<?php

/**

 * Canonical API to handle WordPress Redirecting

 *

 * Based on "Permalink Redirect" from Scott Yang and "Enforce www. Preference"

 * by Mark Jaquith

 *

 * @author Scott Yang

 * @author Mark Jaquith

 * @package WordPress

 * @since 2.3.0

 */

/**

 * Redirects incoming links to the proper URL based on the site url.

 *

 * Search engines consider www.somedomain.com and somedomain.com to be two

 * different URLs when they both go to the same location. This SEO enhancement

 * prevents penality for duplicate content by redirecting all incoming links to

 * one or the other.

 *

 * Prevents redirection for feeds, trackbacks, searches, comment popup, and

 * admin URLs. Does not redirect on IIS, page/post previews, and on form data.

 *

 * Will also attempt to find the correct link when a user enters a URL that does

 * not exist based on exact WordPress query. Will instead try to parse the URL

 * or query in an attempt to figure the correct page to go to.

 *

 * @since 2.3.0

 * @uses $wp_rewrite

 * @uses $is_IIS

 *

 * @param string $requested_url Optional. The URL that was requested, used to

 *		figure if redirect is needed.

 * @param bool $do_redirect Optional. Redirect to the new URL.

 * @return null|false|string Null, if redirect not needed. False, if redirect

 *		not needed or the string of the URL

 */

function redirect_canonical($requested_url=null, $do_redirect=true) {

	global $wp_rewrite, $is_IIS, $wp_query, $wpdb;

	if ( is_trackback() || is_search() || is_comments_popup() || is_admin() || $is_IIS || ( isset($_POST) && count($_POST) ) || is_preview() || is_robots() )

		return;

	if ( !$requested_url ) {

		// build the URL in the address bar

		$requested_url  = ( !empty($_SERVER['HTTPS'] ) && strtolower($_SERVER['HTTPS']) == 'on' ) ? 'https://' : 'http://';

		$requested_url .= $_SERVER['HTTP_HOST'];

		$requested_url .= $_SERVER['REQUEST_URI'];

	}

	$original = @parse_url($requested_url);

	if ( false === $original )

		return;

	// Some PHP setups turn requests for / into /index.php in REQUEST_URI

	// See: http://trac.wordpress.org/ticket/5017

	// See: http://trac.wordpress.org/ticket/7173

	// Disabled, for now:

	// $original['path'] = preg_replace('|/index\.php$|', '/', $original['path']);

	$redirect = $original;

	$redirect_url = false;

	// Notice fixing

	if ( !isset($redirect['path']) )  $redirect['path'] = '';

	if ( !isset($redirect['query']) ) $redirect['query'] = '';

	if ( is_singular() && 1 > $wp_query->post_count && ($id = get_query_var('p')) ) {

		$vars = $wpdb->get_results( $wpdb->prepare("SELECT post_type, post_parent FROM $wpdb->posts WHERE ID = %d", $id) );

		if ( isset($vars[0]) && $vars = $vars[0] ) {

			if ( 'revision' == $vars->post_type && $vars->post_parent > 0 )

				$id = $vars->post_parent;

			if ( $redirect_url = get_permalink($id) )

				$redirect['query'] = remove_query_arg(array('p', 'page_id', 'attachment_id'), $redirect['query']);

		}

	}

	// These tests give us a WP-generated permalink

	if ( is_404() ) {

		$redirect_url = redirect_guess_404_permalink();

	} elseif ( is_object($wp_rewrite) && $wp_rewrite->using_permalinks() ) {

		// rewriting of old ?p=X, ?m=2004, ?m=200401, ?m=20040101

		if ( is_single() && !empty($_GET['p']) && ! $redirect_url ) {

			if ( $redirect_url = get_permalink(get_query_var('p')) )

				$redirect['query'] = remove_query_arg('p', $redirect['query']);

			if ( get_query_var( 'page' ) ) {

				$redirect_url = trailingslashit( $redirect_url ) . user_trailingslashit( get_query_var( 'page' ), 'single_paged' );

				$redirect['query'] = remove_query_arg( 'page', $redirect['query'] );

			}

		} elseif ( is_page() && !empty($_GET['page_id']) && ! $redirect_url ) {

			if ( $redirect_url = get_permalink(get_query_var('page_id')) )

				$redirect['query'] = remove_query_arg('page_id', $redirect['query']);

		} elseif ( !empty($_GET['m']) && ( is_year() || is_month() || is_day() ) ) {

			$m = get_query_var('m');

			switch ( strlen($m) ) {

				case 4: // Yearly

					$redirect_url = get_year_link($m);

					break;

				case 6: // Monthly

					$redirect_url = get_month_link( substr($m, 0, 4), substr($m, 4, 2) );

					break;

				case 8: // Daily

					$redirect_url = get_day_link(substr($m, 0, 4), substr($m, 4, 2), substr($m, 6, 2));

					break;

			}

			if ( $redirect_url )

				$redirect['query'] = remove_query_arg('m', $redirect['query']);

		// now moving on to non ?m=X year/month/day links

		} elseif ( is_day() && get_query_var('year') && get_query_var('monthnum') && !empty($_GET['day']) ) {

			if ( $redirect_url = get_day_link(get_query_var('year'), get_query_var('monthnum'), get_query_var('day')) )

				$redirect['query'] = remove_query_arg(array('year', 'monthnum', 'day'), $redirect['query']);

		} elseif ( is_month() && get_query_var('year') && !empty($_GET['monthnum']) ) {

			if ( $redirect_url = get_month_link(get_query_var('year'), get_query_var('monthnum')) )

				$redirect['query'] = remove_query_arg(array('year', 'monthnum'), $redirect['query']);

		} elseif ( is_year() && !empty($_GET['year']) ) {

			if ( $redirect_url = get_year_link(get_query_var('year')) )

				$redirect['query'] = remove_query_arg('year', $redirect['query']);

		} elseif ( is_category() && !empty($_GET['cat']) && preg_match( '|^[0-9]+$|', $_GET['cat'] ) ) {

			if ( $redirect_url = get_category_link(get_query_var('cat')) )

				$redirect['query'] = remove_query_arg('cat', $redirect['query']);

		} elseif ( is_author() && !empty($_GET['author']) ) {

			$author = get_userdata(get_query_var('author'));

			if ( false !== $author && $redirect_url = get_author_posts_url($author->ID, $author->user_nicename) )

				$redirect['query'] = remove_query_arg('author', $redirect['author']);

		}

	// paging and feeds

		if ( get_query_var('paged') || is_feed() || get_query_var('cpage') ) {

			if ( !$redirect_url )

				$redirect_url = $requested_url;

			$paged_redirect = @parse_url($redirect_url);

			while ( preg_match( '#/page/[0-9]+?(/+)?$#', $paged_redirect['path'] ) || preg_match( '#/(comments/?)?(feed|rss|rdf|atom|rss2)(/+)?$#', $paged_redirect['path'] ) || preg_match( '#/comment-page-[0-9]+(/+)?$#', $paged_redirect['path'] ) ) {

				// Strip off paging and feed

				$paged_redirect['path'] = preg_replace('#/page/[0-9]+?(/+)?$#', '/', $paged_redirect['path']); // strip off any existing paging

				$paged_redirect['path'] = preg_replace('#/(comments/?)?(feed|rss2?|rdf|atom)(/+|$)#', '/', $paged_redirect['path']); // strip off feed endings

				$paged_redirect['path'] = preg_replace('#/comment-page-[0-9]+?(/+)?$#', '/', $paged_redirect['path']); // strip off any existing comment paging

			}

			$addl_path = '';

			if ( is_feed() ) {

				$addl_path = !empty( $addl_path ) ? trailingslashit($addl_path) : '';

				if ( get_query_var( 'withcomments' ) )

					$addl_path .= 'comments/';

				$addl_path .= user_trailingslashit( 'feed/' . ( ( 'rss2' ==  get_query_var('feed') || 'feed' == get_query_var('feed') ) ? '' : get_query_var('feed') ), 'feed' );

				$redirect['query'] = remove_query_arg( 'feed', $redirect['query'] );

			}

			if ( get_query_var('paged') > 0 ) {

				$paged = get_query_var('paged');

				$redirect['query'] = remove_query_arg( 'paged', $redirect['query'] );

				if ( !is_feed() ) {

					if ( $paged > 1 && !is_single() ) {

						$addl_path = ( !empty( $addl_path ) ? trailingslashit($addl_path) : '' ) . user_trailingslashit("page/$paged", 'paged');

					} elseif ( !is_single() ) {

						$addl_path = ( !empty( $addl_path ) ? trailingslashit($addl_path) : '' ) . user_trailingslashit($paged_redirect['path'], 'paged');

					}

				} elseif ( $paged > 1 ) {

					$redirect['query'] = add_query_arg( 'paged', $paged, $redirect['query'] );

				}

			}

			if ( get_option('page_comments') && ( ( 'newest' == get_option('default_comments_page') && get_query_var('cpage') > 0 ) || ( 'newest' != get_option('default_comments_page') && get_query_var('cpage') > 1 ) ) ) {

				$addl_path = ( !empty( $addl_path ) ? trailingslashit($addl_path) : '' ) . user_trailingslashit( 'comment-page-' . get_query_var('cpage'), 'commentpaged' );

				$redirect['query'] = remove_query_arg( 'cpage', $redirect['query'] );

			}

			$paged_redirect['path'] = user_trailingslashit( preg_replace('|/index.php/?$|', '/', $paged_redirect['path']) ); // strip off trailing /index.php/

			if ( !empty( $addl_path ) && $wp_rewrite->using_index_permalinks() && strpos($paged_redirect['path'], '/index.php/') === false )

				$paged_redirect['path'] = trailingslashit($paged_redirect['path']) . 'index.php/';

			if ( !empty( $addl_path ) )

				$paged_redirect['path'] = trailingslashit($paged_redirect['path']) . $addl_path;

			$redirect_url = $paged_redirect['scheme'] . '://' . $paged_redirect['host'] . $paged_redirect['path'];

			$redirect['path'] = $paged_redirect['path'];

		}

	}

	// tack on any additional query vars

	$redirect['query'] = preg_replace( '#^\??&*?#', '', $redirect['query'] );

	if ( $redirect_url && !empty($redirect['query']) ) {

		if ( strpos($redirect_url, '?') !== false )

			$redirect_url .= '&';

		else

			$redirect_url .= '?';

		$redirect_url .= $redirect['query'];

	}

	if ( $redirect_url )

		$redirect = @parse_url($redirect_url);

	// www.example.com vs example.com

	$user_home = @parse_url(get_option('home'));

	if ( !empty($user_home['host']) )

		$redirect['host'] = $user_home['host'];

	if ( empty($user_home['path']) )

		$user_home['path'] = '/';

	// Handle ports

	if ( !empty($user_home['port']) )

		$redirect['port'] = $user_home['port'];

	else

		unset($redirect['port']);

	// trailing /index.php

	$redirect['path'] = preg_replace('|/index.php/*?$|', '/', $redirect['path']);

	// Remove trailing spaces from the path

	$redirect['path'] = preg_replace( '#(%20| )+$#', '', $redirect['path'] );

	if ( !empty( $redirect['query'] ) ) {

		// Remove trailing spaces from certain terminating query string args

		$redirect['query'] = preg_replace( '#((p|page_id|cat|tag)=[^&]*?)(%20| )+$#', '$1', $redirect['query'] );

		// Clean up empty query strings

		$redirect['query'] = trim(preg_replace( '#(^|&)(p|page_id|cat|tag)=?(&|$)#', '&', $redirect['query']), '&');

		// Remove redundant leading ampersands

		$redirect['query'] = preg_replace( '#^\??&*?#', '', $redirect['query'] );

	}

	// strip /index.php/ when we're not using PATHINFO permalinks

	if ( !$wp_rewrite->using_index_permalinks() )

		$redirect['path'] = str_replace('/index.php/', '/', $redirect['path']);

	// trailing slashes

	if ( is_object($wp_rewrite) && $wp_rewrite->using_permalinks() && !is_404() && (!is_front_page() || ( is_front_page() && (get_query_var('paged') > 1) ) ) ) {

		$user_ts_type = '';

		if ( get_query_var('paged') > 0 ) {

			$user_ts_type = 'paged';

		} else {

			foreach ( array('single', 'category', 'page', 'day', 'month', 'year', 'home') as $type ) {

				$func = 'is_' . $type;

				if ( call_user_func($func) ) {

					$user_ts_type = $type;

					break;

				}

			}

		}

		$redirect['path'] = user_trailingslashit($redirect['path'], $user_ts_type);

	} elseif ( is_front_page() ) {

		$redirect['path'] = trailingslashit($redirect['path']);

	}

	// Always trailing slash the Front Page URL

	if ( trailingslashit( $redirect['path'] ) == trailingslashit( $user_home['path'] ) )

		$redirect['path'] = trailingslashit($redirect['path']);

	// Ignore differences in host capitalization, as this can lead to infinite redirects

	// Only redirect no-www <=> yes-www

	if ( strtolower($original['host']) == strtolower($redirect['host']) ||

		( strtolower($original['host']) != 'www.' . strtolower($redirect['host']) && 'www.' . strtolower($original['host']) != strtolower($redirect['host']) ) )

		$redirect['host'] = $original['host'];

	$compare_original = array($original['host'], $original['path']);

	if ( !empty( $original['port'] ) )

		$compare_original[] = $original['port'];

	if ( !empty( $original['query'] ) )

		$compare_original[] = $original['query'];

	$compare_redirect = array($redirect['host'], $redirect['path']);

	if ( !empty( $redirect['port'] ) )

		$compare_redirect[] = $redirect['port'];

	if ( !empty( $redirect['query'] ) )

		$compare_redirect[] = $redirect['query'];

	if ( $compare_original !== $compare_redirect ) {

		$redirect_url = $redirect['scheme'] . '://' . $redirect['host'];

		if ( !empty($redirect['port']) )

			$redirect_url .= ':' . $redirect['port'];

		$redirect_url .= $redirect['path'];

		if ( !empty($redirect['query']) )

			$redirect_url .= '?' . $redirect['query'];

	}

	if ( $redirect_url == $requested_url )

		return false;

	// Note that you can use the "redirect_canonical" filter to cancel a canonical redirect for whatever reason by returning FALSE

	$redirect_url = apply_filters('redirect_canonical', $redirect_url, $requested_url);

	if ( !$redirect_url || $redirect_url == $requested_url ) // yes, again -- in case the filter aborted the request

		return false;

	if ( $do_redirect ) {

		// protect against chained redirects

		if ( !redirect_canonical($redirect_url, false) ) {

			wp_redirect($redirect_url, 301);

			exit();

		} else {

			// Debug

			// die("1: $redirect_url<br />2: " . redirect_canonical( $redirect_url, false ) );

			return false;

		}

	} else {

		return $redirect_url;

	}

}

/**

 * Attempts to guess correct post based on query vars.

 *

 * @since 2.3.0

 * @uses $wpdb

 *

 * @return bool|string Returns False, if it can't find post, returns correct

 *		location on success.

 */

function redirect_guess_404_permalink() {

	global $wpdb;

	if ( !get_query_var('name') )

		return false;

	$where = $wpdb->prepare("post_name LIKE %s", get_query_var('name') . '%');

	// if any of year, monthnum, or day are set, use them to refine the query

	if ( get_query_var('year') )

		$where .= $wpdb->prepare(" AND YEAR(post_date) = %d", get_query_var('year'));

	if ( get_query_var('monthnum') )

		$where .= $wpdb->prepare(" AND MONTH(post_date) = %d", get_query_var('monthnum'));

	if ( get_query_var('day') )

		$where .= $wpdb->prepare(" AND DAYOFMONTH(post_date) = %d", get_query_var('day'));

	$post_id = $wpdb->get_var("SELECT ID FROM $wpdb->posts WHERE $where AND post_status = 'publish'");

	if ( !$post_id )

		return false;

	return get_permalink($post_id);

}

add_action('template_redirect', 'redirect_canonical');

?>