import torch
from transformers import AutoTokenizer, AutoModelForCausalLM
from peft import PeftModel
from huggingface_hub import snapshot_download

# === Base & adapter config ===
BASE_MODEL = "deepseek-ai/DeepSeek-R1-Distill-Qwen-1.5B"
ADAPTER_PATH = "GilbertAkham/deepseek-R1-multitask-lora"

# === System message ===
SYSTEM_PROMPT = (
    "You are Chat-Bot, a helpful and logical assistant trained for reasoning, "
    "email, chatting, summarization, story continuation, and report writing.\n\n"
)

class EndpointHandler:
    def __init__(self, path=""):
        print("🚀 Loading base model...")
        self.tokenizer = AutoTokenizer.from_pretrained(BASE_MODEL, trust_remote_code=True)

        base_model = AutoModelForCausalLM.from_pretrained(
            BASE_MODEL,
            torch_dtype=torch.float16,
            device_map="auto",
            trust_remote_code=True
        )

        print(f"🔗 Downloading LoRA adapter from {ADAPTER_PATH}...")
        adapter_local_path = snapshot_download(repo_id=ADAPTER_PATH, allow_patterns=["*adapter*"])
        print(f"📁 Adapter files cached at {adapter_local_path}")

        print("🧩 Attaching LoRA adapter...")
        self.model = PeftModel.from_pretrained(base_model, adapter_local_path)
        self.model.eval()

        print("✅ Model + LoRA adapter loaded successfully.")

    def __call__(self, data):
        # === Combine system + user prompt ===
        user_prompt = data.get("inputs", "")
        full_prompt = SYSTEM_PROMPT + user_prompt

        params = data.get("parameters", {})
        max_new_tokens = params.get("max_new_tokens", 512)
        temperature = params.get("temperature", 0.7)
        top_p = params.get("top_p", 0.9)

        # === Tokenize and run generation ===
        inputs = self.tokenizer(full_prompt, return_tensors="pt").to(self.model.device)
        with torch.no_grad():
            outputs = self.model.generate(
                **inputs,
                max_new_tokens=max_new_tokens,
                temperature=temperature,
                top_p=top_p,
                do_sample=True,
                pad_token_id=self.tokenizer.eos_token_id,
                eos_token_id=self.tokenizer.eos_token_id,
            )

        # === Decode and strip system message ===
        text = self.tokenizer.decode(outputs[0], skip_special_tokens=True)
        if text.startswith(SYSTEM_PROMPT):
            text = text[len(SYSTEM_PROMPT):].strip()

        return {"generated_text": text}