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1// Syntax highlighting helpers for Highlight.js
2 
3/**
4 * Infer Highlight.js language slug from a filename/path.
5 * Returns null when unknown.
6 */
7export function inferHljsLang(fileName: string): string | null {
8  const name = fileName || "";
9  const lower = name.toLowerCase();
10  // Special filenames
11  if (lower === "makefile") return "makefile";
12  if (lower === "dockerfile" || lower.endsWith("/dockerfile")) return "dockerfile";
13 
14  const lastDot = lower.lastIndexOf(".");
15  const ext = lastDot >= 0 ? lower.slice(lastDot + 1) : "";
16 
17  switch (ext) {
18    case "ts":
19    case "tsx":
20      return "typescript";
21    case "js":
22    case "mjs":
23    case "cjs":
24    case "jsx":
25      return "javascript";
26    case "json":
27      return "json";
28    case "go":
29      return "go";
30    case "py":
31      return "python";
32    case "rb":
33      return "ruby";
34    case "php":
35      return "php";
36    case "java":
37      return "java";
38    case "c":
39      return "c";
40    case "cc":
41    case "cpp":
42    case "cxx":
43    case "hpp":
44      return "cpp";
45    case "cs":
46      return "csharp";
47    case "rs":
48      return "rust";
49    case "kt":
50      return "kotlin";
51    case "swift":
52      return "swift";
53    case "dart":
54      return "dart";
55    case "sql":
56      return "sql";
57    case "sh":
58    case "bash":
59    case "zsh":
60      return "bash"; // highlight.js alias for sh
61    case "ps1":
62    case "psm1":
63      return "powershell";
64    case "less":
65      return "less";
66    case "lua":
67      return "lua";
68    case "yml":
69    case "yaml":
70      return "yaml";
71    case "toml":
72      return "toml";
73    case "proto":
74      return "protobuf";
75    case "gradle":
76      return "groovy";
77    case "mm":
78      return "objectivec";
79    case "pl":
80      return "perl";
81    case "h":
82      return "cpp";
83    case "ini":
84    case "cfg":
85    case "conf":
86      return "ini";
87    case "md":
88    case "markdown":
89      return "markdown";
90    case "html":
91    case "htm":
92    case "xml":
93    case "svg":
94      return "xml"; // highlight.js uses xml for HTML/XML/SVG
95    case "css":
96      return "css";
97    case "scss":
98    case "sass":
99      return "scss";
100    case "diff":
101      return "diff";
102    default:
103      return null;
104  }
105}
106 
107/**
108 * Default small set of languages useful for README/markdown pages.
109 * Keep this list short to honor "load only when needed" while covering common fences.
110 */
111export function getMarkdownHighlightLangs(): string[] {
112  return ["typescript", "javascript", "json", "bash", "yaml", "diff", "go", "python"];
113}
114 
115/**
116 * Infer language from a shebang line (e.g., #!/usr/bin/env python3)
117 */
118function inferFromShebang(text: string): string | null {
119  const firstLine = (text || "").split(/\r?\n/, 1)[0];
120  if (!firstLine || !firstLine.startsWith("#!")) return null;
121  const lower = firstLine.toLowerCase();
122  if (lower.includes("python")) return "python";
123  if (lower.includes("node") || lower.includes("deno")) return "javascript";
124  if (lower.includes("bash") || lower.includes("sh") || lower.includes("zsh")) return "bash";
125  if (lower.includes("ruby")) return "ruby";
126  if (lower.includes("ts-node")) return "typescript";
127  return null;
128}
129 
130/**
131 * Smarter inference: use file extension first, then shebang fallback.
132 */
133export function inferHljsLangSmart(fileName: string, text?: string): string | null {
134  const byExt = inferHljsLang(fileName);
135  if (byExt) return byExt;
136  if (text) {
137    const byShebang = inferFromShebang(text);
138    if (byShebang) return byShebang;
139  }
140  return null;
141}
142 
143/**
144 * Languages to load for a blob using smart inference.
145 */
146export function getHighlightLangsForBlobSmart(fileName: string, text?: string): string[] {
147  const lang = inferHljsLangSmart(fileName, text);
148  const normalized = normalizeLangForCdn(lang);
149  return normalized ? [normalized] : [];
150}
151 
152// Supported language slugs on our pinned CDN build. Keep this conservative.
153const SUPPORTED_LANGS = new Set<string>([
154  "typescript",
155  "javascript",
156  "json",
157  "bash",
158  "yaml",
159  "diff",
160  "go",
161  "python",
162  "ini",
163  "xml",
164  "css",
165  "scss",
166  "less",
167  "java",
168  "c",
169  "cpp",
170  "csharp",
171  "rust",
172  "kotlin",
173  "swift",
174  "php",
175  "ruby",
176  "sql",
177  "powershell",
178  "dockerfile",
179  "makefile",
180  "nginx",
181  "objectivec",
182  "perl",
183  "protobuf",
184  "groovy",
185  "lua",
186]);
187 
188/**
189 * Normalize an inferred language slug to a CDN-available one.
190 * - Map missing or alias languages to closest available grammar (e.g., toml -> ini)
191 */
192export function normalizeLangForCdn(lang: string | null): string | null {
193  if (!lang) return null;
194  let slug = lang;
195  // Aliases or fallbacks
196  if (slug === "toml") slug = "ini"; // close enough for highlighting
197  // Ensure it's in our allowlist
198  return SUPPORTED_LANGS.has(slug) ? slug : null;
199}