<?php


namespace app\service;


use app\model\Department;

use app\model\User;


class DepartmentService

{

    /**

     * 获取部门及其所有下级部门 ID（含自身）。

     *

     * @return int[]

     */

    public static function descendantIds(int $departmentId): array

    {

        $all = Department::field('id,parent_id')->select()->toArray();

        $childrenMap = [];

        foreach ($all as $row) {

            $parentId = (int) ($row['parent_id'] ?? 0);

            $childrenMap[$parentId][] = (int) $row['id'];

        }


        $result = [];

        $stack = [$departmentId];

        while ($stack) {

            $current = array_pop($stack);

            if (in_array($current, $result, true)) {

                continue;

            }

            $result[] = $current;

            foreach ($childrenMap[$current] ?? [] as $childId) {

                $stack[] = $childId;

            }

        }


        return $result;

    }


    /**

     * 构建带层级缩进的部门树（扁平列表，供下拉选择）。

     */

    public static function treeOptions(): array

    {

        $rows = Department::order('sort_order')->order('id')->select()->toArray();

        $childrenMap = [];

        foreach ($rows as $row) {

            $parentId = (int) ($row['parent_id'] ?? 0);

            $childrenMap[$parentId][] = $row;

        }


        $options = [];

        self::walkTree($childrenMap, 0, 0, $options);


        return $options;

    }


    private static function walkTree(array $childrenMap, int $parentId, int $depth, array &$options): void

    {

        foreach ($childrenMap[$parentId] ?? [] as $row) {

            $prefix = $depth > 0 ? str_repeat('　', $depth) . '└ ' : '';

            $options[] = [

                'id'        => (int) $row['id'],

                'name'      => $row['name'],

                'parent_id' => $row['parent_id'] ? (int) $row['parent_id'] : null,

                'label'     => $prefix . $row['name'],

                'depth'     => $depth,

            ];

            self::walkTree($childrenMap, (int) $row['id'], $depth + 1, $options);

        }

    }


    /**

     * 获取某部门及下级部门内的所有用户 ID。

     *

     * @return int[]

     */

    public static function userIdsInDepartments(array $departmentIds): array

    {

        if (empty($departmentIds)) {

            return [];

        }


        return User::whereIn('department_id', $departmentIds)->column('id');

    }

}