Refactor: Replace MarkdownRenderer with MarkdownDisplay component

- This commit refactors the Markdown rendering logic within the CLI UI.
  The existing `MarkdownRenderer.tsx` class-based component has been
  replaced with a new functional component `MarkdownDisplay.tsx`.
- The `MarkdownDisplay` component is a React.memoized component for
  improved performance and maintains the same core Markdown parsing
  and rendering capabilities.

1 files changed, 301 insertions, 0 deletions

diff --git a/packages/cli/src/ui/utils/MarkdownDisplay.tsx b/packages/cli/src/ui/utils/MarkdownDisplay.tsx
new file mode 100644
index 00000000..4e49a013
--- /dev/null
+++ b/packages/cli/src/ui/utils/MarkdownDisplay.tsx
@@ -0,0 +1,301 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import React from 'react';
+import { Text, Box } from 'ink';
+import { Colors } from '../colors.js';
+import { colorizeCode } from './CodeColorizer.js';
+
+interface MarkdownDisplayProps {
+  text: string;
+}
+
+function MarkdownDisplayComponent({
+  text,
+}: MarkdownDisplayProps): React.ReactElement {
+  if (!text) return <></>;
+
+  const lines = text.split('\n');
+  const headerRegex = /^ *(#{1,4}) +(.*)/;
+  const codeFenceRegex = /^ *(`{3,}|~{3,}) *(\S*?) *$/;
+  const ulItemRegex = /^([ \t]*)([-*+]) +(.*)/;
+  const olItemRegex = /^([ \t]*)(\d+)\. +(.*)/;
+  const hrRegex = /^ *([-*_] *){3,} *$/;
+
+  const contentBlocks: React.ReactNode[] = [];
+  let inCodeBlock = false;
+  let codeBlockContent: string[] = [];
+  let codeBlockLang: string | null = null;
+  let codeBlockFence = '';
+
+  lines.forEach((line, index) => {
+    const key = `line-${index}`;
+
+    if (inCodeBlock) {
+      const fenceMatch = line.match(codeFenceRegex);
+      if (
+        fenceMatch &&
+        fenceMatch[1].startsWith(codeBlockFence[0]) &&
+        fenceMatch[1].length >= codeBlockFence.length
+      ) {
+        contentBlocks.push(
+          _renderCodeBlock(key, codeBlockContent, codeBlockLang),
+        );
+        inCodeBlock = false;
+        codeBlockContent = [];
+        codeBlockLang = null;
+        codeBlockFence = '';
+      } else {
+        codeBlockContent.push(line);
+      }
+      return;
+    }
+
+    const codeFenceMatch = line.match(codeFenceRegex);
+    const headerMatch = line.match(headerRegex);
+    const ulMatch = line.match(ulItemRegex);
+    const olMatch = line.match(olItemRegex);
+    const hrMatch = line.match(hrRegex);
+
+    if (codeFenceMatch) {
+      inCodeBlock = true;
+      codeBlockFence = codeFenceMatch[1];
+      codeBlockLang = codeFenceMatch[2] || null;
+    } else if (hrMatch) {
+      contentBlocks.push(
+        <Box key={key}>
+          <Text dimColor>---</Text>
+        </Box>,
+      );
+    } else if (headerMatch) {
+      const level = headerMatch[1].length;
+      const headerText = headerMatch[2];
+      const renderedHeaderText = _renderInline(headerText);
+      let headerNode: React.ReactNode = null;
+      switch (level) {
+        case 1:
+          headerNode = (
+            <Text bold color={Colors.AccentCyan}>
+              {renderedHeaderText}
+            </Text>
+          );
+          break;
+        case 2:
+          headerNode = (
+            <Text bold color={Colors.AccentBlue}>
+              {renderedHeaderText}
+            </Text>
+          );
+          break;
+        case 3:
+          headerNode = <Text bold>{renderedHeaderText}</Text>;
+          break;
+        case 4:
+          headerNode = (
+            <Text italic color={Colors.SubtleComment}>
+              {renderedHeaderText}
+            </Text>
+          );
+          break;
+        default:
+          headerNode = <Text>{renderedHeaderText}</Text>;
+          break;
+      }
+      if (headerNode) contentBlocks.push(<Box key={key}>{headerNode}</Box>);
+    } else if (ulMatch) {
+      const leadingWhitespace = ulMatch[1];
+      const marker = ulMatch[2];
+      const itemText = ulMatch[3];
+      contentBlocks.push(
+        _renderListItem(key, itemText, 'ul', marker, leadingWhitespace),
+      );
+    } else if (olMatch) {
+      const leadingWhitespace = olMatch[1];
+      const marker = olMatch[2];
+      const itemText = olMatch[3];
+      contentBlocks.push(
+        _renderListItem(key, itemText, 'ol', marker, leadingWhitespace),
+      );
+    } else {
+      const renderedLine = _renderInline(line);
+      if (renderedLine.length > 0 || line.length > 0) {
+        contentBlocks.push(
+          <Box key={key}>
+            <Text wrap="wrap">{renderedLine}</Text>
+          </Box>,
+        );
+      } else if (line.trim().length === 0) {
+        if (contentBlocks.length > 0 && !inCodeBlock) {
+          contentBlocks.push(<Box key={key} height={1} />);
+        }
+      }
+    }
+  });
+
+  if (inCodeBlock) {
+    contentBlocks.push(
+      _renderCodeBlock(`line-eof`, codeBlockContent, codeBlockLang),
+    );
+  }
+
+  return <>{contentBlocks}</>;
+}
+
+// Helper functions (adapted from static methods of MarkdownRenderer)
+
+function _renderInline(text: string): React.ReactNode[] {
+  const nodes: React.ReactNode[] = [];
+  let lastIndex = 0;
+  const inlineRegex =
+    /(\*\*.*?\*\*|\*.*?\*|_.*?_|~~.*?~~|\[.*?\]\(.*?\)|`+.+?`+|<u>.*?<\/u>)/g;
+  let match;
+
+  while ((match = inlineRegex.exec(text)) !== null) {
+    if (match.index > lastIndex) {
+      nodes.push(
+        <Text key={`t-${lastIndex}`}>
+          {text.slice(lastIndex, match.index)}
+        </Text>,
+      );
+    }
+
+    const fullMatch = match[0];
+    let renderedNode: React.ReactNode = null;
+    const key = `m-${match.index}`;
+
+    try {
+      if (
+        fullMatch.startsWith('**') &&
+        fullMatch.endsWith('**') &&
+        fullMatch.length > 4
+      ) {
+        renderedNode = (
+          <Text key={key} bold>
+            {fullMatch.slice(2, -2)}
+          </Text>
+        );
+      } else if (
+        ((fullMatch.startsWith('*') && fullMatch.endsWith('*')) ||
+          (fullMatch.startsWith('_') && fullMatch.endsWith('_'))) &&
+        fullMatch.length > 2
+      ) {
+        renderedNode = (
+          <Text key={key} italic>
+            {fullMatch.slice(1, -1)}
+          </Text>
+        );
+      } else if (
+        fullMatch.startsWith('~~') &&
+        fullMatch.endsWith('~~') &&
+        fullMatch.length > 4
+      ) {
+        renderedNode = (
+          <Text key={key} strikethrough>
+            {fullMatch.slice(2, -2)}
+          </Text>
+        );
+      } else if (
+        fullMatch.startsWith('`') &&
+        fullMatch.endsWith('`') &&
+        fullMatch.length > 1
+      ) {
+        const codeMatch = fullMatch.match(/^(`+)(.+?)\1$/s);
+        if (codeMatch && codeMatch[2]) {
+          renderedNode = (
+            <Text key={key} color={Colors.AccentPurple}>
+              {codeMatch[2]}
+            </Text>
+          );
+        } else {
+          renderedNode = (
+            <Text key={key} color={Colors.AccentPurple}>
+              {fullMatch.slice(1, -1)}
+            </Text>
+          );
+        }
+      } else if (
+        fullMatch.startsWith('[') &&
+        fullMatch.includes('](') &&
+        fullMatch.endsWith(')')
+      ) {
+        const linkMatch = fullMatch.match(/\[(.*?)\]\((.*?)\)/);
+        if (linkMatch) {
+          const linkText = linkMatch[1];
+          const url = linkMatch[2];
+          renderedNode = (
+            <Text key={key}>
+              {linkText}
+              <Text color={Colors.AccentBlue}> ({url})</Text>
+            </Text>
+          );
+        }
+      } else if (
+        fullMatch.startsWith('<u>') &&
+        fullMatch.endsWith('</u>') &&
+        fullMatch.length > 6
+      ) {
+        renderedNode = (
+          <Text key={key} underline>
+            {fullMatch.slice(3, -4)}
+          </Text>
+        );
+      }
+    } catch (e) {
+      console.error('Error parsing inline markdown part:', fullMatch, e);
+      renderedNode = null;
+    }
+
+    nodes.push(renderedNode ?? <Text key={key}>{fullMatch}</Text>);
+    lastIndex = inlineRegex.lastIndex;
+  }
+
+  if (lastIndex < text.length) {
+    nodes.push(<Text key={`t-${lastIndex}`}>{text.slice(lastIndex)}</Text>);
+  }
+
+  return nodes.filter((node) => node !== null);
+}
+
+function _renderCodeBlock(
+  key: string,
+  content: string[],
+  lang: string | null,
+): React.ReactNode {
+  const fullContent = content.join('\n');
+  const colorizedCode = colorizeCode(fullContent, lang);
+
+  return (
+    <Box key={key} flexDirection="column" padding={1}>
+      {colorizedCode}
+    </Box>
+  );
+}
+
+function _renderListItem(
+  key: string,
+  text: string,
+  type: 'ul' | 'ol',
+  marker: string,
+  leadingWhitespace: string = '',
+): React.ReactNode {
+  const renderedText = _renderInline(text);
+  const prefix = type === 'ol' ? `${marker}. ` : `${marker} `;
+  const prefixWidth = prefix.length;
+  const indentation = leadingWhitespace.length;
+
+  return (
+    <Box key={key} paddingLeft={indentation + 1} flexDirection="row">
+      <Box width={prefixWidth}>
+        <Text>{prefix}</Text>
+      </Box>
+      <Box flexGrow={1}>
+        <Text wrap="wrap">{renderedText}</Text>
+      </Box>
+    </Box>
+  );
+}
+
+export const MarkdownDisplay = React.memo(MarkdownDisplayComponent);