<?php

/**

 * Canonical API to handle WordPress Redirecting

 *

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

 * by 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 penalty for duplicate content by redirecting all incoming links to

 * one or the other.

 *

 * admin URLs. Does not redirect on non-pretty-permalink-supporting IIS 7+,

 * page/post previews, WP admin, Trackbacks, robots.txt, searches, or on POST

 * requests.

 *

 * 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

 *

 * @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.

 */

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

	if ( isset( $_SERVER['REQUEST_METHOD'] ) && ! in_array( strtoupper( $_SERVER['REQUEST_METHOD'] ), array( 'GET', 'HEAD' ) ) ) {

		return;

	}

	// If we're not in wp-admin and the post has been published and preview nonce

	// is non-existent or invalid then no need for preview in query

	if ( is_preview() && get_query_var( 'p' ) && 'publish' == get_post_status( get_query_var( 'p' ) ) ) {

		if ( ! isset( $_GET['preview_id'] )

			|| ! isset( $_GET['preview_nonce'] )

			|| ! wp_verify_nonce( $_GET['preview_nonce'], 'post_preview_' . (int) $_GET['preview_id'] ) ) {

			$wp_query->is_preview = false;

		}

	}

		return;

	}

		// build the URL in the address bar

		$requested_url  = is_ssl() ? 'https://' : 'http://';

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

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

	}

	$original = @parse_url($requested_url);

		return;

	$redirect = $original;

	$redirect_url = false;

	// Notice fixing

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

		$redirect['path'] = '';

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

		$redirect['query'] = '';

	// If the original URL ended with non-breaking spaces, they were almost

	// certainly inserted by accident. Let's remove them, so the reader doesn't

	// see a 404 error with no obvious cause.

	$redirect['path'] = preg_replace( '|(%C2%A0)+$|i', '', $redirect['path'] );

	// It's not a preview, so remove it from URL

	if ( get_query_var( 'preview' ) ) {

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

	}

	if ( is_feed() && ( $id = get_query_var( 'p' ) ) ) {

		if ( $redirect_url = get_post_comments_feed_link( $id, get_query_var( 'feed' ) ) ) {

			$redirect['query'] = _remove_qs_args_if_not_in_url( $redirect['query'], array( 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type', 'feed'), $redirect_url );

			$redirect['path'] = parse_url( $redirect_url, PHP_URL_PATH );

		}

	}

	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_qs_args_if_not_in_url( $redirect['query'], array( 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type' ), $redirect_url );

		}

	}

	// These tests give us a WP-generated permalink

	if ( is_404() ) {

		// Redirect ?page_id, ?p=, ?attachment_id= to their respective url's

		$id = max( get_query_var('p'), get_query_var('page_id'), get_query_var('attachment_id') );

		if ( $id && $redirect_post = get_post($id) ) {

			$post_type_obj = get_post_type_object($redirect_post->post_type);

				$redirect_url = get_permalink($redirect_post);

				$redirect['query'] = _remove_qs_args_if_not_in_url( $redirect['query'], array( 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type' ), $redirect_url );

			}

		}

		if ( get_query_var( 'day' ) && get_query_var( 'monthnum' ) && get_query_var( 'year' ) ) {

			$year  = get_query_var( 'year' );

			$month = get_query_var( 'monthnum' );

			$day   = get_query_var( 'day' );

			$date  = sprintf( '%04d-%02d-%02d', $year, $month, $day );

			if ( ! wp_checkdate( $month, $day, $year, $date ) ) {

				$redirect_url = get_month_link( $year, $month );

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

			}

		} elseif ( get_query_var( 'monthnum' ) && get_query_var( 'year' ) && 12 < get_query_var( 'monthnum' ) ) {

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

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

		}

		if ( ! $redirect_url ) {

			if ( $redirect_url = redirect_guess_404_permalink() ) {

				$redirect['query'] = _remove_qs_args_if_not_in_url( $redirect['query'], array( 'page', 'feed', 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type' ), $redirect_url );

			}

		}

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

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

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

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

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

		} elseif ( is_single() && !empty($_GET['name'])  && ! $redirect_url ) {

			if ( $redirect_url = get_permalink( $wp_query->get_queried_object_id() ) )

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

			$redirect_url = home_url('/');

		} elseif ( is_home() && !empty($_GET['page_id']) && 'page' == get_option('show_on_front') && get_query_var('page_id') == get_option('page_for_posts')  && ! $redirect_url ) {

			if ( $redirect_url = get_permalink(get_option('page_for_posts')) )

				$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_author() && !empty($_GET['author']) && preg_match( '|^[0-9]+$|', $_GET['author'] ) ) {

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

			if ( ( false !== $author ) && $wpdb->get_var( $wpdb->prepare( "SELECT ID FROM $wpdb->posts WHERE $wpdb->posts.post_author = %d AND $wpdb->posts.post_status = 'publish' LIMIT 1", $author->ID ) ) ) {

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

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

			}

		} elseif ( is_category() || is_tag() || is_tax() ) { // Terms (Tags/categories)

			$term_count = 0;

			foreach ( $wp_query->tax_query->queried_terms as $tax_query )

				$term_count += count( $tax_query['terms'] );

			$obj = $wp_query->get_queried_object();

			if ( $term_count <= 1 && !empty($obj->term_id) && ( $tax_url = get_term_link((int)$obj->term_id, $obj->taxonomy) ) && !is_wp_error($tax_url) ) {

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

					// Strip taxonomy query vars off the url.

					$qv_remove = array( 'term', 'taxonomy');

					if ( is_category() ) {

						$qv_remove[] = 'category_name';

						$qv_remove[] = 'cat';

					} elseif ( is_tag() ) {

						$qv_remove[] = 'tag';

						$qv_remove[] = 'tag_id';

					} else { // Custom taxonomies will have a custom query var, remove those too:

						$tax_obj = get_taxonomy( $obj->taxonomy );

						if ( false !== $tax_obj->query_var )

							$qv_remove[] = $tax_obj->query_var;

					}

					$rewrite_vars = array_diff( array_keys($wp_query->query), array_keys($_GET) );

					if ( !array_diff($rewrite_vars, array_keys($_GET))  ) { // Check to see if all the Query vars are coming from the rewrite, none are set via $_GET

						$redirect['query'] = remove_query_arg($qv_remove, $redirect['query']); //Remove all of the per-tax qv's

						// Create the destination url for this taxonomy

						$tax_url = parse_url($tax_url);

						if ( ! empty($tax_url['query']) ) { // Taxonomy accessible via ?taxonomy=..&term=.. or any custom qv..

							parse_str($tax_url['query'], $query_vars);

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

						} else { // Taxonomy is accessible via a "pretty-URL"

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

						}

					} else { // Some query vars are set via $_GET. Unset those from $_GET that exist via the rewrite

						foreach ( $qv_remove as $_qv ) {

							if ( isset($rewrite_vars[$_qv]) )

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

						}

					}

				}

			}

		} elseif ( is_single() && strpos($wp_rewrite->permalink_structure, '%category%') !== false && $cat = get_query_var( 'category_name' ) ) {

			$category = get_category_by_path( $cat );

				$redirect_url = get_permalink($wp_query->get_queried_object_id());

		}

		// Post Paging

			if ( !$redirect_url )

				$redirect_url = get_permalink( get_queried_object_id() );

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

		}

		// paging and feeds

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

			while ( preg_match( "#/$wp_rewrite->pagination_base/?[0-9]+?(/+)?$#", $redirect['path'] ) || preg_match( '#/(comments/?)?(feed|rss|rdf|atom|rss2)(/+)?$#', $redirect['path'] ) || preg_match( "#/{$wp_rewrite->comments_pagination_base}-[0-9]+(/+)?$#", $redirect['path'] ) ) {

				// Strip off paging and feed

				$redirect['path'] = preg_replace("#/$wp_rewrite->pagination_base/?[0-9]+?(/+)?$#", '/', $redirect['path']); // strip off any existing paging

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

				$redirect['path'] = preg_replace("#/{$wp_rewrite->comments_pagination_base}-[0-9]+?(/+)?$#", '/', $redirect['path']); // strip off any existing comment paging

			}

			$addl_path = '';

			if ( is_feed() && in_array( get_query_var('feed'), $wp_rewrite->feeds ) ) {

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

				if ( !is_singular() && get_query_var( 'withcomments' ) )

					$addl_path .= 'comments/';

				if ( ( 'rss' == get_default_feed() && 'feed' == get_query_var('feed') ) || 'rss' == get_query_var('feed') )

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

				else

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

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

			} elseif ( is_feed() && 'old' == get_query_var('feed') ) {

				$old_feed_files = array(

					'wp-atom.php'         => 'atom',

					'wp-commentsrss2.php' => 'comments_rss2',

					'wp-feed.php'         => get_default_feed(),

					'wp-rdf.php'          => 'rdf',

					'wp-rss.php'          => 'rss2',

					'wp-rss2.php'         => 'rss2',

				);

				if ( isset( $old_feed_files[ basename( $redirect['path'] ) ] ) ) {

					$redirect_url = get_feed_link( $old_feed_files[ basename( $redirect['path'] ) ] );

					wp_redirect( $redirect_url, 301 );

					die();

				}

			}

			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("$wp_rewrite->pagination_base/$paged", 'paged');

					} elseif ( !is_single() ) {

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

					}

				} elseif ( $paged > 1 ) {

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

				}

			}

				$addl_path = ( !empty( $addl_path ) ? trailingslashit($addl_path) : '' ) . user_trailingslashit( $wp_rewrite->comments_pagination_base . '-' . get_query_var('cpage'), 'commentpaged' );

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

			}

			$redirect['path'] = user_trailingslashit( preg_replace('|/' . preg_quote( $wp_rewrite->index, '|' ) . '/?$|', '/', $redirect['path']) ); // strip off trailing /index.php/

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

				$redirect['path'] = trailingslashit($redirect['path']) . $wp_rewrite->index . '/';

			if ( !empty( $addl_path ) )

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