<?php
/**
 * Customer tags.
 *
 * @package HostKhata
 */

namespace HostKhata\Domain\Customers;

defined( 'ABSPATH' ) || exit;

/**
 * Normalises customer tags and converts them to and from the storage format.
 *
 * Tags are stored in one column as `,vip,reseller,` (a comma on both ends), so
 * a tag filter can use `LIKE '%,vip,%'` without matching `vip2`.
 *
 * @since 0.1.0
 */
final class Tags {

	const MAX_TAGS   = 20;
	const MAX_LENGTH = 30;

	/**
	 * Turns user input (array or comma separated string) into a clean list.
	 *
	 * Tags are lower case, limited to letters, numbers, hyphen and underscore,
	 * unique, and capped in number and length.
	 *
	 * @since 0.1.0
	 *
	 * @param mixed $input Raw tags.
	 * @return string[]
	 */
	public static function parse( $input ): array {
		if ( is_string( $input ) ) {
			$input = explode( ',', $input );
		}

		if ( ! is_array( $input ) ) {
			return array();
		}

		$tags = array();

		foreach ( $input as $tag ) {
			if ( ! is_scalar( $tag ) ) {
				continue;
			}

			$tag = mb_strtolower( trim( (string) $tag ) );
			$tag = (string) preg_replace( '/[^\p{L}\p{M}\p{N}\-_ ]/u', '', $tag );
			$tag = (string) preg_replace( '/\s+/u', '-', trim( $tag ) );
			$tag = mb_substr( $tag, 0, self::MAX_LENGTH );

			if ( '' !== $tag && ! in_array( $tag, $tags, true ) ) {
				$tags[] = $tag;
			}

			if ( count( $tags ) >= self::MAX_TAGS ) {
				break;
			}
		}

		return $tags;
	}

	/**
	 * Converts a list to the column format.
	 *
	 * @since 0.1.0
	 *
	 * @param string[] $tags Clean tags.
	 * @return string
	 */
	public static function to_storage( array $tags ): string {
		return array() === $tags ? '' : ',' . implode( ',', $tags ) . ',';
	}

	/**
	 * Converts the column value back to a list.
	 *
	 * @since 0.1.0
	 *
	 * @param string $stored Column value.
	 * @return string[]
	 */
	public static function from_storage( string $stored ): array {
		return array_values( array_filter( explode( ',', $stored ), 'strlen' ) );
	}
}