import { el, onTeardown } from '../lib/dom.js';
import { settings, applyTheme } from '../store/settings.js';
import { selection } from '../store/selection.js';
import { canInstall, onInstallChange, promptInstall } from '../lib/install.js';

export async function SettingsView() {
  const view = el('section', { class: 'view settings' });
  const st = settings.get();

  const themeField = selectField('Theme', st.theme, [
    ['system', 'System'],
    ['light', 'Light'],
    ['dark', 'Dark'],
    ['black', 'Black (OLED)'],
    ['sepia', 'Sepia'],
  ], (v) => {
    settings.set({ theme: v });
    applyTheme();
  });

  const ACCENTS = [
    ['red', '#b3161a'],
    ['blue', '#2f6fed'],
    ['green', '#1f9d57'],
    ['amber', '#d98a00'],
    ['violet', '#7b52e0'],
    ['rose', '#e0417a'],
  ];
  const accentRow = el(
    'div',
    { class: 'swatches' },
    ...ACCENTS.map(([key, hex]) =>
      el('button', {
        class: `swatch${st.accent === key ? ' is-on' : ''}`,
        type: 'button',
        style: `--sw:${hex}`,
        title: key,
        'aria-label': `${key} accent`,
        onclick: () => {
          settings.set({ accent: key });
          applyTheme();
          [...accentRow.children].forEach((b, i) =>
            b.classList.toggle('is-on', ACCENTS[i][0] === key),
          );
        },
      }),
    ),
  );
  const accentField = el('div', { class: 'field' }, el('span', {}, 'Accent colour'), accentRow);

  const fontSizeField = selectField('Text size', st.fontScale || 'default', [
    ['small', 'Small'],
    ['default', 'Default'],
    ['large', 'Large'],
  ], (v) => {
    settings.set({ fontScale: v });
    applyTheme();
  });

  const reduceMotionField = el('label', { class: 'field field--check' },
    el('input', {
      type: 'checkbox',
      checked: !!st.reduceMotion,
      onchange: (e) => {
        settings.set({ reduceMotion: e.target.checked });
        applyTheme();
      },
    }),
    'Reduce motion',
  );

  const spriteField = selectField('Sprite style', st.spriteStyle, [
    ['default', 'Pixel (modern)'],
    ['game', 'Game era (pixel art from the selected game)'],
    ['official', 'Official artwork'],
    ['home', 'Pokémon HOME'],
  ], (v) => settings.set({ spriteStyle: v }));

  const shinyField = el('label', { class: 'field field--check' },
    el('input', {
      type: 'checkbox',
      checked: st.showShiny,
      onchange: (e) => settings.set({ showShiny: e.target.checked }),
    }),
    'Default detail view to shiny sprites',
  );

  const teamNavField = el('label', { class: 'field field--check' },
    el('input', {
      type: 'checkbox',
      checked: st.showTeamNav !== false,
      onchange: (e) => settings.set({ showTeamNav: e.target.checked }),
    }),
    'Show Team in the navigation bar',
  );

  const hapticsField = el('label', { class: 'field field--check' },
    el('input', {
      type: 'checkbox',
      checked: st.haptics !== false,
      onchange: (e) => settings.set({ haptics: e.target.checked }),
    }),
    'Haptic feedback on catch',
  );

  const defaultRouteField = selectField('Landing screen', st.defaultRoute || 'dex', [
    ['dex', 'Dex'],
    ['team', 'Team'],
    ['search', 'Search'],
  ], (v) => settings.set({ defaultRoute: v }));

  const storageNote = el('p', { class: 'settings__note' }, 'Calculating storage…');
  if (navigator.storage?.estimate) {
    navigator.storage.estimate().then(({ usage = 0, quota = 0 }) => {
      const mb = (n) => (n / 1024 / 1024).toFixed(1);
      storageNote.textContent = `Using ${mb(usage)} MB of ~${mb(quota)} MB available (caches + tracking data).`;
    });
  } else {
    storageNote.textContent = 'Storage estimate not available in this browser.';
  }

  const importInput = el('input', {
    type: 'file',
    accept: 'application/json',
    style: 'display:none',
    onchange: async (e) => {
      const file = e.target.files[0];
      if (!file) return;
      try {
        const data = JSON.parse(await file.text());
        if (data.settings) settings.replace(data.settings);
        if (data.selection) selection.replace(data.selection);
        alert('Import complete.');
      } catch {
        alert('That file could not be read as a Pokédex backup.');
      }
    },
  });

  // Install (only when the browser has offered it and the app isn't
  // already installed).
  const installRow = el('div', { class: 'settings__install' });
  function syncInstall() {
    installRow.replaceChildren(
      canInstall()
        ? el(
            'button',
            {
              class: 'button',
              type: 'button',
              onclick: () => promptInstall(),
            },
            'Install app',
          )
        : el(
            'p',
            { class: 'settings__note' },
            window.matchMedia('(display-mode: standalone)').matches
              ? 'Running as an installed app.'
              : 'Use your browser menu to add this Pokédex to your home screen.',
          ),
    );
  }
  syncInstall();
  const offInstall = onInstallChange(syncInstall);

  view.append(
    el('header', { class: 'view__header' }, el('h1', {}, 'Settings')),
    installRow,
    el(
      'div',
      { class: 'settings__group' },
      themeField,
      accentField,
      fontSizeField,
      reduceMotionField,
      spriteField,
      shinyField,
      hapticsField,
      teamNavField,
      defaultRouteField,
    ),

    el('h2', {}, 'Your data'),
    storageNote,
    el('div', { class: 'settings__actions' },
      el('button', {
        class: 'button',
        type: 'button',
        onclick: () => exportData(),
      }, 'Export backup'),
      el('button', {
        class: 'button',
        type: 'button',
        onclick: () => importInput.click(),
      }, 'Import backup'),
      importInput,
      el('button', {
        class: 'button button--danger',
        type: 'button',
        onclick: () => {
          if (confirm('Clear all seen/caught/favorite tracking? This cannot be undone.')) {
            selection.replace({ version: 2, pokemon: {} });
          }
        },
      }, 'Clear tracking data'),
      el('button', {
        class: 'button button--danger',
        type: 'button',
        onclick: async () => {
          if (!('caches' in window)) return;
          if (confirm('Clear cached PokéAPI data and sprites? They will re-download when online.')) {
            for (const key of await caches.keys()) await caches.delete(key);
            alert('Caches cleared.');
          }
        },
      }, 'Clear cached API data'),
    ),

    el('h2', {}, 'About'),
    el('p', { class: 'settings__note' },
      'Data from ',
      el('a', { href: 'https://pokeapi.co/', class: 'link', target: '_blank', rel: 'noreferrer' }, 'PokéAPI'),
      '. Tracking data and preferences are stored locally in your browser.',
    ),
  );

  onTeardown(view, () => {
    offInstall();
  });
  return view;
}

function selectField(label, value, options, onChange) {
  const select = el(
    'select',
    { onchange: (e) => onChange(e.target.value) },
    ...options.map(([v, text]) =>
      el('option', { value: v, selected: v === value }, text),
    ),
  );
  return el('label', { class: 'field' }, el('span', {}, label), select);
}

function exportData() {
  const payload = {
    exportedAt: new Date().toISOString(),
    settings: settings.get(),
    selection: selection.get(),
  };
  const blob = new Blob([JSON.stringify(payload, null, 2)], {
    type: 'application/json',
  });
  const url = URL.createObjectURL(blob);
  const a = el('a', {
    href: url,
    download: `pokedex-backup-${new Date().toISOString().slice(0, 10)}.json`,
  });
  document.body.append(a);
  a.click();
  a.remove();
  setTimeout(() => URL.revokeObjectURL(url), 1000);
}