import type { LayoutNode } from 'officerdev';

/*
  Two columns, with the navigation stacked into the left one.

  ── Why it changed from three ──

  It was `16 / 34 / 50`: a category column, a commander column, and the transcript. So half the screen was
  navigation for a list that holds a handful of commanders — one, on the machine this was written on — while
  the only thing anybody reads got the other half. A category pane of its own is a filter for a list short
  enough to see whole.

  Now: commanders on top, categories beneath them, transcript taking three quarters.

  ── Why the categories are BELOW the commanders ──

  Because the commanders are the thing you came for and the categories are how you narrow them when there
  are too many to scan. Above, the filter would push the list down the screen and be the first thing read;
  below, the list is at the top where a list belongs and the filter is where you reach for it. It also means
  the categories can grow their own scrollbar without ever taking room from the commanders.
*/
export const defaultLayout: LayoutNode = {
  type: 'group',
  id: 'command-hq-root',
  direction: 'horizontal',
  children: [
    {
      node: {
        type: 'group',
        id: 'command-hq-nav',
        direction: 'vertical',
        children: [
          { node: { type: 'panel', id: 'command-hq-grid', appType: 'command-hq-grid' }, size: 62 },
          { node: { type: 'panel', id: 'command-hq-categories', appType: 'command-hq-categories' }, size: 38 },
        ],
      },
      size: 24,
    },
    { node: { type: 'panel', id: 'command-hq-detail', appType: 'command-hq-detail' }, size: 76 },
  ],
};

/**
 * Is this a saved copy of the three-column layout this replaced?
 *
 * No appType was retired — all three panels survive and only their arrangement changed — so `hasAppType`
 * cannot see this the way the /chat migration could. The test is structural instead: the old shape is a
 * horizontal root with THREE children, and the new one has two.
 *
 * It terminates for that reason: the replacement does not satisfy the test.
 *
 * Replacing outright is safe because the screen is `locked` — its structure is dictated by code, and the
 * only thing a person can have contributed is the column sizes, which is a cheap thing to lose once. The
 * same reasoning, and the same warning, as `ChatHistory/index.tsx`: get the test backwards and a stranded
 * panel collapses onto `appTypes.fallback` and is written back, which is how /offscale once rendered three
 * copies of one picker.
 */
export function isLegacyThreeColumn(node: LayoutNode): boolean {
  return node.type === 'group' && node.direction === 'horizontal' && node.children.length === 3;
}