// Generates the /salvation audio from scripts/salvation/narration-case.txt using ElevenLabs.
//
//   node --env-file=.env scripts/generate-salvation-audio.mjs --list-voices   # find your voice id
//   node --env-file=.env scripts/generate-salvation-audio.mjs                 # generate the MP3
//
// Needs, in your local .env (never commit it):
//   ELEVENLABS_API_KEY=...
//   ELEVENLABS_VOICE_ID=...        (from --list-voices, or your cloned voice)
// Optional:
//   ELEVENLABS_MODEL=eleven_multilingual_v2
//   ELEVENLABS_STABILITY=0.5       (lower = more expressive, higher = steadier)
//   ELEVENLABS_SPEED=1
//
// Output goes to audio-out/ (git-ignored). Upload the MP3 in Admin → Asset Manager, then paste its
// URL into Admin → Gospel Page.
import { readFile, writeFile, mkdir } from 'node:fs/promises'
import path from 'node:path'
import { fileURLToPath } from 'node:url'

const ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..')
const API = 'https://api.elevenlabs.io/v1'
const apiKey = process.env.ELEVENLABS_API_KEY
const voiceId = process.env.ELEVENLABS_VOICE_ID
const model = process.env.ELEVENLABS_MODEL || 'eleven_multilingual_v2'
const MAX_CHARS = 4500
let totalCost = 0

function fail(message) {
  console.error(`\n${message}\n`)
  process.exit(1)
}

if (!apiKey) fail('ELEVENLABS_API_KEY is not set. Add it to your local .env file (not to chat or to git).')

async function listVoices() {
  const res = await fetch(`${API}/voices`, { headers: { 'xi-api-key': apiKey } })
  if (!res.ok) fail(`Could not list voices (${res.status}). Check the API key.`)
  const { voices = [] } = await res.json()
  console.log('\nYour voices (name: voice id)\n')
  for (const v of voices) console.log(`  ${v.name}${v.category ? ` [${v.category}]` : ''}: ${v.voice_id}`)
  console.log('\nPut the one you want in .env as ELEVENLABS_VOICE_ID=...\n')
}

// Split on paragraph boundaries so each request stays under MAX_CHARS and never cuts a sentence.
function chunkText(text) {
  const paragraphs = text.split(/\n{2,}/).map(p => p.trim()).filter(Boolean)
  const chunks = []
  let current = ''
  for (const p of paragraphs) {
    if (current && current.length + p.length + 2 > MAX_CHARS) { chunks.push(current); current = '' }
    current = current ? `${current}\n\n${p}` : p
  }
  if (current) chunks.push(current)
  return chunks
}

async function speak(text, previous, next) {
  const res = await fetch(`${API}/text-to-speech/${voiceId}?output_format=mp3_44100_128`, {
    method: 'POST',
    headers: { 'xi-api-key': apiKey, 'Content-Type': 'application/json', Accept: 'audio/mpeg' },
    body: JSON.stringify({
      text,
      model_id: model,
      voice_settings: {
        stability: Number(process.env.ELEVENLABS_STABILITY ?? 0.5),
        similarity_boost: 0.75,
        style: 0,
        use_speaker_boost: true,
        speed: Number(process.env.ELEVENLABS_SPEED ?? 1),
      },
      ...(previous ? { previous_text: previous.slice(-600) } : {}),
      ...(next ? { next_text: next.slice(0, 600) } : {}),
    }),
  })
  if (!res.ok) {
    const detail = await res.text().catch(() => '')
    fail(`ElevenLabs returned ${res.status}.\n${detail.slice(0, 400)}`)
  }
  const cost = res.headers.get('character-cost')
  if (cost) totalCost += Number(cost) || 0
  return Buffer.from(await res.arrayBuffer())
}

async function main() {
  if (process.argv.includes('--list-voices')) { await listVoices(); return }
  if (!voiceId) fail('ELEVENLABS_VOICE_ID is not set. Run with --list-voices to find it, then add it to .env.')

  const src = path.join(ROOT, 'scripts/salvation/narration-case.txt')
  const text = (await readFile(src, 'utf8')).trim()
  const chunks = chunkText(text)
  console.log(`\n${text.length.toLocaleString()} characters in ${chunks.length} parts (model ${model}).`)
  console.log('This uses about that many ElevenLabs credits.\n')

  const parts = []
  for (let i = 0; i < chunks.length; i += 1) {
    process.stdout.write(`  part ${i + 1}/${chunks.length}… `)
    parts.push(await speak(chunks[i], chunks[i - 1], chunks[i + 1]))
    console.log('done')
  }

  const outDir = path.join(ROOT, 'audio-out')
  await mkdir(outDir, { recursive: true })
  const out = path.join(outDir, 'salvation-case.mp3')
  await writeFile(out, Buffer.concat(parts))
  if (totalCost) console.log(`\nElevenLabs reported ${totalCost.toLocaleString()} credits used.`)
  console.log(`\nSaved ${out}\nListen to it before you upload it. Check the Scripture names and references.\n`)
}

main().catch(err => fail(err?.message ?? String(err)))