<?php

namespace App\Http\Controllers;

use App\Models\Category;
use App\Models\GlobalCategory;
use App\Models\Tenants\Tenant;
use Illuminate\Http\Request;
use Illuminate\Http\Response;
use Illuminate\View\View;

class CategoryController extends Controller
{

    /**
     * 카테고리 관리 페이지
     */
    public function index(Request $request): View|Response
    {
        // HTMX 요청 시 전체 페이지 리로드
        if ($request->header('HX-Request')) {
            return response('', 200)->header('HX-Redirect', route('categories.index'));
        }

        $tenantId = session('selected_tenant_id');
        $tenant = $tenantId ? Tenant::find($tenantId) : null;
        $isHQ = $tenantId == 1;

        // 모든 code_group 조회 (글로벌 + 테넌트)
        $globalGroups = GlobalCategory::whereNull('deleted_at')
            ->select('code_group')
            ->distinct()
            ->pluck('code_group')
            ->toArray();

        $tenantGroups = [];
        if ($tenantId) {
            $tenantGroups = Category::where('tenant_id', $tenantId)
                ->whereNull('deleted_at')
                ->select('code_group')
                ->distinct()
                ->pluck('code_group')
                ->toArray();
        }

        $allGroups = array_unique(array_merge($globalGroups, $tenantGroups));
        sort($allGroups);

        $codeGroupLabels = config('categories.code_group_labels', []);

        $codeGroups = [];
        foreach ($allGroups as $group) {
            $codeGroups[$group] = $codeGroupLabels[$group] ?? $group;
        }

        if (empty($codeGroups)) {
            $codeGroups['product'] = $codeGroupLabels['product'] ?? 'product';
        }

        $selectedGroup = $request->get('group', array_key_first($codeGroups));
        if (! isset($codeGroups[$selectedGroup])) {
            $selectedGroup = array_key_first($codeGroups);
        }

        // 글로벌 카테고리 (트리 구조로 평탄화)
        $globalCategoriesRaw = GlobalCategory::where('code_group', $selectedGroup)
            ->whereNull('deleted_at')
            ->orderBy('sort_order')
            ->get();
        $globalCategories = $this->flattenTree($globalCategoriesRaw);

        // 테넌트 카테고리 (트리 구조로 평탄화)
        $tenantCategories = collect();
        $tenantCodes = [];
        if ($tenantId) {
            $tenantCategoriesRaw = Category::where('tenant_id', $tenantId)
                ->where('code_group', $selectedGroup)
                ->whereNull('deleted_at')
                ->orderBy('sort_order')
                ->get();
            $tenantCategories = $this->flattenTree($tenantCategoriesRaw);
            $tenantCodes = $tenantCategoriesRaw->pluck('code')->toArray();
        }

        $globalCodes = $globalCategoriesRaw->pluck('code')->toArray();

        return view('categories.index', [
            'codeGroups' => $codeGroups,
            'codeGroupLabels' => $codeGroupLabels,
            'selectedGroup' => $selectedGroup,
            'globalCategories' => $globalCategories,
            'tenantCategories' => $tenantCategories,
            'tenantCodes' => $tenantCodes,
            'globalCodes' => $globalCodes,
            'tenant' => $tenant,
            'isHQ' => $isHQ,
        ]);
    }

    /**
     * 카테고리 컬렉션을 트리 구조로 평탄화 (부모-자식 순서 유지, depth 추가)
     */
    private function flattenTree($categories): \Illuminate\Support\Collection
    {
        $result = collect();
        $byParent = $categories->groupBy(fn($c) => $c->parent_id ?? 0);

        $this->addChildrenRecursive($result, $byParent, 0, 0);

        return $result;
    }

    /**
     * 재귀적으로 자식 추가
     */
    private function addChildrenRecursive(&$result, $byParent, $parentId, $depth): void
    {
        $children = $byParent->get($parentId, collect());

        foreach ($children as $child) {
            $child->depth = $depth;
            $result->push($child);
            $this->addChildrenRecursive($result, $byParent, $child->id, $depth + 1);
        }
    }
}