Post template filters

page-blog.php

@@ -12,11 +12,51 @@
 				<div class="col-sm-<?php echo (is_active_sidebar( $sidebar )?9:12); ?>">
 					<div id="primary" class="content-area">
 						<main id="main" class="site-main" role="main">
-							<?php the_content();?>
-							<?php query_posts('post_type=post&post_status=publish&paged='. get_query_var('paged')); ?>
-							<?php if( have_posts() ): ?>
-								<?php while( have_posts() ): the_post(); ?>
-
+							<?php 
+							the_content();
+							$cat = get_post_meta( get_the_ID(), 'categories', true );
+							$tag = get_post_meta( get_the_ID(), 'tags', true );
+							$authornames = get_post_meta( get_the_ID(), 'authors', true );
+							$authorsArr = explode(",", $authornames);
+							if( array_key_exists(1, $authorsArr) ){
+								$authorsStr = '';
+								foreach( $authorsArr as $a ){
+									$user = get_user_by('slug', $a);
+									$id = $user->ID;
+									$authorsStr .= $id.',';
+								}
+								$author = rtrim($authorsStr, ',');
+							} else {
+								$author = get_user_by('slug', $authornames)->ID;
+							}
+							$args = array(
+								'post_type' => 'post',
+								'category_name' => $cat,
+								'tag' => $tag,
+								'author' => $author,
+								'post_status' => 'publish',
+								'paged' => get_query_var('paged'),
+							);
+							if( isset($args) ){
+								$pattern = '#[a-zA-Z|~`!@\#$%^&*()_+=|\\}\][{\'/;\-":?>.<]#';
+								$arr = array('category_name'=>$cat, 'tag'=>$tag, 'author'=>$author);
+								foreach( $arr as $k=>$v ){
+									if( empty($v) ){
+										continue;
+									}
+									if( $k == 'author' ){
+										$pattern = '#[0-9|~`!@\#$%^&*()_+=|\\}\][{\'/;\-":?>.<]#';
+									}
+									if( preg_match($pattern, $v) ){
+										$args[$k] = $v;
+									} else {
+										echo '<p>Invalid input in field: "'.$k.'"</p>';
+									}
+								}
+							}
+							query_posts( $args );
+							if( have_posts() ):
+								while( have_posts() ): the_post(); ?>
 									<article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
 										<header class="entry-header">
 											<h1><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h1>