import { isAbsolute, join, normalize } from 'node:path';
import { db } from 'officerdb/db';
import { eq } from 'drizzle-orm';
import { getOwnerHomeDir } from '@@/data-path';
import { fofosAdminSettings } from '../db/schema';

/**
 * Administration's settings — currently one, where the fofos site is on this machine.
 *
 * ── The default is COMPUTED, not written ──
 *
 * No row means `<owner home>/fofos`, worked out on every read. The alternative — writing the default
 * in at install — freezes whatever the home directory was on the day the plugin was installed, and a
 * restore onto a machine with a different owner then points at a directory that does not exist while
 * looking deliberately chosen. Computed, it follows the machine; written, it follows the install.
 *
 * A saved path is a DECISION and is stored exactly as given. Only the absence of one is derived — and
 * once saved it stays saved: there is no route back to the default, because "reset this to something
 * you never chose" is not a thing anybody asked for and it read as a second, quieter Save.
 *
 * ── Absolute, always ──
 *
 * `~` is expanded here and never stored. It means "whoever is asking", and the people asking are not
 * all the same person: this plugin is grantable, and the site is in one place regardless of who is
 * looking at it. Storing the tilde would give every user a different answer to a question that has
 * one.
 */

export type SettingsView = {
  /** Absolute. Never null — an unset root reports its default rather than nothing. */
  rootPath: string;
  /**
   * The same place, relative to the owner's home, with a leading slash.
   *
   * The file browser addresses everything relative to a root — `home` — so a panel embedding it needs
   * this form and cannot work it out: only the server knows what home is, and a browser computing it
   * from the absolute path would be guessing at a prefix.
   *
   * Null when the root is outside home. That is a legitimate configuration — the root may be anywhere
   * absolute — and it means the embedded browser cannot show it, which the panel says rather than
   * rendering an empty folder.
   */
  rootRelative: string | null;
  /** False while the default is standing in, so a form can show it as a suggestion, not a choice. */
  isSet: boolean;
};

const row = async () => {
  const rows = await db.select().from(fofosAdminSettings).limit(1);
  return rows[0] ?? null;
};

/** `<owner home>/fofos`. The owner's, not the caller's — see the note on absoluteness above. */
export const defaultRootPath = (email: string): string => join(getOwnerHomeDir(email), 'fofos');

export async function readSettings(email: string): Promise<SettingsView> {
  const found = await row();
  const stored = found?.rootPath ?? null;
  const rootPath = stored ?? defaultRootPath(email);

  // `home` or a path beneath it — anything else is outside what the file browser can address.
  const home = getOwnerHomeDir(email);
  const inside = rootPath === home || rootPath.startsWith(`${home}/`);

  return {
    rootPath,
    rootRelative: inside ? `/${rootPath.slice(home.length).replace(/^\/+/, '')}`.replace(/\/$/, '') || '/' : null,
    isSet: stored !== null,
  };
}

/**
 * Expand `~`, normalise, and refuse anything that is still not absolute.
 *
 * Refuses rather than resolving against a working directory: a relative path here would be resolved
 * against whatever `process.cwd()` happened to be, which is the platform's checkout — a silently wrong
 * answer that only shows up as an empty listing much later.
 */
export function normaliseRootPath(input: string, email: string): string {
  const trimmed = input.trim();
  if (!trimmed) throw new Error('A path is required.');

  const home = getOwnerHomeDir(email);
  const expanded = trimmed === '~' ? home : trimmed.startsWith('~/') ? join(home, trimmed.slice(2)) : trimmed;

  if (!isAbsolute(expanded)) throw new Error('The root location must be an absolute path.');

  // No trailing slash, so two spellings of the same directory cannot be stored as different values.
  const cleaned = normalize(expanded).replace(/\/+$/, '');
  return cleaned === '' ? '/' : cleaned;
}

export async function saveRootPath(input: string, email: string): Promise<SettingsView> {
  const rootPath = normaliseRootPath(input, email);
  const existing = await row();

  if (existing) {
    await db
      .update(fofosAdminSettings)
      .set({ rootPath, updatedAt: new Date() })
      .where(eq(fofosAdminSettings.id, existing.id));
  } else {
    await db.insert(fofosAdminSettings).values({ rootPath });
  }

  return readSettings(email);
}