app.py

"""
TalkToDoc Flask application.
Wires together speech-to-text, translation, natural language understanding,
and text-to-speech into the patient-provider communication flow described
in the research document.

Two-step flow:
1. Patient submits input (text or audio) in their chosen language.
   The system transcribes it if needed, translates it to English, and
   summarizes the likely symptoms or intent for the provider.
2. Provider submits a reply in English. The system translates it back
   into the patient's language and generates spoken audio for it.
"""

import os
import uuid
from datetime import datetime, timezone

from dotenv import load_dotenv
from flask import Flask, request, jsonify, render_template, session

import database
import stt
import translation
import nlu
import tts

load_dotenv("env")

AUDIO_DIR = os.path.join(os.path.dirname(os.path.abspath(__file__)), "static", "audio")


def create_app():
    flask_app = Flask(__name__)
    flask_app.secret_key = os.environ["SECRET_KEY"]
    os.makedirs(AUDIO_DIR, exist_ok=True)
    return flask_app


app = create_app()

# Runs whether the app is started directly (python app.py, local development)
# or imported by a production server like gunicorn (Render deployment).
# Initialization code inside "if __name__ == '__main__'" only runs on a
# direct start, gunicorn never triggers it, so anything the app needs to
# work at all has to happen here instead.
database.init_db()
tts.preload_models()


def get_current_user_id(language):
    """
    Returns the user_id for the current browser session, creating a new
    user and session record the first time this browser is seen. This is
    what keeps a patient's messages tied to the same person instead of
    creating a brand new anonymous patient on every single submission.
    """
    if "user_id" not in session:
        user_id = database.add_user(name="Patient", preferred_language=language, role="patient")
        session_id = database.add_session(
            user_id=user_id,
            start_time=datetime.now(timezone.utc).isoformat(),
        )
        session["user_id"] = user_id
        session["session_id"] = session_id

    return session["user_id"]


@app.route("/")
def index():
    return render_template("patient.html", languages=translation.SUPPORTED_LANGUAGES)


@app.route("/provider")
def provider_page():
    return render_template("provider.html")


@app.route("/transcribe", methods=["POST"])
def transcribe_only():
    """
    Transcribes an audio recording without saving anything or translating
    it. Used by the transcript review step, so the patient can see and
    edit what was heard before it becomes the message actually sent to
    the provider. Nothing here touches the database.
    """
    language = request.form.get("language")
    if not language or language.lower() not in translation.SUPPORTED_LANGUAGES:
        return jsonify({"error": f"language must be one of {translation.SUPPORTED_LANGUAGES}"}), 400
    language = language.lower()

    audio_file = request.files.get("audio")
    if not audio_file:
        return jsonify({"error": "provide an audio file"}), 400

    temp_path = os.path.join(AUDIO_DIR, f"transcribe_{uuid.uuid4().hex}.wav")
    audio_file.save(temp_path)
    try:
        patient_text = stt.transcribe_audio(temp_path, language)
    finally:
        os.remove(temp_path)

    return jsonify({"patient_text": patient_text})


@app.route("/patient-input", methods=["POST"])
def patient_input():
    language = request.form.get("language")
    if not language or language.lower() not in translation.SUPPORTED_LANGUAGES:
        return jsonify({"error": f"language must be one of {translation.SUPPORTED_LANGUAGES}"}), 400
    language = language.lower()

    text = request.form.get("text")
    audio_file = request.files.get("audio")

    if not text and not audio_file:
        return jsonify({"error": "provide either text or audio"}), 400

    if audio_file:
        temp_path = os.path.join(AUDIO_DIR, f"upload_{uuid.uuid4().hex}.wav")
        audio_file.save(temp_path)
        try:
            patient_text = stt.transcribe_audio(temp_path, language)
        finally:
            os.remove(temp_path)
    else:
        patient_text = text

    english_text = translation.translate(patient_text, language, "english")
    nlu_summary = nlu.interpret_query(english_text)

    user_id = get_current_user_id(language)
    interaction_id = database.add_interaction(
        user_id=user_id,
        input_text=patient_text,
        detected_language=language,
        translated_text=english_text,
        nlu_summary=nlu_summary,
        timestamp=datetime.now(timezone.utc).isoformat(),
    )

    return jsonify({
        "interaction_id": interaction_id,
        "patient_text": patient_text,
        "translated_text": english_text,
        "nlu_summary": nlu_summary,
    })


@app.route("/preview-response", methods=["POST"])
def preview_response():
    """
    Runs the exact same translate + synthesize pipeline as
    /provider-response below, so the provider can read and hear precisely
    what the patient will receive before committing to it. Unlike
    /provider-response, this never touches the database - only "Send
    reply" actually saves a response. Each preview click is a real
    translation + speech synthesis call, same cost as an actual send.
    """
    interaction_id = request.form.get("interaction_id")
    response_text = request.form.get("response_text")

    if not interaction_id or not response_text:
        return jsonify({"error": "interaction_id and response_text are required"}), 400

    interaction = database.get_interaction(interaction_id)
    if not interaction:
        return jsonify({"error": "interaction not found"}), 404

    patient_language = interaction["detected_language"]
    translated_response = translation.translate(response_text, "english", patient_language)

    audio_filename = f"preview_{interaction_id}.wav"
    audio_path = os.path.join(AUDIO_DIR, audio_filename)
    tts.synthesize_speech(translated_response, patient_language, audio_path)

    return jsonify({
        "translated_response": translated_response,
        "audio_url": f"/static/audio/{audio_filename}",
    })


@app.route("/provider-response", methods=["POST"])
def provider_response():
    interaction_id = request.form.get("interaction_id")
    response_text = request.form.get("response_text")
    # Optional cache-reuse fields: if the provider already generated a
    # preview of this exact reply via /preview-response and didn't edit
    # it afterward, the frontend passes the already-computed translation
    # back here so this route can skip re-translating and re-synthesizing
    # speech. Both are best-effort - if the preview audio isn't actually
    # on disk, this quietly falls back to doing the full work itself,
    # exactly as if these fields had never been sent.
    cached_translation = request.form.get("translated_response")
    reuse_audio = request.form.get("reuse_audio") == "true"

    if not interaction_id or not response_text:
        return jsonify({"error": "interaction_id and response_text are required"}), 400

    interaction = database.get_interaction(interaction_id)
    if not interaction:
        return jsonify({"error": "interaction not found"}), 404

    patient_language = interaction["detected_language"]
    audio_filename = f"response_{interaction_id}.wav"
    audio_path = os.path.join(AUDIO_DIR, audio_filename)
    preview_path = os.path.join(AUDIO_DIR, f"preview_{interaction_id}.wav")

    if cached_translation and reuse_audio and os.path.exists(preview_path):
        translated_response = cached_translation
        os.replace(preview_path, audio_path)
    else:
        translated_response = translation.translate(response_text, "english", patient_language)
        tts.synthesize_speech(translated_response, patient_language, audio_path)

    database.update_interaction_response(interaction_id, response_text, translated_response)

    return jsonify({
        "translated_response": translated_response,
        "audio_url": f"/static/audio/{audio_filename}",
    })


@app.route("/interaction/<interaction_id>")
def get_interaction(interaction_id):
    interaction = database.get_interaction(interaction_id)
    if not interaction:
        return jsonify({"error": "interaction not found"}), 404

    audio_filename = f"response_{interaction_id}.wav"
    audio_path = os.path.join(AUDIO_DIR, audio_filename)
    interaction["audio_url"] = f"/static/audio/{audio_filename}" if os.path.exists(audio_path) else None

    return jsonify(interaction)


@app.route("/pending-interactions")
def pending_interactions():
    return jsonify(database.get_pending_interactions())


@app.route("/completed-interactions")
def completed_interactions():
    return jsonify(database.get_completed_interactions())


@app.route("/history")
def history():
    if "user_id" not in session:
        return jsonify([])
    return jsonify(database.get_interactions_for_user(session["user_id"]))


@app.route("/patient-history/<user_id>")
def patient_history(user_id):
    """
    All of one patient's interactions, for the provider workspace's
    "conversation history" panel. Distinct from /history above: that route
    always looks up the current browser's own session, which only works
    for the patient viewing their own messages. The provider needs to look
    up a specific patient's history by id instead.
    """
    return jsonify(database.get_interactions_for_user(user_id))


@app.route("/end-session", methods=["POST"])
def end_session_route():
    if "session_id" in session:
        database.end_session(session["session_id"], datetime.now(timezone.utc).isoformat())
    session.clear()
    return jsonify({"status": "ended"})


if __name__ == "__main__":
    is_production = os.environ.get("ENVIRONMENT") == "production"
    app.run(debug=not is_production, host="0.0.0.0", port=int(os.environ.get("PORT", 5000)))