app.py

"""Gradio app: NLLB-200 translation with selectable source/target languages."""

import os
import time

import gradio as gr

from translator import (
    LANGUAGE_LABELS,
    LABEL_TO_TOKEN,
    TOKEN_TO_LABEL,
    TranslatorClient,
)

AUTO_DETECT = "Auto-detect"

translator = TranslatorClient()


def run_translate(text: str, source_label: str, target_label: str):
    text = (text or "").strip()
    if not text:
        return "", "Enter some text to translate."

    target_token = LABEL_TO_TOKEN.get(target_label)
    if target_token is None:
        return "", "Pick a target language."

    if source_label == AUTO_DETECT:
        src_token = translator.detect_language(text)
        detected_label = TOKEN_TO_LABEL.get(src_token, "Unknown")
        source_info = f"Detected source: {detected_label}"
    else:
        src_token = LABEL_TO_TOKEN.get(source_label)
        if src_token is None:
            return "", "Pick a valid source language."
        source_info = f"Source: {source_label}"

    if src_token == target_token:
        return text, f"{source_info} (same as target — returned as-is)."

    start = time.time()
    translated = translator.translate(text, src_token, target_token)
    elapsed_ms = int((time.time() - start) * 1000)

    status = f"{source_info} → {target_label} ({elapsed_ms} ms)"
    return translated, status


with gr.Blocks(title="Translation") as app:

    gr.Markdown("# Translation")

    gr.Markdown(
        "Translate text between supported languages with **NLLB-200-3.3B** "
        "(`facebook/nllb-200-3.3B`, CTranslate2 int8 — "
        "[`Napron/nllb-200-3.3B-ct2-int8`](https://huggingface.co/Napron/nllb-200-3.3B-ct2-int8)). "
        "Source language can be auto-detected, or you can pick it explicitly. "
        "**CPU-only** — first translation warms the model."
    )

    with gr.Row():
        with gr.Column(scale=1):
            source_dropdown = gr.Dropdown(
                choices=[AUTO_DETECT] + LANGUAGE_LABELS,
                value=AUTO_DETECT,
                label="Source language",
            )
            input_text = gr.Textbox(
                label="Input text",
                placeholder="Type or paste text to translate…",
                lines=10,
                max_lines=20,
            )

            run_btn = gr.Button("Translate", variant="primary")

        with gr.Column(scale=1):
            target_dropdown = gr.Dropdown(
                choices=LANGUAGE_LABELS,
                value="English",
                label="Target language",
            )
            output_text = gr.Textbox(
                label="Translation",
                lines=10,
                max_lines=20,
                interactive=False,
            )

            status_box = gr.Textbox(
                label="Status",
                lines=2,
                interactive=False,
            )

    gr.Examples(
        examples=[
            ["Salam, necəsən? Bu gün hava çox gözəldir.", AUTO_DETECT, "English"],
            ["Привет, как дела? Сегодня прекрасная погода.", "Russian", "English"],
            ["สวัสดีครับ วันนี้อากาศดีมาก", AUTO_DETECT, "English"],
            ["The quick brown fox jumps over the lazy dog.", "English", "French"],
            ["Hola, ¿cómo estás? Hace muy buen tiempo hoy.", "Spanish", "German"],
        ],
        inputs=[input_text, source_dropdown, target_dropdown],
    )

    run_btn.click(
        fn=run_translate,
        inputs=[input_text, source_dropdown, target_dropdown],
        outputs=[output_text, status_box],
        concurrency_limit=1,
    )


app.launch(
    server_name=os.environ.get("GRADIO_SERVER_NAME", "0.0.0.0"),
    server_port=int(
        os.environ.get(
            "PORT",
            os.environ.get("GRADIO_SERVER_PORT", 7860),
        )
    ),
)