function createTomorrowPlan({fetchJson,localDate,timeZone}={}) {
  let plan={revision:0,ids:[],capacity_minutes:null,estimates:{}};
  const state=()=>({...plan,ids:[...plan.ids],estimates:{...plan.estimates}});
  function adopt(value) {
    if (!Number.isInteger(value?.revision)||!Array.isArray(value?.ids)) return false;
    plan={revision:value.revision,ids:[...value.ids],capacity_minutes:value.capacity_minutes??null,
      estimates:{...(value.estimates||{})},...(value.plan_date?{plan_date:value.plan_date,timezone:value.timezone||null}:{})};
    return state();
  }
  function nextLocalDate() {
    const [y,m,d]=localDate().split('-').map(Number);
    return new Date(Date.UTC(y,m-1,d+1)).toISOString().slice(0,10);
  }
  async function load(){return adopt(await fetchJson('api/v1/tomorrow'));}
  async function save(value) {
    const body={base_revision:plan.revision,ids:[...(value.ids||[])],
      capacity_minutes:value.capacity_minutes??null,estimates:{...(value.estimates||{})},
      plan_date:nextLocalDate(),timezone:timeZone()};
    return adopt(await fetchJson('api/v1/tomorrow',{method:'PUT',headers:{'Content-Type':'application/json'},body:JSON.stringify(body)}));
  }
  async function promote(today_revision) {
    if (!plan.plan_date||plan.plan_date>localDate()||!plan.ids.length) return false;
    const promotion_id=`tomorrow-${plan.plan_date}-r${plan.revision}`;
    return fetchJson('api/v1/tomorrow/promote',{method:'POST',headers:{'Content-Type':'application/json'},
      body:JSON.stringify({promotion_id,tomorrow_revision:plan.revision,today_revision})});
  }
  function millisecondsUntilNextDay() {
    const now=Date.now();
    const zone=timeZone();
    let formatter;
    try {
      formatter=new Intl.DateTimeFormat('en-CA',{timeZone:zone,year:'numeric',month:'2-digit',day:'2-digit',
        hour:'2-digit',minute:'2-digit',second:'2-digit',hourCycle:'h23'});
    } catch (_error) {
      const next=new Date(now);
      next.setHours(24,0,0,250);
      return Math.max(1,next.getTime()-now);
    }
    const zoned=value=>Object.fromEntries(formatter.formatToParts(new Date(value))
      .filter(part=>part.type!=='literal').map(part=>[part.type,Number(part.value)]));
    const current=zoned(now);
    const targetWall=Date.UTC(current.year,current.month-1,current.day+1);
    let candidate=targetWall;
    for(let attempt=0;attempt<2;attempt+=1){
      const parts=zoned(candidate);
      const offset=Date.UTC(parts.year,parts.month-1,parts.day,parts.hour,parts.minute,parts.second)-candidate;
      candidate=targetWall-offset;
    }
    return Math.max(1,candidate-now+250);
  }
  function startLifecycle({windowObject,documentObject,check,setTimer=setTimeout,clearTimer=clearTimeout,
    nextDelay=millisecondsUntilNextDay}={}) {
    let flight=null;
    let timer=null;
    const schedule=()=>{
      if(timer!==null) clearTimer(timer);
      timer=setTimer(run,nextDelay());
    };
    function run(){
      if(!flight) flight=Promise.resolve().then(check).finally(()=>{flight=null;schedule();});
      return flight;
    }
    windowObject?.addEventListener?.('online',run);
    documentObject?.addEventListener?.('visibilitychange',()=>documentObject.hidden?false:run());
    run();
    return {run,stop(){if(timer!==null)clearTimer(timer);timer=null;}};
  }
  return {adopt,load,save,promote,state,nextLocalDate,startLifecycle};
}
if(typeof module!=='undefined'&&module.exports)module.exports=createTomorrowPlan;