// Which account the agent is logged in as (novox/hq ADR 0183): not in the token, but in the agent's
// own state file beside the home, `~/.claude.json` → `oauthAccount`. Read to attribute a login; written,
// three keys and nothing else, when a licence is switched, so the file Claude Code shows the account from
// names the account whose token it now holds (as the predecessor learned: two files that disagree make
// a later login look like the wrong account).

import { readFileSync, renameSync, writeFileSync } from "node:fs";

export interface Identity {
  readonly accountUuid: string;
  readonly emailAddress?: string;
  readonly organizationUuid?: string;
}

export function readIdentity(stateFile: string): Identity | null {
  try {
    const raw = JSON.parse(readFileSync(stateFile, "utf8")) as { oauthAccount?: Record<string, unknown> };
    const a = raw.oauthAccount;
    if (!a || typeof a.accountUuid !== "string") return null;
    return {
      accountUuid: a.accountUuid,
      emailAddress: typeof a.emailAddress === "string" ? a.emailAddress : undefined,
      organizationUuid: typeof a.organizationUuid === "string" ? a.organizationUuid : undefined,
    };
  } catch {
    return null;
  }
}

/**
 * Point the state file's account at `id`, keeping every other key as found. Returns whether the file
 * changed; a file that cannot be read as an object is left alone rather than replaced.
 */
export function writeIdentity(stateFile: string, id: Identity): boolean {
  let raw: Record<string, unknown>;
  try {
    raw = JSON.parse(readFileSync(stateFile, "utf8")) as Record<string, unknown>;
    if (!raw || typeof raw !== "object") return false;
  } catch {
    raw = {};
  }
  const current = (raw.oauthAccount ?? {}) as Record<string, unknown>;
  if (current.accountUuid === id.accountUuid && current.emailAddress === id.emailAddress
      && current.organizationUuid === id.organizationUuid) return false;
  raw.oauthAccount = { ...current, accountUuid: id.accountUuid, emailAddress: id.emailAddress, organizationUuid: id.organizationUuid };
  const tmp = `${stateFile}.mesh-tmp`;
  writeFileSync(tmp, JSON.stringify(raw, null, 2), { mode: 0o600 });
  renameSync(tmp, stateFile);
  return true;
}