"""Unified model loading and device management"""

import os
import torch
from transformers import AutoTokenizer, AutoModelForCausalLM

os.environ["TOKENIZERS_PARALLELISM"] = "false"

class ModelLoader:
    """Handles device detection and model/tokenizer loading"""
    
    @staticmethod
    def get_device_and_dtype():
        """Determine the best available device and dtype"""
        if torch.cuda.is_available():
            return "cuda", torch.float16
        elif torch.backends.mps.is_available():
            return "mps", torch.float16
        else:
            return "cpu", torch.float32
    
    @staticmethod
    def load_model_and_tokenizer(model_name="meta-llama/Llama-3.2-1B-Instruct"):
        """Load model and tokenizer with optimal device/dtype settings"""
        device, dtype = ModelLoader.get_device_and_dtype()
        
        tokenizer = AutoTokenizer.from_pretrained(model_name)
        model = AutoModelForCausalLM.from_pretrained(
            model_name, 
            dtype=dtype, 
            low_cpu_mem_usage=True
        )
        model = model.to(device)
        
        # Set pad token if needed
        if tokenizer.pad_token is None:
            tokenizer.pad_token = tokenizer.eos_token
        
        return model, tokenizer, device, dtype