File size: 4,104 Bytes
21ad36a
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
import { CodeToTokenTransformStream, type RecallToken } from '@shikijs/stream';
import { ShikiStreamRenderer } from '@shikijs/stream/react';
import type { ThemedToken } from 'shiki/core';
import { useEffect, useRef, useState } from 'react';
import {
  codeThemeName,
  getCodeHighlighter,
  normalizeCodeLanguage,
  type CodeTheme,
} from '../../lib/code-highlighter';

interface StreamingCodeBlockProps {
  code: string;
  language: string;
  theme: CodeTheme;
  complete: boolean;
}

export function StreamingCodeBlock({
  code,
  language,
  theme,
  complete,
}: StreamingCodeBlockProps) {
  const normalizedLanguage = normalizeCodeLanguage(language);
  const [revision, setRevision] = useState(0);
  const [tokenStream, setTokenStream] = useState<ReadableStream<ThemedToken | RecallToken> | null>(null);
  const [highlightFailed, setHighlightFailed] = useState(false);
  const writerRef = useRef<WritableStreamDefaultWriter<string> | null>(null);
  const writtenRef = useRef('');
  const closedRef = useRef(false);
  const codeRef = useRef(code);
  const completeRef = useRef(complete);
  const queueRef = useRef<Promise<void>>(Promise.resolve());

  codeRef.current = code;
  completeRef.current = complete;

  const queueWrite = (
    writer: WritableStreamDefaultWriter<string>,
    chunk: string,
    closeAfter: boolean,
  ) => {
    queueRef.current = queueRef.current
      .then(async () => {
        if (chunk) await writer.write(chunk);
        if (closeAfter && !closedRef.current) {
          closedRef.current = true;
          await writer.close();
        }
      })
      .catch(() => {
        if (writerRef.current === writer) {
          writerRef.current = null;
          setHighlightFailed(true);
        }
      });
  };

  useEffect(() => {
    let disposed = false;
    let writer: WritableStreamDefaultWriter<string> | null = null;
    setTokenStream(null);
    setHighlightFailed(false);
    writtenRef.current = '';
    closedRef.current = false;
    queueRef.current = Promise.resolve();

    void getCodeHighlighter(normalizedLanguage)
      .then((highlighter) => {
        if (disposed) return;
        const transform = new CodeToTokenTransformStream({
          highlighter,
          lang: normalizedLanguage,
          theme: codeThemeName(theme),
          allowRecalls: true,
        });
        writer = transform.writable.getWriter();
        writerRef.current = writer;
        const currentCode = codeRef.current;
        writtenRef.current = currentCode;
        setTokenStream(transform.readable);
        queueWrite(writer, currentCode, completeRef.current);
      })
      .catch(() => {
        if (!disposed) setHighlightFailed(true);
      });

    return () => {
      disposed = true;
      if (writer && writerRef.current === writer) writerRef.current = null;
      if (writer && !closedRef.current) {
        closedRef.current = true;
        void writer.close().catch(() => undefined);
      }
    };
  }, [normalizedLanguage, revision, theme]);

  useEffect(() => {
    const writer = writerRef.current;
    if (!writer || closedRef.current) return;
    const written = writtenRef.current;
    if (!code.startsWith(written)) {
      writerRef.current = null;
      closedRef.current = true;
      void writer.close().catch(() => undefined);
      setRevision((current) => current + 1);
      return;
    }
    const delta = code.slice(written.length);
    writtenRef.current = code;
    if (delta || complete) queueWrite(writer, delta, complete);
  }, [code, complete]);

  const label = language.trim() || 'plain text';
  const useFallback = !tokenStream || highlightFailed;

  return (
    <figure
      className="code-block"
      data-language={normalizedLanguage}
      data-code-complete={complete ? 'true' : 'false'}
    >
      <figcaption>
        <span>{label}</span>
        {!complete && <span className="code-stream-state"><i /> streaming</span>}
      </figcaption>
      {useFallback
        ? <pre className="code-fallback"><code>{code}</code></pre>
        : <ShikiStreamRenderer stream={tokenStream} />}
    </figure>
  );
}