<?php
namespace Relay\Multisite;

use Relay\Database\Db;
use Relay\Remote\Client;
use Relay\Support\RelayError;

/**
 * Who joins a network before a pull or push into one of its subsites runs (spec 2026-10-16 §5.5): merged accounts,
 * renames, new accounts and the roles that go. The side that has the people sends their logins and emails; the
 * network works it out without changing anything.
 */
final class MergePreview
{
    private Db $db;
    private Client $client;

    public function __construct(Db $db, Client $client)
    {
        $this->db = $db;
        $this->client = $client;
    }

    /**
     * A pull into a subsite of this network ($subsite, or 0 for a new one) from the other site (a subsite of it when
     * $remote_subsite > 0).
     *
     * @return array{merged: array[], renamed: array[], created: int, removed: string[], total: int}
     */
    public function pull(array $connection, int $subsite, int $remote_subsite): array
    {
        if (!is_multisite()) {
            throw new RelayError('subsite.required', esc_html__('Only a network merges the users it receives.', 'siterelay'));
        }
        $list = $this->client->call($connection, 'users.list', '', $remote_subsite > 0 ? ['subsite' => $remote_subsite] : [])['meta'];
        $users = array_values(array_filter((array) ($list['users'] ?? []), 'is_array'));
        return UserMerge::preview($this->db, $subsite > 0 ? Scope::subsite($subsite) : null, $users) + ['total' => (int) ($list['total'] ?? count($users))];
    }

    /**
     * A push from this site (or, on a network, its subsite $subsite) into a subsite of the other network: an existing
     * one ($remote_subsite) or a new one ($new_subsite).
     *
     * @return array{merged: array[], renamed: array[], created: int, removed: string[], total: int}
     */
    public function push(array $connection, int $subsite, int $remote_subsite, ?array $new_subsite): array
    {
        $list = ShapeOut::user_list($this->db, is_multisite() ? Scope::subsite($subsite) : Scope::site());
        $target = $remote_subsite > 0 ? ['subsite' => $remote_subsite] : ['new_subsite' => (array) $new_subsite];
        $answer = $this->client->call($connection, 'users.preview', '', $target + ['users' => $list['users']], '', 60)['meta'];
        return [
            'merged' => array_values(array_filter((array) ($answer['merged'] ?? []), 'is_array')),
            'renamed' => array_values(array_filter((array) ($answer['renamed'] ?? []), 'is_array')),
            'created' => (int) ($answer['created'] ?? 0),
            'removed' => array_values(array_filter((array) ($answer['removed'] ?? []), 'is_string')),
            'total' => $list['total'],
        ];
    }
}