/**
 * @file laneOrderStorage.ts
 * @description Persists the sidebar's user-chosen workspace order to
 * localStorage, the same read/validate/fallback convention as useTheme.ts, and
 * holds the drag-to-reorder math the sidebar and the console tab bar share
 * (the tab bar's own order lives with its tabs, `lib/paneLayout.ts`).
 *
 * The order lives in the browser rather than the lanes table on purpose: it is
 * a per-viewer preference, and nothing
 * server-side (the CLI's `agenthub lanes`, the pipeline-stats picker) has an
 * opinion about it. Ceiling: the order does not follow the user to another
 * browser or to the CLI — move it to a `lanes.sort_order` column if it ever
 * must.
 *
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const STORAGE_KEY = "agenthub.workspace.laneOrder";

export function readLaneOrder(): number[] {
  try {
    const raw = localStorage.getItem(STORAGE_KEY);
    if (!raw) return [];
    const parsed: unknown = JSON.parse(raw);
    if (!Array.isArray(parsed)) return [];
    return parsed.filter((id): id is number => typeof id === "number");
  } catch {
    return [];
  }
}

export function writeLaneOrder(ids: number[]): void {
  try {
    localStorage.setItem(STORAGE_KEY, JSON.stringify(ids));
  } catch {
    /* ignore quota / disabled storage */
  }
}

/**
 * Applies a stored id order to a freshly fetched lane list.
 *
 * Ids the stored order never saw — a lane created since, or created in another
 * tab — keep their server order (id ascending) and land at the END, so a new
 * lane appears predictably rather than wherever a stale index puts it. Stored
 * ids naming a lane that no longer exists are simply skipped.
 *
 * @param lanes Lanes in server order.
 * @param order Stored id order.
 * @returns A new array; the input is never mutated.
 */
export function sortByStoredOrder<T extends { id: number }>(lanes: T[], order: number[]): T[] {
  const rank = new Map(order.map((id, i) => [id, i]));
  const known = lanes
    .filter((l) => rank.has(l.id))
    .sort((a, b) => rank.get(a.id)! - rank.get(b.id)!);
  const fresh = lanes.filter((l) => !rank.has(l.id));
  return [...known, ...fresh];
}

/**
 * Moves the lane at `from` to index `to`, returning the resulting id order.
 * Out-of-range indices yield the unchanged order rather than a hole.
 */
export function moveLane(ids: number[], from: number, to: number): number[] {
  if (from === to || from < 0 || to < 0 || from >= ids.length || to >= ids.length) return ids;
  const next = [...ids];
  next.splice(to, 0, ...next.splice(from, 1));
  return next;
}

/** Where a drop lands: before the first item whose middle (`mids`, on the
 *  drag axis) lies past the pointer, else at the end. Gaps between items —
 *  a workspace's session list, the space between two tabs — count too. */
export function insertionIndex(mids: number[], pos: number): number {
  const i = mids.findIndex((m) => pos < m);
  return i === -1 ? mids.length : i;
}

/** Moves the item at `from` to just before insertion point `before`. */
export function moveBefore<T>(ids: T[], from: number, before: number): T[] {
  if (from < 0 || from >= ids.length || before < 0 || before > ids.length) return ids;
  if (before === from || before === from + 1) return ids;
  const next = [...ids];
  next.splice(before > from ? before - 1 : before, 0, ...next.splice(from, 1));
  return next;
}