import type { SessionState } from "../shared/types";

const DOWNLOAD_SELECTION_PRESERVE_SELECTOR = ".downloads-package-card, .downloads-item-row, .downloads-selection-cell, .package-card, .ctx-menu, .modal-backdrop, .modal-card";

export function shouldClearDownloadSelection(target: Pick<Element, "closest">): boolean {
  return !target.closest(DOWNLOAD_SELECTION_PRESERVE_SELECTOR);
}

export function shouldClearDownloadSelectionOnEscape(tagName: string, inputType = ""): boolean {
  const normalizedTag = tagName.toUpperCase();
  if (normalizedTag === "TEXTAREA") return false;
  if (normalizedTag !== "INPUT") return true;
  return ["checkbox", "radio", "button"].includes(inputType.toLowerCase());
}

export function resolveEscapeSelectionScope(
  view: string,
  settingsSection: string,
  tagName: string,
  inputType = ""
): "downloads" | "collector" | "history" | "accounts" | null {
  if (!shouldClearDownloadSelectionOnEscape(tagName, inputType)) {
    return null;
  }
  if (view === "downloads" || view === "history" || view === "collector") {
    return view;
  }
  return view === "settings" && settingsSection === "accounts" ? "accounts" : null;
}

export function releaseAccountSelectionFocus(
  activeElement: { closest: (selector: string) => unknown; blur: () => void } | null
): boolean {
  if (!activeElement?.closest(".settings-account-row")) {
    return false;
  }
  activeElement.blur();
  return true;
}

/**
 * Drop selected ids whose package OR item no longer exists in the session.
 * The selection set mixes package and item ids; when entries vanish (delta
 * removal, backup-driven session swap, completed-cleanup) a stale id would
 * otherwise inflate the selection count and the "(N)" action labels and keep
 * "multi" styling alive for ghosts.
 *
 * Returns the SAME set instance when nothing changed, so callers can use it
 * directly as a React state updater without forcing a re-render.
 */
export function pruneSelection(
  selected: ReadonlySet<string>,
  session: Pick<SessionState, "packages" | "items">
): Set<string> {
  if (selected.size === 0) {
    return selected as Set<string>;
  }
  const next = new Set<string>();
  for (const id of selected) {
    if (session.packages[id] || session.items[id]) {
      next.add(id);
    }
  }
  return next.size === selected.size ? (selected as Set<string>) : next;
}