#!/usr/bin/env python3
"""
VANI Speech API — hosted speech-to-text and text-to-speech Space.

PURPOSE: Take the two real capabilities already proven locally in
`dashboard_demo/vani_demo_service.py` (speech-to-text, text-to-speech) and make
them reachable over HTTPS from the public website, so the website page stops
depending on a service running on RP's own Mac at http://127.0.0.1:8901.

WHEN TO RUN: as a Hugging Face Space (the platform runs `python app.py` and
proxies port 7860), or locally for testing with the same command.

WHEN NOT TO RUN: do not run this as the local development service — that role
belongs to `dashboard_demo/vani_demo_service.py`, which keeps the local-only
extras (macOS `say`, the LM Studio correction lane, the personal dictionary)
that deliberately do NOT exist here because they are not portable.

PORTABILITY, STATED PLAINLY:
  * Speech-to-text is faster-whisper (CTranslate2), not the MLX Whisper build
    used locally. MLX runs on Apple silicon only and would fail on this Linux
    host. Same model weights family, different runtime.
  * Text-to-speech is Kokoro (pure PyTorch, CPU), not macOS `say`. `say` is an
    operating-system binary that exists only on macOS.
  * Nothing in this file or in requirements.txt needs Apple hardware.
"""

import io
import os
import time
import tempfile
import threading
import uuid

import numpy as np
import soundfile as sf
from fastapi import FastAPI, File, HTTPException, UploadFile
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import HTMLResponse, Response
from pydantic import BaseModel

# --------------------------------------------------------------------------
# Configuration
# --------------------------------------------------------------------------
STT_MODEL_SIZE = os.environ.get("VANI_STT_MODEL", "small")
TTS_VOICE_DEFAULT = os.environ.get("VANI_TTS_VOICE", "af_heart")
TTS_SAMPLE_RATE = 24000  # Kokoro's native output rate
PORT = int(os.environ.get("PORT", "7860"))

# Which browser origins may call this API. The website is the real consumer;
# the localhost entries let the site be previewed locally against the hosted
# API without a second deployment.
ALLOWED_ORIGINS = [
    "https://radhapreetam.com",
    "https://www.radhapreetam.com",
    "http://localhost:4321",
    "http://127.0.0.1:4321",
    "http://localhost:3000",
    "http://127.0.0.1:3000",
]

_TMP_DIR = tempfile.mkdtemp(prefix="vani_api_")

app = FastAPI(title="VANI Speech API", version="1.0.0")
app.add_middleware(
    CORSMiddleware,
    allow_origins=ALLOWED_ORIGINS,
    allow_methods=["GET", "POST", "OPTIONS"],
    allow_headers=["*"],
)

# --------------------------------------------------------------------------
# Lazily-loaded engines.
#
# Both are loaded on first use, not at import, so the Space finishes booting
# and starts answering /health immediately. That matters: a Space that spends
# two minutes loading models before it binds its port looks dead to every
# health check and to any first-time visitor. Load state is reported honestly
# through /health so the page can show a real loading indicator instead of
# silence.
# --------------------------------------------------------------------------
_lock = threading.Lock()
_stt = None
_tts = None
_stt_error = None
_tts_error = None


def get_stt():
    global _stt, _stt_error
    if _stt is not None or _stt_error is not None:
        return _stt
    with _lock:
        if _stt is None and _stt_error is None:
            try:
                from faster_whisper import WhisperModel
                t0 = time.time()
                _stt = WhisperModel(STT_MODEL_SIZE, device="cpu", compute_type="int8")
                print(f"[stt] faster-whisper '{STT_MODEL_SIZE}' loaded in "
                      f"{time.time() - t0:.1f}s (cpu/int8)", flush=True)
            except Exception as e:  # noqa: BLE001 - reported, never swallowed
                _stt_error = f"{type(e).__name__}: {e}"
                print(f"[stt] LOAD FAILED: {_stt_error}", flush=True)
    return _stt


def get_tts():
    global _tts, _tts_error
    if _tts is not None or _tts_error is not None:
        return _tts
    with _lock:
        if _tts is None and _tts_error is None:
            try:
                from kokoro import KPipeline
                t0 = time.time()
                _tts = KPipeline(lang_code="a")  # 'a' = American English
                print(f"[tts] kokoro pipeline loaded in {time.time() - t0:.1f}s (cpu)",
                      flush=True)
            except Exception as e:  # noqa: BLE001
                _tts_error = f"{type(e).__name__}: {e}"
                print(f"[tts] LOAD FAILED: {_tts_error}", flush=True)
    return _tts


def _engine_state(obj, err):
    if err:
        return "error"
    return "ready" if obj is not None else "not_loaded"


# --------------------------------------------------------------------------
# API
# --------------------------------------------------------------------------
@app.get("/health")
def health():
    """Cheap, never loads a model. Answers immediately, even during cold start."""
    return {
        "status": "ok",
        "service": "vani-speech-api",
        "stt_backend": f"faster-whisper ({STT_MODEL_SIZE}, cpu/int8)",
        "tts_backend": "kokoro (cpu)",
        "stt_state": _engine_state(_stt, _stt_error),
        "tts_state": _engine_state(_tts, _tts_error),
        "stt_error": _stt_error,
        "tts_error": _tts_error,
        "apple_silicon_required": False,
    }


@app.post("/warmup")
def warmup():
    """Force both engines to load. Lets a caller pay the cold-start cost up
    front rather than inside a user's first real request."""
    t0 = time.time()
    get_stt()
    stt_done = time.time()
    get_tts()
    return {
        "stt_state": _engine_state(_stt, _stt_error),
        "tts_state": _engine_state(_tts, _tts_error),
        "stt_load_seconds": round(stt_done - t0, 1),
        "tts_load_seconds": round(time.time() - stt_done, 1),
        "stt_error": _stt_error,
        "tts_error": _tts_error,
    }


@app.post("/speech-to-text")
async def speech_to_text(audio: UploadFile = File(...)):
    raw = await audio.read()
    if not raw:
        raise HTTPException(400, "Empty audio upload — no bytes received.")

    model = get_stt()
    if model is None:
        raise HTTPException(503, f"Speech-to-text engine unavailable: {_stt_error}")

    # faster-whisper decodes via PyAV, which reads the browser's webm/opus and
    # mp4/aac MediaRecorder output directly. The local service needed an
    # explicit ffmpeg conversion step because it fed bytes to Python's stdlib
    # `wave` module, which only understands RIFF/PCM. Passing a path here
    # avoids that whole class of bug.
    suffix = os.path.splitext(audio.filename or "recording.webm")[1] or ".webm"
    path = os.path.join(_TMP_DIR, f"in_{uuid.uuid4().hex}{suffix}")
    with open(path, "wb") as f:
        f.write(raw)

    try:
        t0 = time.time()
        segments, info = model.transcribe(path, beam_size=1, vad_filter=True)
        text = "".join(seg.text for seg in segments).strip()
        elapsed = time.time() - t0
    except Exception as e:  # noqa: BLE001
        # The exception text from the decoder embeds the server-side temp file
        # path. That is useless to the user and needlessly exposes the server's
        # filesystem layout to the browser, so it is logged here and kept out of
        # the response body.
        print(f"[stt] decode/transcribe failed for {path}: {type(e).__name__}: {e}",
              flush=True)
        raise HTTPException(
            422,
            "That audio could not be read. Re-record and try again — hold the "
            "button down while you speak. If it keeps happening, your browser is "
            "producing a recording format this server cannot decode.",
        )
    finally:
        try:
            os.remove(path)
        except OSError:
            pass

    print(f"[stt] {len(raw)} bytes ({audio.content_type}) -> {text!r} in {elapsed:.2f}s",
          flush=True)
    return {
        "text": text,
        "language": getattr(info, "language", None),
        "confidence": round(float(getattr(info, "language_probability", 0.0)), 4),
        "seconds": round(elapsed, 2),
        "audio_seconds": round(float(getattr(info, "duration", 0.0)), 2),
        "note": None if text else "No speech detected in that recording.",
    }


class TTSRequest(BaseModel):
    text: str
    voice: str | None = None


@app.post("/text-to-speech")
def text_to_speech(req: TTSRequest):
    text = (req.text or "").strip()
    if not text:
        raise HTTPException(400, "text must not be empty")
    if len(text) > 1000:
        raise HTTPException(400, "text is limited to 1000 characters per request")

    pipeline = get_tts()
    if pipeline is None:
        raise HTTPException(503, f"Text-to-speech engine unavailable: {_tts_error}")

    voice = req.voice or TTS_VOICE_DEFAULT
    try:
        t0 = time.time()
        chunks = []
        for _gs, _ps, audio_chunk in pipeline(text, voice=voice):
            chunks.append(np.asarray(audio_chunk, dtype=np.float32))
        if not chunks:
            raise HTTPException(500, "Text-to-speech produced no audio for that text.")
        samples = np.concatenate(chunks)
        elapsed = time.time() - t0
    except HTTPException:
        raise
    except Exception as e:  # noqa: BLE001
        raise HTTPException(500, f"Text-to-speech failed ({type(e).__name__}: {e}). "
                                 f"Try a shorter, plainer sentence.")

    buf = io.BytesIO()
    sf.write(buf, samples, TTS_SAMPLE_RATE, format="WAV", subtype="PCM_16")
    wav = buf.getvalue()
    print(f"[tts] {len(text)} chars -> {len(wav)} bytes wav "
          f"({len(samples) / TTS_SAMPLE_RATE:.1f}s audio) in {elapsed:.2f}s", flush=True)
    return Response(
        content=wav,
        media_type="audio/wav",
        headers={
            "Content-Disposition": 'inline; filename="vani.wav"',
            "X-Vani-Seconds": str(round(elapsed, 2)),
        },
    )


# --------------------------------------------------------------------------
# Demo page.
#
# Interaction model follows Wispr Flow: one large press-to-talk control, no
# surrounding chrome competing for attention, and the transcript appearing in
# place. Deliberate UX decisions, each one a failure mode seen before:
#   * The microphone permission is EXPLAINED before it is requested. An
#     unexplained browser permission prompt is the single most common
#     first-use dead end.
#   * A real loading state covers cold start. Hosted CPU inference takes over
#     a minute on first call and silence reads as broken.
#   * The text-to-speech box ships with a worked example already in it rather
#     than a blank field.
#   * Every error says what to do next, not just that something failed.
# --------------------------------------------------------------------------
PAGE = """<!doctype html>
<html lang="en"><head>
<meta charset="utf-8"/>
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<title>VANI — Speech Demo</title>
<style>
  :root{--ink:#37434F;--mint:#C7E9D9;--lav:#D9CCEF;--peach:#F8D9B0;--rose:#F6C9C4;--blue:#C4DBF0;}
  *{box-sizing:border-box}
  body{margin:0;background:#F7F8FA;color:var(--ink);
       font:16px/1.55 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif}
  .wrap{max-width:620px;margin:0 auto;padding:32px 20px 64px}
  h1{font-size:24px;margin:0 0 4px}
  .sub{color:#63707C;margin:0 0 24px;font-size:14px}
  .card{background:#fff;border:1px solid #E3E7EB;border-radius:14px;padding:20px;margin-bottom:18px}
  .card h2{font-size:15px;margin:0 0 12px;letter-spacing:.02em;text-transform:uppercase;color:#63707C}
  button{font:inherit;cursor:pointer;border:0;border-radius:10px;padding:12px 18px;color:var(--ink)}
  button:disabled{opacity:.5;cursor:not-allowed}
  #talk{width:100%;padding:26px;font-size:18px;font-weight:600;background:var(--blue)}
  #talk.rec{background:var(--rose)}
  #speak{background:var(--mint)}
  textarea{width:100%;font:inherit;padding:12px;border:1px solid #D7DDE3;border-radius:10px;
           resize:vertical;color:var(--ink);background:#fff}
  .out{margin-top:14px;padding:14px;border-radius:10px;background:var(--lav);min-height:52px;
       white-space:pre-wrap;color:var(--ink)}
  .note{font-size:13px;color:#63707C;margin-top:8px}
  .warn{background:var(--peach);padding:12px;border-radius:10px;font-size:14px;margin-bottom:14px;color:var(--ink)}
  .err{background:var(--rose);padding:12px;border-radius:10px;font-size:14px;margin-top:10px;color:var(--ink)}
  .pill{display:inline-block;background:var(--mint);padding:3px 10px;border-radius:99px;
        font-size:12px;color:var(--ink)}
  .pill.cold{background:var(--peach)}.pill.bad{background:var(--rose)}
</style></head><body><div class="wrap">

<h1>VANI — Speech Demo</h1>
<p class="sub">Speech to text, and text to speech. Running on hosted CPU — no software to install.</p>
<p><span id="status" class="pill cold">checking the server…</span></p>

<div class="card">
  <h2>Speak, and see the words</h2>
  <div class="warn" id="micnote">
    <b>Before you press the button:</b> your browser will ask for permission to use
    the microphone. Nothing is recorded until you press and hold. The audio is sent
    to this server, turned into text, and discarded — it is not stored.
  </div>
  <button id="talk">Hold to talk</button>
  <div class="note">Press and hold, say a sentence, then let go. Try:
    <i>“Book the badminton court for Sunday morning.”</i></div>
  <div class="out" id="sttout">Your words will appear here.</div>
  <div id="stterr"></div>
</div>

<div class="card">
  <h2>Type, and hear it spoken</h2>
  <textarea id="tts" rows="3">Good evening. This is VANI, reading your words aloud.</textarea>
  <div class="note">An example is filled in already — press play, or replace it with your own.</div>
  <p><button id="speak">Play this aloud</button></p>
  <audio id="player" controls style="width:100%;display:none"></audio>
  <div id="ttserr"></div>
</div>

<script>
var API = location.origin;
var st = document.getElementById('status');
function setPill(t, cls){ st.textContent = t; st.className = 'pill' + (cls ? ' ' + cls : ''); }
function err(el, msg){ document.getElementById(el).innerHTML = '<div class="err">' + msg + '</div>'; }
function clr(el){ document.getElementById(el).innerHTML = ''; }

// Cold start is real and slow. Poll health so the page can say so honestly
// instead of looking frozen.
async function poll(){
  try{
    var r = await fetch(API + '/health'); var j = await r.json();
    if(j.stt_state === 'error' || j.tts_state === 'error'){
      setPill('server problem — see the error below', 'bad'); return;
    }
    if(j.stt_state === 'ready' && j.tts_state === 'ready'){ setPill('ready'); return; }
    setPill('waking up — first use takes up to 2 minutes', 'cold');
  }catch(e){ setPill('cannot reach the server', 'bad'); }
  setTimeout(poll, 4000);
}
poll();
fetch(API + '/warmup', {method:'POST'}).catch(function(){});

// ---- speech to text -------------------------------------------------------
var rec = null, chunks = [], talk = document.getElementById('talk');
async function start(){
  clr('stterr');
  if(!navigator.mediaDevices || !window.MediaRecorder){
    err('stterr','This browser cannot record audio. Use Chrome, Edge or Safari — and note that recording needs an https page.'); return;
  }
  var stream;
  try{ stream = await navigator.mediaDevices.getUserMedia({audio:true}); }
  catch(e){
    err('stterr','Microphone permission was not granted. Click the padlock or camera icon in the address bar, set Microphone to Allow, then reload this page.');
    return;
  }
  chunks = []; rec = new MediaRecorder(stream);
  rec.ondataavailable = function(e){ if(e.data.size) chunks.push(e.data); };
  rec.onstop = function(){ stream.getTracks().forEach(function(t){t.stop();}); send(); };
  rec.start(); talk.classList.add('rec'); talk.textContent = 'Listening — let go when done';
}
function stop(){ if(rec && rec.state !== 'inactive') rec.stop();
  talk.classList.remove('rec'); talk.textContent = 'Hold to talk'; }
async function send(){
  var blob = new Blob(chunks, {type: rec.mimeType || 'audio/webm'});
  if(blob.size < 1200){ err('stterr','That recording was too short to contain speech. Hold the button down while you speak, for at least a second.'); return; }
  document.getElementById('sttout').textContent = 'Transcribing…';
  var fd = new FormData(); fd.append('audio', blob, 'recording.webm');
  try{
    var r = await fetch(API + '/speech-to-text', {method:'POST', body: fd});
    var j = await r.json();
    if(!r.ok){ err('stterr', (j.detail || 'The server could not transcribe that.'));
               document.getElementById('sttout').textContent = 'Your words will appear here.'; return; }
    document.getElementById('sttout').textContent = j.text || j.note || '(nothing heard)';
    setPill('ready');
  }catch(e){ err('stterr','Could not reach the server. Check your connection and try again.');
             document.getElementById('sttout').textContent = 'Your words will appear here.'; }
}
talk.addEventListener('mousedown', start); talk.addEventListener('mouseup', stop);
talk.addEventListener('mouseleave', function(){ if(rec && rec.state==='recording') stop(); });
talk.addEventListener('touchstart', function(e){ e.preventDefault(); start(); });
talk.addEventListener('touchend', function(e){ e.preventDefault(); stop(); });

// ---- text to speech -------------------------------------------------------
document.getElementById('speak').addEventListener('click', async function(){
  clr('ttserr');
  var b = this, txt = document.getElementById('tts').value.trim();
  if(!txt){ err('ttserr','Type or paste a sentence first, then press play.'); return; }
  b.disabled = true; b.textContent = 'Generating…';
  try{
    var r = await fetch(API + '/text-to-speech', {method:'POST',
      headers:{'Content-Type':'application/json'}, body: JSON.stringify({text: txt})});
    if(!r.ok){ var j = await r.json().catch(function(){return {};});
      err('ttserr', j.detail || 'The server could not generate audio for that text.'); return; }
    var p = document.getElementById('player');
    p.src = URL.createObjectURL(await r.blob()); p.style.display = 'block'; p.play();
    setPill('ready');
  }catch(e){ err('ttserr','Could not reach the server. Check your connection and try again.'); }
  finally{ b.disabled = false; b.textContent = 'Play this aloud'; }
});
</script>
</div></body></html>"""


@app.get("/", response_class=HTMLResponse)
def index():
    return HTMLResponse(PAGE)


# --------------------------------------------------------------------------
# Gradio surface at /ui.
#
# Mounted so the Space behaves like a normal Gradio Space (the platform's own
# expectation for sdk: gradio), and so there is a second, dependency-free way
# to exercise the same two engines if the custom page ever misbehaves.
# --------------------------------------------------------------------------
def _build_gradio():
    import gradio as gr

    def _stt_fn(filepath):
        if not filepath:
            return "Record or upload some audio first."
        model = get_stt()
        if model is None:
            return f"Speech-to-text engine unavailable: {_stt_error}"
        segments, info = model.transcribe(filepath, beam_size=1, vad_filter=True)
        return "".join(s.text for s in segments).strip() or "(no speech detected)"

    def _tts_fn(text):
        pipeline = get_tts()
        if pipeline is None:
            raise gr.Error(f"Text-to-speech engine unavailable: {_tts_error}")
        chunks = [np.asarray(a, dtype=np.float32)
                  for _g, _p, a in pipeline(text or " ", voice=TTS_VOICE_DEFAULT)]
        return (TTS_SAMPLE_RATE, np.concatenate(chunks))

    with gr.Blocks(title="VANI Speech") as demo:
        gr.Markdown("### VANI Speech — engine check\nThe main demo is at `/`.")
        with gr.Tab("Speech to text"):
            a_in = gr.Audio(sources=["microphone", "upload"], type="filepath",
                            label="Record or upload")
            t_out = gr.Textbox(label="Transcript")
            gr.Button("Transcribe").click(_stt_fn, a_in, t_out)
        with gr.Tab("Text to speech"):
            t_in = gr.Textbox(label="Text",
                              value="Good evening. This is VANI, reading your words aloud.")
            a_out = gr.Audio(label="Audio")
            gr.Button("Speak").click(_tts_fn, t_in, a_out)
    return demo


try:
    import gradio as gr  # noqa: E402
    app = gr.mount_gradio_app(app, _build_gradio(), path="/ui")
    print("[boot] gradio surface mounted at /ui", flush=True)
except Exception as _e:  # noqa: BLE001
    # A missing or incompatible gradio must not take the HTTP API down — the
    # API is the deliverable, /ui is the convenience.
    print(f"[boot] gradio surface unavailable ({type(_e).__name__}: {_e}); "
          f"HTTP API still served", flush=True)


if __name__ == "__main__":
    import uvicorn
    print(f"[boot] VANI Speech API listening on 0.0.0.0:{PORT}", flush=True)
    uvicorn.run(app, host="0.0.0.0", port=PORT)