import asyncio
import torch
from typing import Optional
from doctr.models import ocr_predictor
import spacy
from src.config.config import settings


class ModelManager:
    """Singleton model manager for pre-loading all models at startup."""
    
    _instance = None
    _doctr_model = None
    _spacy_model = None
    _device = None
    _models_loaded = False
    
    def __new__(cls):
        if cls._instance is None:
            cls._instance = super(ModelManager, cls).__new__(cls)
        return cls._instance
    
    def __init__(self):
        if not self._models_loaded:
            self._load_models()
    
    def _load_models(self):
        """Load all models synchronously."""
        print("🚀 Starting model pre-loading...")
        
        # Set device based on config
        if settings.force_cpu:
            self._device = torch.device("cpu")
            print("📱 Using CPU (forced by config)")
        else:
            self._device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
            print(f"📱 Using device: {self._device}")
        
        # Load doctr model
        print("🔄 Loading doctr OCR model...")
        self._doctr_model = ocr_predictor(pretrained=True)
        self._doctr_model.det_predictor.model = self._doctr_model.det_predictor.model.to(self._device)
        self._doctr_model.reco_predictor.model = self._doctr_model.reco_predictor.model.to(self._device)
        print("✅ Doctr model loaded successfully!")
        
        # Load spaCy model
        print(f"🔄 Loading spaCy NER model: {settings.spacy_model_name}...")
        try:
            self._spacy_model = spacy.load(settings.spacy_model_name)
            print(f"✅ spaCy model ({settings.spacy_model_name}) loaded successfully!")
        except OSError:
            print(f"⚠️ spaCy model '{settings.spacy_model_name}' not found.")
            # Try fallback models
            fallback_models = ["en_core_web_sm", "en_core_web_trf"]
            for fallback_model in fallback_models:
                if fallback_model != settings.spacy_model_name:
                    try:
                        print(f"🔄 Trying fallback model: {fallback_model}")
                        self._spacy_model = spacy.load(fallback_model)
                        print(f"✅ spaCy model ({fallback_model}) loaded successfully!")
                        break
                    except OSError:
                        continue
            
            if self._spacy_model is None:
                print("⚠️ No spaCy model found. Please install with: python -m spacy download en_core_web_sm")
        
        self._models_loaded = True
        print("🎉 All models loaded successfully!")
    
    @property
    def doctr_model(self):
        """Get the loaded doctr model."""
        return self._doctr_model
    
    @property
    def spacy_model(self):
        """Get the loaded spaCy model."""
        return self._spacy_model
    
    @property
    def device(self):
        """Get the device being used."""
        return self._device
    
    @property
    def models_loaded(self):
        """Check if models are loaded."""
        return self._models_loaded
    
    async def ensure_models_loaded(self):
        """Ensure models are loaded (async wrapper)."""
        if not self._models_loaded:
            await asyncio.get_event_loop().run_in_executor(None, self._load_models)
        return True
    
    def get_model_status(self):
        """Get status of all models."""
        return {
            "doctr_model": self._doctr_model is not None,
            "spacy_model": self._spacy_model is not None,
            "device": str(self._device),
            "models_loaded": self._models_loaded,
            "spacy_model_name": settings.spacy_model_name,
            "force_cpu": settings.force_cpu
        }


# Global model manager instance
model_manager = ModelManager()