embed_image(images: List[str]) -> List[Optional[List[float]]]:

      if _image_model is None:

          # Graceful degradation: keep API shape but return all None
          logger.warning("embed_image called but image model is not loaded; returning all None vectors")
          return [None] * len(images)

      out: List[Optional[List[float]]] = [None] * len(images)
  

      # Normalize inputs
      urls = []
      indices = []
      for i, url_or_path in enumerate(images):
          if url_or_path is None:
              continue
          if not isinstance(url_or_path, str):
              url_or_path = str(url_or_path)
          url_or_path = url_or_path.strip()
          if url_or_path:
              urls.append(url_or_path)
              indices.append(i)
  
      if not urls:
          return out
  

      with _image_encode_lock:

          try:
              # Both ClipAsServiceImageEncoder and ClipImageModel implement encode_image_urls(urls, batch_size)
              vectors = _image_model.encode_image_urls(urls, batch_size=CONFIG.IMAGE_BATCH_SIZE)
              for j, idx in enumerate(indices):
                  out[idx] = _as_list(vectors[j] if j < len(vectors) else None)
          except Exception:
              for idx in indices:
                  out[idx] = None

      return out