<?php

declare(strict_types=1);

namespace App\Http\Controllers\Api;

use App\Http\Controllers\Controller;
use App\Models\Client;
use App\Services\LogService;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;
use Illuminate\Support\Facades\RateLimiter;
use Illuminate\Validation\ValidationException;

class LlmController extends Controller
{
    private const REQUEST_TIMEOUT = 30;  // 请求超时时间（秒）
    private const MAX_ATTEMPTS = 60;     // 每分钟最大请求次数
    private const DECAY_MINUTES = 1;     // 重置时间（分钟）

    public function __construct(
        private readonly LogService $logService
    ) {}

    /**
     * Send prompt request to LLM provider
     *
     * @param Request $request
     * @return JsonResponse
     *
     * Request headers:
     * - Content-Type: application/json
     * - Authorization: Bearer {access_token}
     *
     * Request body:
     * {
     *     "prompt": "string"
     * }
     *
     * Success response:
     * {
     *     "response": "LLM 提供商返回的响应内容"
     * }
     *
     * Error response:
     * {
     *     "error": "error_code",
     *     "message": "错误描述"
     * }
     */
    public function request(Request $request): JsonResponse
    {
        try {
            $clientId = $request->get('client_id');

            // 检查请求频率限制
            $key = 'llm_request_' . $clientId;
            if (RateLimiter::tooManyAttempts($key, self::MAX_ATTEMPTS)) {
                $seconds = RateLimiter::availableIn($key);
                return response()->json([
                    'error' => 'too_many_requests',
                    'message' => "请求过于频繁，请在 {$seconds} 秒后重试。",
                ], 429);
            }

            $validated = $request->validate([
                'prompt' => 'required|string|max:4096',
            ]);

            $client = Client::with('llmProvider')->findOrFail($clientId);
            $provider = $client->llmProvider;

            // Send request to LLM provider with timeout
            $response = Http::timeout(self::REQUEST_TIMEOUT)
                ->withToken($provider->api_token)
                ->withHeaders([
                    'Content-Type' => 'application/json',
                    'Accept' => 'application/json',
                ])
                ->post($provider->api_url, [
                    'prompt' => $validated['prompt'],
                ]);

            if (!$response->successful()) {
                Log::error('LLM provider request failed', [
                    'status' => $response->status(),
                    'body' => $response->body(),
                    'provider' => $provider->name,
                ]);

                throw new \Exception('LLM provider request failed: ' . $response->body());
            }

            // 记录成功的请求
            RateLimiter::hit($key, self::DECAY_MINUTES * 60);

            $this->logService->logOperation(
                'client',
                $client->id,
                'Sent prompt to LLM provider: ' . $provider->name
            );

            return response()->json([
                'response' => $response->json(),
            ]);

        } catch (ValidationException $e) {
            return response()->json([
                'error' => 'validation_error',
                'message' => '请求参数验证失败。',
                'details' => $e->errors(),
            ], 422);
        } catch (\Illuminate\Database\Eloquent\ModelNotFoundException $e) {
            return response()->json([
                'error' => 'not_found',
                'message' => '客户用户不存在。',
            ], 404);
        } catch (\Illuminate\Http\Client\ConnectionException $e) {
            Log::error('LLM provider connection timeout', [
                'error' => $e->getMessage(),
                'trace' => $e->getTraceAsString(),
            ]);

            return response()->json([
                'error' => 'provider_timeout',
                'message' => 'LLM 提供商响应超时，请稍后重试。',
            ], 504);
        } catch (\Exception $e) {
            Log::error('Error processing LLM request', [
                'error' => $e->getMessage(),
                'trace' => $e->getTraceAsString(),
            ]);

            if (str_contains($e->getMessage(), 'LLM provider request failed')) {
                return response()->json([
                    'error' => 'provider_error',
                    'message' => 'LLM 提供商服务异常，请稍后重试。',
                ], 502);
            }

            return response()->json([
                'error' => 'server_error',
                'message' => '服务器内部错误。',
            ], 500);
        }
    }
}