import {el, initTheme, enhanceSelects} from './util.js';

const CALCS = [
  { id:'interest',  name:'Interest (Simple & Compound)',  about:'Simple/compound interest', path:'../calculators/interest.js' },
  { id:'raid',      name:'RAID',      about:'Usable capacity',         path:'../calculators/raid.js' },
  { id:'bandwidth', name:'Bandwidth', about:'Bits↔bytes unit conv.',   path:'../calculators/bandwidth.js' },
  { id:'nmea',      name:'NMEA',      about:'0183 XOR checksum',       path:'../calculators/nmea.js' },
  { id:'currency',  name:'Currency Converter', about:'Convert between currencies', path:'../calculators/currency.js' },
  { id:'subnet',    name:'IP Subnet', about:'IPv4/IPv6 subnet calculations', path:'../calculators/subnet.js' }
];

const navEl   = document.getElementById('nav');
const viewEl  = document.getElementById('view');
const themeBtn= document.getElementById('themeToggle');
initTheme(themeBtn);

const moduleCache = new Map();
const viewCache   = new Map();

function metaById(id){ return CALCS.find(c=>c.id===id) || CALCS[0] }

/* ---------- History API routing (path + query) ---------- */
function normalize(id, params){
  const qs = params && [...params].length ? `?${params.toString()}` : '';
  return `/${id}${qs}`;
}
function parseRoute(){
  const path = location.pathname.replace(/^\/+/, '');
  const id = path || 'interest';
  const params = new URLSearchParams(location.search);
  return { id, params };
}
function setRoute(id, params, {replace=true}={}){
  const target = normalize(id, params || new URLSearchParams());
  const current = `${location.pathname}${location.search}`;
  if (target === current) return; // no-op if unchanged
  if (replace) history.replaceState(null, '', target);
  else history.pushState(null, '', target);
  mount(); // re-render
}

function formToParams(card){
  const p = new URLSearchParams();
  card.querySelectorAll('input[name], select[name], textarea[name]').forEach(el=>{
    let v = el.type === 'checkbox' ? (el.checked ? '1' : '0') : el.value;
    if (v !== '') p.set(el.name, v);
  });
  return p;
}
function paramsToForm(card, params){
  let touched = false;
  card.querySelectorAll('input[name], select[name], textarea[name]').forEach(el=>{
    const k = el.name;
    if (!params.has(k)) return;
    const v = params.get(k);
    if (el.type === 'checkbox'){
      const val = (v==='1' || v==='true');
      if(el.checked !== val){ el.checked = val; touched = true; }
    }else{
      if(el.value !== v){ el.value = v; touched = true; }
    }
  });
  if (touched) card.dispatchEvent(new Event('input', {bubbles:true}));
}

/* ---------- Nav: anchors + minimal history ---------- */
function renderNav(active){
  navEl.innerHTML = '';
  const ul = el('ul',{class:'navlist'});
  for(const c of CALCS){
    const a = el('a', {
      href: `/${c.id}`,
      'data-calc': c.id,
      'aria-current': c.id===active ? 'page' : null
    }, c.name);
    ul.append(el('li',{}, a));
  }
  navEl.append(ul);
}

// delegate clicks so we can decide push vs replace
navEl.addEventListener('click', (e)=>{
  const a = e.target.closest('a[data-calc]');
  if(!a) return;
  // allow new tab/window/defaults
  if (e.defaultPrevented || e.button !== 0 || e.metaKey || e.ctrlKey || e.altKey) return;
  e.preventDefault();
  const id = a.dataset.calc;
  // shift-click = commit to history (push); otherwise replace (minimal history)
  setRoute(id, null, {replace: !e.shiftKey});
});

function loadModule(spec){
  if(!moduleCache.has(spec)) moduleCache.set(spec, import(spec));
  return moduleCache.get(spec);
}

async function ensureMounted(id){
  if(viewCache.has(id)) return viewCache.get(id);
  const meta = metaById(id);
  const card = el('section',{class:'card'});
  viewCache.set(id, card);

  // placeholder heading
  card.append(el('h2',{}, meta.name), el('div',{class:'muted'}, meta.about||''));
  try{
    const mod = await loadModule(meta.path);
    const calc = mod.default;
    card.innerHTML = '';
    card.append(el('h2',{}, calc.name || meta.name));
    if(calc.about) card.append(el('div',{class:'muted'}, calc.about));
    calc.render(card);
    enhanceSelects(card);
  }catch(e){
    console.error(e);
    card.innerHTML = `<div class="muted">Failed to load calculator. Check console.</div>`;
  }
  return card;
}

function attachUrlSync(card, id){
  // Debounced replaceState on input changes (never pushes to history)
  let t;
  card.addEventListener('input', ()=>{
    clearTimeout(t);
    t = setTimeout(()=>{
      const newParams = formToParams(card);
      const {id:curId, params:curParams} = parseRoute();
      const sameId = (curId === id);
      const sameQs = sameId && newParams.toString() === curParams.toString();
      if(!sameQs) setRoute(id, newParams, {replace:true});
    }, 150);
  });
}

async function show(id, params){
  renderNav(id);
  for(const [cid, card] of viewCache.entries()){
    card.style.display = (cid===id) ? '' : 'none';
  }
  if(!viewCache.has(id)){
    const card = await ensureMounted(id);
    viewEl.append(card);
    attachUrlSync(card, id);
  }
  paramsToForm(viewCache.get(id), params);
}

async function mount(){
  const {id, params} = parseRoute();
  // normalize root to /interest once
  if(!location.pathname || location.pathname === '/' ){
    setRoute('interest', params, {replace:true});
    return;
  }
  await show(id, params);

  // idle prefetch
  const idle = window.requestIdleCallback || ((fn)=>setTimeout(fn,300));
  idle(()=> CALCS.forEach(c=> loadModule(c.path).catch(()=>{})));
}

addEventListener('popstate', mount); // back/forward
mount();