import os
from typing import Iterator

from text_generation import Client

model_id = 'HuggingFaceH4/zephyr-7b-beta'

API_URL = "https://api-inference.huggingface.co/models/" + model_id
HF_TOKEN = os.environ.get("HF_READ_TOKEN", None)

client = Client(
    API_URL,
    headers={"Authorization": f"Bearer {HF_TOKEN}"},
)
EOS_STRING = "</s>"
EOT_STRING = "<EOT>"


def get_prompt(message: str, chat_history: list[tuple[str, str]],
               system_prompt: str) -> str:
    texts = [f'<s>[INST] <<SYS>>\n{system_prompt}\n<</SYS>>\n\n']
    # The first user input is _not_ stripped
    do_strip = False
    for user_input, response in chat_history:
        user_input = user_input.strip() if do_strip else user_input
        do_strip = True
        texts.append(f'{user_input} [/INST] {response.strip()} </s><s>[INST] ')
    message = message.strip() if do_strip else message
    texts.append(f'{message} [/INST]')
    return ''.join(texts)


def run(message: str,
        chat_history: list[tuple[str, str]],
        system_prompt: str,
        max_new_tokens: int = 1024,
        temperature: float = 0.1,
        top_p: float = 0.9,
        top_k: int = 50) -> Iterator[str]:
    prompt = get_prompt(message, chat_history, system_prompt)

    generate_kwargs = dict(
        max_new_tokens=max_new_tokens,
        do_sample=True,
        top_p=top_p,
        top_k=top_k,
        temperature=temperature,
    )
    stream = client.generate_stream(prompt, **generate_kwargs)
    output = ""
    for response in stream:
        if any([end_token in response.token.text for end_token in [EOS_STRING, EOT_STRING]]):
            return output
        else:
            output += response.token.text
        yield output
    return output