import type { Change, Document, Id, OperationIntent, Registry } from '../canvas-core/types.ts';
import { applyChanges, validateDocument } from '../canvas-core/document.ts';
import { equal, fault } from '../canvas-core/values.ts';
import type { LedgerSnapshot } from './ledger.ts';

/** The footprint follows ownership; geometry does not decide which canvas owns an object. */
export function operationCanvases(intent: OperationIntent, document: Document): readonly Id[] {
  if(intent.operationType==='asset.upload'||intent.operationType==='run.cancel')return[];
  if (intent.canvasIds?.length) return intent.canvasIds;
  const ids = new Set<Id>();
  for (const change of intent.changes) {
    if (change.kind === 'canvas') {
      ids.add(change.id);
      if (change.before?.parent) ids.add(change.before.parent.canvasId);
      if (change.after?.parent) ids.add(change.after.parent.canvasId);
    } else if (change.kind === 'element') {
      if (change.before) ids.add(change.before.ownerCanvasId);
      if (change.after) ids.add(change.after.ownerCanvasId);
    } else {
      const owner = document.elements.get(change.target.id)?.ownerCanvasId;
      if (owner) ids.add(owner);
      if (change.field === 'ownerCanvasId') { ids.add(change.before as Id); ids.add(change.after as Id); }
    }
  }
  if (!ids.size) throw fault('missing_participants', [intent.id]);
  return [...ids].sort();
}

/** Replay once, by logical sequence. A receipt can already contain a desired field value. */
export function replayPending(base: Document, ledger: LedgerSnapshot, registry: Registry): Document {
  let document = base;
  for (const record of [...ledger.operations.values()].sort((a, b) => a.intent.sequence - b.intent.sequence)) {
    if (record.phase === 'resolved' || !['document.change','run.apply'].includes(record.intent.operationType)) continue;
    for (const change of record.intent.changes) {
      if (satisfied(document, change)) continue;
      document = applyChanges(document, [change]);
    }
  }
  validateDocument(document, registry);
  return document;
}
function satisfied(document: Document, change: Change) {
  if (change.kind === 'canvas') return equal(document.canvases.get(change.id) ?? null, change.after);
  if (change.kind === 'element') return equal(document.elements.get(change.id) ?? null, change.after);
  const element = document.elements.get(change.target.id);
  if (!element || element.incarnation !== change.target.incarnation) return false;
  if (change.field.startsWith('data.')) {
    const key = change.field.slice(5);
    return Object.hasOwn(element.data, key) === (change.afterPresent ?? true) && equal(element.data[key] ?? null, change.after);
  }
  return equal((element as unknown as Record<string, unknown>)[change.field], change.after);
}