<?php
/**
 * Weighting dashboard for ElasticPress
 *
 * @package elasticpress
 */

namespace ElasticPress\Feature\Search;

use ElasticPress\Features;
use ElasticPress\Utils;

/**
 * Controls search weighting and search fields dashboard
 *
 * @package ElasticPress\Feature\Search
 */
class Weighting {

	/**
	 * Sets up the weighting module
	 */
	public function setup() {
		/**
		 * Filter to disable loading of Search weighting engine.
		 *
		 * @hook ep_disable_search_weighting
		 * @since 4.0
		 * @param bool Whether to disable search weighting engine. Defaults to false.
		 * @return bool Whether to disable search weighting engine.
		 */
		if ( apply_filters( 'ep_disable_search_weighting', false ) ) {
			return;
		}

		add_action( 'admin_menu', [ $this, 'add_weighting_submenu_page' ], 15 );
		add_filter( 'ep_formatted_args', [ $this, 'do_weighting' ], 20, 2 ); // After date decay, etc are injected
		add_filter( 'ep_query_weighting_fields', [ $this, 'adjust_weight_for_cross_fields' ], 10, 5 );
		add_action( 'rest_api_init', [ $this, 'register_rest_routes' ] );
	}

	/**
	 * Returns a grouping of all the fields that support weighting for the post type
	 *
	 * @param string $post_type Post type
	 *
	 * @return array
	 */
	public function get_weightable_fields_for_post_type( $post_type ) {
		$fields = array(
			'attributes' => array(
				'label'    => __( 'Attributes', 'elasticpress' ),
				'children' => array(
					'post_title'   => array(
						'key'   => 'post_title',
						'label' => 'Title',
					),
					'post_content' => array(
						'key'   => 'post_content',
						'label' => 'Content',
					),
					'post_excerpt' => array(
						'key'   => 'post_excerpt',
						'label' => 'Excerpt',
					),
					'author_name'  => array(
						'key'   => 'author_name',
						'label' => 'Author',
					),
				),
			),
		);

		$public_taxonomies = get_taxonomies(
			[
				'public' => true,
			]
		);

		$post_type_taxonomies = get_object_taxonomies( $post_type );

		$taxonomies = array_intersect( $public_taxonomies, $post_type_taxonomies );

		if ( ! empty( $taxonomies ) ) {
			$fields['taxonomies'] = [
				'label'    => __( 'Taxonomies', 'elasticpress' ),
				'children' => [],
			];

			foreach ( $taxonomies as $taxonomy ) {
				$key             = "terms.{$taxonomy}.name";
				$taxonomy_object = get_taxonomy( $taxonomy );

				$fields['taxonomies']['children'][ $key ] = [
					'key'   => $key,
					'label' => $taxonomy_object->labels->name,
				];
			}
		}

		$fields['ep_metadata'] = [
			'label'    => 'Metadata',
			'children' => [],
		];

		$empty_post = new \WP_Post( new \stdClass() );

		$empty_post->post_type = $post_type;

		/** This filter is documented in includes/classes/Indexable/Post/Post.php */
		$allowed_protected_keys = apply_filters( 'ep_prepare_meta_allowed_protected_keys', [], $empty_post );

		sort( $allowed_protected_keys, SORT_STRING );

		/** This filter is documented in includes/classes/Indexable/Post/Post.php */
		$excluded_public_keys = apply_filters( 'ep_prepare_meta_excluded_public_keys', [], $empty_post );

		foreach ( $allowed_protected_keys as $meta_key ) {
			$key = "meta.$meta_key.value";

			if ( in_array( $key, $excluded_public_keys, true ) ) {
				continue;
			}

			$required = in_array( $meta_key, $allowed_protected_keys, true );

			$fields['ep_metadata']['children'][ $key ] = [
				'key'      => $key,
				'label'    => $meta_key,
				'required' => $required,
			];
		}

		/**
		 * Filter weighting fields for a post type
		 *
		 * @hook ep_weighting_fields_for_post_type
		 * @param  {array} $fields Current weighting fields
		 * @param  {string} $post_type Current post type
		 * @return  {array} New fields
		 */
		return apply_filters( 'ep_weighting_fields_for_post_type', $fields, $post_type );
	}

	/**
	 * Get weightable fields for all searchable post types.
	 *
	 * @since 5.0.0
	 * @return array
	 */
	public function get_weightable_fields() {
		$weightable = array();
		$post_types = Features::factory()->get_registered_feature( 'search' )->get_searchable_post_types();

		foreach ( $post_types as $post_type ) {
			$post_type_object = get_post_type_object( $post_type );
			$post_type_labels = get_post_type_labels( $post_type_object );

			$weightable_fields = $this->get_weightable_fields_for_post_type( $post_type );

			$groups = [];
			$fields = [];

			foreach ( $weightable_fields as $group => $weightable_field ) {
				$groups[] = [
					'key'   => $group,
					'label' => $weightable_field['label'],
				];

				foreach ( $weightable_field['children'] as $field ) {
					$fields[] = [
						'group'    => $group,
						'key'      => $field['key'],
						'label'    => $field['label'],
						'required' => isset( $field['required'] ) ? $field['required'] : false,
					];
				}
			}

			$weightable[] = [
				'key'    => $post_type,
				'label'  => $post_type_labels->menu_name,
				'groups' => $groups,
				'fields' => $fields,
			];
		}

		return $weightable;
	}

	/**
	 * Returns default settings for any post type
	 *
	 * Defaults to title, content, excerpt, and author name enabled with zero weight
	 *
	 * @param string $post_type Post Type we need settings for
	 *
	 * @return array Defaults for post type
	 */
	public function get_post_type_default_settings( $post_type ) {
		$post_type_defaults = [
			'post_title'   => [
				'enabled' => true,
				'weight'  => 1,
			],
			'post_content' => [
				'enabled' => true,
				'weight'  => 1,
			],
			'post_excerpt' => [
				'enabled' => true,
				'weight'  => 1,
			],
			'author_name'  => [
				'enabled' => true,
				'weight'  => 1,
			],
		];

		$post_type_taxonomies = get_object_taxonomies( $post_type );

		/**
		 * Filter install status
		 *
		 * Previous behavior had post_tag and category enabled by default, so if this is supported on the post type
		 * we add them as enabled by default
		 *
		 * @hook ep_weighting_default_enabled_taxonomies
		 * @param  {array}  $enabled_taxonomies Taxonomies that should be enabled by default
		 * @param  {string} $post_type          Post type slug
		 * @return {array}  New taxonomies
		 * @since  3.6.5
		 */
		$enabled_by_default = apply_filters( 'ep_weighting_default_enabled_taxonomies', [ 'post_tag', 'category' ], $post_type );

		foreach ( $enabled_by_default as $default_tax ) {
			if ( in_array( $default_tax, $post_type_taxonomies, true ) ) {
				$post_type_defaults[ 'terms.' . $default_tax . '.name' ] = [
					'enabled' => true,
					'weight'  => 1,
				];
			}
		}

		/**
		 * Filter weighting defaults for post type
		 *
		 * @hook ep_weighting_default_post_type_weights
		 * @param  {array} $post_type_defaults Current weighting defaults
		 * @param  {string} $post_type Current post type
		 * @return  {array} New defaults
		 */
		return apply_filters( 'ep_weighting_default_post_type_weights', $post_type_defaults, $post_type );
	}

	/**
	 * Returns the current weighting configuration
	 *
	 * @return array
	 */
	public function get_weighting_configuration() {
		/**
		 * Filter weighting configuration
		 *
		 * @hook ep_weighting_configuration
		 * @param  {array} $config Current configuration
		 * @return  {array} New configuration
		 */
		return apply_filters( 'ep_weighting_configuration', get_option( 'elasticpress_weighting', [] ) );
	}

	/**
	 * Returns the current weighting configuration with defaults for any
	 * missing fields.
	 *
	 * @return array Current weighting configuration with defaults.
	 * @since 5.0.0
	 */
	public function get_weighting_configuration_with_defaults() {
		$search = Features::factory()->get_registered_feature( 'search' );

		$post_types = $search->get_searchable_post_types();
		$weighting  = $this->get_weighting_configuration();

		foreach ( $post_types as $post_type ) {
			$current  = isset( $weighting[ $post_type ] ) ? $weighting[ $post_type ] : [];
			$defaults = $this->get_post_type_default_settings( $post_type );

			$weighting[ $post_type ] = wp_parse_args( $current, $defaults );
		}

		return $weighting;
	}

	/**
	 * Returns the current meta mode.
	 *
	 * @return array
	 * @since 5.0.0
	 */
	public function get_meta_mode() {
		/**
		 * Filter meta management mode.
		 *
		 * Setting the meta mode to 'auto' will restore the pre-5.0.0 behavior
		 * of syncing all public meta fields, but without the ability to
		 * add fields to make them searchable through the UI. Weighting settings
		 * will need to be changed, and a sync performed, any time this value
		 * is changed.
		 *
		 * @hook ep_meta_mode
		 * @since 5.0.0
		 * @param string $ep_meta_mode Meta mode.
		 * @return string New meta mode.
		 */
		return apply_filters( 'ep_meta_mode', 'manual' );
	}

	/**
	 * Adds the submenu page for controlling weighting
	 */
	public function add_weighting_submenu_page() {
		$menu_slug = ( defined( 'EP_IS_NETWORK' ) && EP_IS_NETWORK && ! Utils\is_top_level_admin_context() ) ?
			'elasticpress' :
			'elasticpress-weighting';

		add_submenu_page(
			'elasticpress',
			esc_html__( 'ElasticPress Search Fields & Weighting', 'elasticpress' ),
			esc_html__( 'Search Fields & Weighting', 'elasticpress' ),
			Utils\get_capability(),
			$menu_slug,
			[ $this, 'render_settings_page' ]
		);
	}

	/**
	 * Renders the settings page that controls weighting
	 */
	public function render_settings_page() {
		include EP_PATH . '/includes/partials/header.php'; ?>
		<div class="wrap">
			<div id="ep-weighting-screen"></div>
		</div>
		<?php
	}

	/**
	 * Recursively renders each settings section and its children.
	 *
	 * @param string $post_type      Current post type we're rendering
	 * @param array  $field          Current field to render
	 * @param array  $current_values Current stored weighting values
	 * @deprecated
	 */
	public function render_settings_section( $post_type, $field, $current_values ) {
		_doing_it_wrong(
			__METHOD__,
			esc_html( 'Weighting sections display are now handled via React components.' ),
			'ElasticPress 5.0.0'
		);
	}

	/**
	 * Handles processing the new weighting values and saving them
	 * to the elasticpress.io service.
	 *
	 * @deprecated
	 */
	public function handle_save() {
		_doing_it_wrong(
			__METHOD__,
			esc_html( 'Weighting settings are now updated using the REST API.' ),
			'ElasticPress 5.0.0'
		);
	}

	/**
	 * We need this method to test handle_save properly.
	 *
	 * @param string $redirect_url Redirect URL.
	 * @deprecated
	 */
	protected function redirect( $redirect_url ) {
		_doing_it_wrong(
			__METHOD__,
			esc_html( 'Weighting settings are now updated using the REST API, and do not redirect server-side.' ),
			'ElasticPress 5.0.0'
		);
	}

	/**
	 * Save weighting configuration for each searchable post_type.
	 *
	 * @param array $settings weighting settings
	 * @return void
	 * @since 3.4.1
	 * @deprecated
	 */
	public function save_weighting_configuration( $settings ) {
		_doing_it_wrong(
			__METHOD__,
			esc_html( 'Weighting sections display are now handled via React components.' ),
			'ElasticPress 5.0.0'
		);
	}

	/**
	 * Register REST routes.
	 *
	 * @return void
	 * @since 5.0.0
	 */
	public function register_rest_routes() {
		register_rest_route(
			'elasticpress/v1',
			'weighting',
			[
				'callback'            => [ $this, 'update_weighting' ],
				'methods'             => 'POST',
				'permission_callback' => function() {
					return current_user_can( Utils\get_capability() );
				},
			]
		);
	}

	/**
	 * Handles processing the new weighting values and saving them.
	 *
	 * @param \WP_Rest_Request $request REST API request.
	 * @return array
	 * @since 5.0.0
	 */
	public function update_weighting( $request = null ) {
		$meta_mode = $this->get_meta_mode();
		$weighting = $request->get_json_params();

		$post_types = Features::factory()->get_registered_feature( 'search' )->get_searchable_post_types();

		// Add default fields for post types not sent.
		foreach ( $post_types as $post_type ) {
			if ( ! isset( $weighting[ $post_type ] ) ) {
				$weighting[ $post_type ] = [];
			}
		}

		/**
		 * If metadata is not being managed manually, remove any custom
		 * fields that have not been registered as weightable fields.
		 */
		if ( 'manual' !== $meta_mode ) {
			foreach ( $weighting as $post_type => $fields ) {
				$weightable_fields = $this->get_weightable_fields_for_post_type( $post_type );

				foreach ( $fields as $key => $value ) {
					$is_weightable = false;

					foreach ( $weightable_fields as $group ) {
						if ( isset( $group['children'][ $key ] ) ) {
							$is_weightable = true;
							continue;
						}
					}

					if ( ! $is_weightable ) {
						unset( $weighting[ $post_type ][ $key ] );
					}
				}
			}
		}

		// Cleanup any post type sent (or added via filters) that does not exist.
		foreach ( $weighting as $post_type => $fields ) {
			if ( ! post_type_exists( $post_type ) ) {
				unset( $weighting[ $post_type ] );
			}
		}

		update_option( 'elasticpress_weighting', $weighting );

		/**
		 * Fires right after the weighting configuration is saved.
		 *
		 * @since  3.5.x
		 * @hook ep_saved_weighting_configuration
		 */
		do_action( 'ep_saved_weighting_configuration' );

		return [
			'data'    => $weighting,
			'success' => true,
		];
	}

	/**
	 * Iterates through arrays in the formatted args to find "fields" and injects weighting values
	 *
	 * @param array $fieldset Current subset of formatted ES args
	 * @param array $weights  Weight configuration
	 */
	public function recursively_inject_weights_to_fields( &$fieldset, $weights ) {
		if ( ! is_array( $fieldset ) ) {
			return;
		}

		if ( is_array( $fieldset ) && isset( $fieldset['fields'] ) ) {
			// Add any fields to the search that aren't already in there (weighting handled in next step)
			foreach ( $weights as $field => $settings ) {
				if ( ! in_array( $field, $fieldset['fields'], true ) ) {
					$fieldset['fields'][] = $field;
				}
			}

			foreach ( $fieldset['fields'] as $key => $field ) {
				if ( isset( $weights[ $field ] ) && false !== $weights[ $field ]['enabled'] ) {
					$weight = (int) $weights[ $field ]['weight'];

					if ( 0 !== $weight ) {
						if ( 'author_name' === $field ) {
							$field = 'post_author.display_name';
						}

						/**
						 * Filter fields and their weitghting as used in the Elasticsearch query.
						 *
						 * @hook ep_query_weighting_fields
						 * @param  {string} $weighted_field The field and its weight as used in the ES query.
						 * @param  {string} $field          Field name
						 * @param  {string} $weight         Weight value
						 * @param  {array}  $fieldset       Current subset of formatted ES args
						 * @param  {array}  $weights        Weight configuration
						 * @return  {array} New weighted field string
						 *
						 * @since  3.5.5
						 */
						$fieldset['fields'][ $key ] = apply_filters(
							'ep_query_weighting_fields',
							"{$field}^{$weight}",
							$field,
							$weight,
							$fieldset,
							$weights
						);
					}
				} else {
					// this handles removing post_author.login field added in Post::format_args() if author search field has being disabled
					if ( 'author_name' === $field ) {
						$author_key = array_search( 'post_author.login', $fieldset['fields'], true );
						if ( false !== $author_key ) {
							unset( $fieldset['fields'][ $author_key ] );
						}
					}
					unset( $fieldset['fields'][ $key ] );
				}
				// else: Leave anything that isn't explicitly disabled alone. Could have been added by search_fields, and if it is not present in the UI, we shouldn't touch it here

				// If fieldset has fuzziness enabled and fuzziness is disabled for this field, unset the field
				if ( isset( $fieldset['fuzziness'] ) && $fieldset['fuzziness'] && isset( $weights[ $field ]['fuzziness'] ) && false === $weights[ $field ]['fuzziness'] ) {
					unset( $fieldset['fields'][ $key ] );
				}
			}

			// Reindex the array
			$fieldset['fields'] = array_values( $fieldset['fields'] );
		} else {
			foreach ( $fieldset as &$field ) {
				$this->recursively_inject_weights_to_fields( $field, $weights );
			}
		}

		// Most likely to occur with the ordering results not being allowed in fuzzy, and weighting turning off fields for this otherwise
		if ( isset( $fieldset['fields'] ) && empty( $fieldset['fields'] ) ) {
			$fieldset = null;
		}
	}

	/**
	 * Determine if a post type has any fields enabled for search
	 *
	 * @param string $post_type  Post Type
	 * @param array  $args       WP_Query args
	 * @return boolean true/false depending on any fields enabled == true
	 */
	public function post_type_has_fields( $post_type, $args = [] ) {
		$weight_config = $this->get_weighting_configuration();

		/**
		 * Filter weighting configuration for search
		 *
		 * @hook ep_weighting_configuration_for_search
		 * @param  {array} $weight_config Current weight config
		 * @param  {array} $args WP Query arguments
		 * @return  {array} New configuration
		 */
		$weight_config = apply_filters( 'ep_weighting_configuration_for_search', $weight_config, $args );

		if ( ! isset( $weight_config[ $post_type ] ) ) {
			$weights = $this->get_post_type_default_settings( $post_type );
		} else {
			$weights = $weight_config[ $post_type ];
		}

		/**
		 * Filter fields considered in weighting
		 *
		 * Define keys which are irrelevant for this consideration, like `terms.ep_custom_result.name`.
		 *
		 * @hook ep_weighting_ignore_fields_in_consideration
		 * @param  {array} $fields Current fields
		 * @return  {array} New fields
		 */
		$ignore_keys = apply_filters( 'ep_weighting_ignore_fields_in_consideration', [ 'terms.ep_custom_result.name' => true ] );
		$fields      = array_diff_key( $weights, $ignore_keys );

		$found_enabled = false;
		foreach ( $fields as $field ) {
			if ( filter_var( $field['enabled'], FILTER_VALIDATE_BOOLEAN ) ) {
				$found_enabled = true;
				break;
			}
		}

		return $found_enabled;
	}

	/**
	 * Adjusts the query for configured weighting values
	 *
	 * @param array $formatted_args Formatted ES args
	 * @param array $args           WP_Query args
	 *
	 * @return array Formatted ES args
	 */
	public function do_weighting( $formatted_args, $args ) {

		/**
		 * If search fields is set on the query, we should use those instead of the weighting, since the query was
		 * overridden by some custom code
		 */
		if ( isset( $args['search_fields'] ) && ! empty( $args['search_fields'] ) ) {
			return $formatted_args;
		}

		$weight_config = $this->get_weighting_configuration();

		/**
		 * Filter weighting configuration for search
		 *
		 * @hook ep_weighting_configuration_for_search
		 * @param  {array} $weight_config Current weight config
		 * @param  {array} $args WP Query arguments
		 * @return  {array} New configuration
		 */
		$weight_config = apply_filters( 'ep_weighting_configuration_for_search', $weight_config, $args );

		$should_do_weighting = Utils\is_integrated_request( 'weighting', [ 'public', 'rest' ] ) && ! empty( $args['s'] );

		/**
		 * Filter whether to enable weighting configuration
		 *
		 * @hook ep_enable_do_weighting
		 * @since 4.2.2
		 * @param  {bool}  Whether to enable weight config, defaults to true for search requests that are public or REST
		 * @param  {array} $weight_config Current weight config
		 * @param  {array} $args WP Query arguments
		 * @param  {array} $formatted_args Formatted ES arguments
		 * @return  {bool} Whether to use weighting configuration
		 */
		if ( apply_filters( 'ep_enable_do_weighting', $should_do_weighting, $weight_config, $args, $formatted_args ) ) {
			$formatted_args = $this->apply_weighting( $formatted_args, $args, $weight_config );
		}

		return $formatted_args;
	}

	/**
	 * Applies weighting based on ES args
	 *
	 * @since 4.2.2
	 * @param array $formatted_args Formatted ES args
	 * @param array $args WP_Query args
	 * @param array $weight_config Weight configuration to apply
	 *
	 * @return array $formatted_args Formatted ES args with weightings applied
	 */
	protected function apply_weighting( $formatted_args, $args, $weight_config ) {
		/*
		 * This section splits up the single query clause for all post types into separate nested clauses (one for each post type)
		 * which then get combined into one result set. By having separate clauses for each post type, we can then
		 * weight fields such as post_title per post type so that we can have fine grained control over weights by post
		 * type, rather than globally on the query
		*/
		$new_query = [
			'bool' => [
				'should' => [],
			],
		];

		// grab the query and keep track of whether or not it is nested in a function score
		$function_score = isset( $formatted_args['query']['function_score'] );
		$query          = $function_score ? $formatted_args['query']['function_score']['query'] : $formatted_args['query'];

		foreach ( (array) $args['post_type'] as $post_type ) {
			if ( false === $this->post_type_has_fields( $post_type, $args ) ) {
				continue;
			}
			// Copy the query, so we can set specific weight values
			$current_query = $query;

			if ( isset( $weight_config[ $post_type ] ) ) {
				// Find all "fields" values and inject weights for the current post type
				$this->recursively_inject_weights_to_fields( $current_query, $weight_config[ $post_type ] );
			} else {
				// Use the default values for the post type
				$this->recursively_inject_weights_to_fields( $current_query, $this->get_post_type_default_settings( $post_type ) );
			}

			// Check for any segments with null fields from recursively_inject function and remove them
			if ( isset( $current_query['bool'] ) && isset( $current_query['bool']['should'] ) ) {
				foreach ( $current_query['bool']['should'] as $index => $current_bool_should ) {
					if ( isset( $current_bool_should['multi_match'] ) && null === $current_bool_should['multi_match'] ) {
						unset( $current_query['bool']['should'][ $index ] );
					}
				}
			}

			/**
			 * Filter weighting query for a post type
			 *
			 * @hook ep_weighted_query_for_post_type
			 * @param  {array} $query Weighting query
			 * @param  {string} $post_type Post type
			 * @param  {array} $args WP Query arguments
			 * @return  {array} New query
			 */
			$new_query['bool']['should'][] = apply_filters(
				'ep_weighted_query_for_post_type',
				[
					'bool' => [
						'must'   => [
							$current_query,
						],
						'filter' => [
							[
								'match' => [
									'post_type.raw' => $post_type,
								],
							],
						],
					],
				],
				$post_type,
				$args
			);
		}

		// put the new query back in the correct location
		if ( $function_score ) {
			$formatted_args['query']['function_score']['query'] = $new_query;
		} else {
			$formatted_args['query'] = $new_query;
		}

		/**
		 * Hook after weighting is added to Elasticsearch query
		 *
		 * @hook ep_weighting_added
		 * @param  {array} $formatted_args Elasticsearch query
		 * @param  {array} $args WP Query arguments
		 */
		do_action( 'ep_weighting_added', $formatted_args, $args );

		return $formatted_args;
	}

	/**
	 * Adjust weighting when the type is cross_fields, as it just works with weight = 1.
	 *
	 * @since 4.0.0
	 *
	 * @param string $weighted_field The field and its weight as used in the ES query.
	 * @param string $field          Field name
	 * @param string $weight         Weight value
	 * @param array  $fieldset       Current subset of formatted ES args
	 * @return array New weighted field string
	 */
	public function adjust_weight_for_cross_fields( $weighted_field, $field, $weight, $fieldset ) {
		if ( ! empty( $fieldset['type'] ) && 'cross_fields' === $fieldset['type'] ) {
			$weighted_field = "{$field}^1";
		}
		return $weighted_field;
	}
}