/* Safe, deterministic editor operations. Exported for Node regression tests. */
(function (root, factory) {
  const api=factory();
  if(typeof module==='object' && module.exports)module.exports=api;
  root.SiteForgeEditorHelpers=api;
})(typeof window!=='undefined'?window:globalThis, function(){
  'use strict';
  const deepCopy=value=>JSON.parse(JSON.stringify(value));
  function reorder(items, from, to){
    if(!Array.isArray(items)||!Number.isInteger(from)||!Number.isInteger(to)||from<0||to<0||from>=items.length||to>=items.length)return null;
    if(from===to)return items.slice();
    const next=items.slice();next.splice(to,0,next.splice(from,1)[0]);return next;
  }
  function duplicate(block, idFactory){
    if(!block || typeof idFactory!=='function')throw Error('无效的区块');
    const item=deepCopy(block);
    const rewrite=node=>{
      node.id=idFactory();
      if(node.type==='layout')for(const col of node.columns||[])for(const child of col.blocks||[])rewrite(child);
    };
    rewrite(item);return item;
  }
  function filterBlocks(blocks, term, names={}){
    const query=String(term||'').trim().toLocaleLowerCase();
    if(!query)return blocks.map((block,index)=>({block,index}));
    return blocks.flatMap((block,index)=>{
      const description=[block.title,block.subtitle,block.type,names[block.type]?.name]
        .concat(block.type==='layout'?(block.columns||[]).flatMap(c=>(c.blocks||[]).map(b=>b.title||b.type)):[])
        .filter(x=>typeof x==='string').join(' ').toLocaleLowerCase();
      return description.includes(query)?[{block,index}]:[];
    });
  }
  function historyState(snapshots,cursor){return {canUndo:cursor>0,canRedo:cursor>=0&&cursor<snapshots.length-1};}
  function clampNumber(value,min,max,fallback){const n=Number(value);return Number.isFinite(n)?Math.max(min,Math.min(max,n)):fallback;}
  function shouldAcceptPreview(requestedPage,requestedSeq,currentPage,currentSeq){
    return requestedPage===currentPage&&requestedSeq===currentSeq;
  }
  return {reorder,duplicate,filterBlocks,historyState,clampNumber,shouldAcceptPreview};
});