import fs from 'node:fs';
import path from 'node:path';
import os from 'node:os';
import { Identity } from '../shared/crypto.js';

const DIR = path.join(os.homedir(), '.keep');
const FILE = path.join(DIR, 'identity.json');

interface StoredIdentity {
  seedHex: string;
  // Assigned by whoever runs `keep recipient add` after registering this
  // identity's public key — not derivable from the keypair itself, so it
  // has to be stored once known via `keep identity set-id`.
  recipientId?: string;
}

function readStored(): StoredIdentity | null {
  if (!fs.existsSync(FILE)) return null;
  return JSON.parse(fs.readFileSync(FILE, 'utf8')) as StoredIdentity;
}

function writeStored(data: StoredIdentity): void {
  fs.mkdirSync(DIR, { recursive: true, mode: 0o700 });
  fs.writeFileSync(FILE, JSON.stringify(data, null, 2), { mode: 0o600 });
}

export async function loadOrCreateIdentity(): Promise<{ identity: Identity; recipientId: string | null; created: boolean }> {
  const stored = readStored();
  if (stored) {
    return { identity: await Identity.fromSeedHex(stored.seedHex), recipientId: stored.recipientId ?? null, created: false };
  }
  const identity = await Identity.generate();
  writeStored({ seedHex: identity.seedHex });
  return { identity, recipientId: null, created: true };
}

export function setRecipientId(recipientId: string): void {
  const stored = readStored();
  if (!stored) throw new Error("no local identity — run 'keep identity init' first");
  writeStored({ ...stored, recipientId });
}

export async function requireIdentityAndRecipientId(): Promise<{ identity: Identity; recipientId: string }> {
  const stored = readStored();
  if (!stored) throw new Error("no local identity — run 'keep identity init' first");
  if (!stored.recipientId) {
    throw new Error(
      "this identity has no recipient id set yet — after an admin registers your public key " +
      "('keep identity show' to get it), run 'keep identity set-id <recipient-id>' with the id they give you back",
    );
  }
  return { identity: await Identity.fromSeedHex(stored.seedHex), recipientId: stored.recipientId };
}