// Authenticated POST -> SSE reader. Calls onEvent({ type, ...data }) per frame.
const TOKEN_KEY = 'void_token';

export async function streamTurn(path, body, onEvent) {
  const res = await fetch(path, {
    method: 'POST',
    headers: {
      'Authorization': 'Bearer ' + (localStorage.getItem(TOKEN_KEY) || ''),
      'Content-Type': 'application/json'
    },
    body: JSON.stringify(body)
  });
  if (!res.ok || !res.body) throw new Error('stream failed: ' + res.status);

  const reader = res.body.getReader();
  const decoder = new TextDecoder();
  let buf = '';
  for (;;) {
    const { value, done } = await reader.read();
    if (done) break;
    buf += decoder.decode(value, { stream: true });
    const frames = buf.split('\n\n');
    buf = frames.pop();                       // keep the trailing partial
    for (const frame of frames) {
      let event = 'message', data = '';
      for (const line of frame.split('\n')) {
        if (line.startsWith('event:')) event = line.slice(6).trim();
        else if (line.startsWith('data:')) data += line.slice(5).trim();
      }
      if (data) onEvent({ type: event, ...JSON.parse(data) });
    }
  }
}