app.py

import os
import requests
import wave
import base64
from fastapi import FastAPI, HTTPException
from fastapi.responses import FileResponse
from pydantic import BaseModel
from dotenv import load_dotenv

# Load API key
load_dotenv()
API_KEY = os.getenv("GEMINI_API_KEY")
if not API_KEY:
    raise RuntimeError("Missing GEMINI_API_KEY in environment")

BASE_URL = (
    "https://generativelanguage.googleapis.com/"
    "v1beta/models/gemini-2.5-flash-preview-tts:"
    "generateContent"
    f"?key={API_KEY}"
)

app = FastAPI(title="Gemini TTS JSON API")

def save_wav(path: str, pcm: bytes, channels=1, rate=24000, width=2):
    with wave.open(path, "wb") as wf:
        wf.setnchannels(channels)
        wf.setsampwidth(width)
        wf.setframerate(rate)
        wf.writeframes(pcm)

class SingleTTSRequest(BaseModel):
    prompt: str
    voice_name: str

class MultiTTSRequest(BaseModel):
    prompt: str
    speaker1: str
    voice1: str
    speaker2: str
    voice2: str

@app.get("/")
def health():
    return {"status": "Gemini TTS JSON API up and running!"}

@app.post("/single_tts")
def single_tts(req: SingleTTSRequest):
    payload = {
        "model": "gemini-2.5-flash-preview-tts",
        "contents": [{"parts": [{"text": req.prompt}]}],
        "config": {
            "responseModalities": ["AUDIO"],
            "speechConfig": {
                "voiceConfig": {
                    "prebuiltVoiceConfig": {"voiceName": req.voice_name}
                }
            }
        }
    }

    resp = requests.post(BASE_URL, json=payload)
    if resp.status_code != 200:
        raise HTTPException(status_code=resp.status_code, detail=resp.json())

    b64 = resp.json()["candidates"][0]["content"]["parts"][0]["inlineData"]["data"]
    pcm = base64.b64decode(b64)
    out = "single_output.wav"
    save_wav(out, pcm)
    return FileResponse(out, media_type="audio/wav", filename=out)

@app.post("/multi_tts")
def multi_tts(req: MultiTTSRequest):
    payload = {
        "model": "gemini-2.5-flash-preview-tts",
        "contents": [{"parts": [{"text": req.prompt}]}],
        "config": {
            "responseModalities": ["AUDIO"],
            "speechConfig": {
                "multiSpeakerVoiceConfig": {
                    "speakerVoiceConfigs": [
                        {
                            "speaker": req.speaker1,
                            "voiceConfig": {"prebuiltVoiceConfig": {"voiceName": req.voice1}}
                        },
                        {
                            "speaker": req.speaker2,
                            "voiceConfig": {"prebuiltVoiceConfig": {"voiceName": req.voice2}}
                        }
                    ]
                }
            }
        }
    }

    resp = requests.post(BASE_URL, json=payload)
    if resp.status_code != 200:
        raise HTTPException(status_code=resp.status_code, detail=resp.json())

    b64 = resp.json()["candidates"][0]["content"]["parts"][0]["inlineData"]["data"]
    pcm = base64.b64decode(b64)
    out = "multi_output.wav"
    save_wav(out, pcm)
    return FileResponse(out, media_type="audio/wav", filename=out)