<?php
/**
 * Generates and removes the must-use loader.
 *
 * @package Bloatwright
 */

namespace Bloatwright\Services;

/**
 * Writes the mu-loader/bloatwright-loader.php template into WPMU_PLUGIN_DIR as 0-bloatwright-loader.php,
 * with the plugin directory stamped in as a literal, so the loader never reads its include path from
 * the database.
 */
class LoaderInstaller {

	/**
	 * Target file name. WordPress loads must-use plugins in file-name order, so the leading "0-"
	 * makes the loader run before most other must-use plugins.
	 */
	const FILE = '0-bloatwright-loader.php';

	/**
	 * Target file name used before 1.0.0 shipped; removed on install/remove so an upgrade never
	 * leaves two loaders behind.
	 */
	const LEGACY_FILE = 'bloatwright-loader.php';

	/**
	 * Template file name inside the plugin's mu-loader directory.
	 */
	const TEMPLATE = 'bloatwright-loader.php';

	/**
	 * Option holding the stamped version, plugin path and template hash of the installed loader.
	 */
	const OPTION = 'bloatwright_loader';

	/**
	 * Placeholder replaced by the stamped plugin directory.
	 */
	const PLACEHOLDER = "'{{BLOATWRIGHT_PLUGIN_DIR}}'";

	/**
	 * Template path.
	 */
	public static function source(): string {
		return BLOATWRIGHT_DIR . 'mu-loader/' . self::TEMPLATE;
	}

	/**
	 * Target path.
	 */
	public static function target(): string {
		return trailingslashit( WPMU_PLUGIN_DIR ) . self::FILE;
	}

	/**
	 * Path of the loader under its pre-release name.
	 */
	public static function legacy_target(): string {
		return trailingslashit( WPMU_PLUGIN_DIR ) . self::LEGACY_FILE;
	}

	/**
	 * Plugin directory as stamped into the loader (no trailing slash).
	 */
	public static function plugin_dir(): string {
		return rtrim( wp_normalize_path( plugin_dir_path( BLOATWRIGHT_FILE ) ), '/' );
	}

	/**
	 * Loader file present (under its current or pre-release name)?
	 */
	public static function installed(): bool {
		return '' !== self::installed_path();
	}

	/**
	 * Path of the loader file actually present: the current name, else the pre-release name, else ''.
	 */
	public static function installed_path(): string {
		if ( is_file( self::target() ) ) {
			return self::target();
		}
		return is_file( self::legacy_target() ) ? self::legacy_target() : '';
	}

	/**
	 * Loader state for the admin screens: whether a loader file is present and where
	 * (loader_path: the file found, else where it will be written), where the next run writes it
	 * (loader_target), whether it is up to date (an out-of-date or pre-release loader is replaced by
	 * the next run), whether it can be written and the directory to make writable (loader_dir).
	 *
	 * @return array{loader:bool,loader_path:string,loader_target:string,loader_current:bool,loader_writable:bool,loader_dir:string}
	 */
	public static function status(): array {
		$path = self::installed_path();
		return array(
			'loader'          => '' !== $path,
			'loader_path'     => '' !== $path ? $path : self::target(),
			'loader_target'   => self::target(),
			'loader_current'  => self::current(),
			'loader_writable' => self::writable(),
			'loader_dir'      => self::display_path( WPMU_PLUGIN_DIR ),
		);
	}

	/**
	 * A path as shown in messages: relative to the WordPress folder when it is inside it (for
	 * example wp-content/mu-plugins), else absolute.
	 *
	 * @param string $path Absolute path.
	 */
	public static function display_path( string $path ): string {
		$path = rtrim( wp_normalize_path( $path ), '/' );
		$root = trailingslashit( \Bloatwright\Profiler\Paths::core() );
		return '/' !== $root && 0 === strpos( $path, $root ) && strlen( $path ) > strlen( $root ) ? substr( $path, strlen( $root ) ) : $path;
	}

	/**
	 * Loader present under its current name and generated by this version, for this plugin path,
	 * from the current template? A template change within one version (or a loader stamped before
	 * the hash was recorded) makes it stale, so the next run rewrites it.
	 */
	public static function current(): bool {
		if ( ! is_file( self::target() ) ) {
			return false;
		}
		$stamp = get_option( self::OPTION );
		return is_array( $stamp ) && ( $stamp['version'] ?? '' ) === BLOATWRIGHT_VERSION && ( $stamp['path'] ?? '' ) === self::plugin_dir() && ( $stamp['template'] ?? '' ) === self::template_hash();
	}

	/**
	 * Hash of the loader template ('' when it cannot be read).
	 */
	public static function template_hash(): string {
		$hash = is_readable( self::source() ) ? md5_file( self::source() ) : false;
		return is_string( $hash ) ? $hash : '';
	}

	/**
	 * Can the loader be written (or is it already there)?
	 */
	public static function writable(): bool {
		if ( is_file( self::target() ) ) {
			return wp_is_writable( self::target() );
		}
		return is_dir( WPMU_PLUGIN_DIR ) ? wp_is_writable( WPMU_PLUGIN_DIR ) : wp_is_writable( dirname( WPMU_PLUGIN_DIR ) );
	}

	/**
	 * Render the loader for a plugin directory (pure: no WordPress calls, usable before load).
	 *
	 * @param string $template Template contents.
	 * @param string $plugin_dir Plugin directory without trailing slash.
	 * @param string $version Plugin version for the header.
	 */
	public static function render( string $template, string $plugin_dir, string $version ): string {
		$header  = "<?php\n/**\n * Plugin Name: Bloatwright Loader\n * Description: Boots the Bloatwright profiler for signed profiling requests only. Generated and removed by the Bloatwright plugin.\n * Version: " . $version . "\n * Author: Emtiaz Zahid\n * License: GPL-2.0-or-later\n *\n * @package Bloatwright\n */\n";
		$body    = (string) preg_replace( '/^<\?php\s*\/\*\*.*?\*\/\s*/s', '', $template, 1 );
		$stamped = str_replace( self::PLACEHOLDER, var_export( $plugin_dir, true ), $body ); // phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_var_export -- quoted string literal for generated code.
		return $header . "\n" . $stamped;
	}

	/**
	 * Install or refresh (idempotent).
	 *
	 * @return true|\WP_Error
	 */
	public static function install() {
		global $wp_filesystem;
		if ( ! function_exists( 'WP_Filesystem' ) ) {
			require_once ABSPATH . 'wp-admin/includes/file.php';
		}
		$dir = self::display_path( WPMU_PLUGIN_DIR );
		if ( ! WP_Filesystem() || ! $wp_filesystem ) {
			/* translators: %s: must-use plugins directory, relative to the WordPress folder when inside it. */
			return new \WP_Error( 'bloatwright_loader_fs', sprintf( __( 'WordPress cannot write files directly on this host, so the profiler loader cannot be created in %s.', 'bloatwright' ), $dir ) );
		}
		if ( ! $wp_filesystem->is_dir( WPMU_PLUGIN_DIR ) && ! $wp_filesystem->mkdir( WPMU_PLUGIN_DIR, FS_CHMOD_DIR ) ) {
			/* translators: %s: must-use plugins directory, relative to the WordPress folder when inside it. */
			return new \WP_Error( 'bloatwright_loader_dir', sprintf( __( 'Could not create the must-use plugins directory %s. Create it, or make its parent directory writable, then try again.', 'bloatwright' ), $dir ) );
		}
		$template = $wp_filesystem->get_contents( self::source() );
		if ( ! is_string( $template ) || false === strpos( $template, self::PLACEHOLDER ) ) {
			return new \WP_Error( 'bloatwright_loader_template', __( 'Could not read the profiler loader template.', 'bloatwright' ) );
		}
		$content = self::render( $template, self::plugin_dir(), BLOATWRIGHT_VERSION );
		if ( ! $wp_filesystem->put_contents( self::target(), $content, FS_CHMOD_FILE ) ) {
			/* translators: 1: loader file, 2: must-use plugins directory (both relative to the WordPress folder when inside it). */
			return new \WP_Error( 'bloatwright_loader_write', sprintf( __( 'Could not write the profiler loader to %1$s. Make %2$s writable, then try again.', 'bloatwright' ), self::display_path( self::target() ), $dir ) );
		}
		self::remove_legacy();
		update_option(
			self::OPTION,
			array(
				'version'  => BLOATWRIGHT_VERSION,
				'path'     => self::plugin_dir(),
				'template' => md5( $template ),
			),
			false
		);
		return true;
	}

	/**
	 * Install only when missing or stale.
	 *
	 * @return true|\WP_Error
	 */
	public static function ensure() {
		return self::current() ? true : self::install();
	}

	/**
	 * Remove the loader and its stamp. Returns true when no loader is left behind.
	 */
	public static function remove(): bool {
		if ( is_file( self::target() ) ) {
			wp_delete_file( self::target() );
		}
		self::remove_legacy();
		delete_option( self::OPTION );
		return ! self::installed();
	}

	/**
	 * Delete a loader left under the pre-release file name.
	 */
	public static function remove_legacy(): void {
		if ( is_file( self::legacy_target() ) ) {
			wp_delete_file( self::legacy_target() );
		}
	}
}