<?php

namespace App\Service;

use App\Models\ApiEndpointModel;
use App\Models\RoleEndpointRelationModel;
use App\Service\common\RedisService;

/**
 * 接口级权限
 *
 * 权限码由接口路径推导：admin/list → admin:list，前端 v-access / TableAction 的 auth 直接用它。
 * 不继承 BaseService：中间件在鉴权阶段就要用它，而 BaseService 的构造函数本身会做鉴权，会绕成环。
 */
class PermissionService
{
    private static mixed $_instance;

    /** @var array<int, array{codes: array<int, string>, paths: array<int, string>}> 进程内缓存，一次请求里中间件与 codes 接口各要用一次 */
    private array $roleMemo = [];

    /** @var null|array<string, int> 接口注册表 path => id */
    private ?array $pathMemo = null;

    public static function getInstance(): static
    {
        $name = get_called_class();
        if (!isset(self::$_instance[$name])) {
            self::$_instance[$name] = new static();
        }
        return self::$_instance[$name];
    }

    /**
     * 超级管理员：代码里多处硬判断 role_id === 1 全量放行，这里保持一致
     */
    public function isSuper(int $roleId): bool
    {
        return $roleId === 1;
    }

    /**
     * 角色可用的权限码
     * @return array<int, string>
     */
    public function codes(int $roleId): array
    {
        return $this->load($roleId)['codes'];
    }

    /**
     * 判断角色能否调用某接口
     *
     * @param string $path 已去掉 /api/ 前缀的路径，如 admin/list
     */
    public function allows(int $roleId, string $path): bool
    {
        if ($this->isSuper($roleId)) {
            return true;
        }
        $path = trim($path, '/');
        if ($path === '' || in_array($path, (array) config('nl.api.permission.always_allow', []), true)) {
            return true;
        }
        $registered = $this->registeredPaths();
        if (!isset($registered[$path])) {
            // 没登记进接口注册表的接口：迁移期放行，strict 模式拒绝
            return !config('nl.api.permission.strict', false);
        }
        return in_array($path, $this->load($roleId)['paths'], true);
    }

    /**
     * 接口授权树：按控制器分组，供角色授权抽屉勾选
     * @return array<int, array<string, mixed>>
     */
    public function endpointTree(): array
    {
        $rows = ApiEndpointModel::where('deleted_at', 0)
            ->where('status', 1)
            ->orderBy('controller')
            ->orderBy('url')
            ->get(['id', 'url', 'name', 'method', 'controller'])
            ->toArray();

        $groups = [];
        foreach ($rows as $row) {
            $controller = $row['controller'] !== '' ? $row['controller'] : '未归类';
            if (!isset($groups[$controller])) {
                $groups[$controller] = [
                    // 分组节点的 id 取负值，避免和真实 endpoint_id 混淆
                    'id' => -1 * (count($groups) + 1),
                    'title' => $controller,
                    'code' => '',
                    'children' => [],
                ];
            }
            $groups[$controller]['children'][] = [
                'id' => (int) $row['id'],
                'title' => $row['name'] !== '' ? $row['name'] : $row['url'],
                'code' => $this->pathToCode($row['url']),
                'url' => $row['url'],
            ];
        }
        return array_values($groups);
    }

    /**
     * 角色已授权的接口 id
     * @return array<int, int>
     */
    public function grantedIds(int $roleId): array
    {
        return RoleEndpointRelationModel::where('role_id', $roleId)
            ->pluck('endpoint_id')
            ->map(fn ($v) => (int) $v)
            ->all();
    }

    /**
     * 保存角色的接口授权（全量覆盖）
     */
    public function grant(int $roleId, array $endpointIds): bool
    {
        // 分组节点用的是负 id，落库前剔掉
        $ids = array_values(array_unique(array_filter(array_map('intval', $endpointIds), fn ($id) => $id > 0)));
        $exists = $this->grantedIds($roleId);

        $toDelete = array_diff($exists, $ids);
        if (!empty($toDelete)) {
            RoleEndpointRelationModel::where('role_id', $roleId)
                ->whereIn('endpoint_id', array_values($toDelete))
                ->delete();
        }
        $toAdd = array_diff($ids, $exists);
        if (!empty($toAdd)) {
            $now = time();
            RoleEndpointRelationModel::insert(array_map(
                fn ($id) => ['role_id' => $roleId, 'endpoint_id' => $id, 'created_at' => $now],
                array_values($toAdd)
            ));
        }
        $this->clear($roleId);
        return true;
    }

    /**
     * 清角色权限缓存；不传角色则全清
     */
    public function clear(?int $roleId = null): void
    {
        $this->pathMemo = null;
        $redis = RedisService::getInstance()->init(config('nl.redis.permission_key'));
        if ($roleId === null) {
            $this->roleMemo = [];
            $redis->delAll();
            return;
        }
        unset($this->roleMemo[$roleId]);
        $redis->del($roleId);
    }

    /**
     * admin/list → admin:list
     */
    public function pathToCode(string $path): string
    {
        return str_replace('/', ':', trim($path, '/'));
    }

    /**
     * @return array{codes: array<int, string>, paths: array<int, string>}
     */
    private function load(int $roleId): array
    {
        if (isset($this->roleMemo[$roleId])) {
            return $this->roleMemo[$roleId];
        }
        $redis = RedisService::getInstance()->init(config('nl.redis.permission_key'));
        $cached = $redis->get($roleId);
        if (!empty($cached)) {
            $decoded = json_decode($cached, true);
            if (is_array($decoded) && isset($decoded['codes'], $decoded['paths'])) {
                return $this->roleMemo[$roleId] = $decoded;
            }
        }

        if ($this->isSuper($roleId)) {
            // 超管拿全量码：前端按码匹配，给 ['*'] 反而什么都匹配不上
            $paths = array_keys($this->registeredPaths());
        } else {
            $paths = ApiEndpointModel::where('deleted_at', 0)
                ->where('status', 1)
                ->whereIn('id', $this->grantedIds($roleId))
                ->pluck('url')
                ->all();
        }
        $paths = array_values(array_unique(array_map(fn ($p) => trim((string) $p, '/'), $paths)));
        $data = [
            'paths' => $paths,
            'codes' => array_map(fn ($p) => $this->pathToCode($p), $paths),
        ];
        $redis->set($roleId, json_encode($data, JSON_UNESCAPED_UNICODE), 3600);
        return $this->roleMemo[$roleId] = $data;
    }

    /**
     * 已登记的接口路径表（path => id）
     * @return array<string, int>
     */
    private function registeredPaths(): array
    {
        if ($this->pathMemo !== null) {
            return $this->pathMemo;
        }
        $rows = ApiEndpointModel::where('deleted_at', 0)
            ->where('status', 1)
            ->pluck('id', 'url')
            ->all();
        $normalized = [];
        foreach ($rows as $url => $id) {
            $normalized[trim((string) $url, '/')] = (int) $id;
        }
        return $this->pathMemo = $normalized;
    }
}