# backend/agents/classification_agent.py
import os
import time
import torch
from transformers import pipeline

# --- REMOVED HARDCODED STORAGE CONFIG ---
# Hugging Face Spaces & Docker will manage the HF_HOME cache path automatically.
# DO NOT set 'D:/' paths here anymore.

# --- YOUR EXACT CLASS ---
class ClassificationAgent:
    def __init__(self):
        # --- DYNAMIC PATH RESOLUTION ---
        # Automatically works on local Windows and Linux Docker container
        base_dir = os.path.dirname(os.path.abspath(__file__))
        self.model_path = os.path.join(base_dir, 'classification_model')
        # -------------------------------
        
        self.device = 0 if torch.cuda.is_available() else -1
        print(f"--- Loading Specialist Agent on {'GPU' if self.device == 0 else 'CPU'} ---")
        
        self.classifier = pipeline(
            "text-classification", 
            model=self.model_path, 
            tokenizer=self.model_path,
            device=self.device,
            truncation=True,
            max_length=512
        )

        self.id2label = {
            "LABEL_0": "Work",
            "LABEL_1": "Personal",
            "LABEL_2": "Finance",
            "LABEL_3": "Travel",
            "LABEL_4": "Social"
        }

    def process(self, subject: str, body: str):
        text_input = f"Subject: {subject} | Content: {body}"
        start_time = time.perf_counter()
        result = self.classifier(text_input)[0]
        end_time = time.perf_counter()
        
        predicted_label = self.id2label.get(result['label'], "Uncategorized")
        
        return {
            "category": predicted_label,
            "confidence": round(result['score'], 4),
            "metrics": {
                "latency_s": round(end_time - start_time, 4),
                "model": "classification_model",
                "processor": "gpu" if self.device == 0 else "cpu"
            }
        }

# --- FASTAPI WRAPPERS ---
classification_agent_instance = None

def load_classification_model():
    """Called ONCE by FastAPI when the server starts."""
    global classification_agent_instance
    classification_agent_instance = ClassificationAgent()
    print("🗂️ Classification Agent ready.")

async def run_classification(subject: str, text: str) -> dict:
    """Called on every single email request."""
    global classification_agent_instance
    if classification_agent_instance is None:
        raise RuntimeError("Classification model is not loaded into memory.")
    
    # Run the pipeline inference
    return classification_agent_instance.process(subject, text)