<?php

namespace SpinupWp;

use SpinupWp\Cli\CacheCommands;
use WP_Post;

class Cache {

	/**
	 * @var AdminBar
	 */
	private $admin_bar;

	/**
	 * @var Cli
	 */
	private $cli;

	/**
	 * @var string
	 */
	private $cache_path;

	/**
	 * Cache constructor.
	 *
	 * @param AdminBar $admin_bar
	 */
	public function __construct( AdminBar $admin_bar, Cli $cli ) {
		$this->admin_bar = $admin_bar;
		$this->cli       = $cli;
	}

	/**
	 * Init
	 */
	public function init() {
		$this->set_cache_path();

		$this->cli->register_command( 'spinupwp cache', CacheCommands::class );

		add_action( 'init', array( $this, 'register_admin_bar_menu_items' ) );
		add_action( 'spinupwp_purge_object_cache', array( $this, 'purge_object_cache' ) );
		add_action( 'spinupwp_purge_page_cache', array( $this, 'purge_page_cache' ) );
		add_action( 'spinupwp_purge_url', array( $this, 'purge_url' ) );
		add_action( 'admin_init', array( $this, 'handle_manual_purge_action' ) );
		add_action( 'transition_post_status', array( $this, 'purge_post_on_update' ), 10, 3 );
		add_action( 'delete_post', array( $this, 'purge_post_on_delete' ), 10, 1 );
		add_action( 'switch_theme', array( $this, 'purge_page_cache' ) );
		add_action( 'comment_post', array( $this, 'purge_post_on_comment' ), 10, 2 );
		add_action( 'wp_set_comment_status', array( $this, 'purge_post_by_comment' ) );
		add_action( 'upgrader_process_complete', array( $this, 'purge_page_cache_on_shutdown' ) );
	}

	/**
	 * Register cache purge menu items in the admin bar.
	 *
	 * @return void
	 */
	public function register_admin_bar_menu_items() {
		if ( $this->is_object_cache_enabled() && $this->is_page_cache_enabled() ) {
			$this->admin_bar->add_item( __( 'Purge All Caches', 'spinupwp' ), 'purge-all' );
		}

		if ( $this->is_object_cache_enabled() ) {
			$this->admin_bar->add_item( __( 'Purge Object Cache', 'spinupwp' ), 'purge-object' );
		}

		if ( $this->is_page_cache_enabled() ) {
			$this->admin_bar->add_item( __( 'Purge Page Cache', 'spinupwp' ), 'purge-page' );
		}

		if ( $this->is_page_cache_enabled() && ! is_admin() ) {
			$this->admin_bar->add_item( __( 'Purge this URL', 'spinupwp' ), 'purge-url' );
		}
	}


	/**
	 * Handle manual purge actions.
	 */
	public function handle_manual_purge_action() {
		if ( ! current_user_can( apply_filters( 'spinupwp_purge_cache_capability', 'manage_options' ) ) ) {
			return;
		}

		$action = filter_input( INPUT_GET, 'spinupwp_action' );

		if ( ! $action || ! in_array( $action, array( 'purge-all', 'purge-object', 'purge-page', 'purge-url' ) ) ) {
			return;
		}

		if ( ! wp_verify_nonce( filter_input( INPUT_GET, '_wpnonce' ), $action ) ) {
			return;
		}

		if ( 'purge-all' === $action ) {
			$purge_object_cache = $this->purge_object_cache();
			$purge_page_cache   = $this->purge_page_cache();

			$purge = $purge_object_cache && $purge_page_cache;
			$type  = 'all';
		}

		if ( 'purge-object' === $action ) {
			$purge = $this->purge_object_cache();
			$type  = 'object';
		}

		if ( 'purge-page' === $action ) {
			$purge = $this->purge_page_cache();
			$type  = 'page';
		}

		if ( 'purge-url' === $action ) {
			$url   = $_SERVER['HTTP_REFERER'];
			$purge = $this->purge_url( $url );
			$type  = 'url';
		}

		$redirect_url = isset( $_SERVER['HTTP_REFERER'] ) ? $_SERVER['HTTP_REFERER'] : admin_url();

		wp_safe_redirect( add_query_arg( array(
			'purge_success' => (int) $purge,
			'cache_type'    => $type,
		), $redirect_url ) );
	}

	/**
	 * When a post is transitioned to 'publish' for the first time purge the
	 * entire site cache. This ensures blog pages, category archives, author archives,
	 * search results and the 'Latest Posts' footer section is accurate. Otherwise,
	 * only update the current post URL.
	 *
	 * @param string $new_status
	 * @param string $old_status
	 * @param WP_Post $post
	 *
	 * @return bool
	 */
	public function purge_post_on_update( $new_status, $old_status, $post ) {
		$post_type = get_post_type( $post );

		if ( ! in_array( $post_type, $this->get_public_post_types() ) ) {
			return false;
		}

		if ( in_array( $post_type, $this->get_post_types_excluded_from_purge() ) ) {
			return false;
		}

		if ( ! $this->should_purge_post_status( $new_status, $old_status ) ) {
			return false;
		}

		if ( $post_type === 'customize_changeset' && $new_status === 'trash' ) {
			return false;
		}

		if ( in_array( $post_type, $this->get_post_types_needing_single_purge() ) ) {
			return $this->purge_post( $post );
		}

		return $this->purge_page_cache();
	}

	/**
	 * Purge the entire cache when a post type is deleted.
	 *
	 * @param int $post_id
	 *
	 * @return bool
	 */
	public function purge_post_on_delete( $post_id ) {
		$post_type = get_post_type( $post_id );

		if ( ! in_array( $post_type, $this->get_public_post_types() ) ) {
			return false;
		}

		if ( in_array( $post_type, $this->get_post_types_excluded_from_purge() ) ) {
			return false;
		}

		$post_status = get_post_status( $post_id );

		if ( in_array( $post_status, array( 'auto-draft', 'draft', 'trash' ) ) ) {
			return false;
		}

		return $this->purge_page_cache();
	}

	/**
	 * Purge a post on new comment (if approved).
	 *
	 * @param int $comment_id
	 * @param bool $comment_approved
	 *
	 * @return bool
	 */
	public function purge_post_on_comment( $comment_id, $comment_approved ) {
		if ( ! $comment_approved ) {
			return false;
		}

		return $this->purge_post_by_comment( $comment_id );
	}

	/**
	 * Purge a post by comment ID.
	 *
	 * @param int $comment_id
	 *
	 * @return bool
	 */
	public function purge_post_by_comment( $comment_id ) {
		$comment = get_comment( $comment_id );

		if ( $comment && $comment->comment_post_ID ) {
			$post = get_post( $comment->comment_post_ID );

			return $this->purge_post( $post );
		}

		return false;
	}

	/**
	 * Purge the page cache on shutdown.
	 */
	public function purge_page_cache_on_shutdown() {
		add_action( 'shutdown', array( $this, 'purge_page_cache' ) );
	}

	/**
	 * Set the base cache path.
	 */
	private function set_cache_path() {
		if ( getenv( 'SPINUPWP_CACHE_PATH' ) ) {
			$this->cache_path = getenv( 'SPINUPWP_CACHE_PATH' );
		}

		if ( defined( 'SPINUPWP_CACHE_PATH' ) ) {
			$this->cache_path = SPINUPWP_CACHE_PATH;
		}
	}

	/**
	 * Is the object cache enabled?
	 *
	 * @return bool
	 */
	public function is_object_cache_enabled() {
		return wp_using_ext_object_cache();
	}

	/**
	 * Is the page cache enabled?
	 *
	 * @return bool
	 */
	public function is_page_cache_enabled() {
		return defined( 'SPINUPWP_CACHE_PATH' ) || getenv( 'SPINUPWP_CACHE_PATH' );
	}

	/**
	 * Purge entire object cache.
	 *
	 * @return bool
	 */
	public function purge_object_cache() {
		return wp_cache_flush();
	}

	/**
	 * Purge entire cache.
	 *
	 * @return bool
	 */
	public function purge_page_cache() {
		$result = $this->delete( $this->cache_path, true );

		do_action( 'spinupwp_site_purged', $result );

		return $result;
	}

	/**
	 * Purge the current post URL.
	 *
	 * @param WP_Post $post
	 *
	 * @return bool
	 */
	public function purge_post( $post ) {
		$result = $this->purge_url( get_permalink( $post ) );

		do_action( 'spinupwp_post_purged', $post, $result );

		return $result;
	}

	/**
	 * Purge a single URL from the cache.
	 *
	 * @param string $url
	 *
	 * @return bool
	 */
	public function purge_url( $url ) {
		$cache_paths = $this->get_cache_paths_for_url( $url );

		$all_deleted = true;
		foreach ( $cache_paths as $path ) {
			$deleted = $this->delete( $path );
			do_action( 'spinupwp_url_purged', $url, $deleted );
			$all_deleted &= $deleted;
		}

		return $all_deleted;
	}

	/**
	 * Gets the cache file paths for a given URL.
	 *
	 * Must be using the default Nginx cache options (levels=1:2)
	 * https://www.digitalocean.com/community/tutorials/how-to-setup-fastcgi-caching-with-nginx-on-your-vps#purging-the-cache
	 *
	 * @param string $url
	 *
	 * @return array
	 */
	private function get_cache_paths_for_url( $url ) {
		$cache_keys = $this->get_cache_keys_for_url( $url );

		$cache_paths = array();
		foreach ( $cache_keys as $key ) {
			$hashed_key    = md5( $key );
			$path          = substr( $hashed_key, - 1 ) . '/' . substr( $hashed_key, - 3, 2 ) . '/' . $hashed_key;
			$cache_paths[] = trailingslashit( $this->cache_path ) . $path;
		}

		return $cache_paths;
	}

	/**
	 * Gets the cache keys for a given URL.
	 *
	 * It defaults to a single key: (fastcgi_cache_key "$scheme$request_method$host$request_uri"),
	 * but it can be modified with spinupwp_cache_key_components filter.
	 * This must match the Nginx configuration.
	 *
	 * @param string $url
	 *
	 * @return array
	 */
	private function get_cache_keys_for_url( $url ) {
		$parsed_url = parse_url( $url );

		$cache_keys = array(
			$parsed_url['scheme'] . 'GET' . $parsed_url['host'] . trailingslashit( $parsed_url['path'] ),
			$parsed_url['scheme'] . 'GET' . $parsed_url['host'] . untrailingslashit( $parsed_url['path'] ),
		);

		// Allow the cache keys to be modified
		$cache_keys = apply_filters( 'spinupwp_cache_keys_for_url', $cache_keys, $url );

		return $cache_keys;
	}

	/**
	 * Delete a file/dir from the local filesystem.
	 *
	 * @param string $path Absolute path to file
	 * @param bool $recursive
	 *
	 * @return bool
	 */
	private function delete( $path, $recursive = false ) {
		if ( null !== $path && file_exists( $path ) && is_writable( $path ) ) {
			require_once( ABSPATH . '/wp-admin/includes/file.php' );

			$context = $path;
			if ( is_file( $path ) ) {
				$context = dirname( $path );
			}

			if ( ! WP_Filesystem( false, $context, true ) ) {
				return false;
			}

			global $wp_filesystem;
			$wp_filesystem->delete( $path, $recursive );

			return true;
		}

		return $this->delete_via_cache_daemon( $path );
	}

	/**
	 * Use SpinupWP daemon to purge cache.
	 *
	 * @param string $path
	 *
	 * @return bool
	 */
	private function delete_via_cache_daemon( $path ) {
		$fp = @fsockopen( '127.0.0.1', '7836' );

		if ( $fp ) {
			fwrite( $fp, $path . "\n" );

			$result = fread( $fp, 512 );
			fclose( $fp );

			return (bool) preg_match( '/^Purge:\sSuccess/', $result );
		}

		return false;
	}

	/**
	 * Should a post be purged based on the new/old status.
	 *
	 * @param string $new_status
	 * @param string $old_status
	 *
	 * @return bool
	 */
	private function should_purge_post_status( $new_status, $old_status ) {
		// A newly created post with no content
		if ( $new_status === 'auto-draft' ) {
			return false;
		}

		// A post in draft status
		if ( $new_status === 'draft' && in_array( $old_status, array( 'auto-draft', 'draft', 'trash' ) ) ) {
			return false;
		}

		// A post in trash status
		if ( $new_status === 'trash' && in_array( $old_status, array( 'auto-draft', 'draft', 'trash' ) ) ) {
			return false;
		}

		return apply_filters( 'spinupwp_should_purge_post_status', true );
	}

	/**
	 * Get public post types that should trigger a cache purge.
	 *
	 * @return array
	 */
	private function get_public_post_types() {
		$post_types = get_post_types( [
			'public' => true,
		] );

		return apply_filters( 'spinupwp_public_post_types', $post_types );
	}

	/**
	 * Get post types that should only purge their own public facing URL.
	 *
	 * @return array
	 */
	private function get_post_types_needing_single_purge() {
		return apply_filters( 'spinupwp_post_types_needing_single_purge', array() );
	}

	/**
	 * Get post types that should never trigger a cache purge.
	 *
	 * @return array
	 */
	private function get_post_types_excluded_from_purge() {
		return apply_filters( 'spinupwp_post_types_excluded_from_purge', array(
			'attachment',
			'custom_css',
			'revision',
			'user_request'
		) );
	}
}