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Diffstat (limited to 'src/features/markdown/logic/markdown.ts')
| -rw-r--r-- | src/features/markdown/logic/markdown.ts | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/src/features/markdown/logic/markdown.ts b/src/features/markdown/logic/markdown.ts new file mode 100644 index 0000000..3a6e5a6 --- /dev/null +++ b/src/features/markdown/logic/markdown.ts @@ -0,0 +1,165 @@ +/** + * Pure Markdown → sanitized-HTML renderer for assistant messages. + * + * Mirrors old Dispatch's stack (marked + marked-highlight + highlight.js + + * DOMPurify; GFM + line breaks; streaming delimiter-closing), but kept fully + * SYNCHRONOUS and pure: `input → output`, no effects, no `$effect`. Languages + * are a fixed "hot set" registered at module load (no lazy dynamic import), so a + * single `renderMarkdown(text)` call is deterministic and unit-testable. + * + * The only ambient dependency is DOMPurify, which sanitizes against the DOM — + * present in the browser and in the jsdom test env. + */ + +import DOMPurify from "dompurify"; +import type { LanguageFn } from "highlight.js"; +import hljs from "highlight.js/lib/core"; +import bash from "highlight.js/lib/languages/bash"; +import c from "highlight.js/lib/languages/c"; +import cpp from "highlight.js/lib/languages/cpp"; +import csharp from "highlight.js/lib/languages/csharp"; +import css from "highlight.js/lib/languages/css"; +import go from "highlight.js/lib/languages/go"; +import java from "highlight.js/lib/languages/java"; +import javascript from "highlight.js/lib/languages/javascript"; +import json from "highlight.js/lib/languages/json"; +import markdownLang from "highlight.js/lib/languages/markdown"; +import php from "highlight.js/lib/languages/php"; +import plaintext from "highlight.js/lib/languages/plaintext"; +import python from "highlight.js/lib/languages/python"; +import ruby from "highlight.js/lib/languages/ruby"; +import rust from "highlight.js/lib/languages/rust"; +import shell from "highlight.js/lib/languages/shell"; +import sql from "highlight.js/lib/languages/sql"; +import typescript from "highlight.js/lib/languages/typescript"; +import xml from "highlight.js/lib/languages/xml"; +import yaml from "highlight.js/lib/languages/yaml"; +import { Marked } from "marked"; +import { markedHighlight } from "marked-highlight"; + +// Hot set: registered eagerly so common code blocks highlight on first paint. +const HOT_LANGUAGES: Record<string, LanguageFn> = { + bash, + c, + cpp, + csharp, + css, + go, + java, + javascript, + json, + markdown: markdownLang, + php, + plaintext, + python, + ruby, + rust, + shell, + sql, + typescript, + xml, + yaml, +}; +for (const [name, lang] of Object.entries(HOT_LANGUAGES)) { + hljs.registerLanguage(name, lang); +} + +// Normalize common fence aliases to canonical highlight.js names. +const ALIASES: Record<string, string> = { + js: "javascript", + jsx: "javascript", + mjs: "javascript", + cjs: "javascript", + ts: "typescript", + tsx: "typescript", + py: "python", + py3: "python", + rb: "ruby", + sh: "bash", + zsh: "bash", + yml: "yaml", + "c++": "cpp", + cxx: "cpp", + "c#": "csharp", + cs: "csharp", + htm: "xml", + html: "xml", + svg: "xml", + md: "markdown", + mdx: "markdown", + golang: "go", + rs: "rust", +}; + +function normalizeLang(lang: string): string { + const lower = lang.toLowerCase().trim(); + return ALIASES[lower] ?? lower; +} + +function escapeHtml(s: string): string { + return s + .replace(/&/g, "&") + .replace(/</g, "<") + .replace(/>/g, ">") + .replace(/"/g, """) + .replace(/'/g, "'"); +} + +const md = new Marked( + markedHighlight({ + emptyLangClass: "hljs", + langPrefix: "hljs language-", + highlight(code: string, lang: string): string { + if (!lang) return escapeHtml(code); + const name = normalizeLang(lang); + if (!hljs.getLanguage(name)) return escapeHtml(code); + try { + return hljs.highlight(code, { language: name, ignoreIllegals: true }).value; + } catch { + return escapeHtml(code); + } + }, + }), + { gfm: true, breaks: true }, +); + +/** + * While a message is still streaming, balance dangling fences / emphasis so the + * partial text renders cleanly instead of flashing raw markers. + */ +function closeOpenDelimiters(src: string): string { + let out = src; + const fenceCount = (out.match(/^```/gm) ?? []).length; + if (fenceCount % 2 !== 0) out += "\n```"; + const boldCount = (out.match(/\*\*/g) ?? []).length; + if (boldCount % 2 !== 0) out += "**"; + const inlineCode = (out.match(/(?<!`)`(?!`)/g) ?? []).length; + if (inlineCode % 2 !== 0) out += "`"; + return out; +} + +// Wrap each fenced code block (`<pre>…</pre>`) in a positioned container with a +// copy button. marked emits exactly one `<pre>`/`</pre>` pair per block and +// escapes `<`/`>` inside code, so these literal tags only ever delimit blocks. +// `data-copy` is the delegation hook the component listens for; DOMPurify keeps +// `<button>` + `data-*` by default. Inline `<code>` has no `<pre>`, so it's untouched. +const COPY_BUTTON = + '<button type="button" data-copy aria-label="Copy code"' + + ' class="copy-btn btn btn-xs absolute right-2 top-2 opacity-0 transition-opacity group-hover:opacity-100">Copy</button>'; + +function addCopyButtons(html: string): string { + return html + .replace(/<pre>/g, `<div class="code-block group relative">${COPY_BUTTON}<pre>`) + .replace(/<\/pre>/g, "</pre></div>"); +} + +/** Render Markdown to sanitized HTML. Returns `""` if parsing ever throws. */ +export function renderMarkdown(text: string, opts?: { streaming?: boolean }): string { + const src = opts?.streaming === true ? closeOpenDelimiters(text) : text; + try { + const raw = md.parse(src) as string; + return DOMPurify.sanitize(addCopyButtons(raw)); + } catch { + return ""; + } +} |