export const COCKPIT_VISION_MODES = Object.freeze([
  'optical',
  'crt',
  'nvg',
  'thermal',
  'anime',
  'noir',
]);

const TARGET_STYLE_BY_MODE = Object.freeze({
  crt: 'retro',
  nvg: 'surveillance',
  thermal: 'thermal',
  anime: 'anime',
  noir: 'noir',
});

const COCKPIT_MODE_BY_STYLE = Object.freeze({
  normal: 'optical',
  retro: 'crt',
  surveillance: 'nvg',
  thermal: 'thermal',
  anime: 'anime',
  noir: 'noir',
});

/** Normalize a requested Cockpit vision mode to the unfiltered Normal entry. */
export function normalizeCockpitVisionMode(mode) {
  return COCKPIT_VISION_MODES.includes(mode) ? mode : 'optical';
}

/** Start Cockpit on the equivalent supported map preset. */
export function cockpitVisionModeForStyle(style) {
  return COCKPIT_MODE_BY_STYLE[String(style || '').toLowerCase()] || 'optical';
}

/** Settle pending map-style crossfades and return their intended final intensities. */
export function captureCockpitVisionBaseline(stages, transitions) {
  const baseline = {};
  for (const [name, stage] of Object.entries(stages)) {
    const intensity = transitions?.get(name)?.to ?? stage.uniforms.intensity;
    stage.uniforms.intensity = intensity;
    transitions?.delete(name);
    baseline[name] = intensity;
  }
  return baseline;
}

/**
 * Apply Cockpit-only stage intensities without changing any shader parameters.
 * Returns the temporary style whose parameters should be shown, or null.
 */
export function applyCockpitVisionStageIntensities(stages, mode) {
  const next = normalizeCockpitVisionMode(mode);
  if (next === 'optical') {
    for (const stage of Object.values(stages)) stage.uniforms.intensity = 0;
    return null;
  }

  for (const stage of Object.values(stages)) stage.uniforms.intensity = 0;
  const target = TARGET_STYLE_BY_MODE[next] || null;
  if (target && stages[target]) stages[target].uniforms.intensity = 1;
  return target;
}