<?php
/**
 * Phone verification before checkout.
 *
 * @package Rahkar\WP
 */

declare( strict_types = 1 );

namespace Rahkar\WP\Modules\OtpAuth;

use Rahkar\WP\Support\InlineStyle;

defined( 'ABSPATH' ) || exit;

/**
 * Requires a verified phone number between the cart and the checkout form.
 *
 * Built on WooCommerce's own gate rather than a redirect to a separate page.
 * `form-checkout.php` already stops and shows a message when registration is
 * required but disabled and the visitor is not logged in — flipping those two
 * filters puts the login form in front of the checkout with the cart, the
 * session, and the coupon all untouched. A redirect to an intermediate page
 * would lose the checkout URL the customer was heading for and give caching
 * layers a new page to get wrong.
 *
 * Because the login module already injects the code panel into every login
 * form, the gate needs no form of its own. Pre-filling the billing phone with
 * the verified number is {@see PhonePrefill}'s job, not this one's: a customer
 * who signed in through the header popup should reach checkout with their
 * number filled in whether or not the gate is switched on.
 */
final class CheckoutGate {

	/**
	 * Register the gate.
	 */
	public function register(): void {
		// Nothing to do for a customer who is already signed in, and nothing to
		// gate when the cart is empty — WooCommerce redirects that away anyway.
		if ( is_user_logged_in() ) {
			return;
		}

		add_filter( 'woocommerce_checkout_registration_required', '__return_true', 99 );
		add_filter( 'woocommerce_checkout_registration_enabled', '__return_false', 99 );

		add_filter( 'woocommerce_checkout_must_be_logged_in_message', [ $this, 'message' ], 99 );

		// `checkout/form-login.php` returns without printing anything unless the
		// store has "login reminder at checkout" switched on — which most have
		// not, since it is off by default. Without this the gate would show its
		// message above an empty space, which is exactly what it did the first
		// time it ran on a real store.
		//
		// The option is filtered at read time rather than written to the database:
		// the gate needs the form on the checkout page, and has no business
		// changing a WooCommerce setting the shop owner did not touch.
		add_filter( 'option_woocommerce_enable_checkout_login_reminder', [ $this, 'forceLoginReminder' ], 99 );

		// WooCommerce's own callback renders a "Returning customer? Click here to
		// login" toggle with the form collapsed behind it. That is right for an
		// optional login reminder and wrong for a gate: the customer *must* sign
		// in to go any further, so hiding the only way forward behind a link is
		// pure friction. It is replaced rather than supplemented.
		remove_action( 'woocommerce_before_checkout_form', 'woocommerce_checkout_login_form', 10 );

		add_action( 'woocommerce_before_checkout_form', [ $this, 'renderForm' ], 5 );
	}

	/**
	 * Force the checkout login form to render while the gate is active.
	 *
	 * @return string
	 *
	 * @internal Hooked callback.
	 */
	public function forceLoginReminder(): string {
		return 'yes';
	}

	/**
	 * Suppress the line WooCommerce prints where the checkout form would have been.
	 *
	 * Returns an empty string rather than being left unhooked: without the filter
	 * WooCommerce falls back to its own "You must be logged in to checkout", in
	 * English, which is worse than nothing.
	 *
	 * Nothing belongs there. The text renders *below* the login form, detached
	 * from it, and repeats what the form's own heading already says — so it read
	 * as an orphaned sentence at the bottom of the page rather than as
	 * instructions.
	 *
	 * @internal Hooked callback.
	 */
	public function message(): string {
		return '';
	}

	/**
	 * Render the login form above the checkout.
	 *
	 * @internal Hooked callback.
	 */
	public function renderForm(): void {
		if ( is_user_logged_in() || ! function_exists( 'woocommerce_login_form' ) ) {
			return;
		}

		// The gate's whole purpose is proving a phone number, so the code panel
		// opens straight away here regardless of the site-wide default. A gate
		// that opened on a password form the customer cannot use — because they
		// have no account yet — would be a dead end.
		LoginPanel::forceOpen();

		// A visible heading, because the form is now the page's only content and
		// arriving at a bare input with no explanation is disorienting.
		printf(
			'<h3 class="rahkar-gate__title">%s</h3>',
			esc_html__( 'ورود به حساب کاربری', 'rahkar-toolkit' )
		);

		echo '<div class="rahkar-gate">';

		// `woocommerce_login_form()` rather than `woocommerce_checkout_login_form()`:
		// the former renders the form itself, the latter wraps it in the collapsed
		// "click here to login" toggle that was just removed.
		//
		// Going through WooCommerce's function rather than printing markup here is
		// what keeps this theme-agnostic — it resolves `global/form-login.php`
		// through the template hierarchy, so Woodmart renders the Woodmart form, a
		// different theme renders its own, and a theme with no override gets
		// WooCommerce's default. The code panel arrives inside all of them through
		// the standard `woocommerce_login_form_start` action.
		woocommerce_login_form(
			[
				'redirect' => wc_get_checkout_url(),
				'hidden'   => false,
			]
		);

		echo '</div>';

		$this->printGateStyles();
	}

	/**
	 * Styles that undo the theme's collapsed-form treatment.
	 *
	 * Woodmart stamps `hidden-form` onto its login form whenever `is_checkout()`
	 * is true, because it expects the form to sit behind WooCommerce's toggle.
	 * With the toggle gone the class would leave the gate showing nothing at all,
	 * so it is overridden — scoped to the gate wrapper, so every other login form
	 * on the site keeps the behaviour the theme intended.
	 *
	 * Inline and tiny: this has to apply before first paint, and loading a
	 * stylesheet for six rules would cost a request on the one page where the
	 * customer is closest to buying.
	 */
	private function printGateStyles(): void {
		?>
		<?php ob_start(); ?>
		.rahkar-gate .hidden-form{display:block!important}
		.rahkar-gate form.login{max-width:420px;margin:0 auto}
		.rahkar-gate__title{margin:0 0 18px;text-align:center}
		.woocommerce-form-login-toggle{display:none}
		<?php InlineStyle::printBuffered( 'rahkar-gate-css' ); ?>
		<?php
	}
}