import os
import gradio as gr
from typing import Iterator

from dialog import get_dialog_box
from gateway import check_server_health, request_generation

# CONSTANTS
MAX_NEW_TOKENS: int = 2048

# GET ENVIRONMENT VARIABLES
CLOUD_GATEWAY_API = os.getenv("API_ENDPOINT")


def toggle_ui():
    """
    Function to toggle the visibility of the UI based on the server health
    Returns:
        hide/show main ui/dialog
    """
    health = check_server_health(cloud_gateway_api=CLOUD_GATEWAY_API)
    if health:
        return gr.update(visible=True), gr.update(visible=False)    # Show main UI, hide dialog
    else:
        return gr.update(visible=False), gr.update(visible=True)    # Hide main UI, show dialog


def generate(
        message: str,
        chat_history: list,
        system_prompt: str,
        max_new_tokens: int = 1024,
        temperature: float = 0.6,
        top_p: float = 0.9,
        top_k: int = 50,
        repetition_penalty: float = 1.2,
) -> Iterator[str]:
    """Send a request to backend, fetch the streaming responses and emit to the UI.

    Args:
        message (str): input message from the user
        chat_history (list[tuple[str, str]]): entire chat history of the session
        system_prompt (str): system prompt
        max_new_tokens (int, optional): maximum number of tokens to generate, ignoring the number of tokens in the
                                        prompt. Defaults to 1024.
        temperature (float, optional): the value used to module the next token probabilities. Defaults to 0.6.
        top_p (float, optional): if set to float<1, only the smallest set of most probable tokens with probabilities
                                    that add up to top_p or higher are kept for generation. Defaults to 0.9.
        top_k (int, optional): the number of highest probability vocabulary tokens to keep for top-k-filtering.
                                Defaults to 50.
        repetition_penalty (float, optional): the parameter for repetition penalty. 1.0 means no penalty.
                                Defaults to 1.2.

    Yields:
        Iterator[str]: Streaming responses to the UI
    """
    # sample method to yield responses from the llm model
    outputs = []
    for text in request_generation(message=message,
                                   system_prompt=system_prompt,
                                   max_new_tokens=max_new_tokens,
                                   temperature=temperature,
                                   top_p=top_p,
                                   top_k=top_k,
                                   repetition_penalty=repetition_penalty,
                                   cloud_gateway_api=CLOUD_GATEWAY_API):
        outputs.append(text)
        yield "".join(outputs)


chat_interface = gr.ChatInterface(
    fn=generate,
    additional_inputs=[
        gr.Textbox(label="System prompt", lines=6),
        gr.Slider(
            label="Max New Tokens",
            minimum=1,
            maximum=MAX_NEW_TOKENS,
            step=1,
            value=1024,
        ),
        gr.Slider(
            label="Temperature",
            minimum=0.1,
            maximum=4.0,
            step=0.1,
            value=0.1,
        ),
        gr.Slider(
            label="Top-p (nucleus sampling)",
            minimum=0.05,
            maximum=1.0,
            step=0.05,
            value=0.95,
        ),
        gr.Slider(
            label="Top-k",
            minimum=1,
            maximum=1000,
            step=1,
            value=50,
        ),
        gr.Slider(
            label="Repetition penalty",
            minimum=1.0,
            maximum=2.0,
            step=0.05,
            value=1.2,
        ),
    ],
    stop_btn=None,
    examples=[
        ["Hello there! How are you doing?"],
        ["Can you explain briefly to me what is the Python programming language?"],
        ["Explain the plot of Cinderella in a sentence."],
        ["How many hours does it take a man to eat a Helicopter?"],
        ["Write a 100-word article on 'Benefits of Open-Source in AI research'."],
    ],
    cache_examples=False,
    chatbot=gr.Chatbot(
            height=600)
)

with gr.Blocks(css="style.css", theme=gr.themes.Default()) as demo:
    # Get the server status before displaying UI
    visibility = check_server_health(CLOUD_GATEWAY_API)

    # Container for the main interface
    with gr.Column(visible=visibility, elem_id="main_ui") as main_ui:
        gr.Markdown(f"""
            # Llama-3 8B Chat
            This Space is an Alpha release that demonstrates model [Llama-3-8b-chat](https://huggingface.co/meta-llama/Meta-Llama-3-8B) by Meta, a Llama 3 model with 8B parameters fine-tuned for chat instructions, running on AMD MI210 infrastructure. Feel free to play with it!
            """)
        chat_interface.render()

    # Dialog box using Markdown for the error message
    with gr.Row(visible=(not visibility), elem_id="dialog_box") as dialog_box:
        # Add spinner and message
        get_dialog_box()

    # Timer to check server health every 5 seconds and update UI
    timer = gr.Timer(value=10)
    timer.tick(fn=toggle_ui, outputs=[main_ui, dialog_box])


if __name__ == "__main__":
    demo.queue(max_size=int(os.getenv("QUEUE"))).launch()