export const APP_VERSION="2.3.0";
export const DEFAULTS=Object.freeze({theme:"dark",accent:"green",intro:true,motion:true,compact:false,grid:false,clock:true,newTab:true,remember:false,focusMinutes:25,breakMinutes:5,accentHex:"",iconSet:"1",backgroundHex:"",panelHex:"",textHex:"",borderHex:"",scrollbarHex:"",radius:6,textScale:100,density:"normal",scrollbarSize:8,customCss:""});
export function settingsFrom(raw={}) {
  const output={...DEFAULTS};
  if (!raw || typeof raw!=="object") return output;
  if (["dark","light","system"].includes(raw.theme)) output.theme=raw.theme;
  if (["green","purple","blue","orange"].includes(raw.accent)) output.accent=raw.accent;
  for (const key of ["intro","motion","compact","grid","clock","newTab","remember"]) if(typeof raw[key]==="boolean")output[key]=raw[key];
  for(const [key,max] of [["focusMinutes",180],["breakMinutes",60]])if(Number.isInteger(raw[key])&&raw[key]>=1&&raw[key]<=max)output[key]=raw[key];
  if(typeof raw.accentHex==="string"&&/^#[0-9a-f]{6}$/i.test(raw.accentHex))output.accentHex=raw.accentHex;
  if(["1","2","outline"].includes(raw.iconSet))output.iconSet=raw.iconSet;
  for(const key of ["backgroundHex","panelHex","textHex","borderHex","scrollbarHex"])if(typeof raw[key]==="string"&&/^#[0-9a-f]{6}$/i.test(raw[key]))output[key]=raw[key];
  for(const [key,min,max] of [["radius",0,20],["textScale",85,125],["scrollbarSize",4,16]])if(Number.isInteger(raw[key])&&raw[key]>=min&&raw[key]<=max)output[key]=raw[key];
  if(["compact","normal","roomy"].includes(raw.density))output.density=raw.density;
  if(typeof raw.customCss==="string"&&raw.customCss.length<=12000&&!/url\s*\(|@import|@font-face|image-set\s*\(/i.test(raw.customCss))output.customCss=raw.customCss;
  return output;
}
export function validShortcut(value) {
  if(!value||typeof value!=="object"||typeof value.name!=="string"||!value.name.trim()||value.name.length>48)throw new Error("Give your shortcut a name (up to 48 characters).");
  if(typeof value.url!=="string"||value.url.length>2048)throw new Error("Enter a valid website address.");
  let url;try{url=new URL(value.url);}catch{throw new Error("Use a full website address, starting with https://.");}
  if(url.protocol!=="https:"||url.username||url.password)throw new Error("Use an HTTPS address without embedded login details.");
  if(!["apps","games","utilities"].includes(value.category))throw new Error("Choose a valid category.");
  return {id:typeof value.id==="string"&&/^custom-[a-zA-Z0-9-]{1,80}$/.test(value.id)?value.id:"custom-"+crypto.randomUUID(),name:value.name.trim(),url:url.href,category:value.category,description:typeof value.description==="string"?value.description.slice(0,100):"",kind:"external",icon:"link",color:"#94c7b3",bg:"#1f342d",custom:true};
}
// A small arithmetic parser: no eval(), Function(), or executable expressions.
export function calculate(source) {
  if(typeof source!=="string"||source.length>300)throw new Error("That expression is too long.");
  const text=source.replaceAll("×","*").replaceAll("÷","/").replace(/\s/g,"");
  if(!text||/[^0-9.+\-*/%()]/.test(text))throw new Error("Use numbers, parentheses, and + − × ÷ %.");
  let pos=0;
  function atom(){
    if(text[pos]==="+"){pos++;return atom();}
    if(text[pos]==="-"){pos++;return -atom();}
    if(text[pos]==="("){pos++;const value=sum();if(text[pos++]!==")")throw new Error("Check your parentheses.");return value;}
    const match=/^(?:\d+(?:\.\d*)?|\.\d+)/.exec(text.slice(pos));if(!match)throw new Error("Check your expression.");
    pos+=match[0].length;return Number(match[0]);
  }
  function product(){let value=atom();while(["*","/","%"].includes(text[pos])){const op=text[pos++],right=atom();if((op==="/"||op==="%")&&right===0)throw new Error("Cannot divide by zero.");value=op==="*"?value*right:op==="/"?value/right:value%right;}return value;}
  function sum(){let value=product();while(text[pos]==="+"||text[pos]==="-"){const op=text[pos++],right=product();value=op==="+"?value+right:value-right;}return value;}
  const result=sum();if(pos!==text.length||!Number.isFinite(result))throw new Error("Check your expression.");
  return Number(result.toPrecision(12)).toString();
}

export function relayTarget(value){
 let url;try{url=new URL(value);}catch{throw new Error("Enter a full HTTPS address.");}
 if(url.protocol!=="https:"||url.username||url.password||url.port)throw new Error("Use HTTPS without login details or a custom port.");
 return url.href;
}
export function htmlGame(value){
 if(!value||typeof value.html!=="string"||value.html.length>1024*1024||typeof value.name!=="string")throw new Error("Choose a single HTML game under 1 MB.");
 return {id:typeof value.id==="string"&&/^html-[a-zA-Z0-9-]+$/.test(value.id)?value.id:"html-"+crypto.randomUUID(),name:value.name.slice(0,48)||"HTML game",html:value.html,kind:"html",category:"games",description:"Imported HTML game.",icon:"game",color:"#fff",bg:"#354b38",custom:true};
}

// Choose the higher contrast ink for any valid custom button color.
export function accentInk(hex){
 if(!/^#[0-9a-f]{6}$/i.test(hex))return "#101010";
 const rgb=hex.slice(1).match(/../g).map(value=>parseInt(value,16)/255).map(value=>value<=.04045?value/12.92:((value+.055)/1.055)**2.4);
 const luminance=.2126*rgb[0]+.7152*rgb[1]+.0722*rgb[2];
 return (luminance+.05)/.05>=1.05/(luminance+.05)?"#080808":"#ffffff";
}
export function viewItems(items,{section="all",filter="all",query="",sort="default",favorites=[],recent={}}={}){
 const saved=new Set(favorites),term=query.trim().toLowerCase();
 const result=items.filter(item=>(section==="all"||section==="favorites"&&saved.has(item.id)||item.category===section)&&(filter==="all"||item.category===filter)&&(!term||(item.name+" "+item.description+" "+item.category).toLowerCase().includes(term)));
 if(sort==="name")result.sort((a,b)=>a.name.localeCompare(b.name));
 if(sort==="recent")result.sort((a,b)=>(recent[b.id]||0)-(recent[a.id]||0));
 return result;
}