<?php
/**
 * WooCommerce address field integration.
 *
 * @package Rahkar\WP
 */

declare( strict_types = 1 );

namespace Rahkar\WP\Modules\IranLocations;

use Rahkar\WP\Support\Settings;

defined( 'ABSPATH' ) || exit;

/**
 * Turns WooCommerce's free-text city field into a province-aware dropdown.
 *
 * Only ever constructed on a request that actually renders or processes an
 * address form — the module registers lazy callables, so a product page never
 * loads this class.
 */
final class CheckoutFields {

	/**
	 * Marks that the city selector's assets are needed on this page.
	 *
	 * @var bool
	 */
	private static bool $needsAssets = false;

	/**
	 * Turn the city field into a select on the classic checkout and account pages.
	 *
	 * The field keeps its `billing_city` / `shipping_city` name and stays a plain
	 * string, so everything downstream — emails, invoices, exports, shipping
	 * plugins — sees exactly what it saw before.
	 *
	 * @param array<string, array<string, mixed>> $fields Address fields.
	 *
	 * @return array<string, array<string, mixed>>
	 *
	 * @internal Hooked callback.
	 */
	public function addressFields( array $fields ): array {
		if ( ! isset( $fields['city'] ) ) {
			return $fields;
		}

		self::$needsAssets = true;

		$fields['city']['type']     = 'select';
		$fields['city']['class']    = array_merge(
			(array) ( $fields['city']['class'] ?? [] ),
			[ 'rahkar-city-field' ]
		);
		$fields['city']['options']  = [ '' => __( 'ابتدا استان را انتخاب کنید', 'rahkar-toolkit' ) ];
		$fields['city']['required'] = (bool) Settings::get( IranLocationsModule::SLUG . '.city_required', true );

		// The city list depends on the selected state, so the state field has to
		// come first for the form to make sense when read top to bottom.
		if ( isset( $fields['state']['priority'], $fields['city']['priority'] )
			&& $fields['state']['priority'] > $fields['city']['priority'] ) {
			[ $fields['state']['priority'], $fields['city']['priority'] ] =
				[ $fields['city']['priority'], $fields['state']['priority'] ];
		}

		return $fields;
	}

	/**
	 * Seed the city select with the saved value.
	 *
	 * A select can only show an option it contains. Without this, returning to a
	 * saved address renders an empty city box and the customer has to re-pick a
	 * value they already chose.
	 *
	 * @param array<string, array<string, mixed>> $fields Checkout fields.
	 *
	 * @return array<string, array<string, mixed>>
	 *
	 * @internal Hooked callback.
	 */
	public function seedSavedCity( array $fields ): array {
		foreach ( [ 'billing', 'shipping' ] as $group ) {
			$cityKey  = "{$group}_city";
			$stateKey = "{$group}_state";

			if ( ! isset( $fields[ $group ][ $cityKey ] ) ) {
				continue;
			}

			// The shipping block is hidden until the customer opts into a separate
			// delivery address. Seeding it regardless would put a second province's
			// worth of options — around 8KB — into every checkout page for a form
			// most customers never open. When they do open it, the script fills it.
			if ( 'shipping' === $group && ! $this->shippingAddressInUse() ) {
				continue;
			}

			$state = $this->currentValue( $stateKey );
			$city  = $this->currentValue( $cityKey );

			if ( '' === $state || ! LocationRepository::isProvince( $state ) ) {
				continue;
			}

			$options = [ '' => __( 'انتخاب شهر', 'rahkar-toolkit' ) ];

			foreach ( LocationRepository::cities( $state ) as $name ) {
				$options[ $name ] = $name;
			}

			// Keep an unrecognised saved value selectable rather than silently
			// discarding an address the customer entered before this module ran.
			if ( '' !== $city && ! isset( $options[ $city ] ) ) {
				$options[ $city ] = $city;
			}

			$fields[ $group ][ $cityKey ]['options'] = $options;

			// Tell the script which province these options belong to, so it can
			// skip re-fetching a list the page already carries.
			$fields[ $group ][ $cityKey ]['custom_attributes']['data-rahkar-province'] = $state;
		}

		return $fields;
	}

	/**
	 * Is the customer actually using a separate shipping address?
	 */
	private function shippingAddressInUse(): bool {
		if ( ! function_exists( 'WC' ) || ! WC()->cart ) {
			return false;
		}

		if ( ! WC()->cart->needs_shipping_address() ) {
			return false;
		}

		// phpcs:ignore WordPress.Security.NonceVerification.Missing -- Read-only hint for rendering; the value is re-validated on submit.
		if ( isset( $_POST['ship_to_different_address'] ) ) {
			return true;
		}

		return (bool) get_user_meta( get_current_user_id(), 'shipping_city', true );
	}

	/**
	 * Reject a city that does not belong to the selected province.
	 *
	 * The browser's selection is a suggestion; this is the check that counts.
	 *
	 * @param array<string, mixed> $data     Posted checkout data.
	 * @param \WP_Error            $errors   Error collector.
	 *
	 * @internal Hooked callback.
	 */
	public function validate( array $data, \WP_Error $errors ): void {
		if ( ! Settings::get( IranLocationsModule::SLUG . '.city_required', true ) ) {
			return;
		}

		$group = ! empty( $data['ship_to_different_address'] ) ? 'shipping' : 'billing';

		$country = (string) ( $data[ "{$group}_country" ] ?? '' );
		$state   = (string) ( $data[ "{$group}_state" ] ?? '' );
		$city    = (string) ( $data[ "{$group}_city" ] ?? '' );

		if ( 'IR' !== $country || '' === $state ) {
			return;
		}

		if ( '' === trim( $city ) ) {
			$errors->add( 'rahkar_city_required', __( 'لطفاً شهر را انتخاب کنید.', 'rahkar-toolkit' ) );

			return;
		}

		if ( ! LocationRepository::isValidCity( $state, $city ) ) {
			$errors->add(
				'rahkar_city_invalid',
				sprintf(
					/* translators: 1: city name, 2: province name */
					__( 'شهر «%1$s» در استان %2$s یافت نشد. لطفاً یکی از شهرهای فهرست را انتخاب کنید.', 'rahkar-toolkit' ),
					$city,
					LocationRepository::provinceName( $state )
				)
			);
		}
	}

	/**
	 * Load the city selector assets, on pages that render an address form only.
	 *
	 * @internal Hooked callback.
	 */
	public function enqueue(): void {
		if ( ! self::$needsAssets && ! $this->isAddressPage() ) {
			return;
		}

		$version = LocationRepository::datasetVersion();

		// `selectWoo` is WooCommerce's own select2 build, already enqueued on any
		// checkout page for the country and state fields. Declaring it as a
		// dependency downloads nothing extra — it only guarantees the library is
		// parsed before this script tries to enhance the city field with it, so
		// the two dropdowns end up looking and behaving identically.
		wp_enqueue_script(
			'rahkar-iran-cities',
			RAHKAR_WP_URL . 'assets/dist/iran-cities.js',
			[ 'jquery', 'selectWoo' ],
			RAHKAR_WP_VERSION,
			true
		);

		wp_add_inline_script(
			'rahkar-iran-cities',
			'window.rahkarCities=' . wp_json_encode(
				[
					// Static JSON served straight from disk — no PHP runs to
					// answer it, and the browser caches it across page views.
					'baseUrl'     => RAHKAR_WP_URL . 'assets/data/ir/',
					'version'     => $version,
					// Admin additions ride along inline. There are only ever a
					// handful, so this costs bytes measured in tens rather than
					// invalidating the static files.
					'custom'      => LocationRepository::allCustomCities(),
					'placeholder' => __( 'انتخاب شهر', 'rahkar-toolkit' ),
					'empty'       => __( 'ابتدا استان را انتخاب کنید', 'rahkar-toolkit' ),
				],
				JSON_UNESCAPED_UNICODE
			) . ';',
			'before'
		);
	}

	/**
	 * Does this page render an address form?
	 */
	private function isAddressPage(): bool {
		return function_exists( 'is_checkout' ) && ( is_checkout() || is_account_page() );
	}

	/**
	 * Read a field's current value from the customer session.
	 *
	 * @param string $key Field key, e.g. `billing_state`.
	 */
	private function currentValue( string $key ): string {
		if ( ! function_exists( 'WC' ) || ! WC()->checkout() ) {
			return '';
		}

		return (string) WC()->checkout()->get_value( $key );
	}
}