app.py

"""
Hugging Face Space entrypoint: Hindi / English reading & pronunciation coach.

Set ASR_BACKEND (and GROQ_API_KEY as a Space secret) in Settings -> Variables.
"""

from __future__ import annotations

import hashlib
import os
import tempfile

import gradio as gr
import pandas as pd

from asr_backends import get_backend
from scoring import score

LANGS = {"हिंदी (Hindi)": "hi", "English": "en"}

SAMPLES = {
    "hi": "सूरज सुबह जल्दी उठता है और अपनी किताब पढ़ता है। उसे कहानियाँ बहुत पसंद हैं।",
    "en": "The quick brown fox jumps over the lazy dog while the children watch quietly.",
}

# ---------------------------------------------------------------------------
# TTS -- cached, because on a Space every gTTS call is a network round trip
# ---------------------------------------------------------------------------

TTS_DIR = os.path.join(tempfile.gettempdir(), "coach_tts")
os.makedirs(TTS_DIR, exist_ok=True)


def speak(text: str, lang_label: str, slow: bool):
    if not (text or "").strip():
        raise gr.Error("Type or paste a passage first.")
    lang = LANGS[lang_label]
    key = hashlib.sha1(f"{lang}|{slow}|{text}".encode()).hexdigest()[:20]
    path = os.path.join(TTS_DIR, f"{key}.mp3")
    if not os.path.exists(path):
        from gtts import gTTS

        try:
            gTTS(text=text, lang=lang, slow=slow).save(path)
        except Exception as exc:
            raise gr.Error(f"Text-to-speech unavailable: {exc}") from exc
    return path


def fill_sample(lang_label: str) -> str:
    return SAMPLES[LANGS[lang_label]]


# ---------------------------------------------------------------------------
# Evaluation
# ---------------------------------------------------------------------------

EMPTY = pd.DataFrame(columns=["अपेक्षित / Expected", "सुना गया / Heard",
                              "प्रकार / Error type", "समानता / Similarity"])


def evaluate(audio_path, passage, lang_label, lenient_decoding):
    if not audio_path:
        return {"error": "No recording received — record or upload audio first."}, EMPTY
    if not (passage or "").strip():
        return {"error": "Paste the passage to read first."}, EMPTY

    lang = LANGS[lang_label]
    try:
        backend = get_backend()
        hint = passage.strip() if lenient_decoding else None
        tr = backend.transcribe(audio_path, lang, hint=hint)
    except Exception as exc:
        return {"error": f"{type(exc).__name__}: {exc}"}, EMPTY

    if not tr.text:
        return {"error": "Nothing was transcribed. Check the mic level and try again."}, EMPTY
    return score(passage, tr, lang)


# ---------------------------------------------------------------------------
# UI
# ---------------------------------------------------------------------------

def build() -> gr.Blocks:
    with gr.Blocks(title="Reading & Pronunciation Coach") as app:
        gr.Markdown("## 🗣️ Reading & Pronunciation Coach — हिंदी / English")
        status = gr.Markdown("Resolving ASR backend…")

        with gr.Row():
            lang = gr.Dropdown(list(LANGS), value="हिंदी (Hindi)", label="Language", scale=2)
            sample_btn = gr.Button("Load sample passage", scale=1)

        passage = gr.Textbox(
            label="Passage to read", lines=4,
            placeholder="यहाँ हिंदी टेक्स्ट लिखें… / Paste English text here…",
        )

        with gr.Row():
            slow = gr.Checkbox(label="Slow speech", value=False, scale=1)
            listen = gr.Button("🔊 Listen", scale=1)
        tts_audio = gr.Audio(label="Model reading", type="filepath")

        gr.Markdown("### 🎤 Now read it aloud")
        mic = gr.Audio(sources=["microphone", "upload"], type="filepath",
                       label="Your recording")
        lenient = gr.Checkbox(
            label="Lenient decoding — biases the ASR toward the passage. "
                  "Scores look better but real mistakes get hidden. Leave off for assessment.",
            value=False,
        )
        submit = gr.Button("✅ Check my reading", variant="primary")

        metrics = gr.JSON(label="Results")
        table = gr.Dataframe(label="गलती तालिका / Error table", wrap=True)

        gr.Markdown(
            "**Reading the scores.** *Word accuracy* is strict: a word counts only if it "
            "matches exactly. *Lenient score* gives partial credit by similarity, so a "
            "near-miss on a hard word is not treated like a skipped line. *WER* is the "
            "standard ASR metric and includes extra words, so it can exceed the accuracy gap."
        )

        def backend_line():
            try:
                b = get_backend()
                extra = "" if b.supports_word_confidence else \
                    " · per-word confidence unavailable on this backend"
                return f"**Backend:** {b.describe()}{extra}"
            except Exception as exc:
                return f"⚠️ **Backend not ready:** {exc}"

        app.load(backend_line, None, status)
        sample_btn.click(fill_sample, lang, passage)
        listen.click(speak, [passage, lang, slow], tts_audio)
        submit.click(evaluate, [mic, passage, lang, lenient], [metrics, table])

    return app


if __name__ == "__main__":
    build().queue(max_size=12).launch()