/**
 * Sequence + setpoint orchestration. Pre-refactor lived inline on
 * Machine; extracted so the orchestrator stays focused. All behaviour
 * is preserved verbatim including the interruptible-shutdown abort
 * dance and the operational-state ramp-to-zero before shutdown.
 */

function resolveSetpointBounds(host) {
  const stateMin = Number(host.state?.movementManager?.minPosition);
  const stateMax = Number(host.state?.movementManager?.maxPosition);
  const curveMin = Number(host.predictFlow?.currentFxyXMin);
  const curveMax = Number(host.predictFlow?.currentFxyXMax);
  const minCands = [stateMin, curveMin].filter(Number.isFinite);
  const maxCands = [stateMax, curveMax].filter(Number.isFinite);
  const fbMin = Number.isFinite(stateMin) ? stateMin : 0;
  const fbMax = Number.isFinite(stateMax) ? stateMax : 100;
  let min = minCands.length ? Math.max(...minCands) : fbMin;
  let max = maxCands.length ? Math.min(...maxCands) : fbMax;
  if (min > max) {
    host.logger.warn(`Invalid setpoint bounds detected (min=${min}, max=${max}). Falling back to movement bounds.`);
    min = fbMin; max = fbMax;
  }
  return { min, max };
}

async function setpoint(host, target) {
  try {
    if (!Number.isFinite(target)) { host.logger.error('Invalid setpoint: Setpoint must be a finite number.'); return; }
    const { min, max } = resolveSetpointBounds(host);
    const constrained = Math.min(Math.max(target, min), max);
    if (constrained !== target) host.logger.warn(`Requested setpoint ${target} constrained to ${constrained} (min=${min}, max=${max})`);
    host.logger.info(`Setting setpoint to ${constrained}. Current position: ${host.state.getCurrentPosition()}`);
    await host.state.moveTo(constrained);
  } catch (e) { host.logger.error(`Error setting setpoint: ${e}`); }
}

function waitForOperational(host, timeoutMs = 2000) {
  if (host.state.getCurrentState() === 'operational') return Promise.resolve('operational');
  return new Promise((resolve) => {
    let done = false;
    const timer = setTimeout(() => {
      if (done) return;
      done = true;
      host.state.emitter.off('stateChange', onChange);
      resolve(host.state.getCurrentState());
    }, timeoutMs);
    const onChange = (newState) => {
      if (done) return;
      if (newState === 'operational') {
        done = true; clearTimeout(timer);
        host.state.emitter.off('stateChange', onChange);
        resolve('operational');
      }
    };
    host.state.emitter.on('stateChange', onChange);
  });
}

async function executeSequence(host, rawName) {
  const name = typeof rawName === 'string' ? rawName.toLowerCase() : rawName;
  const sequence = host.config.sequences[name];
  if (!sequence || sequence.size === 0) {
    host.logger.warn(`Sequence '${name}' not defined.`);
    return;
  }
  // Snapshot the sequence-abort token at entry, BEFORE any awaits. If an
  // external abort advances the counter while we're inside this call
  // (setpoint ramp-down, waitForOperational, or the state transition
  // loop), every check below sees the mismatch and breaks out so the
  // new dispatch can claim the FSM. Capturing later would conflate the
  // abort that fired during setpoint(0) with the initial entry state.
  const startToken = host.state.sequenceAbortToken ?? 0;
  const aborted = () => (host.state.sequenceAbortToken ?? 0) !== startToken;

  const interruptible = new Set(['shutdown', 'emergencystop']);
  if (interruptible.has(name)) host.state.delayedMove = null;
  const current = host.state.getCurrentState();
  if (interruptible.has(name) && (current === 'accelerating' || current === 'decelerating')) {
    host.logger.warn(`Sequence '${name}' requested during '${current}'. Aborting active movement.`);
    host.state.abortCurrentMovement(`${name} sequence requested`, { returnToOperational: true });
    await waitForOperational(host, 2000);
  }
  if (host.state.getCurrentState() === 'operational' && name === 'shutdown') {
    host.logger.info(`Machine will ramp down to position 0 before performing ${name} sequence`);
    await setpoint(host, 0);
    if (aborted()) {
      host.logger.warn(`Sequence '${name}' interrupted during ramp-down by external abort; not entering shutdown loop.`);
      host.updatePosition();
      return;
    }
  }
  host.logger.info(` --------- Executing sequence: ${name} -------------`);
  for (const s of sequence) {
    if (aborted()) {
      host.logger.warn(`Sequence '${name}' interrupted at step '${s}' by external abort; stopping further transitions.`);
      break;
    }
    try { await host.state.transitionToState(s); }
    catch (e) { host.logger.error(`Error during sequence '${name}': ${e}`); break; }
  }
  host.updatePosition();
}

module.exports = { setpoint, executeSequence, resolveSetpointBounds, waitForOperational };