<?php
/**
 * Typed options access with per-module namespacing.
 *
 * @package AiRankSuite
 */

declare(strict_types=1);

namespace AiRankSuite\Support;

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

final class Options {

	/**
	 * Every option this plugin reads on a public page view.
	 *
	 * None of these are autoloaded, on purpose: a settings blob that most
	 * requests never touch has no business being in the query WordPress runs
	 * before it knows what page it is serving. The cost of that decision is one
	 * SELECT per option the moment a module *does* need it, and with sixteen
	 * modules hooked into wp_head that came to nineteen extra queries on every
	 * front-end request — a 40% increase over a bare WordPress on this site.
	 *
	 * Nineteen indexed single-row lookups are individually trivial and
	 * collectively the difference between a site that survives a traffic spike
	 * and one that does not, because they are nineteen round trips to a
	 * database that is usually on another machine. Priming them together turns
	 * that into one.
	 *
	 * A name missing from this list is not a bug — it falls back to its own
	 * lazy read, exactly as before. The list is an optimisation, never a
	 * contract.
	 *
	 * @return array<int, string>
	 */
	private static function primeable(): array {
		$names = array(
			// Settings blobs, one per module with a front-end surface.
			'airanksuite_ai_settings',
			'airanksuite_ai_visibility_settings',
			'airanksuite_analytics_settings',
			'airanksuite_audit_alerts_settings',
			'airanksuite_coexistence_settings',
			'airanksuite_core_settings',
			'airanksuite_crawler_controls_settings',
			'airanksuite_feeds_settings',
			'airanksuite_google_settings',
			'airanksuite_hardening_settings',
			'airanksuite_image_seo_settings',
			'airanksuite_indexnow_settings',
			'airanksuite_llms_txt_settings',
			'airanksuite_local_seo_settings',
			'airanksuite_redirects_settings',
			'airanksuite_reports_settings',
			'airanksuite_robots_settings',
			'airanksuite_schema_settings',
			'airanksuite_search_console_settings',
			'airanksuite_seo_settings',
			'airanksuite_sitemap_settings',
			'airanksuite_social_settings',
			'airanksuite_woocommerce_settings',
			// The schema version, and the key it was stored under up to 0.2.35:
			// Migrator::adopt_legacy() asks for both on every request.
			'airanksuite_db_version',
			'airs_db_version',
			// Bare options read outside the settings pattern.
			'airanksuite_disabled_modules',
			'airanksuite_snippets',
			'airanksuite_snippet_running',
			// Transients with fixed names. Without a persistent object cache a
			// transient is two option reads, so the ones the front end always
			// touches belong in this query too.
			'_transient_timeout_airanksuite_redirect_shape',
			'_transient_airanksuite_redirect_shape',
		);

		/**
		 * Filter the options primed in a single query on each request.
		 *
		 * @param array<int, string> $names Option names.
		 */
		return (array) apply_filters( 'airanksuite/options/prime', $names );
	}

	/**
	 * Fetch the whole set in one query and leave it in the object cache.
	 *
	 * Safe to call more than once — WordPress only queries the names it does
	 * not already have cached, so the second call costs nothing. Also safe on a
	 * site with a persistent object cache, where it usually costs nothing at
	 * all.
	 */
	public static function prime( bool $force = false ): void {
		static $done = false;
		if ( ! function_exists( 'wp_prime_option_caches' ) || ( $done && ! $force ) ) {
			return;
		}
		$done = true;
		wp_prime_option_caches( self::primeable() );
	}

	/**
	 * Read a module's settings merged over defaults.
	 *
	 * @param string               $module   Module id.
	 * @param array<string, mixed> $defaults Default values.
	 * @return array<string, mixed>
	 */
	public function get( string $module, array $defaults = array() ): array {
		$stored = get_option( "airanksuite_{$module}_settings", array() );
		if ( ! is_array( $stored ) ) {
			$stored = array();
		}
		return array_merge( $defaults, $stored );
	}

	/**
	 * Persist a module's settings (only known keys survive).
	 *
	 * @param string               $module   Module id.
	 * @param array<string, mixed> $values   New values.
	 * @param array<string, mixed> $defaults Allowed keys with defaults.
	 */
	public function set( string $module, array $values, array $defaults ): void {
		$clean   = array_intersect_key( $values, $defaults );
		$current = $this->get( $module, $defaults );
		$next    = array_merge( $current, $clean );
		update_option( "airanksuite_{$module}_settings", $next, false );

		/*
		 * A saved setting that nobody can see is not saved.
		 *
		 * Nearly every setting here changes what a visitor is served — a title
		 * template, a schema block, the robots line, the cookie banner. On a
		 * cached site the old page keeps being served until the cache is
		 * cleared, so the customer changes a setting, looks at the front end,
		 * sees no difference and concludes the plugin is broken.
		 *
		 * Only when something actually changed: saving a form without editing
		 * it should not throw away a site's whole page cache.
		 */
		if ( $next !== $current ) {
			Cache::purge();
		}
	}
}