<?php
/**
 * Attachment_Taxonomy_Default_Terms class
 *
 * @package AttachmentTaxonomies
 * @author Felix Arntz <felix-arntz@leaves-and-love.net>
 * @since 1.1.0
 */

if ( ! defined( 'ABSPATH' ) ) {
	die();
}

if ( class_exists( 'Attachment_Taxonomy_Default_Terms' ) ) {
	return;
}

/**
 * Handles default terms for taxonomies.
 *
 * @since 1.1.0
 */
final class Attachment_Taxonomy_Default_Terms {
	/**
	 * The Singleton instance.
	 *
	 * @since 1.1.0
	 * @static
	 * @var Attachment_Taxonomy_Default_Terms|null
	 */
	private static $instance = null;

	/**
	 * Returns the Singleton instance.
	 *
	 * @since 1.1.0
	 * @static
	 *
	 * @return Attachment_Taxonomy_Default_Terms The Singleton class instance.
	 */
	public static function instance() {
		if ( null === self::$instance ) {
			self::$instance = new self();
		}
		return self::$instance;
	}

	/**
	 * Constructor.
	 *
	 * @since 1.1.0
	 */
	private function __construct() {}

	/**
	 * Ensures the default term for each taxonomy that supports it is set on an attachment.
	 *
	 * @since 1.1.0
	 *
	 * @param int $attachment_id Attachment ID.
	 */
	public function ensure_default_attachment_taxonomy_terms( $attachment_id ) {
		$attachment = get_post( $attachment_id );
		if ( 'attachment' !== $attachment->post_type || 'auto-draft' === $attachment->post_status ) {
			return;
		}

		foreach ( Attachment_Taxonomies_Core::instance()->get_taxonomies( 'objects' ) as $taxonomy ) {
			if ( 'category' !== $taxonomy->name && ( ! isset( $taxonomy->has_default ) || ! $taxonomy->has_default ) ) {
				continue;
			}

			$default_term = get_option( 'default_' . $taxonomy->name );
			if ( empty( $default_term ) ) {
				continue;
			}

			$terms = wp_get_post_terms( $attachment_id, $taxonomy->name, array(
				'fields'                 => 'ids',
				'update_term_meta_cache' => false,
			) );
			if ( is_wp_error( $terms ) ) {
				continue;
			}

			if ( ! empty( $terms ) ) {
				continue;
			}

			wp_set_post_terms( $attachment_id, array( (int) $default_term ), $taxonomy->name );
		}
	}

	/**
	 * Registers settings for each taxonomy that supports a default term.
	 *
	 * @since 1.1.0
	 */
	public function register_settings() {
		foreach ( Attachment_Taxonomies_Core::instance()->get_taxonomies( 'objects' ) as $taxonomy ) {
			if ( ! isset( $taxonomy->has_default ) || ! $taxonomy->has_default ) {
				continue;
			}

			if ( 'category' === $taxonomy->name ) {
				continue;
			}

			$label = $this->get_taxonomy_label_for_setting( $taxonomy );

			register_setting( 'writing', 'default_' . $taxonomy->name, array(
				'type'              => 'integer',
				/* translators: %s: taxonomy label */
				'description'       => sprintf( _x( 'Default %s.', 'REST API description', 'attachment-taxonomies' ), $label ),
				'sanitize_callback' => 'absint',
				'show_in_rest'      => true,
				'default'           => 0,
			) );
		}
	}

	/**
	 * Adds settings fields for each taxonomy that supports a default term.
	 *
	 * @since 1.1.0
	 */
	public function add_settings_fields() {
		foreach ( Attachment_Taxonomies_Core::instance()->get_taxonomies( 'objects' ) as $taxonomy ) {
			if ( ! isset( $taxonomy->has_default ) || ! $taxonomy->has_default ) {
				continue;
			}

			if ( 'category' === $taxonomy->name ) {
				continue;
			}

			$label = $this->get_taxonomy_label_for_setting( $taxonomy );

			/* translators: %s: taxonomy label */
			$title = sprintf( _x( 'Default %s', 'settings field title', 'attachment-taxonomies' ), $label );

			add_settings_field( 'default_' . $taxonomy->name, $title, array( $this, 'render_settings_field' ), 'writing', 'default', array(
				'label_for' => 'default_' . $taxonomy->name,
				'taxonomy'  => $taxonomy,
			) );
		}
	}

	/**
	 * Renders a default term settings field.
	 *
	 * @since 1.1.0
	 *
	 * @param array $args {
	 *     Settings field arguments.
	 *
	 *     @type string      $label_for 'for' attribute for the field label.
	 *     @type WP_Taxonomy $taxonomy  Taxonomy for which to render the field.
	 * }
	 */
	public function render_settings_field( $args ) {
		$taxonomy = $args['taxonomy'];

		wp_dropdown_categories( array(
			'id'                => ! empty( $args['label_for'] ) ? $args['label_for'] : 'default_' . $taxonomy->name,
			'name'              => 'default_' . $taxonomy->name,
			'value_field'       => 'term_id',
			'selected'          => get_option( 'default_' . $taxonomy->name ),
			'taxonomy'          => $taxonomy->name,
			'hierarchical'      => $taxonomy->hierarchical,
			'hide_empty'        => false,
			'orderby'           => 'name',
			'order'             => 'ASC',
			'show_option_none'  => _x( 'None', 'default term dropdown', 'attachment-taxonomies' ),
			'option_none_value' => 0,
		) );
	}

	/**
	 * Returns the taxonomy label to use for its setting.
	 *
	 * @since 1.1.0
	 *
	 * @param WP_Taxonomy $taxonomy Taxonomy object.
	 * @return string Taxonomy label.
	 */
	private function get_taxonomy_label_for_setting( $taxonomy ) {
		if ( 'attachment_category' === $taxonomy->name ) {
			return __( 'Attachment Category', 'attachment-taxonomies' );
		}

		if ( 'attachment-tag' === $taxonomy->name ) {
			return __( 'Attachment Tag', 'attachment-taxonomies' );
		}

		return $taxonomy->labels->singular_name;
	}
}