// selectionDigest.ts
export type SelectionDigest = {
  kind: 'FRAME'|'COMPONENT'|'VARIANT'|'OTHER';
  id: string;
  name: string;
  autolayout?: { direction:'H|V'; gap:number; padding:[number,number,number,number] };
  constraints?: { x:string; y:string };
  variants?: Array<{prop:string; value:string}>;
  issues: string[]; // lint-y hints we surface to the user
};

export function buildSelectionDigest(sel: SceneNode[]): SelectionDigest | null {
  if (sel.length !== 1) return null;
  const n = sel[0];

  const digest: SelectionDigest = {
    kind: n.type === 'COMPONENT' ? 'COMPONENT'
       : (n.type === 'INSTANCE' && 'variantProperties' in n) ? 'VARIANT'
       : n.type === 'FRAME' ? 'FRAME' : 'OTHER',
    id: n.id,
    name: n.name,
    issues: []
  };

  if ('layoutMode' in n) {
    digest.autolayout = {
      direction: n.layoutMode === 'HORIZONTAL' ? 'H' : 'V',
      gap: n.itemSpacing ?? 0,
      padding: ['paddingTop','paddingRight','paddingBottom','paddingLeft']
        .map(k => (n as any)[k]) as any
    };
    if (n.layoutMode === 'NONE') digest.issues.push('No Auto Layout');
  }

  if ('constraints' in n) {
    digest.constraints = { x: n.constraints.horizontal, y: n.constraints.vertical };
  }

  if ('variantProperties' in (n as any)) {
    const vp = (n as any).variantProperties ?? {};
    digest.variants = Object.entries(vp).map(([prop, value]) => ({ prop, value: String(value) }));
  }

  if (!n.name.match(/\w+\/\w+/)) digest.issues.push('Non-hierarchical name');

  return digest;
}