Filters
#######

Plugin defines many WordPress filters to make it easily extendable:

+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| Filter tag                                        | Occurance                                                        | Arguments                                                                     |
+===================================================+==================================================================+===============================================================================+
| ``horizon_listing_type_supported``                | In listing types configuration, submission                       | supported [bool], post type [string]                                          |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_listing_detail_sections``               | In listing detail                                                | sections [array], post type [string]                                          |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_listing_detail_section_root_dir``       | In listing detail                                                | path to templates dir [string], section [string]                              |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_attribute_value``                       | In listing detail                                                | value [string], field [array]                                                 |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_mail_subject``                          | In notifications, claim and report listing emails                | subject [string], mail action [string], template arguments [array]            |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_mail_body``                             | In notifications, claim listing emails                           | body [string], mail action [string], template arguments [array]               |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_billing_fields``                        | In payments, user profile                                        | billing fields [array]                                                        |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_invoices_types``                        | In invoice post type definition                                  | invoice types [array]                                                         |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_invoices_next_invoice_number``          | When generating the very next invoice number                     | next number [string]                                                          |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_invoices_tax_rate``                     | When calculating item base price                                 | tax rate [double], supplier vat number [string], customer vat number [string] |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_mail_actions_choices``                  | In definition of mail templates                                  | actions [array]                                                               |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_filter_fields``                         | In filter definition                                             | fields [array]                                                                |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+ 
| ``horizon_order_query``                           | In query filtering to set order                                  | query [object], params [array]                                                |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_filter_query``                          | In query filtering to filter posts by ids                        | ids [array], params[array]                                                    |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_currencies_current_currency_index``     | When receiving current currency                                  | currency index [int]                                                          |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_currencies_current_currency_rate``      | When receiving current currency rate                             | currency rate [double]                                                        |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_package_durations``                     | In package system                                                | package durations [array]                                                     |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_payment_proceed_gateway``               | In payment gateway definition                                    | proceed [bool], gateway [string]                                              |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_payment_gateways``                      | In purchase form                                                 | gateways [array]                                                              |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_claims_allowed_listing_post_types``     | In listing detail                                                | allowed post types [array]                                                    |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_shop_allowed_listing_post_types``       | In listing detail                                                | allowed post types [array]                                                    |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_filter_field_plugin_dir``               | In filter form to set field plugin directory for template loader | directory [string], template [string]                                         |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_filter_sort_by_choices``                | In filter form                                                   | sorting choices [array]                                                       | 
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_submission_can_user_create``            | In submission                                                    | permission granted [bool], user id [int]                                      | 
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_metabox_location_polygon_enabled``      | In post type definition (and submission)                         | enabled [bool], post type [string]                                            |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_metabox_location_street_view_enabled``  | In post type definition (and submission)                         | enabled [bool], post type [string]                                            |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+
| ``horizon_metabox_location_inside_view_enabled``  | In post type definition (and submission)                         | enabled [bool], post type [string]                                            |
+---------------------------------------------------+------------------------------------------------------------------+-------------------------------------------------------------------------------+

Each filter can be applied in your code using standard WordPress way, using `apply_filters()`_ function:

.. _`apply_filters()`: https://codex.wordpress.org/Function_Reference/apply_filters

.. code-block:: php

    apply_filters( $filter_tag, $arg1, $arg2 ... );


To hook on filter, use `add_filter()`_ WP function:

.. _`add_filter()`: https://codex.wordpress.org/Function_Reference/add_filter

.. code-block:: php

    add_filter( $filter_tag, $callback, $priority = 10, $accepted_args = 1 );