import {PROFILE} from '../config/profile.ts';
// Transaction/recovery pattern adapted from Photoshot workspace-store.ts.
// Domain validation is injected: no raster document imports or shared database.
export function createWorkspaceStore<T>(validate:(value:unknown)=>T){
 let queue:Promise<void>=Promise.resolve();
 function database(){return new Promise<IDBDatabase>((resolve,reject)=>{
  const r=indexedDB.open(PROFILE.workspaceDatabase,1);
  r.onupgradeneeded=()=>r.result.createObjectStore('documents');
  r.onsuccess=()=>{r.result.onversionchange=()=>r.result.close();resolve(r.result);};
  r.onerror=()=>reject(r.error);
  r.onblocked=()=>reject(Error('다른 창에서 저장소를 사용하고 있습니다.'));
 });}
 function envelope(value:unknown):T {
  if(!value||typeof value!=='object')throw Error('잘못된 작업공간');
  const v=value as {format?:unknown;version?:unknown;savedAt?:unknown;data?:unknown};
  if(v.format!==PROFILE.workspaceFormat||v.version!==1||typeof v.savedAt!=='number'||!Number.isFinite(v.savedAt))throw Error('지원하지 않는 작업공간 형식');
  return validate(v.data);
 }
 return {
  save(value:T):Promise<void>{
   let snapshot:{format:string;version:number;savedAt:number;data:T};
   try{snapshot={format:PROFILE.workspaceFormat,version:1,savedAt:Date.now(),data:structuredClone(validate(value))};}catch(e){return Promise.reject(e);}
   const job=queue.catch(()=>{}).then(async()=>{
    const db=await database();try{await new Promise<void>((resolve,reject)=>{
     const t=db.transaction('documents','readwrite'),s=t.objectStore('documents'),r=s.get('workspace');
     r.onsuccess=()=>{if(r.result!==undefined){try{envelope(r.result);s.put(r.result,'workspace-recovery');}catch{/* Preserve the last known good recovery. */}}s.put(snapshot,'workspace');};
     t.oncomplete=()=>resolve();t.onabort=()=>reject(t.error??Error('저장 취소'));t.onerror=()=>reject(t.error);
    });}finally{db.close();}
   });queue=job;return job;
  },
  async load(recovery=false):Promise<T|null>{
   await queue.catch(()=>{});const db=await database();
   try{const value=await new Promise<unknown>((resolve,reject)=>{const t=db.transaction('documents'),r=t.objectStore('documents').get(recovery?'workspace-recovery':'workspace');r.onsuccess=()=>resolve(r.result);r.onerror=()=>reject(r.error);t.onabort=()=>reject(t.error);});return value===undefined?null:envelope(value);}finally{db.close();}
  }
 };
}