export const dynamic = 'force-dynamic'
export const runtime = 'nodejs'

import { NextResponse } from 'next/server'

const ELEVENLABS_BASE = 'https://api.elevenlabs.io/v1'
const DEFAULT_MODEL = 'eleven_flash_v2_5'

function getVoiceId(agent: string | undefined): string | null {
  if (agent === 'lusya') return process.env.LUSYA_TTS_VOICE || null
  return process.env.COSMO_TTS_VOICE || null
}

export async function POST(req: Request) {
  const apiKey = process.env.ELEVENLABS_API_KEY
  if (!apiKey) {
    return NextResponse.json({ error: 'tts_not_configured' }, { status: 503 })
  }

  const body = await req.json().catch(() => null)
  const text = typeof body?.text === 'string' ? body.text.trim() : ''
  const agent = typeof body?.agent === 'string' ? body.agent : 'cosmo'

  if (!text) {
    return NextResponse.json({ error: 'text required' }, { status: 400 })
  }
  if (text.length > 4000) {
    return NextResponse.json({ error: 'text too long (>4000)' }, { status: 400 })
  }

  const voiceId = getVoiceId(agent)
  if (!voiceId) {
    return NextResponse.json({ error: `no voice configured for agent=${agent}` }, { status: 503 })
  }

  const model = process.env.ELEVENLABS_MODEL || DEFAULT_MODEL

  const upstream = await fetch(
    `${ELEVENLABS_BASE}/text-to-speech/${encodeURIComponent(voiceId)}/stream?output_format=mp3_44100_64`,
    {
      method: 'POST',
      headers: {
        'xi-api-key': apiKey,
        Accept: 'audio/mpeg',
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({
        text,
        model_id: model,
        voice_settings: {
          stability: 0.45,
          similarity_boost: 0.75,
          style: 0.25,
          use_speaker_boost: true,
        },
      }),
    }
  )

  if (!upstream.ok || !upstream.body) {
    const errText = await upstream.text().catch(() => '')
    return NextResponse.json(
      { error: `elevenlabs_${upstream.status}`, detail: errText.slice(0, 300) },
      { status: 502 }
    )
  }

  return new Response(upstream.body, {
    headers: {
      'Content-Type': 'audio/mpeg',
      'Cache-Control': 'no-store',
      'X-Accel-Buffering': 'no',
    },
  })
}