wp-rewrite-plugin.php

https://www.youtube.com/watch?v=Q5QkgK3xcDo
<?php
/**
 * @package WPCamp 2019
 * @version 1.0
 */
/*
Plugin Name: rewrite api custom permalink - BUILD
Description: Creates custom post type and custom permalink
Author: Sergio
Version: 1.0
Author URI: esergio.com

DO NOT use this plugin as is for production. This plugin is for learning purposes only.
*/

class My_Plugin{
	private $post_type = 'stores';

	function __construct(){
		//post type
		//add_action('init', [$this, 'register_custom_post_type']);

		 //metabox
		//add_action( 'load-post.php', [$this, 'state_metabox_setup'] );
		//add_action( 'load-post-new.php', [$this, 'state_metabox_setup'] ); 

		//add_filter( 'post_type_link', [$this,'replace_rewrite_tags'] , 10, 2 ); 

		//query var
		//add_filter ( 'query_vars', [$this, 'create_query_vars']);

		//permalinks + rewrites
        //add_action('init', [$this, 'my_rewrite_rule']);
        
        //link query var
		//add_action('pre_get_posts', [$this, 'before_posts']); 

	}

	function register_custom_post_type(){
		
		$args = [
			'label' => 'Stores',
			'public' => true,
			'rewrite' => [
				// permalink structure: store/store_state/store_name
				'slug' => 'store/%store_state%',
				'with_front' => false,
			],
		];
		register_post_type(
			$this->post_type, 
			$args
		);

		//DON'T RUN HERE ON PRODUCTION!!
		flush_rewrite_rules();
	}

	

	function create_query_vars($vars){
		$vars[] = 'store_state';
		return $vars;
	}

	function replace_rewrite_tags($url, $post){
		
		if ( is_wp_error($post) || $this->post_type != $post->post_type || empty($post->post_name) )
			return $url;

		//get store state from post_meta
		$ba = strtolower(get_post_meta($post->ID, 'store_state', true));

		return str_replace('%store_state%', $ba, $url);
	}

	/***
	* Adds rewrite rule for locations post 
	**/
	function my_rewrite_rule(){
		add_rewrite_tag('%store_state%', '([^&]+)');
				
		//interpret custom structure
		//permalink structure: store/store_state/store-name
		//add_rewrite_rule('^store/([^/]+)/([^/]+)/?','index.php?stores=$matches[2]&store_state=$matches[1]', 'top');
	}

	

	function before_posts($query){
		//return if it is not the main query of it is the admin
		if ( is_admin() || ! $query->is_main_query() ){
			return;
		}

		$meta_query = [];
		
		// add meta_query elements
		$store_state = get_query_var('store_state');
		if( !empty($store_state) ){
			
			$meta_query[] = array( 'key' => 'store_state', 'value' => $store_state , 'compare' => '=' );

            //if there are more meta_query then relation is AND
            if( count( $meta_query ) > 1 ){
                $meta_query['relation'] = 'AND';
			} 
			
            //set meta_query to $query
            if( count( $meta_query ) > 0 ){
                $query->set( 'meta_query', $meta_query );
            }
		}		
	}
	
	function state_metabox_setup(){
		add_action( 'add_meta_boxes', [$this,'add_state_metabox']);
		add_action( 'save_post', [$this, 'save_post_state'], 10, 2);
	}

	function build_state_meta(){
		wp_nonce_field( basename( __FILE__ ), 'store_state_nonce' );
		global $post; 
		$state = get_post_meta($post->ID, 'store_state', true);
		$available_states = [
			'Nebraska',
			'Iowa',
			'Colorado',
			'Kansas'
		]
		?>
		<select name="store_state">
			<?php
				foreach($available_states as $a_state){
					$selected = $a_state == $state ? 'selected' : '';
					?>
						<option value="<?=$a_state?>"<?=$selected?>><?=$a_state?></option>
					<?php
				}
			?>
		</select>
		<?php
	}

	function add_state_metabox(){
		add_meta_box(
			'store_state',
			'State',
			[$this,'build_state_meta'],
			array('post', $this->post_type),
			'side'
		);
	}

	function save_post_state($post_id, $post){
	
		if ( !isset( $_POST['store_state_nonce'] ) || !wp_verify_nonce( $_POST['store_state_nonce'], basename( __FILE__ ) ) ){
			return $post_id;
		}
			
		$post_type = get_post_type_object( $post->post_type );


		//can user edit post and is the post type store
		if ( !current_user_can( $post_type->cap->edit_post, $post_id ) ){
			return $post_id;
		}
		
		update_post_meta($post_id, 'store_state',sanitize_text_field($_POST['store_state']));

	}
	
	
	
}

new My_Plugin();

function debug_func($query){
	global $wp_rewrite;
	echo "<pre>";
	//print_r($query);
	//print_r($wp_rewrite);
	echo "</pre>";
	//exit;
}

function query_debug(){
	global $wp_query;
	echo $wp_query->request; 
	
}
if(!is_admin()){
	//add_action('parse_request', 'debug_func');
	//add_action('the_post', 'query_debug');
}