<?php
/**
 * Diff set.
 *
 * @package Recast\WCS
 */

namespace Recast\WCS\Diff;

defined( 'ABSPATH' ) || exit;

/**
 * Result of a pure compute_diff(): predicted changes, warnings, and before/after state.
 */
final class DiffSet {

	/**
	 * Changes.
	 *
	 * @var FieldDiff[]
	 */
	public $changes = array();

	/**
	 * Warnings: [{code, message}].
	 *
	 * @var array<int, array{code: string, message: string}>
	 */
	public $warnings = array();

	/**
	 * When set, the subscription is skipped (status 'invalid') with this code.
	 *
	 * @var string|null
	 */
	public $skip_reason = null;

	/**
	 * Human message for the skip reason.
	 *
	 * @var string|null
	 */
	public $skip_message = null;

	/**
	 * State before (fingerprint fields).
	 *
	 * @var array<string, mixed>
	 */
	public $before_state = array();

	/**
	 * Predicted state after.
	 *
	 * @var array<string, mixed>
	 */
	public $after_state = array();

	/**
	 * Adds a change if before and after differ.
	 *
	 * @param string      $field     Field.
	 * @param mixed       $before    Before.
	 * @param mixed       $after     After.
	 * @param string|null $item_name Item name.
	 * @return void
	 */
	public function change( $field, $before, $after, $item_name = null ) {
		if ( wp_json_encode( $before ) === wp_json_encode( $after ) ) {
			return;
		}
		$this->changes[] = new FieldDiff( $field, $before, $after, $item_name );
	}

	/**
	 * Adds a warning.
	 *
	 * @param string $code    Code.
	 * @param string $message Message.
	 * @return void
	 */
	public function warn( $code, $message ) {
		$this->warnings[] = array(
			'code'    => $code,
			'message' => $message,
		);
	}

	/**
	 * Marks the subscription as not applicable.
	 *
	 * @param string $code    Code.
	 * @param string $message Message.
	 * @return void
	 */
	public function skip( $code, $message ) {
		$this->skip_reason  = $code;
		$this->skip_message = $message;
	}

	/**
	 * Whether any change is predicted.
	 *
	 * @return bool
	 */
	public function has_changes() {
		return ! empty( $this->changes );
	}

	/**
	 * Whether the subscription must be skipped.
	 *
	 * @return bool
	 */
	public function is_skipped() {
		return null !== $this->skip_reason;
	}

	/**
	 * Fields with predicted changes.
	 *
	 * @return string[]
	 */
	public function changed_fields() {
		return array_map(
			static function ( FieldDiff $diff ) {
				return $diff->field;
			},
			$this->changes
		);
	}

	/**
	 * Array form of the changes for storage.
	 *
	 * @return array<int, array<string, mixed>>
	 */
	public function changes_to_array() {
		return array_map(
			static function ( FieldDiff $diff ) {
				return $diff->to_array();
			},
			$this->changes
		);
	}
}