import React, { useState, useEffect } from 'react';
import { useParams, useNavigate } from 'react-router-dom';
import {
  Card,
  Avatar,
  Typography,
  Divider,
  List,
  Form,
  Input,
  Button,
  message,
  Spin,
  Space,
  Tag,
  Empty
} from 'antd';
import { ArrowLeftOutlined, MessageOutlined, UserOutlined, CommentOutlined } from '@ant-design/icons';
import { getComments, addComment } from '@/api/forum';
import { useAuth } from '@/features/auth/contexts/AuthContext';

const { Title, Paragraph, Text } = Typography;
const { TextArea } = Input;

const PostDetailPage = () => {
  const { postId } = useParams();
  const navigate = useNavigate();
  const { user, isAuthenticated } = useAuth();
  const [loading, setLoading] = useState(true);
  const [commenting, setCommenting] = useState(false);
  const [postContent, setPostContent] = useState('');
  const [comments, setComments] = useState([]);
  const [form] = Form.useForm();
  const [replyForms] = Form.useForm(); // 用于回复的表单
  const [replyingTo, setReplyingTo] = useState(null); // 当前正在回复的评论ID
  const [replying, setReplying] = useState(false); // 回复中状态

  // 获取帖子详情和评论
  useEffect(() => {
    if (isAuthenticated && user?.username && postId) {
      fetchPostAndComments();
    }
  }, [isAuthenticated, user, postId]);

  // 监听ESC键取消回复
  useEffect(() => {
    const handleKeyDown = (event) => {
      if (event.key === 'Escape' && replyingTo) {
        cancelReply();
      }
    };

    document.addEventListener('keydown', handleKeyDown);
    return () => {
      document.removeEventListener('keydown', handleKeyDown);
    };
  }, [replyingTo]);

  const fetchPostAndComments = async () => {
    try {
      setLoading(true);
      
      const params = {
        postId: postId,
        username: user.username
      }
      const response = await getComments(params);

      if (response && response.data) {
        setPostContent(response.data.content || '');
        // 直接按发布时间排序，最新的在前面
        const allComments = response.data.comments || [];
        const sortedComments = allComments.sort((a, b) => 
          new Date(b.publishDate) - new Date(a.publishDate)
        );
        setComments(sortedComments);
      } else {
        message.error('获取帖子详情失败');
      }
    } catch (error) {
      console.error('获取帖子详情失败:', error);
      message.error(error.message || '获取帖子详情失败');
    } finally {
      setLoading(false);
    }
  };

  // 提交主评论
  const handleSubmitComment = async () => {
    try {
      const values = await form.validateFields();
      setCommenting(true);

      const params = {
        content: values.comment,
        username: user.username,
        postId: postId
      };

      console.log('提交评论数据:', params);
      const response = await addComment(params);
      
      if (response && response.message === 'Comment added successfully') {
        message.success('评论发布成功');
        form.resetFields();
        fetchPostAndComments();
      } else {
        message.error('评论发布失败');
      }
    } catch (error) {
      console.error('发布评论失败:', error);
      message.error(error.message || '发布评论失败');
    } finally {
      setCommenting(false);
    }
  };

  // 提交回复评论
  const handleSubmitReply = async (reviewerId) => {
    try {
      const values = await replyForms.validateFields();
      setReplying(true);

      const replyData = {
        content: values.reply,
        username: user.username,
        postId: postId,
        reviewer: reviewerId
      };

      console.log('提交回复数据:', replyData);
      const response = await addComment(replyData);
      
      if (response && response.message === 'Comment added successfully') {
        message.success('回复发布成功');
        replyForms.resetFields();
        setReplyingTo(null);
        fetchPostAndComments();
      } else {
        message.error('回复发布失败');
      }
    } catch (error) {
      console.error('发布回复失败:', error);
      message.error(error.message || '发布回复失败');
    } finally {
      setReplying(false);
    }
  };

  // 开始回复评论
  const startReply = (commentId) => {
    setReplyingTo(commentId);
    replyForms.resetFields();
  };

  // 取消回复
  const cancelReply = () => {
    setReplyingTo(null);
    replyForms.resetFields();
  };

  // 格式化日期
  const formatDate = (dateString) => {
    try {
      return new Date(dateString).toLocaleString('zh-CN', {
        year: 'numeric',
        month: '2-digit',
        day: '2-digit',
        hour: '2-digit',
        minute: '2-digit'
      });
    } catch {
      return dateString;
    }
  };

  // 查找被回复的评论
  const getReviewedComment = (reviewerId) => {
    return comments.find(comment => comment.commentId === reviewerId);
  };

  // 如果用户未认证
  if (!isAuthenticated) {
    return (
      <div className="text-center py-8">
        <Title level={3}>请先登录</Title>
        <Paragraph>您需要登录后才能查看帖子详情</Paragraph>
      </div>
    );
  }

  return (
    <div className="max-w-4xl mx-auto space-y-6">
      {/* 返回按钮 */}
      <Button 
        icon={<ArrowLeftOutlined />} 
        onClick={() => navigate('/forum')}
        className="mb-4"
      >
        返回论坛
      </Button>

      {loading ? (
        <div className="flex justify-center py-8">
          <Spin size="large" tip="加载中..." />
        </div>
      ) : (
        <>
          {/* 帖子内容 */}
          <Card title={
            <Space>
              <MessageOutlined />
              <span>帖子详情</span>
            </Space>
          }>
            <div className="mb-4">
              <Title level={4}>帖子内容</Title>
              <Paragraph style={{ fontSize: '16px', lineHeight: 1.6 }}>
                {postContent || '暂无内容'}
              </Paragraph>
            </div>
            <Divider />
            <div className="flex justify-between items-center text-sm text-gray-500">
              <span>帖子ID: {postId}</span>
              <Space>
                <Tag color="blue">
                  <MessageOutlined /> {comments.length} 条评论
                </Tag>
              </Space>
            </div>
          </Card>

          {/* 评论区 */}
          <Card title={
            <Space>
              <MessageOutlined />
              <span>评论区 ({comments.length})</span>
            </Space>
          }>
            {/* 发表评论 */}
            <div className="mb-6">
              <Title level={5}>发表评论</Title>
              <Form form={form} layout="vertical">
                <Form.Item
                  name="comment"
                  rules={[{ required: true, message: '请输入评论内容' }]}
                >
                  <TextArea 
                    rows={4} 
                    placeholder="请输入您的评论..."
                    maxLength={500}
                    showCount
                  />
                </Form.Item>
                <Form.Item>
                  <Button 
                    type="primary" 
                    onClick={handleSubmitComment}
                    loading={commenting}
                  >
                    发布评论
                  </Button>
                </Form.Item>
              </Form>
            </div>

            <Divider />

            {/* 评论列表 */}
            {comments.length > 0 ? (
              <List
                itemLayout="vertical"
                dataSource={comments}
                renderItem={(comment) => (
                  <List.Item 
                    key={comment.commentId}
                    className={`border-l-2 pl-4 hover:bg-gray-50 transition-colors ${
                      comment.reviewerId ? 'border-l-orange-200 bg-orange-50' : 'border-l-blue-100'
                    }`}
                  >
                    <List.Item.Meta
                      avatar={
                        <Avatar 
                          src={`https://api.dicebear.com/7.x/avataaars/svg?seed=${comment.writer || 'anonymous'}`}
                          icon={<UserOutlined />}
                        />
                      }
                      title={
                        <div className="flex flex-wrap items-center gap-2">
                          <Text strong>{comment.writer || '匿名用户'}</Text>
                          <Text type="secondary" className="text-sm">
                            {formatDate(comment.publishDate)}
                          </Text>
                          <Tag size="small" color="blue">
                            #{comment.commentId}
                          </Tag>
                          {comment.reviewerId && (
                            <Tag size="small" color="orange" className="ml-2">
                              回复 #{comment.reviewerId}
                            </Tag>
                          )}
                        </div>
                      }
                      description={
                        <div>
                          {/* 显示被回复的评论 */}
                          {comment.reviewerId && (
                            <div className="mb-3 p-3 bg-gray-100 rounded border-l-4 border-l-orange-400">
                              <Text type="secondary" className="text-xs">
                                回复 #{comment.reviewerId}:
                              </Text>
                              {(() => {
                                const reviewedComment = getReviewedComment(comment.reviewerId);
                                return reviewedComment ? (
                                  <div className="mt-1">
                                    <Text type="secondary" className="text-sm">
                                      {reviewedComment.writer || '匿名用户'}: 
                                    </Text>
                                    <Text className="text-sm ml-1">
                                      {reviewedComment.content.length > 50 
                                        ? reviewedComment.content.substring(0, 50) + '...' 
                                        : reviewedComment.content}
                                    </Text>
                                  </div>
                                ) : (
                                  <Text type="secondary" className="text-sm">
                                    原评论已被删除
                                  </Text>
                                );
                              })()}
                            </div>
                          )}
                          
                          <Paragraph className="mt-2 mb-3">
                            {comment.content}
                          </Paragraph>
                          
                          {/* 回复按钮 */}
                          <div className="mb-3">
                            <Button
                              type="link"
                              icon={<CommentOutlined />}
                              onClick={() => startReply(comment.commentId)}
                              size="small"
                              disabled={replyingTo === comment.commentId}
                              className="p-0"
                            >
                              {replyingTo === comment.commentId ? '回复中...' : '回复'}
                            </Button>
                          </div>
                          
                          {/* 回复表单 */}
                          {replyingTo === comment.commentId && (
                            <div className="mt-4 p-4 bg-gray-50 rounded-lg">
                              <Form form={replyForms} layout="vertical">
                                <Form.Item
                                  name="reply"
                                  rules={[{ required: true, message: '请输入回复内容' }]}
                                >
                                  <TextArea 
                                    rows={3} 
                                    placeholder={`回复 ${comment.writer || '匿名用户'}...`}
                                    maxLength={500}
                                    showCount
                                  />
                                </Form.Item>
                                <Form.Item className="mb-0">
                                  <Space>
                                    <Button 
                                      type="primary" 
                                      size="small"
                                      onClick={() => handleSubmitReply(comment.commentId)}
                                      loading={replying}
                                    >
                                      发布回复
                                    </Button>
                                    <Button 
                                      size="small"
                                      onClick={cancelReply}
                                    >
                                      取消
                                    </Button>
                                  </Space>
                                </Form.Item>
                              </Form>
                            </div>
                          )}
                        </div>
                      }
                    />
                  </List.Item>
                )}
              />
            ) : (
              <Empty 
                description="暂无评论，快来发表第一条评论吧！"
                image={Empty.PRESENTED_IMAGE_SIMPLE}
              />
            )}
          </Card>
        </>
      )}
    </div>
  );
};

export default PostDetailPage;