/*
 * The navigation (docs/navigation.md): diora's sections, sorted by what one does —
 * Home; Lesen: Bücher, Zeitschriften, Nachrichten, Blogs; Hören: Hörbücher, Podcasts,
 * Radio, Ambient. One definition for every platform: the web page's #tabs are drawn
 * here, the apps' tab bar and sidebar (native-radio.js) from DioraNav.groups() and
 * DioraNav.sections(). A section is a panel (showTab, as before) plus a view in it.
 * On a phone, Lesen and Hören show their sections as a row on top (#nav-segments).
 * Loaded before the app scripts (99-init.js restores the section through it).
 * Chrome-61-safe: no ?. / ??.
 */
(function () {
  'use strict';
  const html = document.documentElement;
  const authed = typeof IS_AUTHENTICATED === 'undefined' || !!IS_AUTHENTICATED;

  const SECTIONS = [
    {id: 'home', group: 'home', label: 'Home', icon: '⌂', panel: 'home', account: true},
    {id: 'books', group: 'lesen', label: 'Bücher', icon: '▤', panel: 'books', view: 'books'},
    {id: 'magazines', group: 'lesen', label: 'Zeitschriften', icon: '▥', panel: 'books', view: 'magazines', account: true},
    {id: 'news', group: 'lesen', label: 'Nachrichten', icon: '☰', panel: 'feeds', view: 'news', account: true},
    {id: 'blogs', group: 'lesen', label: 'Blogs', icon: '✎', panel: 'feeds', view: 'blogs', account: true},
    {id: 'audiobooks', group: 'hoeren', label: 'Hörbücher', icon: '◐', panel: 'audiobooks', account: true, needsPodcasts: true},
    {id: 'podcasts', group: 'hoeren', label: 'Podcasts', icon: '◎', panel: 'podcasts'},
    {id: 'radio', group: 'hoeren', label: 'Radio', icon: '◉', panel: 'radio'},
    {id: 'ambient', group: 'hoeren', label: 'Ambient', icon: '∿', panel: 'ambient'},
    // The focus timer: the web page's own (the apps never had it).
    {id: 'focus', group: 'hoeren', label: 'Fokus', icon: '◷', panel: 'focus', webOnly: true},
  ];
  const GROUPS = [
    {id: 'home', label: 'Home', icon: '⌂'},
    {id: 'lesen', label: 'Lesen', icon: '▤'},
    {id: 'hoeren', label: 'Hören', icon: '◉'},
  ];
  const byId = {};
  SECTIONS.forEach(s => { byId[s.id] = s; });

  const nativeUi = () => html.classList.contains('nui-radio');   // the apps' own bars (native-radio.js)
  const readerApp = () => html.classList.contains('nui-reader-app');
  const noRead = () => html.classList.contains('nui-noread');     // TV
  // Audiobooks need the podcast player: the page has them where it loads audiobooks.js
  // (diora Reader's build leaves it out). Known before the player's script has run.
  const podcastHost = () => !!document.querySelector('script[src$="/static/js/audiobooks.js"]');

  function available(s) {
    if (!document.getElementById('tab-' + s.panel)) return false;
    if (s.account && !authed) return false;
    if (s.webOnly && nativeUi()) return false;
    if (s.needsPodcasts && !podcastHost()) return false;
    if (readerApp() && s.group !== 'lesen') return false;   // diora Reader: reading only
    if (noRead() && s.group === 'lesen') return false;       // TV: no reading
    return true;
  }

  function sections() {
    return SECTIONS.filter(available).map(s => ({id: s.id, group: s.group, label: s.label, icon: s.icon}));
  }

  function groups() {
    const list = sections();
    return GROUPS.map(g => ({id: g.id, label: g.label, icon: g.icon,
      sections: list.filter(s => s.group === g.id).map(s => s.id)})).filter(g => g.sections.length);
  }

  function load(key) {
    try { return localStorage.getItem(key); } catch (e) { return null; }
  }

  function save(key, value) {
    try { localStorage.setItem(key, value); } catch (e) {}
  }

  let current = null;
  const listeners = [];

  // A section of `group`: the one used last there, else its first.
  function lastOf(group) {
    const list = sections().filter(s => s.group === group);
    const last = load('diora_nav_last_' + group);
    const found = list.filter(s => s.id === last)[0];
    return (found || list[0] || {}).id || null;
  }

  // What a name means: a section, a group (its last section), or a panel (its section).
  function resolve(name) {
    if (byId[name] && available(byId[name])) return name;
    if (GROUPS.some(g => g.id === name)) return lastOf(name);
    const inPanel = sections().filter(s => byId[s.id].panel === name);
    if (!inPanel.length) return null;
    const last = lastOf(byId[inPanel[0].id].group);
    return inPanel.some(s => s.id === last) ? last : inPanel[0].id;
  }

  function applyView(s) {
    if (s.panel === 'books' && window.__dioraBooksView) window.__dioraBooksView(s.view);
    if (s.panel === 'feeds' && window.__dioraFeedsView) window.__dioraFeedsView(s.view);
  }

  function setCurrent(id) {
    current = id;
    const s = byId[id];
    save('diora_nav_section', id);
    save('diora_nav_last_' + s.group, id);
    syncHash();
    render();
    listeners.slice().forEach(fn => { try { fn(id); } catch (e) {} });
  }

  let going = false;
  function go(name) {
    wrapShowTab();
    const id = resolve(name);
    if (!id) return false;
    const s = byId[id];
    applyView(s);   // first: the panel then shows the chosen view
    going = true;
    try { window.showTab(s.panel); } finally { going = false; }   // with everything hooked onto it
    setCurrent(id);
    return true;
  }

  // Anything that shows a panel directly (Home's cards, the offline switch to the books,
  // a notification …): the section follows. Hooked on when first needed: this file comes
  // before the app's scripts, which define showTab.
  let wrapped = false;
  function wrapShowTab() {
    if (wrapped || typeof window.showTab !== 'function') return;
    wrapped = true;
    const showTab = window.showTab;
    window.showTab = function (name) {
      const r = showTab.apply(this, arguments);
      if (!going) {
        const cur = current && byId[current];
        if (!cur || cur.panel !== name) {
          const id = resolve(name);
          if (id) {
            if (byId[id].view) applyView(byId[id]);
            setCurrent(id);
          }
        }
      }
      return r;
    };
  }

  // ---- the URL hash: #books, #news, #audiobooks … (old ones like #feeds, #radio/saved too)

  let routing = false;
  function syncHash() {
    if (routing) return;
    let hash = current;
    if (current === 'radio') hash += '/' + (load('diora_active_radio_tab') || 'saved');
    if (location.hash.slice(1) !== hash) history.pushState(null, '', '#' + hash);
  }

  function route() {
    const parts = (location.hash || '').replace(/^#/, '').split('/').filter(Boolean);
    if (!parts.length || !resolve(parts[0])) return false;
    routing = true;
    try {
      go(parts[0]);
      if (parts[0] === 'radio' && parts[1] && typeof showRadioTab === 'function') showRadioTab(parts[1]);
    } finally {
      routing = false;
    }
    return true;
  }

  // At the start (99-init.js): the hash, else the section used last; offline the books.
  function restore(offline) {
    if (offline) { go('books'); return; }
    if (route()) return;
    const saved = load('diora_nav_section') || load('diora_active_tab') || 'radio';
    if (!go(saved)) go(sections()[0] ? sections()[0].id : 'radio');
  }

  // ---- the web page's bar and the segment row --------------------------------------------

  function esc(s) {
    return String(s).replace(/[&<>"]/g, c => ({'&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;'}[c]));
  }

  function button(id, label, cls, on) {
    return '<button type="button" class="' + cls + (on ? ' active' : '') + '" data-nav="' + id + '">' + esc(label) + '</button>';
  }

  let tabs = null;
  let segs = null;
  function render() {
    const cur = current && byId[current];
    const gs = groups();
    if (tabs && !nativeUi()) {
      // Wide: every section under its group; narrow: the groups (their sections on top).
      tabs.innerHTML =
        '<div class="nav-wide">' + gs.map(g => g.id === 'home'
          ? button('home', 'Home', 'tab-btn', current === 'home')
          : '<span class="nav-group-label">' + esc(g.label) + '</span>' +
            g.sections.map(id => button(id, byId[id].label, 'tab-btn', current === id)).join('')).join('') + '</div>' +
        '<div class="nav-narrow">' + gs.map(g =>
          button(g.id, g.label, 'tab-btn', !!cur && cur.group === g.id)).join('') + '</div>';
    }
    if (segs) {
      const g = cur ? gs.filter(x => x.id === cur.group)[0] : null;
      const show = !!g && g.sections.length > 1 && html.classList.contains('nav-bars');
      segs.hidden = !show;
      segs.innerHTML = show ? g.sections.map(id => button(id, byId[id].label, 'nav-seg', current === id)).join('') : '';
    }
  }

  function setup() {
    wrapShowTab();
    tabs = document.getElementById('tabs');
    const first = document.querySelector('section.tab-panel');
    if (first) {
      segs = document.createElement('nav');
      segs.id = 'nav-segments';
      segs.hidden = true;
      first.parentNode.insertBefore(segs, first);
      segs.addEventListener('click', onClick);
    }
    if (tabs && !nativeUi()) {
      html.classList.add('nav-bars');   // the page's own bar knows the sections
      tabs.addEventListener('click', onClick);
    }
    render();
  }

  function onClick(e) {
    const b = e.target.closest('[data-nav]');
    if (!b) return;
    e.preventDefault();
    go(b.dataset.nav);
    window.scrollTo(0, 0);
  }

  window.DioraNav = {
    sections,
    groups,
    current: () => current,
    go,
    onChange(fn) { if (typeof fn === 'function') listeners.push(fn); },
    // For a bar drawn elsewhere (native-radio.js): it shows the sections itself.
    barsReady() { html.classList.add('nav-bars'); render(); },
    route,
    restore,
  };

  if (document.readyState === 'loading') document.addEventListener('DOMContentLoaded', setup);
  else setup();
  window.addEventListener('popstate', route);
  window.addEventListener('hashchange', route);

  // ---- styles ----------------------------------------------------------------------------

  const style = document.createElement('style');
  style.textContent = [
    '#tabs .nav-wide, #tabs .nav-narrow { display: flex; flex-wrap: wrap; align-items: center; gap: 2px; }',
    '#tabs .nav-narrow { display: none; }',
    '#tabs .nav-group-label { margin: 0 4px 0 14px; font-size: 11px; text-transform: uppercase; letter-spacing: 0.08em; color: var(--muted, #9a9a9a); }',
    '@media (max-width: 720px) { #tabs .nav-wide { display: none; } #tabs .nav-narrow { display: flex; } }',
    '#nav-segments { display: flex; gap: 6px; overflow-x: auto; padding: 8px 0 12px; scrollbar-width: none; }',
    '#nav-segments[hidden] { display: none; }',
    '#nav-segments::-webkit-scrollbar { display: none; }',
    '.nav-seg { flex: none; min-height: 36px; padding: 0 14px; border-radius: 18px; border: 1px solid var(--border-strong, #444); background: none; color: inherit; font: inherit; font-size: 14px; cursor: pointer; }',
    '.nav-seg.active { background: var(--accent, #e63946); border-color: var(--accent, #e63946); color: var(--on-accent, #fff); }',
    // Wide web page: every section is in the bar, the row would repeat it.
    '@media (min-width: 721px) { html:not(.nui-radio) #nav-segments { display: none; } }',
    // The sidebar (apps, wide): the sections are in it.
    'html.nui-sidebar #nav-segments { display: none; }',
  ].join('\n');
  document.head.appendChild(style);
})();