import * as crypto from 'crypto';
import * as dotenv from 'dotenv';
import logger from '../../middleware/logger.js';

dotenv.config();

/**
 * One place that reads the admin module's environment. Both admin.auth.ts
 * (better-auth trustedOrigins, passkey origins) and app.ts (CORS) need the
 * same origin list, and a second parser would drift from this one.
 *
 * Read this before changing the environment handling below: several security
 * properties depend on it, and they are deliberately arranged to fail *safe*.
 *
 * `NODE_ENV` is opt-in to relaxed behaviour, not opt-in to strict behaviour.
 * Only the explicit values 'development' and 'test' relax anything; anything
 * else - including NODE_ENV being unset, which is exactly what a fresh Plesk
 * vhost gives you - is treated as production. The inverse arrangement is a
 * trap: it degrades the cookie domain, the CORS origin list and the signing
 * key all at once, and every one of those failures is silent.
 *
 * The signing key is never allowed to be a known constant. In dev, an unset
 * BETTER_AUTH_SECRET becomes a random per-process value: sessions do not
 * survive a restart, which is mildly annoying and much better than a default
 * secret that can be copied out of this file and used against production.
 */

const nodeEnv = process.env.NODE_ENV;

// Explicitly relaxed environments. Everything else, unset included, is strict.
const isRelaxedEnv = nodeEnv === 'development' || nodeEnv === 'test';

export const isProd = !isRelaxedEnv;

const required = (name: string, devDefault: string): string => {
	const value = process.env[name];
	if (value) {
		return value;
	}
	if (isProd) {
		logger.error(
			`Admin module: ${name} is not set (NODE_ENV=${nodeEnv ?? 'unset'}, so strict mode applies; ` +
			'set NODE_ENV=development for local work)'
		);
		throw new Error(`${name} must be set unless NODE_ENV is development or test`);
	}
	return devDefault;
};

export const API_BASE_URL = required('API_BASE_URL', 'http://localhost:3000');
export const ADMIN_APP_URL = required('ADMIN_APP_URL', 'http://localhost:3002');

// 32+ random bytes; better-auth signs cookies and reset tokens with it.
// Rotating it invalidates every session, which is why it is not derived.
// There is no hardcoded fallback on purpose: a constant committed here would
// be a published signing key the moment someone deploys without setting it.
export const BETTER_AUTH_SECRET = required(
	'BETTER_AUTH_SECRET',
	crypto.randomBytes(48).toString('base64')
);

// Passkeys are bound to this: a credential registered for "nachklang.art"
// works on every *.nachklang.art host, one registered for "localhost" only
// works in dev. Changing it invalidates every registered passkey.
export const PASSKEY_RP_ID = process.env.PASSKEY_RP_ID || (isProd ? 'nachklang.art' : 'localhost');

const parseList = (value: string | undefined, fallback: string[]): string[] => {
	const parsed = (value || '')
		.split(',')
		.map(entry => entry.trim())
		.filter(entry => entry.length > 0);

	return parsed.length > 0 ? parsed : fallback;
};

// The apps whose frontends may talk to /admin/* with credentials.
export const APP_ORIGINS = parseList(process.env.APP_ORIGINS, []).map(origin => origin.replace(/\/$/, ''));

// Kept in sync by construction rather than by three separate lists: the admin
// app itself always counts, and dev adds the local ports.
export const ADMIN_ALLOWED_ORIGINS = Array.from(new Set([
	ADMIN_APP_URL.replace(/\/$/, ''),
	...APP_ORIGINS
]));

/**
 * The header the reverse proxy puts the real client IP in, and the proxy hops
 * to trust when reading it.
 *
 * This matters more than it looks. better-auth does not know about Express's
 * `trust proxy`; it reads the request itself. If it cannot resolve a client IP
 * it falls back to a single shared bucket ("no-trusted-ip") for the whole
 * process - and /sign-in/* carries a default of 3 requests per 10 seconds, so
 * one noisy client would lock every user out of every app.
 *
 * Without TRUSTED_PROXY_IPS, better-auth rejects a multi-value
 * x-forwarded-for outright (it cannot tell which hop is the client), which is
 * exactly the case that produces that shared bucket. Set it to the address or
 * CIDR of Plesk's nginx. Conversely, listing a header the proxy does not
 * overwrite lets a client set its own IP and mint itself an unlimited
 * brute-force budget - so the default is the single header nginx sets, not a
 * permissive list.
 */

/**
 * `CLIENT_IP_HEADERS=none` trusts no header at all.
 *
 * This is the escape hatch for the one case where the wrong setting is worse
 * than no setting: if the proxy turns out NOT to overwrite the header we are
 * trusting, any client can send it and mint itself an unlimited brute-force
 * budget against /sign-in. Falling back to the shared bucket is bad (one noisy
 * client can lock the organisation out for ten seconds at a time) but it is
 * bad in a way that fails closed, and it can be reverted from the environment
 * without a deploy.
 *
 * Reach for it only after a check has actually failed - `SELECT ipAddress FROM
 * session ORDER BY createdAt DESC` showing 127.0.0.1 or NULL for a real remote
 * sign-in - and take it back out once the header is configured.
 *
 * An empty or unset value still means "use the default", not "trust nothing":
 * a stray blank line in a .env must not silently change how requests are
 * bucketed. Only the explicit word does that.
 */
const TRUST_NO_HEADER = 'none';

export const TRUST_NO_CLIENT_IP_HEADER =
	(process.env.CLIENT_IP_HEADERS || '').trim().toLowerCase() === TRUST_NO_HEADER;

// An empty array is what better-auth reads as "no headers": it only falls back
// to its own default when the option is absent, and `[]` is truthy.
export const CLIENT_IP_HEADERS = TRUST_NO_CLIENT_IP_HEADER
	? []
	: parseList(process.env.CLIENT_IP_HEADERS, ['x-real-ip']);

export const TRUSTED_PROXY_IPS = parseList(process.env.TRUSTED_PROXY_IPS, []);

if (isProd && TRUST_NO_CLIENT_IP_HEADER) {
	logger.warn(
		'Admin module: CLIENT_IP_HEADERS=none - no client-IP header is trusted, so every ' +
		'request shares one rate-limit bucket and /sign-in allows 3 attempts per 10 seconds ' +
		'for everyone combined. This is the safe fallback, not a destination: configure the ' +
		'header the proxy actually sets and remove it.'
	);
} else if (isProd && TRUSTED_PROXY_IPS.length === 0) {
	logger.warn(
		'Admin module: TRUSTED_PROXY_IPS is not set. If the proxy sends a multi-value ' +
		`${CLIENT_IP_HEADERS.join('/')}, better-auth cannot resolve a client IP and every ` +
		'request shares one rate-limit bucket. Verify with: SELECT `key` FROM rateLimit - ' +
		'a "no-trusted-ip" row means this is happening. A single-value header needs no ' +
		'trusted proxies, so this warning is expected on a plain single-proxy setup.'
	);
}

export const ADMIN_BOOTSTRAP_EMAIL = process.env.ADMIN_BOOTSTRAP_EMAIL || '';

/**
 * Whether to write invitation links to the log. An invitation link is a live
 * account-creation credential, so this is an explicit opt-in rather than
 * something inferred from NODE_ENV: local work needs it (the mail relay is
 * usually off, and only the token's hash is stored, so there is otherwise no
 * way to walk the accept flow), and production must never have it.
 *
 * Refused outright in strict mode, so setting it in a production .env by
 * accident fails at boot instead of quietly filling the log with credentials.
 */
export const LOG_INVITE_LINKS = process.env.ADMIN_LOG_INVITE_LINKS === 'true' && !isProd;

if (process.env.ADMIN_LOG_INVITE_LINKS === 'true' && isProd) {
	logger.error('Admin module: ADMIN_LOG_INVITE_LINKS is set outside development - refusing to log invitation tokens');
}