<?php

namespace App\Http\Controllers\Api;

use App\Http\Controllers\Controller;
use App\Models\TicketCategory;
use hg\apidoc\annotation as Apidoc;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Illuminate\Validation\Rule;
use Illuminate\Validation\ValidationException;

#[Apidoc\Title('工单分类管理')]
class TicketCategoryController extends Controller
{
    public function __construct()
    {
        $this->middleware('auth:api');
        $this->middleware('permission:tickets.use|platform.tickets.view|platform.tickets.manage,api')->only(['index']);
        $this->middleware('permission:platform.tickets.manage,api')->only(['store', 'update', 'destroy']);
    }

    #[Apidoc\Title('工单分类列表'), Apidoc\Method('GET'), Apidoc\Url('/ticket-categories')]
    public function index(Request $request): JsonResponse
    {
        $validated = $request->validate([
            'active_only' => ['nullable', 'boolean'],
        ]);

        $query = TicketCategory::query()
            ->with('parent:id,name,parent_id')
            ->orderBy('parent_id')
            ->orderBy('id');
        if ((bool) ($validated['active_only'] ?? false)) {
            $query->where('is_active', true);
        }

        $categories = $query->get();

        return response()->json([
            'code' => 0,
            'message' => 'ok',
            'data' => $categories,
            'tree' => $this->buildCategoryTree($categories),
        ]);
    }

    #[Apidoc\Title('创建工单分类'), Apidoc\Method('POST'), Apidoc\Url('/ticket-categories')]
    public function store(Request $request): JsonResponse
    {
        $validated = $request->validate([
            'parent_id' => ['nullable', 'integer', 'exists:ticket_categories,id'],
            'name' => ['required', 'string', 'max:100'],
            'description' => ['nullable', 'string', 'max:255'],
            'is_active' => ['sometimes', 'boolean'],
        ]);
        $this->ensureUniqueNameInParent($validated['name'], $validated['parent_id'] ?? null);

        $category = TicketCategory::query()->create([
            'parent_id' => $validated['parent_id'] ?? null,
            'name' => $validated['name'],
            'description' => $validated['description'] ?? null,
            'is_active' => (bool) ($validated['is_active'] ?? true),
        ]);

        $this->auditLog($request, 'ticket_category_create', ['metadata' => ['ticket_category_id' => $category->id]]);

        return response()->json(['code' => 0, 'message' => 'ok', 'data' => $category], 201);
    }

    #[Apidoc\Title('更新工单分类'), Apidoc\Method('PUT'), Apidoc\Url('/ticket-categories/{id}')]
    public function update(Request $request, int $id): JsonResponse
    {
        $category = TicketCategory::query()->findOrFail($id);
        $validated = $request->validate([
            'parent_id' => ['nullable', 'integer', Rule::exists('ticket_categories', 'id')->where(fn ($query) => $query->where('id', '!=', $category->id))],
            'name' => ['required', 'string', 'max:100'],
            'description' => ['nullable', 'string', 'max:255'],
            'is_active' => ['sometimes', 'boolean'],
        ]);
        $parentId = $validated['parent_id'] ?? null;
        if ($parentId !== null && $this->isDescendant((int) $parentId, $category)) {
            throw ValidationException::withMessages([
                'parent_id' => ['不能选择当前分类的下级分类作为父级。'],
            ]);
        }
        $this->ensureUniqueNameInParent($validated['name'], $parentId, $category->id);

        $category->update([
            'parent_id' => $parentId,
            'name' => $validated['name'],
            'description' => $validated['description'] ?? null,
            'is_active' => array_key_exists('is_active', $validated) ? (bool) $validated['is_active'] : $category->is_active,
        ]);

        $this->auditLog($request, 'ticket_category_update', ['metadata' => ['ticket_category_id' => $category->id]]);

        return response()->json(['code' => 0, 'message' => 'ok', 'data' => $category->fresh()]);
    }

    #[Apidoc\Title('删除工单分类'), Apidoc\Method('DELETE'), Apidoc\Url('/ticket-categories/{id}')]
    public function destroy(Request $request, int $id): JsonResponse
    {
        $category = TicketCategory::query()->findOrFail($id);
        $this->auditLog($request, 'ticket_category_delete', ['metadata' => ['ticket_category_id' => $category->id]]);
        $category->delete();

        return response()->json(['code' => 0, 'message' => 'ok', 'data' => null]);
    }

    private function buildCategoryTree($categories): array
    {
        $items = $categories
            ->map(function (TicketCategory $category): array {
                return [
                    'id' => $category->id,
                    'parent_id' => $category->parent_id,
                    'name' => $category->name,
                    'description' => $category->description,
                    'is_active' => $category->is_active,
                    'children' => [],
                ];
            })
            ->keyBy('id')
            ->all();

        $tree = [];
        foreach ($items as $id => &$item) {
            $parentId = $item['parent_id'];
            if ($parentId !== null && isset($items[$parentId])) {
                $items[$parentId]['children'][] = &$item;

                continue;
            }

            $tree[] = &$item;
        }
        unset($item);

        return $tree;
    }

    private function isDescendant(int $parentId, TicketCategory $category): bool
    {
        $childrenByParent = TicketCategory::query()
            ->whereNotNull('parent_id')
            ->get(['id', 'parent_id'])
            ->groupBy('parent_id');
        $pending = collect($childrenByParent->get($category->id, []))->pluck('id')->all();

        while (! empty($pending)) {
            $nextId = (int) array_shift($pending);
            if ($nextId === $parentId) {
                return true;
            }

            $pending = [
                ...$pending,
                ...collect($childrenByParent->get($nextId, []))->pluck('id')->all(),
            ];
        }

        return false;
    }

    private function ensureUniqueNameInParent(string $name, ?int $parentId, ?int $exceptId = null): void
    {
        $exists = TicketCategory::query()
            ->where('name', $name)
            ->when($parentId === null, fn ($query) => $query->whereNull('parent_id'), fn ($query) => $query->where('parent_id', $parentId))
            ->when($exceptId !== null, fn ($query) => $query->where('id', '!=', $exceptId))
            ->exists();

        if ($exists) {
            throw ValidationException::withMessages([
                'name' => ['同级分类下已存在相同名称。'],
            ]);
        }
    }
}