BP_Search::do_search( mixed $args = '' )

		public function do_search( $args = '' ) {
			global $wpdb;

			$args = $this->sanitize_args( $args );

			$defaults = array(
				//the search term
				'search_term'   => '',
				//Restrict search results to only this subset. eg: posts, members, groups, etc.
				//See Setting > what to search?
				'search_subset' => 'all',
				//
				//What all to search for. e.g: members.
				//See Setting > what to search?
				//The options passed here must be a subset of all options available on Setting > what to search, nothing extra can be passed here.
				//
				//This is different from search_subset.
				//If search_subset is 'all', then search is performed for all searchable items.
				//If search_subset is 'members' then only total match count for other searchable_items is calculated( so that it can be displayed in tabs)
				//members(23) | posts(201) | groups(2) and so on.
				//	'searchable_items' => BP_Search::instance()->option( 'items-to-search' ),
				//how many search results to display per page
				'per_page'      => 20,
				//current page
				'current_page'  => 1,
				//should we calculate total match count for all different types?
				//it should be set to false while calling this function for ajax search
				'count_total'   => true,
				//template type to load for each item
				//search results will be styled differently(minimal) while in ajax search
				//options ''|'minimal'
				'template_type' => '',
				'forum_search'  => false,
				'number'        => 3
			);

			$args = wp_parse_args( $args, $defaults );

			if ( true === $args['forum_search'] ) {
				$this->searchable_items = array( 'forum', 'topic', 'reply' );
			}

			$this->search_args = $args;//save it for using in other methods

			//bail out if nothing to search for
			if ( ! $args['search_term'] ) {
				return;
			}

			if ( 'all' == $args['search_subset'] ) {

				/**
				 * 1. Generate a 'UNION' sql query for all searchable items with only ID, RANK, TYPE(posts|members|..) as columns, order by RANK DESC.
				 * 3. Generate html for each of them
				 */
				/* an example UNION query :-
				-----------------------------------------------------
				(
					SELECT
					wp_posts.id , 'posts' as type, wp_posts.post_title LIKE '%ho%' AS relevance, wp_posts.post_date as entry_date
					FROM
						wp_posts
					WHERE
						1=1
						AND (
								(
										(wp_posts.post_title LIKE '%ho%')
									OR 	(wp_posts.post_content LIKE '%ho%')
								)
							)
						AND wp_posts.post_type IN ('post', 'page', 'attachment')
						AND (
							wp_posts.post_status = 'publish'
							OR wp_posts.post_author = 1
							AND wp_posts.post_status = 'private'
						)
				)
				UNION
				(
					SELECT
						DISTINCT g.id, 'groups' as type, g.name LIKE '%ho%' AS relevance, gm2.meta_value as entry_date
					FROM
						wp_bp_groups_groupmeta gm1, wp_bp_groups_groupmeta gm2, wp_bp_groups g
					WHERE
						1=1
						AND g.id = gm1.group_id
						AND g.id = gm2.group_id
						AND gm2.meta_key = 'last_activity'
						AND gm1.meta_key = 'total_member_count'
						AND ( g.name LIKE '%ho%' OR g.description LIKE '%ho%' )
				)

				ORDER BY
					relevance DESC, entry_date DESC LIMIT 0, 10
				----------------------------------------------------
				*/

				$sql_queries   = [];
				$total = [];

				foreach ( $this->searchable_items as $search_type ) {
					if ( ! isset( $this->search_helpers[ $search_type ] ) ) {
						continue;
					}

					/**
					 * the following variable will be an object of current search type helper class
					 * e.g: an object of Bp_Search_Groups or Bp_Search_Posts etc.
					 * so we can safely call the public methods defined in those classes.
					 * This also means that all such classes must have a common set of methods.
					 */
					$obj                   = $this->search_helpers[ $search_type ];
					$limit                 = isset( $_REQUEST['view'] ) ? " LIMIT " . ( $args['number'] ) : '';
					$sql_queries[]         = "( " . $obj->union_sql( $args['search_term'] ) . " $limit ) ";
					$total[ $search_type ] = $obj->get_total_match_count( $args['search_term'] );
				}

				if ( empty( $sql_queries ) ) {
					//thigs will get messy if program reaches here!!
					return;
				}

				$pre_search_query = implode( ' UNION ', $sql_queries ) . " ORDER BY relevance, type DESC, entry_date DESC ";

				if ( isset( $args['ajax_per_page'] ) && $args['ajax_per_page'] > 0 ) {
					$pre_search_query .= " LIMIT {$args['ajax_per_page']} ";
				}

				$results = $wpdb->get_results( $pre_search_query );
				/* $results will have a structure like below */
				/*
				id | type | relevance | entry_date
				45 | groups | 1 | 2014-10-28 17:05:18
				40 | posts | 1 | 2014-10-26 13:52:06
				4 | groups | 0 | 2014-10-21 15:15:36
				*/
				if ( ! empty( $results ) ) {
					$this->search_results['all'] = array(
						'total_match_count' => 0,
						'items'             => array(),
						'items_title'       => array()
					);
					//segregate items of a type together and pass it to corresponsing search handler, so that an aggregate query can be done
					//e.g one single wordpress loop can be done for all posts

					foreach ( $results as $item ) {
						$obj = $this->search_helpers[ $item->type ];
						$obj->add_search_item( $item->id );
					}

					//now get html for each item
					foreach ( $results as $item ) {

						$obj = $this->search_helpers[ $item->type ];

						$result = array(
							'id'    => $item->id,
							'type'  => $item->type,
							'html'  => $obj->get_html( $item->id, $args['template_type'] ),
							'title' => $obj->get_title( $item->id )
						);

						$this->search_results['all']['items'][ $item->type . '_' . $item->id ] = $result;
					}
					//now we've html saved for search results

					if ( ! empty( $this->search_results['all']['items'] ) && $args['template_type'] != 'ajax' ) {
						/* ++++++++++++++++++++++++++++++++++
						group items of same type together
						++++++++++++++++++++++++++++++++++ */
						//create another copy, of items, this time, items of same type grouped together
						$ordered_items_group = array();
						foreach ( $this->search_results['all']['items'] as $item_id => $item ) {
							$type = $item['type'];
							if ( ! isset( $ordered_items_group[ $type ] ) ) {
								$ordered_items_group[ $type ] = array();
							}
							$item_id = absint( str_replace( $type . '_', '', $item_id ) );
							$ordered_items_group[ $type ][ $item_id ] = $item;
						}

						$search_items = bp_search_items();
						$search_url = $this->search_page_search_url();


						foreach ( $ordered_items_group as $type => &$items ) {
							//now prepend html (opening tags) to first item of each
							$category_search_url = esc_url( add_query_arg( array( 'subset' => $type, 'bp_search' => 1 ), $search_url ) );
							$label               = isset( $search_items[ $type ] ) ? trim( $search_items[ $type ] ) : trim( $type );
							$first_item          = reset( $items );
							$total_results       = $total[ $type ];
							$start_html = "<div class='results-group results-group-{$type} " . apply_filters( 'bp_search_class_search_wrap', 'bp-search-results-wrap', $label ) . "'>"
							              . "<header class='results-group-header clearfix'>"
							              . "<h3 class='results-group-title'><span>" . apply_filters( 'bp_search_label_search_type', $label ) . "</span></h3>"
							              . "<span class='total-results'>" . sprintf( _n( '%d result', '%d results', $total_results, 'buddyboss' ), $total_results ) . "</a>"
							              . "</header>"
							              . "<ul id='{$type}-stream' class='item-list {$type}-list bp-list " . apply_filters( 'bp_search_class_search_list', 'bp-search-results-list', $label ) . "'>";

							$group_start_html = apply_filters( "bp_search_results_group_start_html", $start_html, $type );

							$first_item['html']         = $group_start_html . $first_item['html'];
							$items[ $first_item['id'] ] = $first_item;

							//and append html (closing tags) to last item of each type
							$last_item = end( $items );
							$end_html  = "</ul>";

							if ( $total_results > 3 ) {
								$end_html .= "<footer class='results-group-footer'>";
								$end_html .= "<a href='" . $category_search_url . "' class='view-all-link'>" .
								               sprintf( esc_html__( 'View (%d) more', 'buddyboss' ), $total_results -  $args['number'] ).
								             "</a>";
								$end_html .= "</footer>";
							}

							$end_html  .= "</div>";

							$group_end_html = apply_filters( "bp_search_results_group_end_html", $end_html, $type );

							$last_item['html']         = $last_item['html'] . $group_end_html;
							$items[ $last_item['id'] ] = $last_item;
						}

						//replace orginal items with this new, grouped set of items
						$this->search_results['all']['items'] = array();
						foreach ( $ordered_items_group as $type => $grouped_items ) {

							// Remove last item from list
							if ( count( $grouped_items ) > 3 ) {
								array_pop( $grouped_items );
							}

							foreach ( $grouped_items as $item_id => $item ) {
								$this->search_results['all']['items'][ $type . '_' . $item_id ] = $item;
							}
						}
						/* ________________________________ */
					}
				}
			} else {
				//if subset not in searchable items, bail out.
				if ( ! in_array( $args['search_subset'], $this->searchable_items ) ) {
					return;
				}

				if ( ! isset( $this->search_helpers[ $args['search_subset'] ] ) ) {
					return;
				}

				/**
				 * 1. Search top top 20( $args['per_page'] ) item( posts|members|..)
				 * 2. Generate html for each of them
				 */
				//$args['per_page'] = get_option( 'posts_per_page' );
				$obj              = $this->search_helpers[ $args['search_subset'] ];
				$pre_search_query = $obj->union_sql( $args['search_term'] ) . " ORDER BY relevance DESC, entry_date DESC ";

				if ( $args['per_page'] > 0 ) {
					$offset           = ( $args['current_page'] * $args['per_page'] ) - $args['per_page'];
					$pre_search_query .= " LIMIT {$offset}, {$args['per_page']} ";
				}

				$results = $wpdb->get_results( $pre_search_query );

				/* $results will have a structure like below */
				/*
				id | type | relevance | entry_date
				45 | groups | 1 | 2014-10-28 17:05:18
				40 | posts | 1 | 2014-10-26 13:52:06
				4 | groups | 0 | 2014-10-21 15:15:36
				*/
				if ( ! empty( $results ) ) {
					$obj                                            = $this->search_helpers[ $args['search_subset'] ];
					$this->search_results[ $args['search_subset'] ] = array(
						'total_match_count' => 0,
						'items'             => array()
					);
					//segregate items of a type together and pass it to corresponsing search handler, so that an aggregate query can be done
					//e.g one single wordpress loop can be done for all posts
					foreach ( $results as $item ) {
						$obj->add_search_item( $item->id );
					}

					//now get html for each item
					foreach ( $results as $item ) {
						$html = $obj->get_html( $item->id, $args['template_type'] );

						$result = array(
							'id'    => $item->id,
							'type'  => $args['search_subset'],
							'html'  => $obj->get_html( $item->id, $args['template_type'] ),
							'title' => $obj->get_title( $item->id ),
						);

						$this->search_results[ $args['search_subset'] ]['items'][ $item->id ] = $result;
					}

					//now prepend html (opening tags) to first item of each type
					$first_item = reset( $this->search_results[ $args['search_subset'] ]['items'] );
					$start_html = "<div class='results-group results-group-{$args['search_subset']} " . apply_filters( 'bp_search_class_search_wrap', 'bp-search-results-wrap', $args['search_subset'] ) . "'>"
					              . "<ul id='{$args['search_subset']}-stream' class='item-list {$args['search_subset']}-list bp-list " . apply_filters( 'bp_search_class_search_list', 'bp-search-results-list', $args['search_subset'] ) . "'>";

					$group_start_html = apply_filters( "bp_search_results_group_start_html", $start_html, $args['search_subset'] );

					$first_item['html']                                                           = $group_start_html . $first_item['html'];
					$this->search_results[ $args['search_subset'] ]['items'][ $first_item['id'] ] = $first_item;

					//and append html (closing tags) to last item of each type
					$last_item = end( $this->search_results[ $args['search_subset'] ]['items'] );
					$end_html  = "</ul></div>";

					$group_end_html = apply_filters( "bp_search_results_group_end_html", $end_html, $args['search_subset'] );

					$last_item['html']                                                           = $last_item['html'] . $group_end_html;
					$this->search_results[ $args['search_subset'] ]['items'][ $last_item['id'] ] = $last_item;
				}
			}

			//html for search results is generated.
			//now, lets calculate the total number of search results, for all different types
			if ( $args['count_total'] ) {
				$all_items_count = 0;
				foreach ( $this->searchable_items as $search_type ) {
					if ( ! isset( $this->search_helpers[ $search_type ] ) ) {
						continue;
					}

					$obj                                                       = $this->search_helpers[ $search_type ];
					$total_match_count                                         = $obj->get_total_match_count( $this->search_args['search_term'] );
					$this->search_results[ $search_type ]['total_match_count'] = $total_match_count;

					$all_items_count += $total_match_count;
				}

				$this->search_results['all']['total_match_count'] = $all_items_count;
			}
		}