<?php

namespace App\Services;

use App\Models\AdminUser;
use App\Models\Menu;
use Illuminate\Support\Collection;
use Illuminate\Support\Facades\DB;

class AdminMenuService
{
    /** @return array<int, array<string, mixed>> */
    public function treeForUser(AdminUser $user): array
    {
        $menus = $this->menusQueryForUser($user);
        $tree = $this->buildTree($menus);

        return $tree->values()->all();
    }

    protected function menusQueryForUser(AdminUser $user): Collection
    {
        $base = Menu::query()->where('status', 1)->orderBy('sort');

        if ($user->isSuperAdmin()) {
            return $base->get();
        }

        $roleIds = $user->roles()->where('status', 1)->pluck('id');
        $menuIds = DB::table('role_menus')
            ->whereIn('role_id', $roleIds)
            ->pluck('menu_id')
            ->unique()
            ->all();

        if ($menuIds === []) {
            return collect();
        }

        $expandedIds = $this->expandMenuParents($menuIds);

        return $base->whereIn('id', $expandedIds)->get();
    }

    /**
     * @param  array<int, int>  $menuIds
     * @return array<int, int>
     */
    protected function expandMenuParents(array $menuIds): array
    {
        $idSet = collect($menuIds)->flip()->all();
        $queue = $menuIds;

        while ($queue !== []) {
            $id = array_pop($queue);
            $m = Menu::query()->find($id);
            if ($m && $m->parent_id && ! isset($idSet[$m->parent_id])) {
                $idSet[$m->parent_id] = 0;
                $queue[] = $m->parent_id;
            }
        }

        return array_map('intval', array_keys($idSet));
    }

    /**
     * @param  Collection<int, Menu>  $menus
     * @return \Illuminate\Support\Collection<int, array<string, mixed>>
     */
    protected function buildTree(Collection $menus): Collection
    {
        $byParent = $menus->groupBy(fn (Menu $m) => $m->parent_id ?? 0);

        $build = function ($parentId) use (&$build, $byParent): Collection {
            return ($byParent->get($parentId, collect()))->map(function (Menu $m) use (&$build) {
                $node = [
                    'id' => $m->id,
                    'parent_id' => $m->parent_id,
                    'path' => $m->path,
                    'name' => $m->name,
                    'title' => $m->title,
                    'component' => $m->component,
                    'icon' => $m->icon,
                    'sort' => $m->sort,
                    'visible' => $m->visible,
                    'keep_alive' => $m->keep_alive,
                    'permission_code' => $m->permission_code,
                    'status' => (int) $m->status,
                ];
                $children = $build($m->id);
                if ($children->isNotEmpty()) {
                    $node['children'] = $children->values()->all();
                }

                return $node;
            });
        };

        return $build(0);
    }
}