import { json, error } from '@sveltejs/kit';
import type { RequestHandler } from './$types';
import { createUser, mergeSessionProgress, createUserSession } from '$lib/server/pocketbase';
import { createAuthToken } from '../../../../hooks.server';
import { log } from '$lib/server/logger';
import { randomBytes } from 'node:crypto';

const AUTH_COOKIE = 'libnovel_auth';
const ONE_YEAR = 60 * 60 * 24 * 365;

/**
 * POST /api/auth/register
 * Body: { username: string, password: string }
 * Returns: { token: string, user: { id, username, role } }
 *
 * Sets the libnovel_auth cookie and returns the raw token value so the
 * iOS app can persist it for subsequent requests.
 */
export const POST: RequestHandler = async ({ request, cookies, locals }) => {
	let body: { username?: string; password?: string };
	try {
		body = await request.json();
	} catch {
		error(400, 'Invalid JSON body');
	}

	const username = (body.username ?? '').trim();
	const password = body.password ?? '';

	if (!username || !password) {
		error(400, 'Username and password are required');
	}
	if (username.length < 3 || username.length > 32) {
		error(400, 'Username must be between 3 and 32 characters');
	}
	if (!/^[a-zA-Z0-9_-]+$/.test(username)) {
		error(400, 'Username may only contain letters, numbers, underscores and hyphens');
	}
	if (password.length < 8) {
		error(400, 'Password must be at least 8 characters');
	}

	let user;
	try {
		user = await createUser(username, password);
	} catch (e: unknown) {
		const msg = e instanceof Error ? e.message : 'Registration failed.';
		if (msg.includes('Username already taken')) {
			error(409, 'That username is already taken');
		}
		log.error('api/auth/register', 'unexpected error', { username, err: String(e) });
		error(500, 'An error occurred. Please try again.');
	}

	// Merge anonymous session progress (non-fatal)
	mergeSessionProgress(locals.sessionId, user.id).catch((e) =>
		log.warn('api/auth/register', 'mergeSessionProgress failed (non-fatal)', { err: String(e) })
	);

	const authSessionId = randomBytes(16).toString('hex');

	const userAgent = request.headers.get('user-agent') ?? '';
	const ip =
		request.headers.get('x-forwarded-for')?.split(',')[0]?.trim() ??
		request.headers.get('x-real-ip') ??
		'';
	createUserSession(user.id, authSessionId, userAgent, ip).catch((e) =>
		log.warn('api/auth/register', 'createUserSession failed (non-fatal)', { err: String(e) })
	);

	const token = createAuthToken(user.id, user.username, user.role ?? 'user', authSessionId);

	cookies.set(AUTH_COOKIE, token, {
		path: '/',
		httpOnly: true,
		sameSite: 'lax',
		maxAge: ONE_YEAR
	});

	return json({
		token,
		user: { id: user.id, username: user.username, role: user.role ?? 'user' }
	});
};