<?php
/**
 * Provides a custom example of hooking the filters provided by the [mla_gallery] shortcode:
 *
 *  - In the "mla_gallery_arguments" filter is an example of detecting MLA pagination, e.g.,
 *    mla_output="paginate_links,prev_next and supplying the count required to accomodate it.
 *
 *  - In the "mla_gallery_query_arguments" filter is an example of a custom SQL query
 *    that replaces the usual "simple taxonomy" get_posts/WP_Query results.
 *
 * All of the real action happens in the "_query()" function at the bottom of the source.
 * The simplification relies on the assumption that the taxonomy and term(s) given as input are
 * ONLY used for Media Library image items, so we can omit tests on post_mime_type, post_type
 * and post_status.
 *
 * @package MLA tax query Example
 * @version 1.00
 */

/*
Plugin Name: MLA tax query Example
Plugin URI: http://fairtradejudaica.org/media-library-assistant-a-wordpress-plugin/
Description: Provides an example of hooking the filters provided by the [mla_gallery] shortcode
Author: David Lingren
Version: 1.00
Author URI: http://fairtradejudaica.org/our-story/staff/

Copyright 2013, 2014 David Lingren

	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You can get a copy of the GNU General Public License by writing to the
	Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110, USA
*/

/**
 * Class MLA tax query Example hooks three of the filters provided by the [mla_gallery] shortcode
 *
 * Call it anything you want, but give it an unlikely and hopefully unique name. Hiding enerything
 * else inside a class means this is the only name you have to worry about.
 *
 * @package MLA tax query Example
 * @since 1.00
 */
class MLATaxQueryExample {
	/**
	 * Initialization function, similar to __construct()
	 *
	 * @since 1.00
	 *
	 * @return	void
	 */
	public static function initialize() {
		/*
		 * The filters are only useful for front-end posts/pages; exit if in the admin section
		 */
		if ( is_admin() )
			return;

		/*
		 * add_filter parameters:
		 * $tag - name of the hook you're filtering; defined by [mla_gallery]
		 * $function_to_add - function to be called when [mla_gallery] applies the filter
		 * $priority - default 10; lower runs earlier, higher runs later
		 * $accepted_args - number of arguments your function accepts
		 */
		add_filter( 'mla_gallery_attributes', 'MLATaxQueryExample::mla_gallery_attributes_filter', 10, 1 );
		add_filter( 'mla_gallery_arguments', 'MLATaxQueryExample::mla_gallery_arguments_filter', 10, 1 );
		add_filter( 'mla_gallery_query_arguments', 'MLATaxQueryExample::mla_gallery_query_arguments_filter', 10, 1 );
	}

	/**
	 * Save the shortcode attributes
	 *
	 * @since 1.00
	 *
	 * @var	array
	 */
	private static $shortcode_attributes = array();
	
	/**
	 * MLA Gallery (Display) Attributes
	 *
	 * This filter gives you an opportunity to record or modify the arguments passed in to the shortcode
	 * before they are merged with the default arguments used for the gallery display.
	 *
	 * The $shortcode_attributes array is where you will find any of your own parameters that are coded in the
	 * shortcode, e.g., [mla_gallery my_custom_sql="attachment_tag=fireplaces"].
	 *
	 * @since 1.00
	 *
	 * @param	array	the shortcode parameters passed in to the shortcode
	 *
	 * @return	array	updated shortcode attributes
	 */
	public static function mla_gallery_attributes_filter( $shortcode_attributes ) {
		/*
		 * Uncomment the error_log statements in any of the filters to see what's passed in
		 */
		//error_log( 'MLATaxQueryExample::mla_gallery_attributes_filter $shortcode_attributes = ' . var_export( $shortcode_attributes, true ), 0 );
		
		/*
		 * Save the attributes for use in the later filters
		 */
		self::$shortcode_attributes = $shortcode_attributes;

		return $shortcode_attributes;
	} // mla_gallery_attributes_filter

	/**
	 * Save the shortcode arguments
	 *
	 * @since 1.00
	 *
	 * @var	array
	 */
	private static $all_display_parameters = array();
	
	/**
	 * MLA Gallery (Display) Arguments
	 *
	 * This filter gives you an opportunity to record or modify the gallery display arguments
	 * after the shortcode attributes are merged with the default arguments.
	 *
	 * Note that the values in this array are input or default values, not the final computed values
	 * used for the gallery display.
	 *
	 * @since 1.00
	 *
	 * @param	array	shortcode arguments merged with gallery display defaults, so every possible parameter is present
	 *
	 * @return	array	updated gallery display arguments
	 */
	public static function mla_gallery_arguments_filter( $all_display_parameters ) {
		if ( isset( self::$shortcode_attributes['my_custom_sql'] ) ) {
			/*
			 * Determine output type; if it's pagination, count the rows and add the result to the parameters.
			 * See the _query() function for details.
			 */
			$output_parameters = array_map( 'strtolower', array_map( 'trim', explode( ',', $all_display_parameters['mla_output'] ) ) );
			$is_pagination = in_array( $output_parameters[0], array( 'previous_page', 'next_page', 'paginate_links' ) ); 
	
			if ( $is_pagination ) {
				$all_display_parameters['mla_paginate_rows'] = self::_query( NULL, true );
			}
		} // my_custom_sql present
		
		//error_log( 'MLATaxQueryExample::mla_gallery_arguments_filter $all_display_parameters = ' . var_export( $all_display_parameters, true ), 0 );

		self::$all_display_parameters = $all_display_parameters;
		return $all_display_parameters;
	} // mla_gallery_arguments_filter

	/**
	 * MLA Gallery Query Arguments
	 *
	 * This filter gives you an opportunity to record or modify the attachment query arguments
	 * after the shortcode attributes are merged with the default arguments.
	 *
	 * @since 1.00
	 *
	 * @param	array	shortcode arguments merged with attachment selection defaults, so every possible parameter is present
	 *
	 * @return	array	updated attachment query arguments
	 */
	public static function mla_gallery_query_arguments_filter( $all_query_parameters ) {
		/*
		 * This example executes a custom SQL query that is much simpler than the usual
		 * WordPress WP_Query arguments. See the _query() function for details.
		 *
		 * We use a shortcode parameter of our own to apply this filter on a gallery-by-gallery
		 * basis, leaving other [mla_gallery] instances untouched. If the "my_custom_sql" parameter
		 * is not present, we have nothing to do. If the parameter IS present, _query() extracts 
		 * taxonomy values, then builds a custom query that does a simple, high-performance search.
		 */		
		if ( isset( self::$shortcode_attributes['my_custom_sql'] ) ) {
			$all_query_parameters = self::_query( $all_query_parameters );
		}

		//error_log( 'MLATaxQueryExample::mla_gallery_query_arguments_filter $all_query_parameters = ' . var_export( $all_query_parameters, true ), 0 );
		return $all_query_parameters;
	} // mla_gallery_query_arguments_filter
	
	/**
	 * Custom query support function
	 *
	 * Calculates found_rows for pagination or included attachments for gallery.
	 *
	 * @since 1.00
	 *
	 * @param	array	shortcode arguments merged with attachment selection defaults, so every possible parameter is present
	 * @param	boolean	true for pagination result, false for gallery result
	 *
	 * @return	integer|array	found_rows or updated query parameters
	 */
	private static function _query( $all_query_parameters, $is_pagination = false ) {
		global $wpdb;
		//error_log( 'MLATaxQueryExample::_query $all_query_parameters = ' . var_export( $all_query_parameters, true ), 0 );
		//error_log( 'MLATaxQueryExample::_query $is_pagination = ' . var_export( $is_pagination, true ), 0 );

		/*
		 * This example executes a custom SQL query that is much simpler than the usual
		 * WordPress WP_Query arguments.
		 *
		 * For pagination controls, the number of terms satisfying the query parameters is returned.
		 * For gallery display, the query results are fed back to the [mla_gallery] shortcode as a
		 * list of attachments using the "include" parameter.
		 *
		 * The simplification relies on the assumption that the taxonomy and term(s) given as input are
		 * ONLY used for Media Library image items, so we can omit tests on post_mime_type, post_type
		 * and post_status.
		 */		
		
		// Make sure $my_query_vars is an array, even if it's empty
		$my_query_vars = self::$shortcode_attributes['my_custom_sql'];
		if ( empty( $my_query_vars ) ) {
			$my_query_vars = array();
		} elseif ( is_string( $my_query_vars ) ) {
			$my_query_vars = shortcode_parse_atts( $my_query_vars );
		}

		// Start with empty parameter values
		$ttids = array();
		
		// Find taxonomy argument, if present, and collect terms
		$taxonomies = get_taxonomies( array( 'object_type' => array( 'attachment' ) ), 'names' );
		foreach( $taxonomies as $taxonomy ) {
			if ( empty( $my_query_vars[ $taxonomy ] ) ) {
				continue;
			}
			
			// Found the taxonomy; collect the terms
			$include_children =  isset( $my_query_vars['include_children'] ) && 'true' == strtolower( trim( $my_query_vars['include_children'] ) );

			// Allow for multiple term slug values
			$terms = array();
			$slugs = explode( ',', $my_query_vars[ $taxonomy ] );
			foreach ( $slugs as $slug ) {
				$args = array( 'slug' => $slug, 'hide_empty' => false );
				$terms = array_merge( $terms, get_terms( $taxonomy, $args ) );
			}

			foreach( $terms as $term ) {
				// Index by ttid to remove duplicates
				$ttids[ $term->term_taxonomy_id ] = $term->term_taxonomy_id;

				if ( $include_children ) {
					$args = array( 'child_of' => $term->term_id, 'hide_empty' => false );
					$children = get_terms( 'attachment_category', $args );
					foreach( $children as $child ) {
						$ttids[] = $child->term_taxonomy_id;
					}
				} // include_children
			} // $term
			
			break;
		}
		
		// Build an array of SQL clauses
		$query = array();
		$query_parameters = array();

		if ( $is_pagination ) {
			$query[] = "SELECT COUNT( DISTINCT object_id ) FROM {$wpdb->term_relationships} as tr";
		} else {
			$query[] = "SELECT DISTINCT tr.object_id FROM {$wpdb->term_relationships} as tr";
		}

		$placeholders = array();
		if ( ! empty( $ttids ) ) {
			foreach ( $ttids as $ttid ) {
				$placeholders[] = '%s';
				$query_parameters[] = $ttid;
			}
		} else {
				$placeholders[] = '%s';
				$query_parameters[] = '0';
		}
			
		$query[] = 'WHERE ( tr.term_taxonomy_id IN (' . join( ',', $placeholders ) . ') )';
		
		// ORDER BY clause would go here, if needed

		if ( ! $is_pagination ) {
			/*
			 * Add pagination to our query, then remove it from the query
			 * that WordPress will process after we're done.
			 * MLA pagination will override WordPress pagination
			 */
			if ( ! empty( $all_query_parameters['mla_paginate_current'] ) ) {
				if ( isset( $all_query_parameters['mla_paginate_total'] ) && ( $all_query_parameters['mla_paginate_current'] > $all_query_parameters['mla_paginate_total'] ) ) {
					$paged = 0xFFFF; // suppress further output
				} else {
					$paged = $all_query_parameters['mla_paginate_current'];
				}
			} else {
				$paged = $all_query_parameters['paged'];
			}
			
			if ( empty( $paged ) ) {
				$paged = 1;
			} elseif ( 'current' == strtolower( $paged ) ) {
				/*
				 * Note: The query variable 'page' holds the pagenumber for a single paginated
				 * Post or Page that includes the <!--nextpage--> Quicktag in the post content. 
				 */
				if ( get_query_var( 'page' ) ) {
					$paged = get_query_var( 'page' );
				} else {
					$paged = ( get_query_var('paged') ) ? get_query_var('paged') : 1;
				}
			} elseif ( is_numeric( $paged ) ) {
				$paged = absint( $paged );
			} elseif ( '' === $paged ) {
				$paged = 1;
			}

			$limit = absint( ! empty( $all_query_parameters['posts_per_page'] ) ? $all_query_parameters['posts_per_page'] : $all_query_parameters['numberposts'] );
			$offset = $limit * ( $paged - 1);
			if ( 0 < $offset && 0 < $limit ) {
				$query[] = 'LIMIT %d, %d';
				$query_parameters[] = $offset;
				$query_parameters[] = $limit;
			} elseif ( 0 < $limit ) {
				$query[] = 'LIMIT %d';
				$query_parameters[] = $limit;
			} elseif ( 0 < $offset ) {
				$query[] = 'LIMIT %d, %d';
				$query_parameters[] = $offset;
				$query_parameters[] = 0x7FFFFFFF; // big number!
			}
			
			$all_query_parameters['nopaging'] = true;
			$all_query_parameters['numberposts'] = 0;
			$all_query_parameters['posts_per_page'] = 0;
			$all_query_parameters['paged'] = NULL;
			$all_query_parameters['offset'] = NULL;
			$all_query_parameters['mla_paginate_current'] = NULL;
			$all_query_parameters['mla_paginate_total'] = NULL ;
		} // ! is_pagination

		$query =  join(' ', $query);
		if ( $is_pagination ) {
			$count = $wpdb->get_var( $wpdb->prepare( $query, $query_parameters ) );
			//error_log( 'MLATaxQueryExample::_query $count = ' . var_export( $count, true ), 0 );
			return $count;
		}
		
		$ids = $wpdb->get_results( $wpdb->prepare( $query, $query_parameters ) );
		if ( is_array( $ids ) ) {
			$includes = array();
			foreach ( $ids as $id ) {
				$includes[] = $id->object_id;
			}
			$all_query_parameters['include'] = implode( ',', $includes );
		} else {
			$all_query_parameters['include'] = '1'; // return no images
		}

		//error_log( 'MLATaxQueryExample::_query $all_query_parameters = ' . var_export( $all_query_parameters, true ), 0 );
		return $all_query_parameters;
	} // _query
} // Class MLATaxQueryExample

/*
 * Install the filters at an early opportunity
 */
add_action('init', 'MLATaxQueryExample::initialize');
?>