import spaces
import gradio as gr
from transformers import AutoTokenizer, AutoModelForSeq2SeqLM, pipeline
from flores import code_mapping
import platform

device = "cpu" if platform.system() == "Darwin" else "cuda"
MODEL_NAME = "facebook/nllb-200-distilled-600M"

code_mapping = dict(sorted(code_mapping.items(), key=lambda item: item[1]))
flores_codes = list(code_mapping.keys())


def load_model():
    model = AutoModelForSeq2SeqLM.from_pretrained(MODEL_NAME).to(device)
    tokenizer = AutoTokenizer.from_pretrained(MODEL_NAME)
    return model, tokenizer


model, tokenizer = load_model()


@spaces.GPU
def _translate(text: str, src_lang: str, tgt_lang: str):
    source = code_mapping[src_lang]
    target = code_mapping[tgt_lang]
    translator = pipeline(
        "translation",
        model=model,
        tokenizer=tokenizer,
        src_lang=source,
        tgt_lang=target,
        device=device,
    )
    output = translator(text, max_length=400)
    return output[0]["translation_text"]


def translate(text: str, src_lang: str, tgt_lang: str):
    # split the input text into smaller chunks
    # split first on newlines
    outputs = ""
    paragraph_chunks = text.split("\n")
    for chunk in paragraph_chunks:
        # check if the chunk is too long
        if len(chunk) > 500:
            # split on full stops
            sentence_chunks = chunk.split(".")
            for sentence in sentence_chunks:
                outputs += f"{_translate(sentence, src_lang, tgt_lang)}. "
        else:
            outputs += _translate(chunk, src_lang, tgt_lang) + "\n\n"

    return outputs


description = """
No Language Left Behind (NLLB) is a series of open-source models aiming to provide high-quality translations between 200 language."""


with gr.Blocks() as demo:
    gr.Markdown("# No Language Left Behind (NLLB) Translation Demo")
    gr.Markdown(description)
    with gr.Row():
        src_lang = gr.Dropdown(label="Source Language", choices=flores_codes)
        target_lang = gr.Dropdown(label="Target Language", choices=flores_codes)
    with gr.Row():
        input_text = gr.Textbox(label="Input Text", lines=6)
    with gr.Row():
        btn = gr.Button("Translate text")
    with gr.Row():
        output = gr.Textbox(label="Output Text", lines=6)
    btn.click(
        translate,
        inputs=[input_text, src_lang, target_lang],
        outputs=output,
    )
demo.launch()