import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter/foundation.dart' show kIsWeb;
import '../theme/app_theme.dart';
import '../services/export_service.dart';

// Web 平台需要的导入
import 'dart:html' as html show Blob, Url, AnchorElement;

class ExportDataScreen extends StatefulWidget {
  const ExportDataScreen({super.key});

  @override
  State<ExportDataScreen> createState() => _ExportDataScreenState();
}

class _ExportDataScreenState extends State<ExportDataScreen> {
  final ExportService _exportService = ExportService();
  DateTime _startDate = DateTime.now().subtract(const Duration(days: 7));
  DateTime _endDate = DateTime.now();
  bool _isExporting = false;

  Future<void> _exportCSV() async {
    setState(() {
      _isExporting = true;
    });

    try {
      final csvData = await _exportService.exportToCSV(
        startDate: _startDate,
        endDate: _endDate,
      );

      if (csvData.isEmpty || csvData.trim().isEmpty) {
        if (mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            const SnackBar(
              content: Text('所选日期范围内没有数据可导出'),
              backgroundColor: AppTheme.warningColor,
            ),
          );
        }
        return;
      }

      if (kIsWeb) {
        // Web 平台：下载文件
        final blob = html.Blob([csvData], 'text/csv');
        final url = html.Url.createObjectUrlFromBlob(blob);
        html.AnchorElement(href: url)
          ..setAttribute('download', 'autotime_export_${DateTime.now().millisecondsSinceEpoch}.csv')
          ..click();
        html.Url.revokeObjectUrl(url);
      } else {
        // 移动端：复制到剪贴板
        await Clipboard.setData(ClipboardData(text: csvData));
      }

      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(kIsWeb ? '文件已下载' : '数据已复制到剪贴板'),
            backgroundColor: AppTheme.successColor,
          ),
        );
      }
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(_getExportErrorMessage(e)),
            backgroundColor: AppTheme.errorColor,
            action: SnackBarAction(
              label: '重试',
              textColor: Colors.white,
              onPressed: _exportReport,
            ),
          ),
        );
      }
    } finally {
      if (mounted) {
        setState(() {
          _isExporting = false;
        });
      }
    }
  }

  Future<void> _exportReport() async {
    setState(() {
      _isExporting = true;
    });

    try {
      final report = await _exportService.exportStatsReport(
        startDate: _startDate,
        endDate: _endDate,
      );

      if (report.isEmpty || report.trim().isEmpty) {
        if (mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            const SnackBar(
              content: Text('所选日期范围内没有统计数据可导出'),
              backgroundColor: AppTheme.warningColor,
            ),
          );
        }
        return;
      }

      if (kIsWeb) {
        // Web 平台：下载文件
        final blob = html.Blob([report], 'text/plain');
        final url = html.Url.createObjectUrlFromBlob(blob);
        html.AnchorElement(href: url)
          ..setAttribute('download', 'autotime_report_${DateTime.now().millisecondsSinceEpoch}.txt')
          ..click();
        html.Url.revokeObjectUrl(url);
      } else {
        // 移动端：复制到剪贴板
        await Clipboard.setData(ClipboardData(text: report));
      }

      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(kIsWeb ? '文件已下载' : '报告已复制到剪贴板'),
            backgroundColor: AppTheme.successColor,
          ),
        );
      }
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(_getExportErrorMessage(e)),
            backgroundColor: AppTheme.errorColor,
            action: SnackBarAction(
              label: '重试',
              textColor: Colors.white,
              onPressed: _exportReport,
            ),
          ),
        );
      }
    } finally {
      if (mounted) {
        setState(() {
          _isExporting = false;
        });
      }
    }
  }

  Future<void> _exportTodayReport() async {
    setState(() {
      _isExporting = true;
    });

    try {
      final report = await _exportService.exportTodayReport();

      if (report.isEmpty || report.trim().isEmpty) {
        if (mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            const SnackBar(
              content: Text('今日暂无数据可导出'),
              backgroundColor: AppTheme.warningColor,
            ),
          );
        }
        return;
      }

      if (kIsWeb) {
        // Web 平台：下载文件
        final blob = html.Blob([report], 'text/plain');
        final url = html.Url.createObjectUrlFromBlob(blob);
        html.AnchorElement(href: url)
          ..setAttribute('download', 'autotime_today_${DateTime.now().millisecondsSinceEpoch}.txt')
          ..click();
        html.Url.revokeObjectUrl(url);
      } else {
        // 移动端：复制到剪贴板
        await Clipboard.setData(ClipboardData(text: report));
      }

      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(kIsWeb ? '文件已下载' : '今日报告已复制到剪贴板'),
            backgroundColor: AppTheme.successColor,
          ),
        );
      }
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(_getExportErrorMessage(e)),
            backgroundColor: AppTheme.errorColor,
            action: SnackBarAction(
              label: '重试',
              textColor: Colors.white,
              onPressed: _exportTodayReport,
            ),
          ),
        );
      }
    } finally {
      if (mounted) {
        setState(() {
          _isExporting = false;
        });
      }
    }
  }

  Future<void> _selectDateRange() async {
    final DateTimeRange? picked = await showDateRangePicker(
      context: context,
      firstDate: DateTime(2020),
      lastDate: DateTime.now(),
      initialDateRange: DateTimeRange(start: _startDate, end: _endDate),
    );

    if (picked != null) {
      setState(() {
        _startDate = picked.start;
        _endDate = picked.end;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    return Scaffold(
      appBar: AppBar(
        title: const Text('数据导出'),
      ),
      body: SingleChildScrollView(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            // 日期范围选择
            Card(
              child: Padding(
                padding: const EdgeInsets.all(16),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      '选择日期范围',
                      style: theme.textTheme.titleMedium?.copyWith(
                        fontWeight: FontWeight.w600,
                      ),
                    ),
                    const SizedBox(height: 16),
                    Row(
                      children: [
                        Expanded(
                          child: OutlinedButton.icon(
                            onPressed: _selectDateRange,
                            icon: const Icon(Icons.calendar_today),
                            label: Text(
                              '${_startDate.toString().split(' ')[0]} 至 ${_endDate.toString().split(' ')[0]}',
                            ),
                          ),
                        ),
                      ],
                    ),
                  ],
                ),
              ),
            ),
            const SizedBox(height: 16),

            // 导出选项
            Card(
              child: Padding(
                padding: const EdgeInsets.all(16),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      '导出选项',
                      style: theme.textTheme.titleMedium?.copyWith(
                        fontWeight: FontWeight.w600,
                      ),
                    ),
                    const SizedBox(height: 16),
                    
                    // CSV 导出
                    _buildExportOption(
                      theme,
                      icon: Icons.table_chart,
                      title: '导出 CSV 数据',
                      subtitle: '导出原始应用使用数据（CSV 格式）',
                      onTap: _exportCSV,
                    ),
                    const SizedBox(height: 12),
                    
                    // 统计报告
                    _buildExportOption(
                      theme,
                      icon: Icons.description,
                      title: '导出统计报告',
                      subtitle: '导出时间范围内的统计报告（文本格式）',
                      onTap: _exportReport,
                    ),
                    const SizedBox(height: 12),
                    
                    // 今日报告
                    _buildExportOption(
                      theme,
                      icon: Icons.today,
                      title: '导出今日报告',
                      subtitle: '导出今日的详细统计报告',
                      onTap: _exportTodayReport,
                    ),
                  ],
                ),
              ),
            ),

            if (_isExporting)
              const Padding(
                padding: EdgeInsets.all(16),
                child: Center(child: CircularProgressIndicator()),
              ),
          ],
        ),
      ),
    );
  }

  Widget _buildExportOption(
    ThemeData theme, {
    required IconData icon,
    required String title,
    required String subtitle,
    required VoidCallback onTap,
  }) {
    return InkWell(
      onTap: _isExporting ? null : onTap,
      borderRadius: BorderRadius.circular(8),
      child: Container(
        padding: const EdgeInsets.all(12),
        decoration: BoxDecoration(
          border: Border.all(
            color: theme.colorScheme.onSurface.withOpacity(0.1),
          ),
          borderRadius: BorderRadius.circular(8),
        ),
        child: Row(
          children: [
            Icon(icon, color: AppTheme.primaryColor),
            const SizedBox(width: 12),
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    title,
                    style: theme.textTheme.bodyLarge?.copyWith(
                      fontWeight: FontWeight.w600,
                    ),
                  ),
                  const SizedBox(height: 4),
                  Text(
                    subtitle,
                    style: theme.textTheme.bodySmall?.copyWith(
                      color: theme.colorScheme.onSurface.withOpacity(0.6),
                    ),
                  ),
                ],
              ),
            ),
            const Icon(Icons.chevron_right),
          ],
        ),
      ),
    );
  }

  String _getExportErrorMessage(Object error) {
    final errorString = error.toString().toLowerCase();
    if (errorString.contains('permission') || errorString.contains('权限')) {
      return '需要授予应用使用权限';
    } else if (errorString.contains('database') || errorString.contains('数据库')) {
      return '数据库操作失败，请稍后重试';
    } else if (errorString.contains('file') || errorString.contains('文件')) {
      return '文件操作失败，请检查存储权限';
    }
    return '导出失败，请稍后重试';
  }
}