// =====================================================
// Flashcards — flippable cards with category filter
// =====================================================

let fcData = null;
let fcState = {
  filter: 'all',
  index: 0,
  flipped: false,
  cards: [],
  known: new Set(),  // localStorage-backed
  hard: new Set()
};

async function fcLoad() {
  if (fcData) return fcData;
  try {
    const res = await fetch('data/flashcards.json');
    fcData = await res.json();
  } catch (e) {
    console.error('Klarte ikke laste flashcards:', e);
    fcData = [];
  }
  // Load saved state
  try {
    const saved = JSON.parse(localStorage.getItem('smf-fc-state') || '{}');
    if (saved.known) fcState.known = new Set(saved.known);
    if (saved.hard) fcState.hard = new Set(saved.hard);
  } catch {}
  return fcData;
}

function fcSaveState() {
  localStorage.setItem('smf-fc-state', JSON.stringify({
    known: [...fcState.known],
    hard: [...fcState.hard]
  }));
}

function fcFilterCards(filter) {
  if (filter === 'all') return fcData;
  if (filter === 'hard') return fcData.filter(c => fcState.hard.has(c.id));
  if (filter === 'new') return fcData.filter(c => !fcState.known.has(c.id) && !fcState.hard.has(c.id));
  return fcData.filter(c => c.category === filter);
}

function fcSetFilter(filter) {
  fcState.filter = filter;
  fcState.cards = fcFilterCards(filter);
  // shuffle once when filter changes
  fcShuffle(fcState.cards);
  fcState.index = 0;
  fcState.flipped = false;
  fcRender();
}

function fcShuffle(arr) {
  for (let i = arr.length - 1; i > 0; i--) {
    const j = Math.floor(Math.random() * (i + 1));
    [arr[i], arr[j]] = [arr[j], arr[i]];
  }
}

function fcRender() {
  const total = fcState.cards.length;
  document.getElementById('fcCurrent').textContent = total > 0 ? (fcState.index + 1) : 0;
  document.getElementById('fcTotal').textContent = total;
  document.getElementById('fcKnown').textContent = fcState.known.size;

  const card = document.getElementById('fcCard');

  if (total === 0) {
    document.getElementById('fcFront').textContent = 'Ingen kort i denne kategorien';
    document.getElementById('fcBack').textContent = 'Prøv et annet filter';
    document.getElementById('fcCategory').textContent = '—';
    card.classList.remove('fc-card--flipped');
    return;
  }

  const c = fcState.cards[fcState.index];
  document.getElementById('fcFront').textContent = c.front;
  document.getElementById('fcBack').innerHTML = c.back;
  document.getElementById('fcCategory').textContent = (c.subcategory || categoryLabel(c.category));

  card.classList.toggle('fc-card--flipped', fcState.flipped);
}

function categoryLabel(cat) {
  return {
    etikk: 'Etikk',
    baerekraft: 'Bærekraft',
    samfunn: 'Samfunnsansvar',
    verktoy: 'Verktøy',
    case: 'Case'
  }[cat] || cat;
}

function fcRenderFilters() {
  const container = document.getElementById('fcFilters');
  if (!container) return;
  const filters = [
    { id: 'all', label: 'Alle' },
    { id: 'new', label: 'Nye' },
    { id: 'hard', label: 'Glemt' },
    { id: 'etikk', label: 'Etikk' },
    { id: 'baerekraft', label: 'Bærekraft' },
    { id: 'samfunn', label: 'Samfunnsansvar' },
    { id: 'verktoy', label: 'Verktøy' },
    { id: 'case', label: 'Case' }
  ];
  container.innerHTML = filters.map(f => {
    const active = fcState.filter === f.id ? 'fc-filter--active' : '';
    return `<button class="fc-filter ${active}" data-filter="${f.id}">${f.label}</button>`;
  }).join('');
}

function fcNext() {
  if (!fcState.cards.length) return;
  fcState.flipped = false;
  fcState.index = (fcState.index + 1) % fcState.cards.length;
  fcRender();
}

function fcPrev() {
  if (!fcState.cards.length) return;
  fcState.flipped = false;
  fcState.index = (fcState.index - 1 + fcState.cards.length) % fcState.cards.length;
  fcRender();
}

function fcMark(level) {
  if (!fcState.cards.length) return;
  const c = fcState.cards[fcState.index];
  if (level === 'hard') {
    fcState.hard.add(c.id);
    fcState.known.delete(c.id);
  } else if (level === 'good') {
    fcState.hard.delete(c.id);
  } else if (level === 'easy') {
    fcState.known.add(c.id);
    fcState.hard.delete(c.id);
  }
  fcSaveState();
  fcNext();
}

async function fcInit() {
  await fcLoad();
  fcState.cards = fcFilterCards(fcState.filter);
  fcShuffle(fcState.cards);
  fcState.index = 0;
  fcState.flipped = false;

  fcRenderFilters();
  fcRender();

  // Card click → flip
  const card = document.getElementById('fcCard');
  card.addEventListener('click', () => {
    fcState.flipped = !fcState.flipped;
    fcRender();
  });

  document.getElementById('fcNext').addEventListener('click', (e) => { e.stopPropagation(); fcNext(); });
  document.getElementById('fcPrev').addEventListener('click', (e) => { e.stopPropagation(); fcPrev(); });
  document.getElementById('fcHard').addEventListener('click', (e) => { e.stopPropagation(); fcMark('hard'); });
  document.getElementById('fcGood').addEventListener('click', (e) => { e.stopPropagation(); fcMark('good'); });
  document.getElementById('fcEasy').addEventListener('click', (e) => { e.stopPropagation(); fcMark('easy'); });

  document.getElementById('fcFilters').addEventListener('click', (e) => {
    const btn = e.target.closest('[data-filter]');
    if (btn) {
      fcSetFilter(btn.dataset.filter);
      fcRenderFilters();
    }
  });

  // Keyboard
  const handler = (e) => {
    if (location.hash !== '#/flashcards') {
      document.removeEventListener('keydown', handler);
      return;
    }
    const tag = document.activeElement?.tagName;
    if (tag === 'INPUT' || tag === 'TEXTAREA') return;
    if (e.key === ' ' || e.key === 'Enter') { e.preventDefault(); fcState.flipped = !fcState.flipped; fcRender(); }
    else if (e.key === 'ArrowRight') { e.preventDefault(); fcNext(); }
    else if (e.key === 'ArrowLeft') { e.preventDefault(); fcPrev(); }
    else if (e.key === '1') { fcMark('hard'); }
    else if (e.key === '2') { fcMark('good'); }
    else if (e.key === '3') { fcMark('easy'); }
  };
  document.addEventListener('keydown', handler);
}

SMF.fcInit = fcInit;