import numpy as np
import joblib
import torch
from transformers import AutoModel
import os

class FinancialFilingClassifier:
    def __init__(self, model_dir):
        self.device = 'cuda' if torch.cuda.is_available() else 'cpu'
        print(f"Loading Jina Encoder on {self.device}...")
        
        # Jina-v3 handles Flash Attention internally if installed
        self.encoder = AutoModel.from_pretrained(
            "jinaai/jina-embeddings-v3", 
            trust_remote_code=True, 
            torch_dtype=torch.float16 if self.device == 'cuda' else torch.float32
        ).to(self.device)
        
        print("Loading XGBoost Cascade...")
        self.router = joblib.load(os.path.join(model_dir, "router_xgb.pkl"))
        self.router_le = joblib.load(os.path.join(model_dir, "router_le.pkl"))
        self.specialists = {}
        self.model_dir = model_dir

    def _get_vector(self, text, doc_length=None):
        """
        Generates the feature vector: [Embedding (1024) + Log_Length (1)]
        
        Args:
            text (str): The document text content.
            doc_length (int, optional): The real length of the document. 
                                      If None, defaults to len(text).
        """
        # 1. Feature Engineering: Log Length
        # We use the explicitly passed length if available. This allows
        # the model to know a document is massive (e.g. Annual Report) 
        # even if we only run inference on the first 8k tokens.
        val = int(doc_length) if doc_length is not None else len(str(text))
        log_len = np.log1p(val)

        with torch.no_grad():
            # 2. Embedding Generation
            # SAFETY MARGIN: We cap at 8100 (instead of 8192) to prevent 
            # "Rotary Embedding" off-by-one crashes in Flash Attention.
            vec = self.encoder.encode([text], task="classification", max_length=8100)
            
            # 3. XGBoost Compatibility
            # XGBoost requires CPU-bound Numpy arrays.
            if isinstance(vec, torch.Tensor):
                vec = vec.cpu().numpy()
            elif isinstance(vec, list):
                vec = np.array(vec)

        # 4. Concatenate: [Embedding vector, Log_Length]
        return np.hstack([vec, [[log_len]]])

    def _load_specialist(self, category):
        """Lazy loads specialist models to save RAM until needed."""
        safe_name = category.replace(" ", "_").replace("&", "and").replace("/", "_")
        if safe_name not in self.specialists:
            try:
                clf = joblib.load(os.path.join(self.model_dir, f"specialist_{safe_name}_xgb.pkl"))
                le = joblib.load(os.path.join(self.model_dir, f"specialist_{safe_name}_le.pkl"))
                self.specialists[safe_name] = (clf, le)
            except FileNotFoundError:
                return None
        return self.specialists[safe_name]

    def predict(self, text, doc_length=None):
        """
        Predicts the category and type of a financial document.
        
        Args:
            text (str): The document text.
            doc_length (int, optional): The true character length of the document.
                                      Recommended for highest accuracy.
        """
        vector = self._get_vector(text, doc_length=doc_length)
        
        # 1. Router Prediction (General Category)
        router_probs = self.router.predict_proba(vector)[0]
        # We look at the top 2 candidates to handle ambiguous edge cases
        top_indices = np.argsort(router_probs)[::-1][:2]
        
        candidates = []
        for idx in top_indices:
            category = self.router_le.classes_[idx]
            router_conf = router_probs[idx]
            
            # 2. Specialist Prediction (Specific Type)
            specialist = self._load_specialist(category)
            
            if specialist:
                clf, le = specialist
                spec_probs = clf.predict_proba(vector)[0]
                best_idx = np.argmax(spec_probs)
                label = le.classes_[best_idx]
                spec_conf = spec_probs[best_idx]
                
                # Combine Confidence Scores (Geometric Mean)
                combined_score = np.sqrt(router_conf * spec_conf)
                candidates.append({
                    "category": category, 
                    "label": label, 
                    "score": float(combined_score)
                })
            else:
                # Fallback if no specialist exists for this category
                candidates.append({
                    "category": category, 
                    "label": category, 
                    "score": float(router_conf)
                })
        
        # Return the highest scoring candidate
        return max(candidates, key=lambda x: x['score'])