// Trip list dashboard: cards, a "new trip" form, and a "join a trip" form.
import { api } from '../api.js';
import { el, mount, clear, loading, errorBox, emptyState, toast } from '../dom.js';
import { formatRange, ymd, parseYMD, pluralize, normalizeCode } from '../format.js';
import { enableTripReorder } from './dragdrop.js';

export function renderTrips(container, ctx) {
  mount(container, loading('Loading your trips…'));
  load();

  async function load() {
    try {
      const data = await api.trips.list();
      draw(data.trips || []);
    } catch (err) {
      mount(container, errorBox(err.message, load));
    }
  }

  function draw(trips) {
    const page = el('div', { class: 'page' });

    // The form slot is created up front so every button below can capture a
    // fully-initialized reference (no reliance on declaration ordering).
    const formSlot = el('div', { class: 'form-slot' });

    const newTripBtn = el('button', { class: 'btn btn-primary', onClick: () => openNewTrip(formSlot) }, '+ New trip');
    const joinBtn = el('button', { class: 'btn', onClick: () => openJoin(formSlot) }, 'Join a trip');

    page.appendChild(
      el(
        'div',
        { class: 'page-head' },
        el(
          'div',
          {},
          el('h1', {}, 'Your Trips'),
          el('p', { class: 'muted' }, trips.length
            ? pluralize(trips.length, 'trip', 'trips')
            : 'Start planning your next adventure.'),
        ),
        el('div', { class: 'page-head-actions' }, joinBtn, newTripBtn),
      ),
    );

    page.appendChild(formSlot);

    if (!trips.length) {
      page.appendChild(
        emptyState(
          'No trips yet',
          'Create your first trip, or join one with a code a friend shared.',
          el('div', { class: 'empty-actions' },
            el('button', { class: 'btn btn-primary', onClick: () => openNewTrip(formSlot) }, '+ New trip'),
            el('button', { class: 'btn', onClick: () => openJoin(formSlot) }, 'Join a trip'),
          ),
        ),
      );
    } else {
      const grid = el('div', { class: 'trip-grid' });
      // Reordering only makes sense with 2+ trips (mirrors the day editor's
      // entry-row reorder — see dragdrop.js).
      const reorderable = trips.length > 1;
      const rows = [];
      for (const trip of trips) {
        const { node, handle } = tripCard(trip, reorderable);
        if (reorderable) rows.push({ node, handle, trip });
        grid.appendChild(node);
      }
      page.appendChild(grid);
      if (reorderable) enableTripReorder(rows, load);
    }

    mount(container, page);
  }

  function tripCard(trip, reorderable) {
    const today = ymd(new Date());
    const future = trip.start_date > today;
    const daysUntil = future
      ? Math.round((parseYMD(trip.start_date) - parseYMD(today)) / 86400000)
      : 0;
    const handle = reorderable
      ? el('span', {
          class: 'trip-drag-handle',
          title: 'Drag to reorder',
          'aria-hidden': 'true',
          onClick: (e) => e.preventDefault(),
        }, '⋮⋮')
      : null;
    const node = el(
      'a',
      { class: 'trip-card card', href: `#/trip/${trip.id}`, draggable: 'false' },
      el(
        'div',
        { class: 'trip-card-top' },
        el('h3', { class: 'trip-card-name' }, trip.name),
        el('div', { class: 'trip-card-top-right' },
          handle,
          el('span', { class: `role-badge role-${trip.role}` }, trip.role)),
      ),
      el(
        'div',
        { class: 'trip-card-dates' },
        '📅 ', formatRange(trip.start_date, trip.end_date),
        future ? el('span', { class: 'trip-card-countdown' }, `in ${daysUntil} ${daysUntil === 1 ? 'day' : 'days'}`) : null,
      ),
      el(
        'div',
        { class: 'trip-card-meta' },
        el('span', {}, '👥 ', pluralize(trip.member_count ?? 1, 'member', 'members')),
        el('span', {}, '📝 ', pluralize(trip.entry_count ?? 0, 'entry', 'entries')),
        el('span', { class: 'trip-card-currency' }, trip.currency || 'USD'),
      ),
    );
    return { node, handle };
  }

  // Render `build()` into the slot, or close it if the same panel is open.
  function togglePanel(slot, kind, build) {
    if (slot.dataset.open === kind) {
      clear(slot);
      slot.dataset.open = '';
      return;
    }
    mount(slot, build());
    slot.dataset.open = kind;
  }

  function openNewTrip(slot) {
    togglePanel(slot, 'new', () => newTripForm(slot));
  }

  function openJoin(slot) {
    togglePanel(slot, 'join', () => joinForm(slot));
  }

  function closeSlot(slot) {
    clear(slot);
    slot.dataset.open = '';
  }

  function newTripForm(slot) {
    const today = ymd(new Date());
    const nameInput = el('input', { class: 'input', type: 'text', maxlength: '120', placeholder: 'e.g. Northern Thailand' });
    const startInput = el('input', { class: 'input', type: 'date', value: today });
    const endInput = el('input', { class: 'input', type: 'date', value: today });
    const currencyInput = el('input', { class: 'input input-currency', type: 'text', maxlength: '3', value: 'USD', placeholder: 'USD', 'aria-label': 'Currency code' });
    const errorEl = el('p', { class: 'form-error' });
    const submitBtn = el('button', { class: 'btn btn-primary', type: 'submit' }, 'Create trip');

    async function onSubmit(e) {
      e.preventDefault();
      errorEl.textContent = '';
      const name = nameInput.value.trim();
      const start_date = startInput.value;
      const end_date = endInput.value;
      const currency = currencyInput.value.trim().toUpperCase() || 'USD';
      if (!name) return (errorEl.textContent = 'Please give the trip a name.');
      if (!start_date || !end_date) return (errorEl.textContent = 'Pick a start and end date.');
      if (end_date < start_date) return (errorEl.textContent = 'End date must be on or after the start date.');
      if (!/^[A-Z]{3}$/.test(currency)) return (errorEl.textContent = 'Currency must be a 3-letter code, e.g. USD.');

      submitBtn.disabled = true;
      submitBtn.textContent = 'Creating…';
      try {
        const data = await api.trips.create({ name, start_date, end_date, currency });
        toast('Trip created', 'success');
        ctx.navigate(`#/trip/${data.trip.id}`);
      } catch (err) {
        errorEl.textContent = err.message;
        submitBtn.disabled = false;
        submitBtn.textContent = 'Create trip';
      }
    }

    const form = el(
      'form',
      { class: 'card new-trip-form', onSubmit },
      el('h3', {}, 'New trip'),
      el('div', { class: 'form-row' },
        el('label', { class: 'field field-grow' }, el('span', { class: 'field-label' }, 'Name'), nameInput)),
      el('div', { class: 'form-row' },
        el('label', { class: 'field' }, el('span', { class: 'field-label' }, 'Start date'), startInput),
        el('label', { class: 'field' }, el('span', { class: 'field-label' }, 'End date'), endInput),
        el('label', { class: 'field field-currency' }, el('span', { class: 'field-label' }, 'Currency'), currencyInput)),
      errorEl,
      el('div', { class: 'form-actions' },
        el('button', { class: 'btn btn-ghost', type: 'button', onClick: () => closeSlot(slot) }, 'Cancel'),
        submitBtn),
    );
    setTimeout(() => nameInput.focus(), 0);
    return form;
  }

  function joinForm(slot) {
    const codeInput = el('input', {
      class: 'input token-input',
      type: 'text',
      autocomplete: 'off',
      autocapitalize: 'characters',
      spellcheck: 'false',
      placeholder: 'XXXX-XXXX',
      'aria-label': 'Join code',
    });
    const errorEl = el('p', { class: 'form-error' });
    const submitBtn = el('button', { class: 'btn btn-primary', type: 'submit' }, 'Join trip');

    async function onSubmit(e) {
      e.preventDefault();
      errorEl.textContent = '';
      const code = normalizeCode(codeInput.value);
      if (code.length < 4) return (errorEl.textContent = 'Enter the join code your friend shared.');
      submitBtn.disabled = true;
      submitBtn.textContent = 'Joining…';
      try {
        const data = await api.trips.join(code);
        toast('Joined trip', 'success');
        ctx.navigate(`#/trip/${data.trip.id}`);
      } catch (err) {
        errorEl.textContent = err.status === 404 ? 'No trip found for that code.' : err.message;
        submitBtn.disabled = false;
        submitBtn.textContent = 'Join trip';
      }
    }

    const form = el(
      'form',
      { class: 'card join-form', onSubmit },
      el('h3', {}, 'Join a trip'),
      el('p', { class: 'muted' }, 'Paste the join code from a trip you were invited to.'),
      el('div', { class: 'form-row' },
        el('label', { class: 'field field-grow' }, el('span', { class: 'field-label' }, 'Join code'), codeInput)),
      errorEl,
      el('div', { class: 'form-actions' },
        el('button', { class: 'btn btn-ghost', type: 'button', onClick: () => closeSlot(slot) }, 'Cancel'),
        submitBtn),
    );
    setTimeout(() => codeInput.focus(), 0);
    return form;
  }
}