// robot/FCodeClient.js
// Translates FCode messages (FPoint, FPlus, FList, …) into REST calls to appRobotFileservice.
// The Driver is the only gateway — controllers never contact the fileservice directly.

function _baseUrl() {
  return process.env.FILESERVICE_URL || 'http://appRobot_Fileservice:2100';
}

/** Returns true when the message is an FCode (F + uppercase letter + lowercase, at start). */
function isFCode(message) {
  return /^F[A-Z][a-z]+/.test(String(message).trim());
}

/**
 * Dispatch an FCode message to the appropriate fileservice endpoint.
 * @param {object} robot  Current robot state (x,y,z,phi,theta,psi,e,feedrate).
 * @param {string} message  Raw FCode string, e.g. "FPoint", "FPlus", "FLoad demo".
 * @returns {Promise<{type: string, data?: string, line?: string}>}
 *   type 'step'  → line (driver-native GCode, Radian) ready to execute
 *   type 'list'|'show'|'point'|'ok' → data (JSON string) to broadcast
 */
async function handle(robot, message) {
  const msg = String(message).trim();

  if (msg.startsWith('FList')) {
    const data = await _req('GET', '/api/programs');
    return { type: 'list', data: JSON.stringify(data) };
  }
  if (msg.startsWith('FShow')) {
    const id = msg.slice('FShow'.length).trim();
    const data = id
      ? await _req('GET', `/api/programs/${encodeURIComponent(id)}`)
      : await _req('GET', '/api/active');
    return { type: 'show', data: JSON.stringify(data) };
  }
  if (msg.startsWith('FLoad')) {
    const id = msg.slice('FLoad'.length).trim();
    const data = await _req('PUT', '/api/active', { id });
    return { type: 'ok', data: JSON.stringify(data) };
  }
  if (msg.startsWith('FSave')) {
    const name = msg.slice('FSave'.length).trim() || 'unnamed';
    const data = await _req('POST', '/api/programs', { name, fromActive: true });
    return { type: 'ok', data: JSON.stringify(data) };
  }
  if (msg.startsWith('FClear')) {
    const data = await _req('POST', '/api/active/clear');
    return { type: 'ok', data: JSON.stringify(data) };
  }
  if (msg.startsWith('FPoint')) {
    // Driver attaches the current pose (Radian) — fileservice converts to degrees for storage.
    const pose = {
      x: robot.x, y: robot.y, z: robot.z,
      a: robot.phi, b: robot.theta, c: robot.psi, e: robot.e,
    };
    const feedrate = robot.feedrate || 1000;
    const data = await _req('POST', '/api/active/points', { pose, feedrate });
    return { type: 'point', data: JSON.stringify(data) };
  }
  if (msg.startsWith('FPlus'))  { const d = await _req('POST', '/api/active/next');  return { type: 'step', line: d.line }; }
  if (msg.startsWith('FMinus')) { const d = await _req('POST', '/api/active/prev');  return { type: 'step', line: d.line }; }
  if (msg.startsWith('FFirst')) { const d = await _req('POST', '/api/active/first'); return { type: 'step', line: d.line }; }
  if (msg.startsWith('FLast'))  { const d = await _req('POST', '/api/active/last');  return { type: 'step', line: d.line }; }
  if (msg.startsWith('FGoto')) {
    const index = parseInt(msg.slice('FGoto'.length).trim(), 10);
    const d = await _req('POST', '/api/active/goto', { index });
    return { type: 'step', line: d.line };
  }
  if (msg.startsWith('FPlay')) { const d = await _req('POST', '/api/active/play'); return { type: 'ok', data: JSON.stringify(d) }; }
  if (msg.startsWith('FStop')) { const d = await _req('POST', '/api/active/stop'); return { type: 'ok', data: JSON.stringify(d) }; }

  throw new Error(`Unbekannter FCode: ${msg}`);
}

async function _req(method, path, body) {
  const url = `${_baseUrl()}${path}`;
  const opts = { method };
  if (body !== undefined && body !== null) {
    opts.headers = { 'content-type': 'application/json' };
    opts.body = JSON.stringify(body);
  }
  console.log(`[FCode] → ${method} ${url}${body ? ' ' + JSON.stringify(body) : ''}`);

  let res;
  try {
    res = await fetch(url, opts);
  } catch (netErr) {
    // Fileservice nicht erreichbar (DNS/Connection refused): klare Meldung statt "fetch failed".
    console.error(`[FCode] ✖ ${method} ${url}: Fileservice nicht erreichbar (${netErr.message})`);
    const e = new Error(`Fileservice nicht erreichbar: ${netErr.message}`);
    e.code = 'FILESERVICE_UNREACHABLE';
    throw e;
  }

  if (!res.ok) {
    const err = await res.json().catch(() => ({}));
    console.error(`[FCode] ✖ ${res.status} ${method} ${path}: ${err.code || ''} ${err.message || res.statusText}`);
    const e = new Error(err.message || res.statusText);
    e.code = err.code;
    e.status = res.status;
    throw e;
  }

  const data = await res.json();
  console.log(`[FCode] ← ${res.status} ${method} ${path} ${JSON.stringify(data).slice(0, 160)}`);
  return data;
}

module.exports = { isFCode, handle };