<?php

namespace App\Services;

use Illuminate\Http\Client\Response;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;

/**
 * 统一异步任务管理器
 * 负责所有异步任务的创建、状态管理、进度更新和回调通知
 */
class TaskManager
{
    /**
     * 任务类型常量
     */
    const TASK_TYPE_EXAM = 'exam';           // 智能出卷任务
    const TASK_TYPE_ANALYSIS = 'analysis';   // 学情分析任务

    /**
     * 任务状态常量
     */
    const STATUS_PENDING = 'pending';
    const STATUS_PROCESSING = 'processing';
    const STATUS_COMPLETED = 'completed';
    const STATUS_FAILED = 'failed';

    /**
     * 创建异步任务
     */
    public function createTask(string $type, array $data): string
    {
        $taskId = $this->generateTaskId($type, $data);

        $taskData = [
            'task_id' => $taskId,
            'type' => $type,
            'status' => self::STATUS_PROCESSING,
            'progress' => 0,
            'message' => '任务已创建，正在处理...',
            'data' => $data,
            'created_at' => now()->toISOString(),
            'updated_at' => now()->toISOString(),
            'callback_url' => $data['callback_url'] ?? null,
        ];

        $this->saveTask($taskId, $taskData);

        Log::info('TaskManager: 任务已创建', [
            'task_id' => $taskId,
            'type' => $type,
            'data_keys' => array_keys($data),
        ]);

        return $taskId;
    }

    /**
     * 获取任务状态
     */
    public function getTaskStatus(string $taskId): ?array
    {
        return $this->loadTask($taskId);
    }

    /**
     * 更新任务状态
     */
    public function updateTaskStatus(string $taskId, array $updates): void
    {
        $task = $this->loadTask($taskId);
        if (!$task) {
            Log::warning('TaskManager: 尝试更新不存在的任务', ['task_id' => $taskId]);
            return;
        }

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

        $this->saveTask($taskId, $updatedTask);

        Log::info('TaskManager: 任务状态已更新', [
            'task_id' => $taskId,
            'status' => $updates['status'] ?? 'N/A',
            'progress' => $updates['progress'] ?? 'N/A',
        ]);
    }

    /**
     * 更新任务进度
     */
    public function updateTaskProgress(string $taskId, int $progress, string $message): void
    {
        $this->updateTaskStatus($taskId, [
            'progress' => $progress,
            'message' => $message,
        ]);
    }

    /**
     * 标记任务完成
     */
    public function markTaskCompleted(string $taskId, array $result): void
    {
        $this->updateTaskStatus($taskId, array_merge($result, [
            'status' => self::STATUS_COMPLETED,
            'progress' => 100,
            'message' => '任务已完成',
            'completed_at' => now()->toISOString(),
        ]));
    }

    /**
     * 标记任务失败
     */
    public function markTaskFailed(string $taskId, string $error): void
    {
        $this->updateTaskStatus($taskId, [
            'status' => self::STATUS_FAILED,
            'progress' => 0,
            'message' => '任务失败: ' . $error,
            'error' => $error,
        ]);

        Log::error('TaskManager: 任务执行失败', [
            'task_id' => $taskId,
            'error' => $error,
        ]);
    }

    /**
     * 发送回调通知
     */
    public function sendCallback(string $taskId): void
    {
        $task = $this->loadTask($taskId);
        if (!$task || !$task['callback_url']) {
            return; // 没有回调URL或任务不存在
        }

        try {
            $payload = $this->buildCallbackPayload($task);

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

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

    /**
     * 生成任务ID
     */
    private function generateTaskId(string $type, array $data): string
    {
        $prefix = match ($type) {
            self::TASK_TYPE_EXAM => 'exam_task',
            self::TASK_TYPE_ANALYSIS => 'analysis_task',
            default => 'task_' . $type,
        };

        return $prefix . '_' . uniqid() . '_' . substr(md5(serialize($data) . time()), 0, 8);
    }

    /**
     * 保存任务到缓存
     */
    private function saveTask(string $taskId, array $taskData): void
    {
        Cache::put($this->getCacheKey($taskId), $taskData, now()->addDay());
    }

    /**
     * 从缓存加载任务
     */
    private function loadTask(string $taskId): ?array
    {
        return Cache::get($this->getCacheKey($taskId));
    }

    /**
     * 获取缓存键
     */
    private function getCacheKey(string $taskId): string
    {
        return "task:{$taskId}";
    }

    /**
     * 构建回调负载
     */
    private function buildCallbackPayload(array $task): array
    {
        $basePayload = [
            'task_id' => $task['task_id'],
            'type' => $task['type'],
            'status' => $task['status'],
            'completed_at' => $task['completed_at'] ?? null,
        ];

        // 根据任务类型添加特定数据
        if ($task['type'] === self::TASK_TYPE_EXAM) {
            $basePayload['callback_type'] = 'exam_pdf_generated';
            $basePayload['paper_id'] = $task['data']['paper_id'] ?? null;
            $basePayload['pdfs'] = $task['pdfs'] ?? null;
            $basePayload['exam_content'] = $task['exam_content'] ?? null;
        } elseif ($task['type'] === self::TASK_TYPE_ANALYSIS) {
            $basePayload['callback_type'] = 'analysis_report_generated';
            $basePayload['paper_id'] = $task['data']['paper_id'] ?? $task['data']['paperId'] ?? null;
            $basePayload['student_id'] = $task['data']['student_id'] ?? $task['data']['studentId'] ?? null;
            $basePayload['pdf_url'] = $task['pdf_url'] ?? null;
        }

        return $basePayload;
    }
}