import { homedir } from "os";
import { join } from "path";
import { mkdir } from "fs/promises";

const CONFIG_DIR = join(homedir(), ".config", "tangled");
const CONFIG_PATH = join(CONFIG_DIR, "config.json");

export interface Account {
  handle: string;
  did: string;
  pds: string;
  accessJwt: string;
  refreshJwt: string;
}

export interface Config {
  current: string | null;
  accounts: Record<string, Account>;
  recentKnots: string[];
}

const EMPTY: Config = { current: null, accounts: {}, recentKnots: [] };

export async function loadConfig(): Promise<Config> {
  const f = Bun.file(CONFIG_PATH);
  if (!(await f.exists())) return structuredClone(EMPTY);
  try {
    const data = await f.json();
    return { ...EMPTY, ...data };
  } catch {
    return structuredClone(EMPTY);
  }
}

export async function saveConfig(cfg: Config): Promise<void> {
  await mkdir(CONFIG_DIR, { recursive: true, mode: 0o700 });
  await Bun.write(CONFIG_PATH, JSON.stringify(cfg, null, 2));
  await Bun.$`chmod 600 ${CONFIG_PATH}`.quiet();
}

export async function setCurrent(did: string): Promise<void> {
  const cfg = await loadConfig();
  if (!cfg.accounts[did]) throw new Error(`no account for ${did}`);
  cfg.current = did;
  await saveConfig(cfg);
}

export async function upsertAccount(account: Account): Promise<void> {
  const cfg = await loadConfig();
  cfg.accounts[account.did] = account;
  cfg.current = account.did;
  await saveConfig(cfg);
}

export async function removeAccount(did: string): Promise<void> {
  const cfg = await loadConfig();
  delete cfg.accounts[did];
  if (cfg.current === did) {
    const remaining = Object.keys(cfg.accounts);
    cfg.current = remaining[0] ?? null;
  }
  await saveConfig(cfg);
}

export async function getCurrentAccount(): Promise<Account | null> {
  const cfg = await loadConfig();
  if (!cfg.current) return null;
  return cfg.accounts[cfg.current] ?? null;
}

export async function requireCurrentAccount(): Promise<Account> {
  const a = await getCurrentAccount();
  if (!a) throw new Error("not logged in — run `tangle auth login <handle>`");
  return a;
}

export async function findAccountByHandle(handle: string): Promise<Account | null> {
  const cfg = await loadConfig();
  const normalized = handle.replace(/^@/, "").toLowerCase();
  for (const a of Object.values(cfg.accounts)) {
    if (a.handle.toLowerCase() === normalized) return a;
  }
  return null;
}

export async function rememberKnot(host: string): Promise<void> {
  const cfg = await loadConfig();
  cfg.recentKnots = [host, ...cfg.recentKnots.filter((k) => k !== host)].slice(0, 10);
  await saveConfig(cfg);
}

export async function updateTokens(did: string, accessJwt: string, refreshJwt: string): Promise<void> {
  const cfg = await loadConfig();
  const a = cfg.accounts[did];
  if (!a) return;
  a.accessJwt = accessJwt;
  a.refreshJwt = refreshJwt;
  await saveConfig(cfg);
}