import { uuidv7 } from '../api';

const KEY = 'albedo.shell-attempts.v1';
export interface ShellAttempt { session: string; id: string; command: string; at: number }

function read(): ShellAttempt[] {
  let raw: string | null;
  try { raw = localStorage.getItem(KEY); }
  catch (error) { throw new Error(`browser storage is unavailable: ${(error as Error).message ?? error}`); }
  if (raw === null) return [];
  let value: unknown;
  try { value = JSON.parse(raw); }
  catch { throw new Error('saved shell retry identity is corrupt; refusing to run a new command'); }
  if (!Array.isArray(value) || !value.every((item) => typeof item?.session === 'string' && typeof item?.id === 'string' && typeof item?.command === 'string' && Number.isFinite(item?.at))) {
    throw new Error('saved shell retry identity is invalid; refusing to run a new command');
  }
  return value;
}

/** A pending shell intent is durable before its first PUT, so uncertain retries keep the same identity. */
export function pendingShell(session: string, command: string): ShellAttempt {
  const all = read();
  const prior = all.find((item) => item.session === session && item.command === command);
  if (prior) return prior;
  if (all.length >= 32) throw new Error('too many unresolved shell retry identities; resolve one before running another');
  const attempt = { session, id: uuidv7(), command, at: Date.now() };
  try { localStorage.setItem(KEY, JSON.stringify([...all, attempt])); }
  catch (error) { throw new Error(`couldn't save shell retry identity: ${(error as Error).message ?? error}`); }
  return attempt;
}

/** Removes only after an authoritative server record was read or admitted. */
export function resolveShell(attempt: ShellAttempt): void {
  const rest = read().filter((item) => item.session !== attempt.session || item.id !== attempt.id);
  try {
    if (rest.length) localStorage.setItem(KEY, JSON.stringify(rest));
    else localStorage.removeItem(KEY);
  } catch (error) { throw new Error(`couldn't clear resolved shell retry identity: ${(error as Error).message ?? error}`); }
}