import React, { useState, useEffect } from 'react';
import axios from '../../services/axios'
import { toast } from 'react-toastify';
import { Link } from 'react-router-dom';
import { Bar } from 'react-chartjs-2';
import { Chart, registerables } from 'chart.js';

// 注册Chart.js组件
Chart.register(...registerables);

const Dashboard = () => {
  const [stats, setStats] = useState({
    totalUsers: 0,
    activeUsers: 0,
    totalFiles: 0,
    takenFiles: 0,
    availableFiles: 0,
    recentUploads: {},
    recentDownloads: {}
  });
  const [loading, setLoading] = useState(true);

  useEffect(() => {
    const fetchDashboardData = async () => {
      try {
        const [userRes, fileRes] = await Promise.all([
          axios.get('/api/admin/analytics/users'),
          axios.get('/api/admin/analytics/files')
        ]);
        
        setStats({
          totalUsers: userRes.data.total_users || 0,
          activeUsers: userRes.data.active_users || 0,
          totalFiles: fileRes.data.total_files || 0,
          takenFiles: fileRes.data.taken_files || 0,
          availableFiles: fileRes.data.available_files || 0,
          recentUploads: fileRes.data.upload_stats || {},
          recentDownloads: fileRes.data.take_stats || {}
        });
      } catch (err) {
        console.error('获取统计数据失败:', err);
        toast.error('获取统计数据失败');
      } finally {
        setLoading(false);
      }
    };

    fetchDashboardData();
  }, []);

  // 准备图表数据
  const getChartData = () => {
    // 确保数据存在且为对象
    const recentUploads = stats.recentUploads || {};
    const recentDownloads = stats.recentDownloads || {};
    
    // 确保日期顺序正确
    const uploadDates = Object.keys(recentUploads);
    const downloadDates = Object.keys(recentDownloads);
    const allDates = [...new Set([...uploadDates, ...downloadDates])].sort();
    
    return {
      labels: allDates.map(date => new Date(date).toLocaleDateString()),
      datasets: [
        {
          label: '文件上传',
          data: allDates.map(date => recentUploads[date] || 0),
          backgroundColor: 'rgba(54, 162, 235, 0.5)',
          borderColor: 'rgba(54, 162, 235, 1)',
          borderWidth: 1
        },
        {
          label: '文件领取',
          data: allDates.map(date => recentDownloads[date] || 0),
          backgroundColor: 'rgba(75, 192, 192, 0.5)',
          borderColor: 'rgba(75, 192, 192, 1)',
          borderWidth: 1
        }
      ]
    };
  };

  if (loading) {
    return (
      <div className="d-flex justify-content-center align-items-center vh-100">
        <div className="spinner-border text-primary" role="status">
          <span className="visually-hidden">Loading...</span>
        </div>
      </div>
    );
  }

  return (
    <div>
      <div className="d-flex justify-content-between align-items-center mb-4">
        <h1>仪表盘</h1>
      </div>

      {/* 统计卡片 */}
      <div className="row mb-4">
        <div className="col-md-3 mb-4">
          <div className="stats-card">
            <div className="stats-number">{stats.totalUsers}</div>
            <div className="stats-label">总用户数</div>
            <Link to="/admin/users" className="btn btn-sm btn-admin-outline mt-3">
              查看详情 <i className="bi bi-arrow-right ms-1"></i>
            </Link>
          </div>
        </div>
        <div className="col-md-3 mb-4">
          <div className="stats-card">
            <div className="stats-number">{stats.activeUsers}</div>
            <div className="stats-label">活跃用户</div>
            <Link to="/admin/users" className="btn btn-sm btn-admin-outline mt-3">
              查看详情 <i className="bi bi-arrow-right ms-1"></i>
            </Link>
          </div>
        </div>
        <div className="col-md-3 mb-4">
          <div className="stats-card">
            <div className="stats-number">{stats.totalFiles}</div>
            <div className="stats-label">总文件数</div>
            <Link to="/admin/files" className="btn btn-sm btn-admin-outline mt-3">
              查看详情 <i className="bi bi-arrow-right ms-1"></i>
            </Link>
          </div>
        </div>
        <div className="col-md-3 mb-4">
          <div className="stats-card">
            <div className="stats-number">{stats.availableFiles}</div>
            <div className="stats-label">可领取文件</div>
            <Link to="/admin/files" className="btn btn-sm btn-admin-outline mt-3">
              查看详情 <i className="bi bi-arrow-right ms-1"></i>
            </Link>
          </div>
        </div>
      </div>

      {/* 图表 */}
      <div className="admin-card mb-4">
        <div className="card-header">
          <h5>近7天数据统计</h5>
        </div>
        <div className="card-body">
          <div className="chart-container" style={{ height: '300px' }}>
            <Bar
              data={getChartData()}
              options={{
                responsive: true,
                maintainAspectRatio: false,
                plugins: {
                  legend: {
                    labels: {
                      color: '#e8e9ea'
                    }
                  }
                },
                scales: {
                  y: {
                    beginAtZero: true,
                    ticks: {
                      precision: 0,
                      color: '#b8bcc8'
                    },
                    grid: {
                      color: 'rgba(100, 255, 218, 0.1)'
                    }
                  },
                  x: {
                    ticks: {
                      color: '#b8bcc8'
                    },
                    grid: {
                      color: 'rgba(100, 255, 218, 0.1)'
                    }
                  }
                }
              }}
            />
          </div>
        </div>
      </div>

      {/* 快捷操作 */}
      <div className="admin-card">
        <div className="card-header">
          <h5>快捷操作</h5>
        </div>
        <div className="card-body">
          <div className="d-flex flex-wrap gap-3">
            <Link to="/admin/users" className="btn btn-admin">
              <i className="bi bi-people me-2"></i>管理用户
            </Link>
            <Link to="/admin/files/upload" className="btn btn-admin">
              <i className="bi bi-upload me-2"></i>上传新文件
            </Link>
            <Link to="/admin/files" className="btn btn-admin">
              <i className="bi bi-file-earmark me-2"></i>管理文件
            </Link>
            <Link to="/admin/analytics" className="btn btn-admin">
              <i className="bi bi-bar-chart me-2"></i>详细数据分析
            </Link>
          </div>
        </div>
      </div>
    </div>
  );
};

export default Dashboard;