import os
import torch
import random
import numpy as np
from transformers import AutoModelForCausalLM, AutoTokenizer, set_seed
from typing import Optional

from .utils import dbg

# Ensure deterministic CuBLAS operations for reproducibility on GPU
os.environ["CUBLAS_WORKSPACE_CONFIG"] = ":4096:8"

class LLM:
    """
    Eine robuste, bereinigte Schnittstelle zum Laden und Interagieren mit einem Sprachmodell.
    Garantiert Isolation und Reproduzierbarkeit.
    """
    def __init__(self, model_id: str, device: str = "auto", seed: int = 42):
        self.model_id = model_id
        self.seed = seed
        self.set_all_seeds(self.seed)

        token = os.environ.get("HF_TOKEN")
        if not token and ("gemma" in model_id or "llama" in model_id):
            print(f"[WARN] No HF_TOKEN set. If '{model_id}' is gated, loading will fail.", flush=True)

        kwargs = {"torch_dtype": torch.bfloat16} if torch.cuda.is_available() else {}

        dbg(f"Loading tokenizer for '{model_id}'...")
        self.tokenizer = AutoTokenizer.from_pretrained(model_id, use_fast=True, token=token)

        dbg(f"Loading model '{model_id}' with kwargs: {kwargs}")
        self.model = AutoModelForCausalLM.from_pretrained(model_id, device_map=device, token=token, **kwargs)

        try:
            self.model.set_attn_implementation('eager')
            dbg("Successfully set attention implementation to 'eager'.")
        except Exception as e:
            print(f"[WARN] Could not set 'eager' attention: {e}.", flush=True)

        self.model.eval()
        self.config = self.model.config
        print(f"[INFO] Model '{model_id}' loaded on device: {self.model.device}", flush=True)

    def set_all_seeds(self, seed: int):
        """Setzt alle relevanten Seeds für maximale Reproduzierbarkeit."""
        os.environ['PYTHONHASHSEED'] = str(seed)
        random.seed(seed)
        np.random.seed(seed)
        torch.manual_seed(seed)
        if torch.cuda.is_available():
            torch.cuda.manual_seed_all(seed)
        set_seed(seed)
        torch.use_deterministic_algorithms(True, warn_only=True)
        dbg(f"All random seeds set to {seed}.")

def get_or_load_model(model_id: str, seed: int) -> LLM:
    """Lädt bei jedem Aufruf eine frische, isolierte Instanz des Modells."""
    dbg(f"--- Force-reloading model '{model_id}' for total run isolation ---")
    if torch.cuda.is_available():
        torch.cuda.empty_cache()
    return LLM(model_id=model_id, seed=seed)