'use strict';
const fs = require('node:fs'), path = require('node:path'), crypto = require('node:crypto');
// Lazy, owner-bound, single-flight tasks. Account jobs persist. Guest photos
// remain in RAM for at most five minutes; no paid work starts until requested.
module.exports = function({dir, collect, load, complete, now = Date.now}) {
  const jobs = new Map();
  function remember(job) {
    jobs.set(job.token,job);
    const timer=setTimeout(()=>{jobs.delete(job.token);job.context=null;},300000);timer.unref();
  }
  function save(job) {
    if (!job.persist) return;
    fs.mkdirSync(dir, {recursive:true, mode:0o700});
    const file=path.join(dir,job.token+'.json'),tmp=file+'.tmp';
    fs.writeFileSync(tmp,JSON.stringify({token:job.token,owner:job.owner,record:job.record,persist:true,status:job.status,views:job.views}),{mode:0o600});
    fs.renameSync(tmp,file);
  }
  function register(owner,record,context) {
    const job={token:crypto.randomBytes(24).toString('hex'),owner:owner.id,record,persist:['wechat','taobao','browser_persistent'].includes(owner.kind),status:'pending',context};
    save(job);remember(job);
    return {token:job.token,status:'pending'};
  }
  function unavailable(code) {return {version:'independent-side-wrinkles-v1',left:{status:'unavailable',error_code:code},right:{status:'unavailable',error_code:code}};}
  async function run(owner,token) {
    if (!/^[a-f0-9]{48}$/.test(token||'')) return null;
    let job=jobs.get(token);
    if (!job) {
      try {job=JSON.parse(fs.readFileSync(path.join(dir,token+'.json'),'utf8'));} catch (_) {return null;}
      if (job.owner!==owner.id || !['wechat','taobao','browser_persistent'].includes(owner.kind)) return null;
      remember(job);
    }
    if (job.owner!==owner.id) return null;
    if (job.promise) return job.promise;
    if (job.status==='complete') return job.views;
    // A persisted running marker means a process restart interrupted the task.
    // Never silently repeat potentially charged requests after a restart.
    const interrupted=job.status==='running';
    job.status='running';save(job);
    job.promise=(async()=>{
      const started=now();let views;
      try {
        const context=job.context || (job.persist && load(job.owner,job.record));
        views=interrupted?unavailable('WRINKLE_JOB_INTERRUPTED'):context?await collect(context):unavailable('WRINKLE_JOB_EXPIRED');
      } catch (_) {views=unavailable('WRINKLE_JOB_FAILED');}
      job.context=null;job.views=views;job.status='complete';
      // Save the completed cache BEFORE patching snapshots; duplicates never
      // re-run paid work, even if a snapshot or admin update fails.
      save(job);
      if (job.persist) {try {complete(job.owner,job.record,views,now()-started);} catch (_) {}}
      return views;
    })();
    return job.promise;
  }
  return {register,run};
};