<?php

namespace App\Http\Controllers\Api;

use App\Http\Controllers\Controller;
use App\Models\Paper;
use App\Services\ExamPdfExportService;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;
use Illuminate\Support\Facades\URL;

class ExamAnalysisApiController extends Controller
{
    /**
     * 生成学情报告（异步模式）
     * 立即返回任务ID，PDF生成在后台进行
     */
    public function store(Request $request, ExamPdfExportService $pdfExportService): JsonResponse
    {
        $data = $request->validate([
            'paper_id' => 'required|string',
            'student_id' => 'nullable|string',
            'callback_url' => 'nullable|url',
        ]);

        $paperId = $data['paper_id'];
        $studentId = $data['student_id'] ?? null;

        $paper = Paper::find($paperId);
        if (!$paper) {
            return response()->json([
                'success' => false,
                'message' => '未找到试卷',
            ], 404);
        }

        if (!$studentId) {
            $studentId = $paper->student_id;
        }

        if (!$studentId) {
            return response()->json([
                'success' => false,
                'message' => '缺少 student_id',
            ], 422);
        }

        try {
            // 创建异步任务
            $taskId = $this->createAsyncTask($paperId, $studentId, $data);

            // 立即返回任务信息
            $viewUrl = URL::to("/admin/exam-analysis?paperId={$paperId}&studentId={$studentId}");
            $payload = [
                'success' => true,
                'message' => '学情报告任务已创建，正在后台生成PDF...',
                'data' => [
                    'task_id' => $taskId,
                    'paper_id' => $paperId,
                    'student_id' => $studentId,
                    'status' => 'processing',
                    'analysis_url' => $viewUrl,
                    'pdf_url' => null,  // 稍后生成
                    'created_at' => now()->toISOString(),
                ],
            ];

            return response()->json($payload, 200, [], JSON_UNESCAPED_SLASHES);
        } catch (\Exception $e) {
            Log::error('学情报告API失败', [
                'paper_id' => $paperId,
                'student_id' => $studentId,
                'error' => $e->getMessage(),
            ]);

            return response()->json([
                'success' => false,
                'message' => '服务异常，请稍后重试',
            ], 500);
        }
    }

    /**
     * 轮询任务状态
     */
    public function status(string $taskId): JsonResponse
    {
        try {
            $task = $this->getTaskStatus($taskId);

            if (!$task) {
                return response()->json([
                    'success' => false,
                    'message' => '任务不存在',
                ], 404);
            }

            return response()->json([
                'success' => true,
                'data' => $task,
            ]);
        } catch (\Exception $e) {
            Log::error('查询学情报告任务状态失败', [
                'task_id' => $taskId,
                'error' => $e->getMessage(),
            ]);

            return response()->json([
                'success' => false,
                'message' => '查询失败，请稍后重试',
            ], 500);
        }
    }

    /**
     * 创建异步任务
     */
    private function createAsyncTask(string $paperId, string $studentId, array $data): string
    {
        $taskId = 'analysis_' . uniqid() . '_' . substr(md5($paperId . $studentId . time()), 0, 8);

        // 保存任务信息到缓存
        $taskData = [
            'task_id' => $taskId,
            'paper_id' => $paperId,
            'student_id' => $studentId,
            'status' => 'processing',
            'created_at' => now()->toISOString(),
            'updated_at' => now()->toISOString(),
            'progress' => 0,
            'message' => '正在生成学情报告...',
            'data' => $data,
            'callback_url' => $data['callback_url'] ?? null,
        ];

        // 保存到缓存，24小时过期
        cache()->put("analysis_task:{$taskId}", $taskData, now()->addDay());

        // 触发后台处理
        $this->processAnalysisGeneration($taskId, $paperId, $studentId);

        return $taskId;
    }

    /**
     * 获取任务状态
     */
    private function getTaskStatus(string $taskId): ?array
    {
        return cache()->get("analysis_task:{$taskId}");
    }

    /**
     * 处理学情报告生成
     */
    private function processAnalysisGeneration(string $taskId, string $paperId, string $studentId): void
    {
        try {
            // 更新任务状态
            $this->updateTaskStatus($taskId, [
                'status' => 'processing',
                'progress' => 10,
                'message' => '开始生成学情报告...',
            ]);

            // 生成学情报告PDF
            $pdfUrl = app(ExamPdfExportService::class)->generateAnalysisReportPdf($paperId, $studentId);

            // 更新任务状态为完成
            $this->updateTaskStatus($taskId, [
                'status' => 'completed',
                'progress' => 100,
                'message' => '学情报告生成完成',
                'pdf_url' => $pdfUrl,
                'completed_at' => now()->toISOString(),
            ]);

            Log::info('学情报告异步任务完成', [
                'task_id' => $taskId,
                'paper_id' => $paperId,
                'student_id' => $studentId,
                'pdf_url' => $pdfUrl,
            ]);

            // 发送回调通知
            $this->sendCallbackNotification($taskId);

        } catch (\Exception $e) {
            Log::error('学情报告生成失败', [
                'task_id' => $taskId,
                'paper_id' => $paperId,
                'student_id' => $studentId,
                'error' => $e->getMessage(),
            ]);

            // 更新任务状态为失败
            $this->updateTaskStatus($taskId, [
                'status' => 'failed',
                'progress' => 0,
                'message' => '学情报告生成失败: ' . $e->getMessage(),
                'error' => $e->getMessage(),
            ]);
        }
    }

    /**
     * 更新任务状态
     */
    private function updateTaskStatus(string $taskId, array $updates): void
    {
        $task = $this->getTaskStatus($taskId);
        if (!$task) {
            return;
        }

        $updatedTask = array_merge($task, $updates, [
            'updated_at' => now()->toISOString(),
        ]);

        cache()->put("analysis_task:{$taskId}", $updatedTask, now()->addDay());
    }

    /**
     * 发送回调通知
     */
    private function sendCallbackNotification(string $taskId): void
    {
        $task = $this->getTaskStatus($taskId);
        if (!$task || !$task['callback_url']) {
            return;
        }

        try {
            $payload = [
                'task_id' => $task['task_id'],
                'paper_id' => $task['paper_id'],
                'student_id' => $task['student_id'],
                'status' => $task['status'],
                'pdf_url' => $task['pdf_url'] ?? null,
                'completed_at' => $task['completed_at'],
                'callback_type' => 'analysis_report_generated',
            ];

            $response = Http::timeout(30)
                ->post($task['callback_url'], $payload);

            if ($response->successful()) {
                Log::info('学情报告回调通知发送成功', [
                    'task_id' => $taskId,
                    'callback_url' => $task['callback_url'],
                ]);
            } else {
                Log::warning('学情报告回调通知发送失败', [
                    'task_id' => $taskId,
                    'callback_url' => $task['callback_url'],
                    'status' => $response->status(),
                ]);
            }
        } catch (\Exception $e) {
            Log::error('学情报告回调通知异常', [
                'task_id' => $taskId,
                'callback_url' => $task['callback_url'] ?? 'unknown',
                'error' => $e->getMessage(),
            ]);
        }
    }
}