<?php

namespace AdPresso\Fields;

/**
 * Abstract class for managing and registering fields for the entities.
 */
abstract class AbstractFieldRegistry {
	protected static ?self $instance = null;

	protected array $base_fields = [];
	protected array $type_fields = [];
	protected bool  $initialized = false;

	/**
	 * @return void
	 */
	abstract protected function load_default_fields(): void;

	/**
	 * @return self
	 */
	public static function get(): self {
		if ( static::$instance === null ) {
			static::$instance = new static();
		}
		return static::$instance;
	}

	protected function __construct() {
		if ( ! $this->initialized ) {
			$this->load_default_fields();
			$this->initialized = true;
		}
	}

	/**
	 * Get the base fields that are always available.
	 *
	 * @return array
	 */
	public function get_base_fields(): array {
		return $this->base_fields;
	}

	/**
	 * Registers fields that come from a specific type.
	 *
	 * @param string $type_id
	 * @param array  $fields
	 *
	 * @return void
	 */
	public function register_type_fields( string $type_id, array $fields ): void {
		$this->type_fields[ $type_id ] = array_merge(
			$this->type_fields[ $type_id ] ?? [],
			$fields
		);
	}

	/**
	 * IDs of every base or type field that stores raw code (sanitize_type 'custom_code').
	 *
	 * @return string[]
	 */
	public function get_custom_code_field_ids(): array {
		$fields = array_merge( $this->base_fields, ...array_values( $this->type_fields ) );
		$ids    = [];
		foreach ( $fields as $field ) {
			if ( ( $field['sanitize_type'] ?? '' ) === 'custom_code' && ! empty( $field['id'] ) ) {
				$ids[] = $field['id'];
			}
		}

		return array_values( array_unique( $ids ) );
	}

	public function get_fields_for_type( ?string $type_id = null, bool $include_global = false ): array {
		$fields = $include_global ? $this->base_fields : [];

		if ( is_null( $type_id ) ) {
			return $fields;
		}

		if ( isset( $this->type_fields[ $type_id ] ) ) {
			$fields = array_merge( $fields, $this->type_fields[ $type_id ] );
		}

		return $fields;
	}

	/**
	 * Get fields for a specific type, optionally including global base fields.
	 *
	 * @param string|null $type_id
	 * @param bool        $include_global
	 *
	 * @return array
	 */
	public function get_fields_for_type_filtered( ?string $type_id = null, bool $include_global = false ): array {
		$fields = $this->get_fields_for_type( $type_id, $include_global );

		/**
		 * Filters the list of fields for a specific placement type.
		 *
		 * @param array  $fields  The list of field definitions.
		 * @param string $type_id The ID of the placement type (e.g. 'content').
		 */
		return apply_filters( 'adpresso_placement_type_fields', $fields, $type_id );
	}
}