<?php
// ElevenLabs TTS proxy — keeps API key server-side, streams MP3 back to browser.
// POST body: {"text":"..."}  Returns: audio/mpeg  or  JSON error

$text = trim((json_decode(file_get_contents('php://input'), true) ?? [])['text'] ?? '');

if (!$text) {
    http_response_code(400);
    echo json_encode(['error' => 'No text']);
    exit;
}

// Cap at 400 chars to protect free-tier quota
$text = mb_substr($text, 0, 400);

if (!defined('ELEVENLABS_API_KEY') || !ELEVENLABS_API_KEY) {
    http_response_code(503);
    echo json_encode(['error' => 'ElevenLabs not configured']);
    exit;
}

$payload = json_encode([
    'text'           => $text,
    'model_id'       => ELEVENLABS_MODEL,
    'voice_settings' => ['stability' => 0.45, 'similarity_boost' => 0.80, 'style' => 0.10],
]);

$ch = curl_init('https://api.elevenlabs.io/v1/text-to-speech/' . ELEVENLABS_VOICE_ID);
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_POST           => true,
    CURLOPT_HTTPHEADER     => [
        'xi-api-key: '   . ELEVENLABS_API_KEY,
        'Content-Type: application/json',
        'Accept: audio/mpeg',
    ],
    CURLOPT_POSTFIELDS     => $payload,
    CURLOPT_TIMEOUT        => 20,
    CURLOPT_CONNECTTIMEOUT => 5,
]);

$audio = curl_exec($ch);
$code  = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);

if ($code === 200 && $audio) {
    header('Content-Type: audio/mpeg');
    header('Cache-Control: no-store');
    echo $audio;
} else {
    http_response_code(502);
    echo json_encode(['error' => 'ElevenLabs error', 'code' => $code]);
}