app.py

import gradio as gr
import torch
from transformers import (
    AutoTokenizer,
    AutoModelForCausalLM,
    SpeechT5Processor,
    SpeechT5ForTextToSpeech,
    SpeechT5HifiGan,
    WhisperProcessor,
    WhisperForConditionalGeneration
)
from datasets import load_dataset
import os
import spaces
import tempfile
import soundfile as sf
import librosa

# --- Configuration ---
HUGGINGFACE_MODEL_ID = "HuggingFaceH4/Qwen2.5-1.5B-Instruct-gkd"
TORCH_DTYPE = torch.bfloat16
MAX_NEW_TOKENS = 512
DO_SAMPLE = True
TEMPERATURE = 0.7
TOP_K = 50
TOP_P = 0.95

TTS_MODEL_ID = "microsoft/speecht5_tts"
TTS_VOCODER_ID = "microsoft/speecht5_hifigan"
STT_MODEL_ID = "openai/whisper-small"

# --- Global Variables ---
tokenizer = None
llm_model = None
tts_processor = None
tts_model = None
tts_vocoder = None
speaker_embeddings = None
whisper_processor = None
whisper_model = None
first_load = True

# --- Load Models Function ---
@spaces.GPU
def load_models():
    global tokenizer, llm_model, tts_processor, tts_model, tts_vocoder, speaker_embeddings
    global whisper_processor, whisper_model

    if (tokenizer is not None and llm_model is not None and tts_model is not None and
        whisper_model is not None):
        print("All models already loaded.")
        return

    hf_token = os.environ.get("HF_TOKEN")

    # LLM
    try:
        tokenizer = AutoTokenizer.from_pretrained(HUGGINGFACE_MODEL_ID, token=hf_token)
        if tokenizer.pad_token is None:
            tokenizer.pad_token = tokenizer.eos_token
        llm_model = AutoModelForCausalLM.from_pretrained(
            HUGGINGFACE_MODEL_ID,
            torch_dtype=TORCH_DTYPE,
            device_map="auto",
            token=hf_token
        ).eval()
        print("LLM loaded successfully.")
    except Exception as e:
        print(f"Error loading LLM: {e}")

    # TTS
    try:
        tts_processor = SpeechT5Processor.from_pretrained(TTS_MODEL_ID, token=hf_token)
        tts_model = SpeechT5ForTextToSpeech.from_pretrained(TTS_MODEL_ID, token=hf_token)
        tts_vocoder = SpeechT5HifiGan.from_pretrained(TTS_VOCODER_ID, token=hf_token)
        embeddings = load_dataset("Matthijs/cmu-arctic-xvectors", split="validation", token=hf_token)
        speaker_embeddings = torch.tensor(embeddings[7306]["xvector"]).unsqueeze(0)
        device = llm_model.device if llm_model else 'cpu'
        tts_model.to(device)
        tts_vocoder.to(device)
        speaker_embeddings = speaker_embeddings.to(device)
        print("TTS models loaded.")
    except Exception as e:
        print(f"Error loading TTS: {e}")

    # STT
    try:
        whisper_processor = WhisperProcessor.from_pretrained(STT_MODEL_ID, token=hf_token)
        whisper_model = WhisperForConditionalGeneration.from_pretrained(STT_MODEL_ID, token=hf_token)
        whisper_model.to(llm_model.device if llm_model else 'cpu')
        print("Whisper loaded.")
    except Exception as e:
        print(f"Error loading Whisper: {e}")

# --- Generate Response + Audio ---
@spaces.GPU
def generate_response_and_audio(message, history):
    global first_load
    if first_load:
        load_models()
        first_load = False

    global tokenizer, llm_model, tts_processor, tts_model, tts_vocoder, speaker_embeddings

    if tokenizer is None or llm_model is None:
        return [{"role": "assistant", "content": "Error: LLM not loaded."}], None

    messages = history.copy()
    messages.append({"role": "user", "content": message})

    try:
        input_text = tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
    except:
        input_text = ""
        for item in history:
            input_text += f"{item['role'].capitalize()}: {item['content']}\n"
        input_text += f"User: {message}\nAssistant:"

    try:
        inputs = tokenizer(input_text, return_tensors="pt", padding=True, truncation=True).to(llm_model.device)
        output_ids = llm_model.generate(
            inputs["input_ids"],
            attention_mask=inputs["attention_mask"],
            max_new_tokens=MAX_NEW_TOKENS,
            do_sample=DO_SAMPLE,
            temperature=TEMPERATURE,
            top_k=TOP_K,
            top_p=TOP_P,
            pad_token_id=tokenizer.eos_token_id
        )
        generated_text = tokenizer.decode(output_ids[0][inputs["input_ids"].shape[-1]:], skip_special_tokens=True).strip()
    except Exception as e:
        print(f"LLM error: {e}")
        return history + [{"role": "assistant", "content": "I had an issue generating a response."}], None

    audio_path = None
    if None not in [tts_processor, tts_model, tts_vocoder, speaker_embeddings]:
        try:
            tts_inputs = tts_processor(text=generated_text, return_tensors="pt", max_length=550, truncation=True).to(llm_model.device)
            speech = tts_model.generate_speech(tts_inputs["input_ids"], speaker_embeddings, vocoder=tts_vocoder)
            with tempfile.NamedTemporaryFile(suffix=".wav", delete=False) as tmp_file:
                audio_path = tmp_file.name
                sf.write(audio_path, speech.cpu().numpy(), samplerate=16000)
        except Exception as e:
            print(f"TTS error: {e}")

    return history + [{"role": "assistant", "content": generated_text}], audio_path

# --- Transcribe Audio ---
@spaces.GPU
def transcribe_audio(filepath):
    global first_load
    if first_load:
        load_models()
        first_load = False

    global whisper_processor, whisper_model
    if whisper_model is None:
        return "Whisper model not loaded."

    try:
        audio, sr = librosa.load(filepath, sr=16000)
        inputs = whisper_processor(audio, sampling_rate=sr, return_tensors="pt").input_features.to(whisper_model.device)
        outputs = whisper_model.generate(inputs)
        return whisper_processor.batch_decode(outputs, skip_special_tokens=True)[0]
    except Exception as e:
        return f"Transcription failed: {e}"

# --- Gradio UI ---
with gr.Blocks() as demo:
    gr.Markdown("# Qwen2.5 Chatbot with Voice Input/Output")
    
    with gr.Tab("Chat"):
        chatbot = gr.Chatbot(type='messages')
        text_input = gr.Textbox(placeholder="Type your message...")
        audio_output = gr.Audio(label="Response Audio", autoplay=True)
        text_input.submit(generate_response_and_audio, [text_input, chatbot], [chatbot, audio_output])

    with gr.Tab("Transcribe"):
        audio_input = gr.Audio(type="filepath", label="Upload Audio")
        transcribed = gr.Textbox(label="Transcription")
        audio_input.upload(transcribe_audio, audio_input, transcribed)

    clear_btn = gr.Button("Clear All")
    clear_btn.click(lambda: ([], "", None), None, [chatbot, text_input, audio_output])

demo.queue().launch()