import { useState, useEffect, useCallback, useRef } from 'react';
import {
  Paper,
  Textarea,
  Group,
  Text,
  Stack,
  Button,
  Box,
} from '@mantine/core';
import { useDebouncedValue } from '@mantine/hooks';
import ReactMarkdown from 'react-markdown';
import remarkGfm from 'remark-gfm';
import rehypeSanitize from 'rehype-sanitize';
import { IconDeviceFloppy } from '@tabler/icons-react';
import { useAppStore } from '../../stores';

interface NoteEditorProps {
  onSave?: () => void;
}

type ViewMode = 'edit' | 'preview';

export function NoteEditor({ onSave }: NoteEditorProps) {
  const notes = useAppStore((state) => state.notes);
  const updateNotesContent = useAppStore((state) => state.updateNotesContent);
  const saveNotes = useAppStore((state) => state.saveNotes);
  const fetchNotes = useAppStore((state) => state.fetchNotes);

  const [content, setContent] = useState('');
  const [saving, setSaving] = useState(false);
  const [lastSaved, setLastSaved] = useState<Date | null>(null);
  const [viewMode] = useState<ViewMode>('edit');

  // Initialize content from notes
  useEffect(() => {
    if (notes) {
      setContent(notes.content);
    }
  }, [notes]);

  // Fetch notes on mount
  useEffect(() => {
    fetchNotes();
  }, [fetchNotes]);

  // Auto-save with 3 second debounce
  const [debouncedContent] = useDebouncedValue(content, 3000);

  // 滚动条样式 - 仅在悬停时显示
  const scrollbarStyle = `
    .note-scroll::-webkit-scrollbar {
      width: 4px;
      height: 4px;
    }
    .note-scroll::-webkit-scrollbar-track {
      background: transparent;
    }
    .note-scroll::-webkit-scrollbar-thumb {
      background: transparent;
      border-radius: 2px;
    }
    .note-scroll:hover::-webkit-scrollbar-thumb {
      background: rgba(0, 0, 0, 0.15);
    }
  `;

  useEffect(() => {
    if (debouncedContent !== undefined && notes && debouncedContent !== content) {
      handleSave(debouncedContent);
    }
  }, [debouncedContent]);

  const handleSave = useCallback(
    async (value: string) => {
      if (!notes) return;

      setSaving(true);
      try {
        updateNotesContent(value);
        await saveNotes(value);
        setLastSaved(new Date());
        onSave?.();
      } catch (error) {
        console.error('Failed to save note:', error);
      } finally {
        setSaving(false);
      }
    },
    [notes, updateNotesContent, saveNotes, onSave]
  );

  const formatLastSaved = () => {
    if (!lastSaved) return '未保存';
    const now = new Date();
    const diff = now.getTime() - lastSaved.getTime();
    if (diff < 1000) return '刚刚保存';
    if (diff < 60000) return `${Math.floor(diff / 1000)}秒前保存`;
    return lastSaved.toLocaleTimeString('zh-CN');
  };

  const handleManualSave = () => {
    if (content && notes) {
      handleSave(content);
    }
  };

  const scrollContainerRef = useRef<HTMLDivElement>(null);

  // 处理滚轮事件，实现列表独立滚动
  const handleWheel = (e: React.WheelEvent) => {
    const container = scrollContainerRef.current;
    if (!container) return;

    const { scrollTop, scrollHeight, clientHeight } = container;
    // 使用 1px 缓冲避免浮点数精度问题
    const isAtTop = scrollTop <= 0;
    const isAtBottom = scrollTop + clientHeight >= scrollHeight - 1;

    // 如果已经滚动到顶部且向下滚动，或者已经滚动到底部且向上滚动，则阻止事件冒泡
    if ((isAtTop && e.deltaY > 0) || (isAtBottom && e.deltaY < 0)) {
      e.stopPropagation();
    }
    // 如果在滚动范围内，允许事件继续传递以实现正常滚动
  };

  return (
    <Paper p="md" withBorder radius={4} style={{ display: 'flex', flexDirection: 'column', height: '100%' }}>
      <style>{scrollbarStyle}</style>
      <Stack gap="sm" style={{ flex: 1, display: 'flex', flexDirection: 'column' }}>
        {/* Header */}
        <Group justify="space-between" style={{ flexShrink: 0 }}>
          <Group gap="sm">
            <Text fw={400} size="sm" style={{ letterSpacing: '0.1em', color: '#1a1a1a' }}>
              便签
            </Text>
          </Group>
          <Group gap="sm">
            <Button
              size="xs"
              variant="outline"
              leftSection={<IconDeviceFloppy size={12} />}
              onClick={handleManualSave}
              loading={saving}
              style={{
                borderColor: '#ccc',
                color: '#1a1a1a',
                borderRadius: 2,
              }}
            >
              保存
            </Button>
            <Text size="xs" c={saving ? '#666' : lastSaved ? '#999' : '#bbb'}>
              {saving ? '保存中...' : formatLastSaved()}
            </Text>
          </Group>
        </Group>

        {/* Editor/Preview Area */}
        <Box
          ref={scrollContainerRef}
          onWheel={handleWheel}
          data-scroll-container="note"
          className="note-scroll"
          style={{ flex: 1, minHeight: 0, display: 'flex', overflowY: 'auto' }}
        >
          {viewMode === 'edit' && (
            <Textarea
              value={content}
              onChange={(e) => setContent(e.target.value)}
              placeholder="在这里记录你的想法...&#10;&#10;支持 Markdown 语法：&#10;- # 一级标题&#10;- **粗体**&#10;- *斜体*&#10;- [链接](url)"
              autosize
              minRows={8}
              styles={{
                input: {
                  border: 'none',
                  resize: 'none',
                  fontFamily: 'Monaco, Menlo, Ubuntu Mono, monospace',
                  fontSize: '13px',
                  lineHeight: '1.6',
                  background: 'transparent',
                  '&:focus': { outline: 'none' },
                },
              }}
              style={{
                flex: 1,
                width: '100%',
                overflowY: 'auto',
              }}
            />
          )}

          {viewMode === 'preview' && (
            <Box
              style={{
                flex: 1,
                overflowY: 'auto',
                padding: '8px',
                fontSize: '13px',
                lineHeight: '1.6',
              }}
            >
              {content ? (
                <Box
                  style={{
                    '& h1, & h2, & h3': {
                      marginTop: '1em',
                      marginBottom: '0.5em',
                      fontWeight: 500,
                    },
                    '& h1': { fontSize: '1.25em', borderBottom: '1px solid rgba(0,0,0,0.08)', paddingBottom: '0.3em' },
                    '& h2': { fontSize: '1.1em', borderBottom: '1px solid rgba(0,0,0,0.06)', paddingBottom: '0.3em' },
                    '& p': { marginBottom: '0.8em', color: '#333' },
                    '& ul, & ol': { paddingLeft: '1.5em', marginBottom: '0.8em' },
                    '& li': { marginBottom: '0.3em', color: '#333' },
                    '& blockquote': {
                      borderLeft: '3px solid rgba(0,0,0,0.1)',
                      paddingLeft: '1em',
                      marginLeft: 0,
                      color: '#888',
                    },
                    '& code': {
                      backgroundColor: 'rgba(0,0,0,0.04)',
                      padding: '0.2em 0.4em',
                      borderRadius: '2px',
                      fontSize: '0.9em',
                    },
                    '& pre': {
                      backgroundColor: 'rgba(0,0,0,0.03)',
                      padding: '1em',
                      borderRadius: '2px',
                      overflow: 'auto',
                    },
                    '& pre code': {
                      backgroundColor: 'transparent',
                      padding: 0,
                    },
                    '& a': {
                      color: '#1a1a1a',
                      textDecoration: 'underline',
                      textUnderlineOffset: 2,
                    },
                    '& hr': {
                      border: 'none',
                      borderTop: '1px solid rgba(0,0,0,0.06)',
                      margin: '1em 0',
                    },
                  } as any}
                >
                  <ReactMarkdown remarkPlugins={[remarkGfm]} rehypePlugins={[rehypeSanitize]}>
                    {content}
                  </ReactMarkdown>
                </Box>
              ) : (
                <Text c="#999" ta="center" py="xl" size="sm" style={{ letterSpacing: '0.05em' }}>
                  暂无内容
                  <br />
                  <Text size="xs" c="#bbb" mt={4}>
                    使用 Markdown 格式记录你的想法
                  </Text>
                </Text>
              )}
            </Box>
          )}
        </Box>
      </Stack>
    </Paper>
  );
}