SortableATM

@layer components {

  .sortable {

    list-style: none;

    margin: 0;

    padding: 0;

    display: flex;

    flex-direction: column;

    gap: 0.25rem;

    /* Horizontal orientation */

    &[data-orientation="horizontal"] {

      flex-direction: row;

      flex-wrap: wrap;

    }

  }

  .sortable-item {

    display: flex;

    align-items: center;

    gap: 0.5rem;

    padding: 0.5rem 0.75rem;

    border: 1px solid var(--border);

    border-radius: var(--radius-md);

    background-color: var(--card);

    font-size: 0.875rem;

    color: var(--foreground);

    cursor: grab;

    transition: box-shadow 150ms ease, opacity 150ms ease, border-color 150ms ease;

    user-select: none;

    &:active { cursor: grabbing; }

    /* Keyboard focus (roving tabindex) */

    &:focus-visible {

      outline: 2px solid var(--ring);

      outline-offset: 2px;

    }

    /* Active descendant highlight (keyboard navigation) */

    &[data-active] {

      border-color: var(--ring);

      background-color: var(--accent);

      color: var(--accent-foreground);

    }

    /* Drag in progress */

    &[data-dragging] {

      opacity: 0.5;

      box-shadow: var(--shadow-md);

      border-style: dashed;

    }

    /* Drop target indicator */

    &[data-over="before"] {

      border-top: 2px solid var(--primary);

    }

    &[data-over="after"] {

      border-bottom: 2px solid var(--primary);

    }

    /* Horizontal drop indicators */

    .sortable[data-orientation="horizontal"] &[data-over="before"] {

      border-top: 1px solid var(--border);

      border-inline-start: 2px solid var(--primary);

    }

    .sortable[data-orientation="horizontal"] &[data-over="after"] {

      border-bottom: 1px solid var(--border);

      border-inline-end: 2px solid var(--primary);

    }

    /* Disabled */

    &[aria-disabled="true"] {

      opacity: 0.5;

      cursor: not-allowed;

      pointer-events: none;

    }

  }

  .sortable-handle {

    color: var(--muted-foreground);

    cursor: grab;

    font-size: 1rem;

    line-height: 1;

    flex-shrink: 0;

    display: inline-flex;

    align-items: center;

    &:active { cursor: grabbing; }

    & svg { width: 1rem; height: 1rem; }

  }

  /* -- Move buttons: reorder by tap / click --------------------

     Native drag-and-drop mostly never starts on touch screens, so a list

     people must reorder by tapping carries Up / Down buttons per item.

     They sit at the item's end; Up/Down disable at the list's edges. */

  .sortable-moves {

    display: inline-flex;

    gap: 0.25rem;

    flex-shrink: 0;

    margin-inline-start: auto;

  }

  .sortable-move {

    display: inline-grid;

    place-items: center;

    box-sizing: border-box;

    width: 2rem;

    height: 2rem;

    padding: 0;

    border: 1px solid var(--border);

    border-radius: var(--radius-sm);

    background: var(--background);

    color: var(--foreground);

    cursor: pointer;

    transition: background-color 150ms, color 150ms;

    & svg { width: 1rem; height: 1rem; }

    &:hover { background: var(--accent); color: var(--accent-foreground); }

    &:focus-visible { outline: 2px solid var(--ring); outline-offset: 2px; }

    /* legible but inert, like every disabled control (no opacity fade) */

    &:disabled {

      background: var(--muted);

      color: var(--muted-foreground);

      cursor: not-allowed;

    }

    /* a finger needs a bigger target than a pointer (WCAG 2.5.5: 44px) */

    @media (pointer: coarse) {

      width: 2.75rem;

      height: 2.75rem;

    }

  }

  /* -- Connected lists (data-group) ------------------------------

     A list that items can be dragged INTO needs a body even when empty:

     an empty grouped list is a dashed drop zone (its data-empty text, if

     any, says what goes there), and a drag over the list's own box - gap,

     padding, empty zone - marks it as "drop at the end". */

  .sortable[data-group] {

    min-height: 2.75rem;

    &:not(:has(.sortable-item)) {

      align-items: center;

      justify-content: center;

      border: 1px dashed var(--border);

      border-radius: var(--radius-md);

      color: var(--muted-foreground);

      font-size: 0.875rem;

      &::before { content: attr(data-empty); }

    }

  }

  .sortable[data-over="end"] {

    outline: 2px dashed var(--primary);

    outline-offset: 2px;

    border-radius: var(--radius-md);

  }

  /* Live region for screen reader announcements */

  .sortable-live {

    position: absolute;

    width: 1px;

    height: 1px;

    padding: 0;

    margin: -1px;

    overflow: hidden;

    clip: rect(0, 0, 0, 0);

    white-space: nowrap;

    border: 0;

  }

  @media (prefers-reduced-motion: reduce) {

    .sortable-item, .sortable-move { transition: none; }

  }

  @media (prefers-contrast: more) {

    .sortable-item {

      border-width: 2px;

      &[data-active] { outline: 2px solid LinkText; }

      &[data-over="before"] { border-top-width: 3px; }

      &[data-over="after"] { border-bottom-width: 3px; }

    }

  }

  @media (forced-colors: active) {

    .sortable-item {

      border-color: ButtonBorder;

      color: ButtonText;

      background-color: ButtonFace;

      &[data-active] { border-color: Highlight; color: HighlightText; }

      &[data-dragging] { border-color: GrayText; }

      &[data-over="before"] { border-top-color: Highlight; }

      &[data-over="after"] { border-bottom-color: Highlight; }

      &[aria-disabled="true"] { color: GrayText; border-color: GrayText; }

    }

    .sortable-handle { color: GrayText; }

    .sortable-move {

      border-color: ButtonText;

      color: ButtonText;

      &:disabled { border-color: GrayText; color: GrayText; }

    }

    .sortable[data-over="end"] { outline-color: Highlight; }

  }

  /* -- Density ----------------------------------------------------

     data-density on the .sortable root scales the list gap and the item

     padding. comfortable == the unsized default. */

  .sortable:where([data-density="compact"]) {

    gap: 0.125rem;

    & .sortable-item { padding: 0.375rem 0.5rem; }

  }

  .sortable:where([data-density="comfortable"]) {

    gap: 0.25rem;

    & .sortable-item { padding: 0.5rem 0.75rem; }

  }

  .sortable:where([data-density="spacious"]) {

    gap: 0.375rem;

    & .sortable-item { padding: 0.625rem 1rem; }

  }

}

// -- Sortable -------------------------------------------------

// Drag-and-drop + keyboard reordering for sortable lists.

// Keyboard: Arrow keys navigate, Alt+Arrow reorders, Home/End jump.

// Move buttons (.sortable-move[data-move="up|down"]) reorder by tap/click -

// the path for touch screens, where native drag-and-drop mostly never starts.

// Connected lists (same data-group) exchange items: drag across, or

// Alt + the cross-axis arrow moves the focused item to the neighbouring list.

// Live region announces position changes to screen readers.

// Named-state API (AGENTS.md "State API"): the list's observable state is

// its item order + active item, so 'default' restores the authored order

// (optional { index } activates one item) and getState() reports both live.

// Shared preamble (AGENTS.md "State API"); the implementation lives in core.js —

// build.ts rewrites this import into a df$.shadcn.shared binding in dist/.

// defussQuery: the callable runtime - order restoration moves existing nodes

// through query .append(), drops/reorders through query .before()/.after(),

// and drag/active flags ride query scalar writes (§3 sortable row: native

// moves already keep identity; the shared adapter is the win, no morph).

import { defussGlobals, defussQuery } from '../../shared/state-api.js';

const df$ = defussGlobals();

const dfDollar = defussQuery();

const sortableStates = ['default'];

/**

 * The one drag in flight on this document: the picked-up item and the list it

 * left. Transient pointer (set on dragstart, cleared on dragend) - shared at

 * module level because a drop into a CONNECTED list is handled by that list,

 * not the one the drag started in. Never state: the State API stays per list.

 */

let drag: { item: HTMLElement; from: HTMLElement } | null = null;

const sortableLabels = (list) =>

  dfDollar(list)

    .find('.sortable-item')

    .map((item: HTMLElement) => dfDollar(item).find('span:not(.sortable-handle):not(.sortable-moves)').text().trim());

/**

 * UI side of setState: 'default' restores the authored order snapshot (taken

 * at init) and optionally activates the item at config.index.

 */

function triggerStateChange(list, stateName, config) {

  if (stateName !== 'default') return;

  // one query move of the existing nodes in snapshot order (§3: .append on

  // one parent - nodes are MOVED, never re-created, handlers survive)

  dfDollar(list).append(list._defaultOrder ?? []);

  list._syncMoves?.();

  if (config?.index !== undefined) {

    const item = dfDollar(list).find('.sortable-item')[Number(config.index)];

    list._setActive?.(item);

  }

}

/** Registry-level API; pass the list element explicitly. Unknown names throw. */

export const sortableApi = {

  setState(list, stateName, config = {}) {

    if (!sortableStates.includes(stateName)) {

      throw new Error(`sortable: unknown state "${stateName}" (supported: ${sortableStates.join(', ')})`);

    }

    triggerStateChange(list, stateName, config);

    // state lives on the ELEMENT, not the module (many lists per page)

    list.dataset.stateName = stateName;

    list._stateConfig = config;

  },

  getState(list) {

    const items = Array.from(dfDollar(list).find('.sortable-item'));

    const active = dfDollar(list).find('.sortable-item[data-active]')[0];

    return {

      name: list.dataset.stateName || 'default',

      config: {

        ...list._stateConfig,

        order: sortableLabels(list),

        activeIndex: active ? items.indexOf(active) : -1,

      },

    };

  },

};

df$.sortableApi = sortableApi;

df$.sortableStates = sortableStates;

function init() {

document.querySelectorAll('.sortable:not([data-init])').forEach((list) => {

  list.dataset.init = '';

  // bind-scope the api per instance: `$('#tasks').api.setState('default')`

  list.api = {

    setState: (stateName, config) => sortableApi.setState(list, stateName, config),

    getState: () => sortableApi.getState(list),

  };

  const isHorizontal = list.dataset.orientation === 'horizontal';

  const NEXT_KEY = isHorizontal ? 'ArrowRight' : 'ArrowDown';

  const PREV_KEY = isHorizontal ? 'ArrowLeft' : 'ArrowUp';

  // connected lists sit side by side (vertical) or stacked (horizontal):

  // the cross-axis arrows step between them

  const NEXT_LIST_KEY = isHorizontal ? 'ArrowDown' : 'ArrowRight';

  const PREV_LIST_KEY = isHorizontal ? 'ArrowUp' : 'ArrowLeft';

  // -- Live region for announcements --

  // Look only at the node directly after the list (where init inserts it): a

  // parent-wide query would hand sibling lists the same region, so one list

  // would announce through a region anchored to the other list.

  let liveRegion = list.nextElementSibling;

  if (!liveRegion || !liveRegion.classList.contains('sortable-live')) {

    liveRegion = document.createElement('span');

    liveRegion.className = 'sortable-live';

    liveRegion.setAttribute('aria-live', 'assertive');

    liveRegion.setAttribute('role', 'status');

    // mount right after the list (§5.1: query's exact .after(), one branch)

    dfDollar(list).after(liveRegion);

  }

  function announce(msg) {

    // double write re-triggers the live region for repeated identical messages

    dfDollar(liveRegion).text('');

    requestAnimationFrame(() => { dfDollar(liveRegion).text(msg); });

  }

  function getItems() {

    return Array.from(dfDollar(list).find('.sortable-item:not([aria-disabled="true"])'));

  }

  function getAllItems() {

    return Array.from(dfDollar(list).find('.sortable-item'));

  }

  const isLocked = (el) => el.getAttribute('aria-disabled') === 'true';

  const listName = () => list.getAttribute('aria-label') || 'the list';

  /**

   * Why: a locked item (aria-disabled="true") is a fixed SLOT, not just an

   * item you can't pick up - it keeps its position while the others move

   * around it, so a locked row in the middle stays a stable divider (the

   * groups above and below keep their size). Moves are therefore expressed

   * as "take this item to slot t": if t is locked, the item continues to the

   * next free slot in its direction of travel (or, at the list's edge, the

   * nearest free slot back); the movable items then refill the free slots in

   * order around the untouched locked ones. One query .append() of the final

   * order moves the existing nodes (identity + handlers survive).

   * Returns the slot the item landed in, or -1 for a no-op.

   */

  function place(item, target) {

    const all = getAllItems();

    const from = all.indexOf(item);

    const n = all.length;

    const fixed = all.map(isLocked);

    const t = Math.max(0, Math.min(n - 1, target));

    const dir = t < from ? -1 : 1;

    let slot = t;

    while (slot >= 0 && slot < n && fixed[slot]) slot += dir;

    if (slot < 0 || slot >= n) {

      slot = t;

      while (slot >= 0 && slot < n && fixed[slot]) slot -= dir;

    }

    if (slot < 0 || slot >= n || slot === from) return -1;

    const movable = all.filter((el) => !isLocked(el) && el !== item);

    // the item becomes the k-th free slot; the rest fill the others in order

    const k = fixed.slice(0, slot).filter((f) => !f).length;

    movable.splice(k, 0, item);

    let m = 0;

    dfDollar(list).append(all.map((el, i) => (fixed[i] ? el : movable[m++])));

    return slot;

  }

  /**

   * Move buttons: Up is disabled where the item has no free slot before it,

   * Down where it has none after it (locked slots don't count - place() steps

   * over them). Unlabelled buttons get "Move {item} up/down".

   */

  function syncMoves() {

    const all = getAllItems();

    const free = all.map((el) => !isLocked(el));

    all.forEach((item, i) => {

      const label = getItemLabel(item);

      dfDollar(item).find('.sortable-move').each(function (this: HTMLButtonElement) {

        const up = this.dataset.move === 'up';

        const room = up ? free.slice(0, i).some(Boolean) : free.slice(i + 1).some(Boolean);

        dfDollar(this).prop('disabled', isLocked(item) || !room);

        if (!this.hasAttribute('aria-label') || this.dataset.autoLabel !== undefined) {

          dfDollar(this).attr('aria-label', `Move ${label} ${up ? 'up' : 'down'}`).data('autoLabel', '');

        }

      });

    });

  }

  list._syncMoves = syncMoves;

  /** announce + activate + sortable-change after a move (index = slot in the full list). */

  function moved(item, slot, focus = true) {

    const n = getAllItems().length;

    announce(`${getItemLabel(item)}, moved to position ${slot + 1} of ${n}`);

    setActive(item, focus);

    syncMoves();

    list.dispatchEvent(new CustomEvent('sortable-change', {

      bubbles: true,

      detail: { item, index: slot }

    }));

  }

  /**

   * Take an item from a connected list and insert it at `index` (clamped;

   * past the end = append). The receiving list owns the follow-up: roving

   * tabindex, move buttons, announcement and both lists' sortable-change

   * (`detail.from` here, `detail.to` on the list it left).

   */

  function receive(item, index, from, focus = true) {

    const all = getAllItems();

    const before = all[Math.max(0, index)];

    if (before) dfDollar(before).before(item);

    else dfDollar(list).append(item);

    const slot = getAllItems().indexOf(item);

    announce(`${getItemLabel(item)}, moved to ${listName()}, position ${slot + 1} of ${getAllItems().length}`);

    setActive(item, focus);

    syncMoves();

    from._released?.(item);

    list.dispatchEvent(new CustomEvent('sortable-change', {

      bubbles: true,

      detail: { item, index: slot, from }

    }));

  }

  list._receive = receive;

  /** The list an item just left: repair roving tabindex + buttons, report it. */

  list._released = (item) => {

    const items = getItems();

    if (items.length && !items.some((el) => el.getAttribute('tabindex') === '0')) {

      dfDollar(items[0]).attr('tabindex', '0');

    }

    if (!items.length) list.removeAttribute('data-active-index');

    syncMoves();

    list.dispatchEvent(new CustomEvent('sortable-change', {

      bubbles: true,

      detail: { item, index: -1, to: item.closest('.sortable') }

    }));

  };

  /** Lists this one exchanges items with (same data-group), document order. */

  const groupLists = () => {

    const group = list.dataset.group;

    return group

      ? Array.from(document.querySelectorAll('.sortable[data-group]')).filter((l) => (l as HTMLElement).dataset.group === group)

      : [list];

  };

  function getActiveItem() {

    return dfDollar(list).find('.sortable-item[data-active]')[0];

  }

  function setActive(item, focus = true) {

    // active flag + roving tabindex through query scalars

    getAllItems().forEach((el) => { dfDollar(el).data('active', null).attr('tabindex', '-1'); });

    if (item) {

      dfDollar(item).data('active', '').attr('tabindex', '0');

      // mirror the active position onto the LIST root - the schema's

      // activeIndex observation reads one stable attribute instead of

      // scanning children (and survives item reorder/moves)

      list.dataset.activeIndex = String(getItems().indexOf(item));

      if (focus) item.focus(); // native focus protocol stays native

    } else {

      list.removeAttribute('data-active-index');

    }

  }

  // expose for the State API (element member, not module scope)

  list._setActive = setActive;

  // authored-order snapshot for setState('default')

  list._defaultOrder = getAllItems();

  function getItemLabel(item) {

    const clone = item.cloneNode(true);

    clone.querySelectorAll('.sortable-handle, .sortable-moves, .sortable-move').forEach((el) => el.remove());

    return clone.textContent.trim();

  }

  // -- Initialize tabindex + move buttons --

  const allItems = getAllItems();

  allItems.forEach((item, i) => {

    dfDollar(item).attr('tabindex', i === 0 ? '0' : '-1');

  });

  syncMoves();

  // -- Drag and drop (delegated on the list, so an item that arrives from a

  //    connected list is draggable here without re-binding) --

  const accepts = () =>

    !!drag && (drag.from === list || (!!list.dataset.group && list.dataset.group === drag.from.dataset.group));

  const clearOver = () => {

    dfDollar(list).find('[data-over]').data('over', null);

    dfDollar(list).data('over', null);

  };

  list.addEventListener('dragstart', (e) => {

    const item = (e.target as HTMLElement).closest?.('.sortable-item') as HTMLElement | null;

    if (!item || !list.contains(item) || isLocked(item)) return;

    drag = { item, from: list };

    dfDollar(item).data('dragging', '');

    e.dataTransfer.effectAllowed = 'move';

    e.dataTransfer.setData('text/plain', '');

  });

  list.addEventListener('dragend', () => {

    if (drag) dfDollar(drag.item).data('dragging', null);

    groupLists().forEach((l) => {

      dfDollar(l).data('over', null);

      dfDollar(l).find('[data-over]').data('over', null);

    });

    drag = null;

  });

  list.addEventListener('dragover', (e) => {

    if (!accepts()) return;

    e.preventDefault();

    e.dataTransfer.dropEffect = 'move';

    const item = (e.target as HTMLElement).closest?.('.sortable-item') as HTMLElement | null;

    clearOver();

    if (item && list.contains(item)) {

      if (item === drag!.item) return;

      const rect = item.getBoundingClientRect();

      const midpoint = isHorizontal ? rect.left + rect.width / 2 : rect.top + rect.height / 2;

      const pos = isHorizontal ? e.clientX : e.clientY;

      dfDollar(item).data('over', pos < midpoint ? 'before' : 'after');

    } else {

      // over the list's own box (gap, padding, an empty list): drop at the end

      dfDollar(list).data('over', 'end');

    }

  });

  list.addEventListener('dragleave', (e) => {

    if (!list.contains(e.relatedTarget as Node)) clearOver();

  });

  list.addEventListener('drop', (e) => {

    if (!accepts()) return;

    e.preventDefault();

    const target = dfDollar(list).find('.sortable-item[data-over]')[0] as HTMLElement | undefined;

    const position = target ? dfDollar(target).data('over') : 'end';

    clearOver();

    const { item: dragged, from } = drag!;

    const all = getAllItems();

    if (from !== list) {

      // from a connected list: insert at the drop point

      const index = target ? all.indexOf(target) + (position === 'before' ? 0 : 1) : all.length;

      receive(dragged, index, from);

      return;

    }

    if (target === dragged) return;

    // the drop point as a slot in the full list (the dragged item's own

    // slot frees up first when it moves down), then a slot-preserving move

    const fromIndex = all.indexOf(dragged);

    let slotTarget = target ? all.indexOf(target) + (position === 'before' ? 0 : 1) : all.length;

    if (fromIndex < slotTarget) slotTarget -= 1;

    const slot = place(dragged, slotTarget);

    if (slot >= 0) moved(dragged, slot);

  });

  // -- Move buttons (tap / click reordering) --

  list.addEventListener('click', (e) => {

    const button = (e.target as HTMLElement).closest?.('.sortable-move') as HTMLButtonElement | null;

    if (!button || button.disabled || !list.contains(button)) return;

    const item = button.closest('.sortable-item') as HTMLElement;

    const from = getAllItems().indexOf(item);

    const slot = place(item, from + (button.dataset.move === 'up' ? -1 : 1));

    if (slot < 0) return;

    // keep focus on the pressed button so repeated taps keep moving the item;

    // at the list's edge the button disables itself - hand focus to its twin

    moved(item, slot, false);

    const target = button.disabled

      ? (item.querySelector(`.sortable-move[data-move="${button.dataset.move === 'up' ? 'down' : 'up'}"]`) as HTMLElement | null)

      : button;

    target?.focus();

  });

  // -- Keyboard navigation --

  list.addEventListener('keydown', (e) => {

    // keys pressed on a move button belong to the button (Enter / Space)

    if ((e.target as HTMLElement).closest?.('.sortable-move')) return;

    const active = getActiveItem() || dfDollar(list).find('.sortable-item[tabindex="0"]')[0];

    if (!active) return;

    const items = getItems();

    const idx = items.indexOf(active);

    // Arrow navigation

    if (e.key === NEXT_KEY && !e.altKey) {

      e.preventDefault();

      const next = items[idx + 1];

      if (next) setActive(next);

    } else if (e.key === PREV_KEY && !e.altKey) {

      e.preventDefault();

      const prev = items[idx - 1];

      if (prev) setActive(prev);

    } else if (e.key === 'Home') {

      e.preventDefault();

      if (items.length) setActive(items[0]);

    } else if (e.key === 'End') {

      e.preventDefault();

      if (items.length) setActive(items[items.length - 1]);

    // Alt+Arrow reorders by one slot - a locked slot is stepped around, never

    // displaced (see place())

    } else if ((e.key === NEXT_KEY || e.key === PREV_KEY) && e.altKey) {

      e.preventDefault();

      const from = getAllItems().indexOf(active);

      const slot = place(active, from + (e.key === NEXT_KEY ? 1 : -1));

      if (slot >= 0) moved(active, slot);

    // Alt + cross-axis arrow: move the item to the neighbouring connected list,

    // at the same position (clamped to its length)

    } else if ((e.key === NEXT_LIST_KEY || e.key === PREV_LIST_KEY) && e.altKey && list.dataset.group) {

      e.preventDefault();

      const lists = groupLists();

      const other = lists[lists.indexOf(list) + (e.key === NEXT_LIST_KEY ? 1 : -1)] as any;

      if (!other?._receive) return;

      other._receive(active, getAllItems().indexOf(active), list);

    }

  });

  // -- Focus management --

  list.addEventListener('focusin', (e) => {

    const target = e.target as HTMLElement;

    const item = target.closest('.sortable-item');

    if (!item || !list.contains(item)) return;

    // focus on a control INSIDE the item (a move button) marks the item

    // active but must not pull focus off that control

    setActive(item, target === item);

  });

});

}

init();

new MutationObserver(init).observe(document, { childList: true, subtree: true });