<?php
/**
 * Storage for old URL paths.
 *
 * @package Adminkeep
 */

namespace Adminkeep\Service;

defined( 'ABSPATH' ) || exit;

/*
 * The only thing interpolated into SQL in this file is self::table(), which is $wpdb->prefix
 * followed by a literal — no caller can influence it. Table names cannot be passed as prepare()
 * placeholders, so there is no version of these queries that satisfies the sniff. Every value
 * that does come from outside is placeholdered.
 *
 * phpcs:disable WordPress.DB.PreparedSQL.NotPrepared
 * phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery
 * phpcs:disable WordPress.DB.DirectDatabaseQuery.NoCaching
 *
 * The schema-change warning is disabled for the same reason: creating and dropping this table is
 * this class's job, and uninstall depends on drop() actually dropping it.
 *
 * phpcs:disable WordPress.DB.DirectDatabaseQuery.SchemaChange
 */

/**
 * One table mapping a path a page used to answer on to the post that owns it now.
 *
 * WHY A TABLE AND NOT POST META.
 *
 * The lookup happens on a 404 — for a path, with no post in hand. Post meta is indexed on
 * meta_key only, so finding "which post used to live at about/team/jo" would mean scanning every
 * row carrying the key. A 404 handler runs on every miss, including bot traffic, so that scan is
 * the hot path on exactly the requests you least want to spend money on.
 *
 * The path is stored twice: hashed for the unique index, and readable for the settings screen.
 * The hash exists because a utf8mb4 VARCHAR(255) index overruns MySQL's key length on older
 * servers, and because equality is the only comparison ever needed.
 */
class PathRedirectStore {

	/**
	 * Schema version, bumped when the table changes.
	 */
	const SCHEMA_VERSION = 1;

	/**
	 * Option holding the installed schema version.
	 */
	const VERSION_OPTION = 'adminkeep_redirect_schema';

	/**
	 * Fully-qualified table name.
	 *
	 * @return string
	 */
	public static function table() {
		global $wpdb;

		return $wpdb->prefix . 'adminkeep_path_redirects';
	}

	/**
	 * Create the table if it is missing or out of date.
	 *
	 * Called lazily, the first time a redirect actually needs recording — a site that never
	 * enables this feature never gets the table.
	 *
	 * @return void
	 */
	public static function maybe_install() {
		if ( (int) get_option( self::VERSION_OPTION ) === self::SCHEMA_VERSION ) {
			return;
		}

		global $wpdb;

		require_once ABSPATH . 'wp-admin/includes/upgrade.php';

		$table   = self::table();
		$collate = $wpdb->get_charset_collate();

		dbDelta(
			"CREATE TABLE {$table} (
				id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
				path_hash char(40) NOT NULL,
				old_path varchar(255) NOT NULL,
				post_id bigint(20) unsigned NOT NULL,
				created_at datetime NOT NULL,
				PRIMARY KEY  (id),
				UNIQUE KEY path_hash (path_hash),
				KEY post_id (post_id)
			) {$collate};"
		);

		update_option( self::VERSION_OPTION, self::SCHEMA_VERSION, false );
	}

	/**
	 * Normalise a URL path into the form stored.
	 *
	 * Query strings, fragments, leading and trailing slashes and percent-encoding all vary
	 * between the request and what the site generates. Everything is reduced to "about/team".
	 *
	 * @param string $path Raw path.
	 * @return string
	 */
	public static function normalise( $path ) {
		$path = (string) $path;
		$path = explode( '#', $path )[0];
		$path = explode( '?', $path )[0];
		$path = rawurldecode( $path );

		return trim( $path, '/' );
	}

	/**
	 * Record that a post used to answer on a path.
	 *
	 * @param string $old_path Path the post used to live at.
	 * @param int    $post_id  Post that owns it.
	 * @return void
	 */
	public static function record( $old_path, $post_id ) {
		$old_path = self::normalise( $old_path );

		if ( '' === $old_path ) {
			return;
		}

		self::maybe_install();

		global $wpdb;

		$table = self::table();

		// A path can only ever belong to one post, and the newest claim wins: if two pages have
		// occupied this address over time, the one that just moved away from it is the one whose
		// inbound links are about to break.
		// This plugin's own table, so there is no core API for it; the name is $wpdb->prefix plus a
		// literal and every value is bound.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
		$wpdb->query(
			$wpdb->prepare(
				// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
				"INSERT INTO {$table} (path_hash, old_path, post_id, created_at)
				 VALUES (%s, %s, %d, %s)
				 ON DUPLICATE KEY UPDATE post_id = VALUES(post_id), created_at = VALUES(created_at)",
				sha1( $old_path ),
				$old_path,
				(int) $post_id,
				current_time( 'mysql', true )
			)
		);
	}

	/**
	 * The post that used to answer on a path.
	 *
	 * @param string $path Requested path.
	 * @return int|null
	 */
	public static function lookup( $path ) {
		$path = self::normalise( $path );

		if ( '' === $path || ! self::installed() ) {
			return null;
		}

		global $wpdb;

		$table = self::table();

		// Plugin-owned table; name is $wpdb->prefix plus a literal, the hash is bound. Runs only on
		// a 404, so caching a miss would keep serving the 404 after the redirect is recorded.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
		$post_id = $wpdb->get_var(
			$wpdb->prepare(
				// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
				"SELECT post_id FROM {$table} WHERE path_hash = %s LIMIT 1",
				sha1( $path )
			)
		);

		return null === $post_id ? null : (int) $post_id;
	}

	/**
	 * Forget a path.
	 *
	 * @param string $path Path to forget.
	 * @return void
	 */
	public static function forget( $path ) {
		$path = self::normalise( $path );

		if ( '' === $path || ! self::installed() ) {
			return;
		}

		global $wpdb;

		$wpdb->delete( self::table(), array( 'path_hash' => sha1( $path ) ), array( '%s' ) );
	}

	/**
	 * Forget every path belonging to a post.
	 *
	 * @param int $post_id Post id.
	 * @return void
	 */
	public static function forget_post( $post_id ) {
		if ( ! self::installed() ) {
			return;
		}

		global $wpdb;

		$wpdb->delete( self::table(), array( 'post_id' => (int) $post_id ), array( '%d' ) );
	}

	/**
	 * Delete one row by id.
	 *
	 * @param int $id Row id.
	 * @return void
	 */
	public static function delete( $id ) {
		if ( ! self::installed() ) {
			return;
		}

		global $wpdb;

		$wpdb->delete( self::table(), array( 'id' => (int) $id ), array( '%d' ) );
	}

	/**
	 * Recorded paths, newest first.
	 *
	 * @param int $limit Maximum rows.
	 * @return array[]
	 */
	public static function all( $limit = 100 ) {
		if ( ! self::installed() ) {
			return array();
		}

		global $wpdb;

		$table = self::table();

		// Plugin-owned table; name is $wpdb->prefix plus a literal, the limit is bound. Feeds the
		// settings screen, which must show what is stored right now.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
		return $wpdb->get_results(
			$wpdb->prepare(
				// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
				"SELECT id, old_path, post_id, created_at FROM {$table} ORDER BY id DESC LIMIT %d",
				(int) $limit
			),
			ARRAY_A
		);
	}

	/**
	 * How many paths are recorded.
	 *
	 * @return int
	 */
	public static function count() {
		if ( ! self::installed() ) {
			return 0;
		}

		global $wpdb;

		$table = self::table();

		// Plugin-owned table, no parameters at all; the name is $wpdb->prefix plus a literal.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
		return (int) $wpdb->get_var( "SELECT COUNT(*) FROM {$table}" );
	}

	/**
	 * Whether the table exists.
	 *
	 * @return bool
	 */
	public static function installed() {
		return (int) get_option( self::VERSION_OPTION ) === self::SCHEMA_VERSION;
	}

	/**
	 * Drop the table entirely. Used by uninstall.
	 *
	 * @return void
	 */
	public static function drop() {
		global $wpdb;

		$table = self::table();

		// Plugin-owned table being dropped on uninstall; DDL has no prepared form.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
		$wpdb->query( "DROP TABLE IF EXISTS {$table}" );

		delete_option( self::VERSION_OPTION );
	}
}