#!/usr/bin/env python3
"""A small terminal chat UI for PertMind."""

from __future__ import annotations

import argparse
from dataclasses import dataclass


DEFAULT_SYSTEM_PROMPT = (
    "You are PertMind, a biomedical assistant. For biomedical prediction, "
    "screen-ranking, or gene-set interpretation tasks, answer first and then "
    "provide a concise explanation. Use this style when applicable:\n"
    "Final Answer: <answer>\nExplanation: <brief explanation>"
)


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--model", default=".", help="Path or Hugging Face model id.")
    parser.add_argument("--backend", choices=["vllm", "transformers"], default="vllm")
    parser.add_argument("--system-prompt", default=DEFAULT_SYSTEM_PROMPT)
    parser.add_argument("--max-new-tokens", type=int, default=768)
    parser.add_argument("--temperature", type=float, default=0.0)
    parser.add_argument("--top-p", type=float, default=0.95)
    parser.add_argument("--max-model-len", type=int, default=12288)
    parser.add_argument("--gpu-memory-utilization", type=float, default=0.85)
    return parser.parse_args()


def render_chat(tokenizer, messages: list[dict[str, str]]) -> str:
    try:
        return tokenizer.apply_chat_template(
            messages,
            tokenize=False,
            add_generation_prompt=True,
            enable_thinking=False,
        )
    except TypeError:
        return tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)


@dataclass
class VllmBackend:
    model: str
    max_model_len: int
    gpu_memory_utilization: float

    def __post_init__(self) -> None:
        from vllm import LLM

        self.llm = LLM(
            model=self.model,
            trust_remote_code=True,
            dtype="bfloat16",
            max_model_len=self.max_model_len,
            gpu_memory_utilization=self.gpu_memory_utilization,
        )
        self.tokenizer = self.llm.get_tokenizer()

    def generate(self, messages: list[dict[str, str]], max_new_tokens: int, temperature: float, top_p: float) -> str:
        from vllm import SamplingParams

        prompt = render_chat(self.tokenizer, messages)
        params = SamplingParams(temperature=temperature, top_p=top_p, max_tokens=max_new_tokens)
        return self.llm.generate([prompt], params)[0].outputs[0].text.strip()


@dataclass
class TransformersBackend:
    model: str

    def __post_init__(self) -> None:
        import torch
        from transformers import AutoModelForCausalLM, AutoTokenizer

        self.torch = torch
        self.tokenizer = AutoTokenizer.from_pretrained(self.model, trust_remote_code=True)
        self.llm = AutoModelForCausalLM.from_pretrained(
            self.model,
            torch_dtype=torch.bfloat16 if torch.cuda.is_available() else torch.float32,
            device_map="auto",
            trust_remote_code=True,
        )

    def generate(self, messages: list[dict[str, str]], max_new_tokens: int, temperature: float, top_p: float) -> str:
        prompt = render_chat(self.tokenizer, messages)
        inputs = self.tokenizer(prompt, return_tensors="pt").to(self.llm.device)
        do_sample = temperature > 0
        outputs = self.llm.generate(
            **inputs,
            max_new_tokens=max_new_tokens,
            do_sample=do_sample,
            temperature=temperature if do_sample else None,
            top_p=top_p if do_sample else None,
            pad_token_id=self.tokenizer.eos_token_id,
        )
        generated = outputs[0, inputs["input_ids"].shape[-1] :]
        return self.tokenizer.decode(generated, skip_special_tokens=True).strip()


def print_panel(title: str, text: str) -> None:
    line = "=" * min(88, max(20, len(title) + 8))
    print(f"\n{line}\n{title}\n{line}\n{text}\n")


def main() -> int:
    args = parse_args()
    if args.backend == "vllm":
        backend = VllmBackend(args.model, args.max_model_len, args.gpu_memory_utilization)
    else:
        backend = TransformersBackend(args.model)

    messages: list[dict[str, str]] = [{"role": "system", "content": args.system_prompt}]
    print_panel("PertMind TUI", "Type your question and press Enter. Commands: /reset, /exit")
    while True:
        try:
            user_text = input("You> ").strip()
        except (EOFError, KeyboardInterrupt):
            print()
            break
        if not user_text:
            continue
        if user_text.lower() in {"/exit", "exit", "quit", "/quit"}:
            break
        if user_text.lower() == "/reset":
            messages = [{"role": "system", "content": args.system_prompt}]
            print_panel("PertMind", "Conversation reset.")
            continue
        messages.append({"role": "user", "content": user_text})
        answer = backend.generate(messages, args.max_new_tokens, args.temperature, args.top_p)
        messages.append({"role": "assistant", "content": answer})
        print_panel("PertMind", answer)
    return 0


if __name__ == "__main__":
    raise SystemExit(main())