import os
from functools import lru_cache
from time import time

import streamlit as st
from grouped_sampling import GroupedSamplingPipeLine

from download_repo import download_pytorch_model


def is_downloaded(model_name: str) -> bool:
    """
    Checks if the model is downloaded.
    :param model_name: The name of the model to check.
    :return: True if the model is downloaded, False otherwise.
    """
    models_dir = os.path.join(os.path.expanduser("~"), ".cache", "huggingface", "hub")
    model_dir = os.path.join(models_dir, f"models--{model_name.replace('/', '--')}")
    return os.path.isdir(model_dir)


@lru_cache(maxsize=10)
def create_pipeline(model_name: str) -> GroupedSamplingPipeLine:
    """
    Creates a pipeline with the given model name and group size.
    :param model_name: The name of the model to use.
    :return: A pipeline with the given model name and group size.
    """
    if not is_downloaded(model_name):
        download_repository_start_time = time()
        st.write(f"Starts downloading model: {model_name} from the internet.")
        download_pytorch_model(model_name)
        download_repository_end_time = time()
        download_time = download_repository_end_time - download_repository_start_time
        st.write(f"Finished downloading model: {model_name} from the internet in {download_time:,.2f} seconds.")
    st.write(f"Starts creating pipeline with model: {model_name}")
    pipeline_start_time = time()
    pipeline = GroupedSamplingPipeLine(
        model_name=model_name,
        group_size=512,
        end_of_sentence_stop=False,
        top_k=50,
        load_in_8bit=False,
    )
    pipeline_end_time = time()
    pipeline_time = pipeline_end_time - pipeline_start_time
    st.write(f"Finished creating pipeline with model: {model_name} in {pipeline_time:,.2f} seconds.")
    return pipeline


def generate_text(
        pipeline: GroupedSamplingPipeLine,
        prompt: str,
        output_length: int,
) -> str:
    """
    Generates text using the given pipeline.
    :param pipeline: The pipeline to use. GroupedSamplingPipeLine.
    :param prompt: The prompt to use. str.
    :param output_length: The size of the text to generate in tokens. int > 0.
    :return: The generated text. str.
    """
    return pipeline(
        prompt_s=prompt,
        max_new_tokens=output_length,
        return_text=True,
        return_full_text=False,
    )["generated_text"]


def on_form_submit(
        model_name: str,
        output_length: int,
        prompt: str,
) -> str:
    """
    Called when the user submits the form.
    :param model_name: The name of the model to use.
    :param output_length: The size of the groups to use.
    :param prompt: The prompt to use.
    :return: The output of the model.
    :raises ValueError: If the model name is not supported, the output length is <= 0,
     the prompt is empty or longer than
     16384 characters, or the output length is not an integer.
     TypeError: If the output length is not an integer or the prompt is not a string.
     RuntimeError: If the model is not found.
    """
    if len(prompt) == 0:
        raise ValueError("The prompt must not be empty.")
    st.write(f"Loading model: {model_name}...")
    loading_start_time = time()
    pipeline = create_pipeline(
        model_name=model_name,
    )
    loading_end_time = time()
    loading_time = loading_end_time - loading_start_time
    st.write(f"Finished loading model: {model_name}  in {loading_time:,.2f} seconds.")
    st.write("Generating text...")
    generation_start_time = time()
    generated_text = generate_text(
        pipeline=pipeline,
        prompt=prompt,
        output_length=output_length,
    )
    generation_end_time = time()
    generation_time = generation_end_time - generation_start_time
    st.write(f"Finished generating text in {generation_time:,.2f} seconds.")
    if not isinstance(generated_text, str):
        raise RuntimeError(f"The model {model_name} did not generate any text.")
    if len(generated_text) == 0:
        raise RuntimeError(f"The model {model_name} did not generate any text.")
    return generated_text