<?php
declare(strict_types=1);

namespace Unsupervised\Schedular\Auth;

use Unsupervised\Schedular\Val;

/**
 * The account lifecycle for a self-signup student, expressed entirely as user
 * meta so it lives alongside the WordPress user and needs no extra table.
 *
 * States (see {@see docs/features/account-registration.md}):
 * - Email unconfirmed — `us_awaiting_approval='1'`, no `us_email_confirmed`, a
 *   hashed confirmation token + expiry set. Login is blocked.
 * - Confirmed, awaiting approval — `us_awaiting_approval='1'`,
 *   `us_email_confirmed='1'`, token/expiry cleared. Login allowed but the
 *   booking capability is withheld.
 * - Approved / active — `us_awaiting_approval` deleted; a normal student.
 *
 * Invite- and admin-created students carry none of these metas, so they behave
 * exactly as before.
 */
class RegistrationStatus {

	public const META_AWAITING_APPROVAL = 'us_awaiting_approval';
	public const META_EMAIL_CONFIRMED   = 'us_email_confirmed';
	public const META_CONFIRM_TOKEN     = 'us_email_confirm_token';
	public const META_CONFIRM_EXPIRES   = 'us_email_confirm_expires';

	/**
	 * Set on accounts created via a group invite link: confirming the email
	 * approves the account immediately instead of queueing it for admin review.
	 */
	public const META_AUTO_APPROVE = 'us_auto_approve';

	/**
	 * Hours a self-signup email-confirmation link stays valid after the account
	 * is created. Limits the window in which a leaked link can be redeemed.
	 */
	public const EMAIL_CONFIRM_EXPIRY_HOURS = 48;

	/**
	 * Hash a raw confirmation token for storage and lookup. Only the hash is
	 * persisted (mirrors {@see Invite::hashToken()}), so a database leak cannot
	 * be used to confirm an account — the raw token exists only in the email.
	 */
	public static function hashToken( string $rawToken ): string {
		return hash( 'sha256', $rawToken );
	}

	/**
	 * Put a freshly created user into the pending state and issue an email
	 * confirmation token. Returns the raw token to embed in the emailed link.
	 * With `$autoApprove` (group invite links) confirming the email approves
	 * the account immediately — no admin review step.
	 */
	public static function markPending( int $userId, bool $autoApprove = false ): string {
		$rawToken = wp_generate_password( 32, false );

		update_user_meta( $userId, self::META_AWAITING_APPROVAL, '1' );
		update_user_meta( $userId, self::META_CONFIRM_TOKEN, self::hashToken( $rawToken ) );
		update_user_meta(
			$userId,
			self::META_CONFIRM_EXPIRES,
			gmdate( 'Y-m-d H:i:s', time() + self::EMAIL_CONFIRM_EXPIRY_HOURS * 3600 )
		);

		if ( $autoApprove ) {
			update_user_meta( $userId, self::META_AUTO_APPROVE, '1' );
		}

		return $rawToken;
	}

	/**
	 * Mark the account's email confirmed and discard the (now spent) token. The
	 * account stays awaiting approval.
	 */
	public static function confirmEmail( int $userId ): void {
		update_user_meta( $userId, self::META_EMAIL_CONFIRMED, '1' );
		delete_user_meta( $userId, self::META_CONFIRM_TOKEN );
		delete_user_meta( $userId, self::META_CONFIRM_EXPIRES );
	}

	/**
	 * Approve the account: clear the pending flag and any leftover token so the
	 * student becomes a normal, active student.
	 */
	public static function approve( int $userId ): void {
		delete_user_meta( $userId, self::META_AWAITING_APPROVAL );
		delete_user_meta( $userId, self::META_CONFIRM_TOKEN );
		delete_user_meta( $userId, self::META_CONFIRM_EXPIRES );
		delete_user_meta( $userId, self::META_AUTO_APPROVE );
	}

	public static function isAwaitingApproval( int $userId ): bool {
		return '1' === Val::string( get_user_meta( $userId, self::META_AWAITING_APPROVAL, true ) );
	}

	/**
	 * Whether confirming this account's email should approve it immediately
	 * (group invite link signups).
	 */
	public static function isAutoApprove( int $userId ): bool {
		return '1' === Val::string( get_user_meta( $userId, self::META_AUTO_APPROVE, true ) );
	}

	public static function emailConfirmed( int $userId ): bool {
		return '1' === Val::string( get_user_meta( $userId, self::META_EMAIL_CONFIRMED, true ) );
	}

	/**
	 * Find the user awaiting confirmation whose stored hash matches the supplied
	 * raw token, or null when none matches.
	 */
	public static function userIdForToken( string $rawToken ): ?int {
		if ( '' === $rawToken ) {
			return null;
		}

		$users = get_users(
			[
				'meta_key'   => self::META_CONFIRM_TOKEN, // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_key
				'meta_value' => self::hashToken( $rawToken ), // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_value
				'number'     => 1,
				'fields'     => 'ID',
			]
		);

		if ( [] === $users ) {
			return null;
		}

		return Val::int( $users[0] );
	}

	/**
	 * Whether the confirmation token for a user has passed its expiry, measured
	 * against the supplied `Y-m-d H:i:s` (UTC) timestamp. A user with no stored
	 * expiry is treated as expired (there is nothing valid to confirm).
	 */
	public static function isTokenExpired( int $userId, string $now ): bool {
		$expires = Val::string( get_user_meta( $userId, self::META_CONFIRM_EXPIRES, true ) );
		if ( '' === $expires ) {
			return true;
		}

		$expiresTs = strtotime( $expires );
		$nowTs     = strtotime( $now );
		if ( false === $expiresTs || false === $nowTs ) {
			return true;
		}

		return $nowTs > $expiresTs;
	}
}