<?php
/**
 * Templates registry functions.
 *
 * @package WordPress
 * @since 6.7.0
 */

/**
 * Core class used for interacting with templates.
 *
 * @since 6.7.0
 */
final class WP_Block_Templates_Registry {
    /**
     * Registered templates, as `$name => $instance` pairs.
     *
     * @since 6.7.0
     * @var WP_Block_Template[] $registered_block_templates Registered templates.
     */
    private $registered_templates = array();

    /**
     * Container for the main instance of the class.
     *
     * @since 6.7.0
     * @var WP_Block_Templates_Registry|null
     */
    private static $instance = null;

    /**
     * Registers a template.
     *
     * @since 6.7.0
     *
     * @param string $template_name Template name including namespace.
     * @param array  $args          Optional. Array of template arguments.
     * @return WP_Block_Template|WP_Error The registered template on success, or WP_Error on failure.
     */
    public function register( $template_name, $args = array() ) {

        $template = null;

        $error_message = '';
        $error_code    = '';

        if ( ! is_string( $template_name ) ) {
            $error_message = __( 'Template names must be strings.' );
            $error_code    = 'template_name_no_string';
        } elseif ( preg_match( '/[A-Z]+/', $template_name ) ) {
            $error_message = __( 'Template names must not contain uppercase characters.' );
            $error_code    = 'template_name_no_uppercase';
        } elseif ( ! preg_match( '/^[a-z0-9_\-]+\/\/[a-z0-9_\-]+$/', $template_name ) ) {
            $error_message = __( 'Template names must contain a namespace prefix. Example: my-plugin//my-custom-template' );
            $error_code    = 'template_no_prefix';
        } elseif ( $this->is_registered( $template_name ) ) {
            /* translators: %s: Template name. */
            $error_message = sprintf( __( 'Template "%s" is already registered.' ), $template_name );
            $error_code    = 'template_already_registered';
        }

        if ( $error_message ) {
            _doing_it_wrong( __METHOD__, $error_message, '6.7.0' );

            return new WP_Error( $error_code, $error_message );
        }

        if ( ! $template ) {
            $theme_name             = get_stylesheet();
            list( $plugin, $slug )  = explode( '//', $template_name );
            $default_template_types = get_default_block_template_types();

            $template              = new WP_Block_Template();
            $template->id          = $theme_name . '//' . $slug;
            $template->theme       = $theme_name;
            $template->plugin      = $plugin;
            $template->author      = null;
            $template->content     = $args['content'] ?? '';
            $template->source      = 'plugin';
            $template->slug        = $slug;
            $template->type        = 'wp_template';
            $template->title       = $args['title'] ?? $template_name;
            $template->description = $args['description'] ?? '';
            $template->status      = 'publish';
            $template->origin      = 'plugin';
            $template->is_custom   = ! isset( $default_template_types[ $template_name ] );
            $template->post_types  = $args['post_types'] ?? array();
        }

        $this->registered_templates[ $template_name ] = $template;

        return $template;
    }

    /**
     * Retrieves all registered templates.
     *
     * @since 6.7.0
     *
     * @return WP_Block_Template[] Associative array of `$template_name => $template` pairs.
     */
    public function get_all_registered() {
        return $this->registered_templates;
    }

    /**
     * Retrieves a registered template by its name.
     *
     * @since 6.7.0
     *
     * @param string $template_name Template name including namespace.
     * @return WP_Block_Template|null The registered template, or null if it is not registered.
     */
    public function get_registered( $template_name ) {
        if ( ! $this->is_registered( $template_name ) ) {
            return null;
        }

        return $this->registered_templates[ $template_name ];
    }

    /**
     * Retrieves a registered template by its slug.
     *
     * @since 6.7.0
     *
     * @param string $template_slug Slug of the template.
     * @return WP_Block_Template|null The registered template, or null if it is not registered.
     */
    public function get_by_slug( $template_slug ) {
        $all_templates = $this->get_all_registered();

        if ( ! $all_templates ) {
            return null;
        }

        foreach ( $all_templates as $template ) {
            if ( $template->slug === $template_slug ) {
                return $template;
            }
        }

        return null;
    }

    /**
     * Retrieves registered templates matching a query.
     *
     * @since 6.7.0
     *
     * @param array  $query {
     *     Arguments to retrieve templates. Optional, empty by default.
     *
     *     @type string[] $slug__in     List of slugs to include.
     *     @type string[] $slug__not_in List of slugs to skip.
     *     @type string   $post_type    Post type to get the templates for.
     * }
     * @return WP_Block_Template[] Associative array of `$template_name => $template` pairs.
     */
    public function get_by_query( $query = array() ) {
        $all_templates = $this->get_all_registered();

        if ( ! $all_templates ) {
            return array();
        }

        $query            = wp_parse_args(
            $query,
            array(
                'slug__in'     => array(),
                'slug__not_in' => array(),
                'post_type'    => '',
            )
        );
        $slugs_to_include = $query['slug__in'];
        $slugs_to_skip    = $query['slug__not_in'];
        $post_type        = $query['post_type'];

        $matching_templates = array();
        foreach ( $all_templates as $template_name => $template ) {
            if ( $slugs_to_include && ! in_array( $template->slug, $slugs_to_include, true ) ) {
                continue;
            }

            if ( $slugs_to_skip && in_array( $template->slug, $slugs_to_skip, true ) ) {
                continue;
            }

            if ( $post_type && ! in_array( $post_type, $template->post_types, true ) ) {
                continue;
            }

            $matching_templates[ $template_name ] = $template;
        }

        return $matching_templates;
    }

    /**
     * Checks if a template is registered.
     *
     * @since 6.7.0
     *
     * @param string|null $template_name Template name.
     * @return bool True if the template is registered, false otherwise.
     */
    public function is_registered( $template_name ) {
        return isset( $template_name, $this->registered_templates[ $template_name ] );
    }

    /**
     * Unregisters a template.
     *
     * @since 6.7.0
     *
     * @param string $template_name Template name including namespace.
     * @return WP_Block_Template|WP_Error The unregistered template on success, or WP_Error on failure.
     */
    public function unregister( $template_name ) {
        if ( ! $this->is_registered( $template_name ) ) {
            /* translators: %s: Template name. */
            $error_message = sprintf( __( 'Template "%s" is not registered.' ), $template_name );

            _doing_it_wrong( __METHOD__, $error_message, '6.7.0' );

            return new WP_Error( 'template_not_registered', $error_message );
        }

        $unregistered_template = $this->registered_templates[ $template_name ];
        unset( $this->registered_templates[ $template_name ] );

        return $unregistered_template;
    }

    /**
     * Utility method to retrieve the main instance of the class.
     *
     * The instance will be created if it does not exist yet.
     *
     * @since 6.7.0
     *
     * @return WP_Block_Templates_Registry The main instance.
     */
    public static function get_instance() {
        if ( null === self::$instance ) {
            self::$instance = new self();
        }

        return self::$instance;
    }
}