import { el, clear, onTeardown } from '../lib/dom.js';
import { loadSnapshot } from '../data/snapshot.js';
import { resolvePokedex, dexRows, prettify } from '../data/pokedex-resolver.js';
import { settings } from '../store/settings.js';
import { ui } from '../store/ui.js';
import { selection, stats } from '../store/selection.js';
import { Card } from '../components/Card.js';
import { ProgressRing } from '../components/ProgressRing.js';

const FILTERS = [
  { key: 'all', label: 'All', test: () => true },
  { key: 'caught', label: 'Caught', test: (e) => e.caught },
  { key: 'missing', label: 'Missing', test: (e) => !e.caught },
  { key: 'favorite', label: 'Favorites', test: (e) => e.favorite },
  { key: 'legendary', label: 'Legendary', test: (e, sp) => sp.isLegendary || sp.isMythical },
];

const SORTS = [
  { key: 'dex', label: 'Dex number', desc: false },
  { key: 'name', label: 'Name (A–Z)', desc: false },
  { key: 'bst', label: 'Base stat total', desc: true },
  { key: 'hp', label: 'HP', desc: true },
  { key: 'atk', label: 'Attack', desc: true },
  { key: 'def', label: 'Defense', desc: true },
  { key: 'spa', label: 'Sp. Attack', desc: true },
  { key: 'spd', label: 'Sp. Defense', desc: true },
  { key: 'spe', label: 'Speed', desc: true },
  { key: 'height', label: 'Height', desc: true },
  { key: 'weight', label: 'Weight', desc: true },
  { key: 'baseExp', label: 'Base EXP', desc: true },
  { key: 'catchrate', label: 'Catch rate', desc: true },
  { key: 'caught', label: 'Recently caught', desc: true },
];
const STAT_SHORT = { hp: 'HP', atk: 'Atk', def: 'Def', spa: 'SpA', spd: 'SpD', spe: 'Spe' };

const SEARCH_ICON =
  '<svg viewBox="0 0 24 24" width="18" height="18" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><circle cx="11" cy="11" r="7"/><path d="m20 20-3.5-3.5"/></svg>';

function sortValue(row, key) {
  const sp = row.species;
  switch (key) {
    case 'dex': return row.number ?? sp.id;
    case 'name': return sp.name;
    case 'bst': return sp.bst ?? 0;
    case 'hp': case 'atk': case 'def': case 'spa': case 'spd': case 'spe':
      return sp.stats?.[key] ?? 0;
    case 'height': return sp.height ?? 0;
    case 'weight': return sp.weight ?? 0;
    case 'baseExp': return sp.baseExp ?? 0;
    case 'catchrate': return sp.captureRate ?? 0;
    case 'caught': return selection.get().pokemon[sp.id]?.updatedAt || '';
    default: return 0;
  }
}

function metricLabel(key, sp) {
  switch (key) {
    case 'bst': return `BST ${sp.bst}`;
    case 'hp': case 'atk': case 'def': case 'spa': case 'spd': case 'spe':
      return `${STAT_SHORT[key]} ${sp.stats?.[key] ?? 0}`;
    case 'height': return `${((sp.height ?? 0) / 10).toFixed(1)} m`;
    case 'weight': return `${((sp.weight ?? 0) / 10).toFixed(1)} kg`;
    case 'baseExp': return sp.baseExp != null ? `${sp.baseExp} EXP` : null;
    case 'catchrate': return `Catch ${sp.captureRate ?? '?'}`;
    default: return null;
  }
}

export async function DexGrid() {
  const view = el('section', { class: 'view dexgrid' });
  const snap = await loadSnapshot();

  const grid = el('div', { class: 'grid' });
  let query = '';
  let filterKey = ui.get().filter || 'all';
  let sortKey = ui.get().sort || 'dex';
  let sortDesc = !!ui.get().sortDesc;
  let rows = [];
  let ids = [];

  const ring = ProgressRing();

  const title = el('h1', {});
  // Which game is active — a quiet label, not a control. Change it from the
  // Games button in the nav.
  const gameLabel = el('span', { class: 'feed-head__game' });

  const search = el('input', {
    class: 'field-search__input',
    type: 'search',
    placeholder: 'Filter this Pokédex…',
    oninput: (e) => {
      query = e.target.value.trim().toLowerCase();
      paintGrid();
    },
  });

  const filterBar = el('div', { class: 'feed-chips' });
  const chipEls = FILTERS.map((f) => {
    const count = el('span', { class: 'feed-chip__count' });
    const btn = el(
      'button',
      {
        class: `feed-chip${f.key === filterKey ? ' is-active' : ''}`,
        type: 'button',
        onclick: () => {
          filterKey = f.key;
          ui.set({ filter: f.key });
          chipEls.forEach((c, i) => c.btn.classList.toggle('is-active', FILTERS[i].key === f.key));
          paintGrid();
          resetScroll();
        },
      },
      el('span', {}, f.label),
      count,
    );
    filterBar.append(btn);
    return { btn, count };
  });

  const sortSelect = el(
    'select',
    {
      class: 'feed-sort__select',
      onchange: (e) => {
        sortKey = e.target.value;
        sortDesc = SORTS.find((s) => s.key === sortKey).desc;
        ui.set({ sort: sortKey, sortDesc });
        syncDirBtn();
        paintGrid();
        resetScroll();
      },
    },
    ...SORTS.map((s) => el('option', { value: s.key, selected: s.key === sortKey }, s.label)),
  );
  const dirBtn = el('button', {
    class: 'feed-sort__dir',
    type: 'button',
    title: 'Reverse order',
    onclick: () => {
      sortDesc = !sortDesc;
      ui.set({ sortDesc });
      syncDirBtn();
      paintGrid();
      resetScroll();
    },
  });
  function syncDirBtn() {
    dirBtn.textContent = sortDesc ? '↓' : '↑';
    dirBtn.setAttribute('aria-label', sortDesc ? 'Descending' : 'Ascending');
  }
  syncDirBtn();

  // Changing the list order/contents makes the old scroll offset meaningless.
  function resetScroll() {
    ui.set({ feedScroll: 0 });
    window.scrollTo(0, 0);
  }

  // Return to the saved scroll offset. Retry a few times — the grid's height
  // isn't final until the webfont loads and off-screen cards settle — but
  // stop once we've reached the target or the user starts scrolling.
  function restoreScroll() {
    const y = ui.get().feedScroll || 0;
    if (!y) return;
    let applied = null;
    const go = () => {
      if (applied != null && Math.abs(window.scrollY - applied) > 8) return; // user moved
      window.scrollTo(0, y);
      applied = Math.round(window.scrollY);
    };
    go();
    setTimeout(go, 80);
    setTimeout(go, 250);
    if (document.fonts && document.fonts.ready) document.fonts.ready.then(go);
  }

  view.append(
    el(
      'header',
      { class: 'feed-head' },
      el(
        'div',
        { class: 'feed-head__top' },
        el('div', { class: 'feed-head__id' }, title, gameLabel),
        ring.node,
      ),
      el(
        'div',
        { class: 'field-search' },
        el('span', { class: 'field-search__icon', html: SEARCH_ICON, 'aria-hidden': 'true' }),
        search,
      ),
      filterBar,
      el(
        'div',
        { class: 'feed-sort' },
        el('span', { class: 'feed-sort__label' }, 'Sort'),
        sortSelect,
        dirBtn,
      ),
    ),
    grid,
  );

  function counts() {
    const p = selection.get().pokemon;
    let caught = 0;
    let favorite = 0;
    let legendary = 0;
    for (const { species } of rows) {
      const e = p[species.id];
      if (e?.caught) caught++;
      if (e?.favorite) favorite++;
      if (species.isLegendary || species.isMythical) legendary++;
    }
    return { all: rows.length, caught, missing: rows.length - caught, favorite, legendary };
  }

  function refreshMeta() {
    ring.update(stats(ids));
    const c = counts();
    chipEls.forEach(({ count }, i) => {
      count.textContent = c[FILTERS[i].key];
    });
  }

  function paintGrid() {
    const st = settings.get();
    const pokemonState = selection.get().pokemon;
    const boxed =
      st.spriteStyle === 'game' &&
      (snap.versionGroupByKey.get(st.versionGroup)?.generation ?? 9) <= 2;
    const filterTest = FILTERS.find((f) => f.key === filterKey).test;

    let list = rows.filter(({ species, number }) => {
      if (
        query &&
        !species.name.includes(query) &&
        String(number) !== query &&
        String(species.id) !== query
      ) {
        return false;
      }
      const e = pokemonState[species.id] || { seen: false, caught: false, favorite: false };
      return filterTest(e, species);
    });

    const dir = sortDesc ? -1 : 1;
    list = list
      .map((row) => ({ row, v: sortValue(row, sortKey) }))
      .sort((a, b) => {
        if (a.v < b.v) return -dir;
        if (a.v > b.v) return dir;
        return (a.row.number ?? a.row.species.id) - (b.row.number ?? b.row.species.id);
      })
      .map((x) => x.row);

    const frag = document.createDocumentFragment();
    list.forEach(({ species, number }, i) => {
      const card = Card(species, number, {
        spriteStyle: st.spriteStyle,
        versionGroup: st.versionGroup,
        boxed,
        metric: metricLabel(sortKey, species),
      });
      if (i < 30) card.style.setProperty('--i', String(i));
      frag.append(card);
    });

    clear(grid);
    grid.append(
      list.length === 0
        ? el('p', { class: 'grid__empty' }, 'Nothing matches those filters.')
        : frag,
    );
  }

  function rebuild() {
    const st = settings.get();
    const dex = resolvePokedex(snap, st);
    rows = dexRows(snap, dex);
    ids = rows.map((r) => r.species.id);

    title.textContent = prettify(dex.name || dex.key);
    gameLabel.textContent =
      st.versionGroup === 'all' ? 'All games' : prettify(st.versionGroup);
    refreshMeta();
    paintGrid();
  }

  let mountedVG = settings.get().versionGroup;
  rebuild();
  // Return to where the user last scrolled (e.g. after viewing a Pokémon).
  requestAnimationFrame(restoreScroll);

  const offSettings = settings.subscribe((s) => {
    if (s.versionGroup !== mountedVG) {
      mountedVG = s.versionGroup;
      ui.set({ feedScroll: 0 });
    }
    rebuild();
  });
  const offSelection = selection.subscribe(() => {
    refreshMeta();
    if (filterKey !== 'all' && filterKey !== 'legendary') paintGrid();
    else if (sortKey === 'caught') paintGrid();
  });
  onTeardown(view, () => {
    ui.set({ feedScroll: window.scrollY });
    offSettings();
    offSelection();
  });

  return view;
}