<?php
/**
 * Tags on stored entries.
 *
 * @package TFlexForms
 */

declare( strict_types = 1 );

namespace TFlexForms;

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

/**
 * Free-form labels such as "follow up" or "VIP". A tag is plain text of up to
 * 50 characters without commas; an entry has at most 20.
 *
 * phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Custom table; results are request-specific.
 */
final class Entry_Tags {

	public const MAX_LENGTH = 50;
	public const MAX_TAGS   = 20;

	/**
	 * Cleans a list of tags: plain text, no commas, single spaces, at most
	 * MAX_LENGTH characters, duplicates (ignoring case) removed.
	 *
	 * @param string|string[] $tags Comma-separated string or list.
	 * @return string[]
	 */
	public static function sanitize( $tags ): array {
		$list = is_array( $tags ) ? $tags : explode( ',', (string) $tags );
		$out  = array();
		foreach ( $list as $tag ) {
			$tag = sanitize_text_field( str_replace( ',', ' ', (string) $tag ) );
			$tag = trim( mb_substr( (string) preg_replace( '/\s+/u', ' ', $tag ), 0, self::MAX_LENGTH ) );
			$key = mb_strtolower( $tag );
			if ( '' !== $tag && ! isset( $out[ $key ] ) ) {
				$out[ $key ] = $tag;
			}
		}
		return array_slice( array_values( $out ), 0, self::MAX_TAGS );
	}

	/**
	 * Replaces an entry's tags.
	 *
	 * @param int             $entry_id Entry ID.
	 * @param string|string[] $tags     New tags.
	 * @return string[] The tags saved.
	 */
	public static function set( int $entry_id, $tags ): array {
		global $wpdb;
		$tags  = self::sanitize( $tags );
		$table = Database::table( 'entry_tags' );
		$wpdb->delete( $table, array( 'entry_id' => $entry_id ), array( '%d' ) );
		foreach ( $tags as $tag ) {
			// IGNORE: the database may treat two spellings as the same tag (for example "Café" and "cafe").
			$wpdb->query( $wpdb->prepare( 'INSERT IGNORE INTO %i (entry_id, tag) VALUES (%d, %s)', $table, $entry_id, $tag ) );
		}
		return self::for_entries( array( $entry_id ) )[ $entry_id ] ?? array();
	}

	/**
	 * Tags of several entries: entry ID => tags (alphabetical, ignoring case).
	 *
	 * @param int[] $ids Entry IDs.
	 * @return array<int,string[]>
	 */
	public static function for_entries( array $ids ): array {
		global $wpdb;
		$ids = array_values( array_filter( array_map( 'intval', $ids ) ) );
		if ( array() === $ids ) {
			return array();
		}
		$placeholders = implode( ',', array_fill( 0, count( $ids ), '%d' ) );
		// $placeholders is a list of %d markers; all values are bound by prepare().
		// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQLPlaceholders.UnfinishedPrepare, WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber
		$rows = $wpdb->get_results( $wpdb->prepare( "SELECT entry_id, tag FROM %i WHERE entry_id IN ({$placeholders})", array_merge( array( Database::table( 'entry_tags' ) ), $ids ) ) );
		$out  = array();
		foreach ( (array) $rows as $row ) {
			$out[ (int) $row->entry_id ][] = (string) $row->tag;
		}
		return array_map(
			static function ( array $tags ): array {
				usort( $tags, 'strnatcasecmp' );
				return $tags;
			},
			$out
		);
	}

	/**
	 * Every tag in use with its number of entries, alphabetical (ignoring case).
	 *
	 * @param int $limit Max tags.
	 * @return array<string,int>
	 */
	public static function all( int $limit = 200 ): array {
		global $wpdb;
		$rows = $wpdb->get_results( $wpdb->prepare( 'SELECT tag, COUNT(*) AS total FROM %i GROUP BY tag ORDER BY tag LIMIT %d', Database::table( 'entry_tags' ), $limit ) );
		$out  = array();
		foreach ( (array) $rows as $row ) {
			$out[ (string) $row->tag ] = (int) $row->total;
		}
		uksort( $out, 'strnatcasecmp' );
		return $out;
	}

	/**
	 * Removes an entry's tags (when the entry is deleted).
	 *
	 * @param int $entry_id Entry ID.
	 */
	public static function delete_for_entry( int $entry_id ): void {
		global $wpdb;
		$wpdb->delete( Database::table( 'entry_tags' ), array( 'entry_id' => $entry_id ), array( '%d' ) );
	}
}