<?php

declare( strict_types=1 );

namespace AcezSeo\Rewrite;

use AcezSeo\Data\GlobalSettingsRepositoryInterface;

if ( ! defined( 'ABSPATH' ) )
{
	exit;
}

/**
 * Removes the "/category/" prefix from category archive URLs. Opt-in
 * (disabled by default): changing URL structure is disruptive for a site
 * already indexed by search engines, so this only activates when a site
 * owner explicitly enables it in the Global settings tab. Old
 * "/category/slug/" URLs 301-redirect to the new short URL so nothing breaks.
 *
 * Standard, widely-used approach (same technique as the historical "No
 * Category Base" plugin): rebuild the category rewrite rules without the
 * base, and redirect the old base URL pattern to the new one.
 */
final class NoCategoryBase
{
	private GlobalSettingsRepositoryInterface $global_settings;

	public function __construct( GlobalSettingsRepositoryInterface $global_settings )
	{
		$this->global_settings = $global_settings;
	}

	public function register(): void
	{
		// Rewrite rules must be flushed whenever this setting is toggled on or
		// off, not just when it's currently on — otherwise turning it off
		// leaves the short URLs active until something else triggers a flush.
		add_action( 'update_option_acez_seo_global_settings', 'flush_rewrite_rules' );

		if ( ! $this->is_enabled() )
		{
			return;
		}

		add_filter( 'category_rewrite_rules', array( $this, 'rewrite_rules' ) );
		add_filter( 'query_vars', array( $this, 'add_query_var' ) );
		add_action( 'template_redirect', array( $this, 'redirect_old_urls' ) );
	}

	private function is_enabled(): bool
	{
		return (bool) ( $this->global_settings->get()['no_category_base'] ?? false );
	}

	/**
	 * @param array<string, string> $category_rewrite
	 *
	 * @return array<string, string>
	 */
	public function rewrite_rules( array $category_rewrite ): array
	{
		$category_rewrite = array();
		$categories       = get_categories( array( 'hide_empty' => false ) );

		foreach ( $categories as $category )
		{
			$category_nicename = $category->slug;

			if ( $category->parent === $category->term_id )
			{
				$category->parent = 0;
			}
			elseif ( 0 !== $category->parent )
			{
				$category_nicename = get_category_parents( $category->parent, false, '/', true ) . $category_nicename;
			}

			$category_rewrite[ '(' . $category_nicename . ')/(?:feed/(feed|rdf|rss|rss2|atom)/?)?$' ] = 'index.php?category_name=$matches[1]&feed=$matches[2]';
			$category_rewrite[ '(' . $category_nicename . ')/(?:page/([0-9]{1,}))?/?$' ]              = 'index.php?category_name=$matches[1]&paged=$matches[2]';
		}

		// Keep old "/category/slug/" URLs working via a 301 redirect below.
		$old_base = trim( (string) get_option( 'category_base' ), '/' );
		$old_base = '' !== $old_base ? $old_base : 'category';

		$category_rewrite[ $old_base . '/(.+)$' ] = 'index.php?acez_seo_category_redirect=$matches[1]';

		return $category_rewrite;
	}

	/**
	 * @param string[] $vars
	 *
	 * @return string[]
	 */
	public function add_query_var( array $vars ): array
	{
		$vars[] = 'acez_seo_category_redirect';

		return $vars;
	}

	public function redirect_old_urls(): void
	{
		$redirect_to = get_query_var( 'acez_seo_category_redirect' );

		if ( ! is_string( $redirect_to ) || '' === $redirect_to )
		{
			return;
		}

		$target = trailingslashit( home_url() ) . user_trailingslashit( $redirect_to, 'category' );

		wp_safe_redirect( $target, 301 );
		exit;
	}
}