feat: implement Shiki theme support for VS Code webview and enhance theme handling

packages/vscode/src/shikiThemes.ts

@@ -0,0 +1,232 @@
+import * as vscode from 'vscode';
+
+type VSCodeThemeContribution = {
+  label?: string;
+  uiTheme?: string;
+  path?: string;
+};
+
+export type WebviewShikiThemePayload = {
+  light?: Record<string, unknown>;
+  dark?: Record<string, unknown>;
+};
+
+const stripJsonc = (input: string): string => {
+  let output = '';
+  let inString = false;
+  let stringQuote: '"' | '\'' | null = null;
+  let escaped = false;
+  let inLineComment = false;
+  let inBlockComment = false;
+
+  for (let i = 0; i < input.length; i++) {
+    const ch = input[i];
+    const next = input[i + 1];
+
+    if (inLineComment) {
+      if (ch === '\n') {
+        inLineComment = false;
+        output += ch;
+      }
+      continue;
+    }
+
+    if (inBlockComment) {
+      if (ch === '*' && next === '/') {
+        inBlockComment = false;
+        i++;
+      }
+      continue;
+    }
+
+    if (inString) {
+      output += ch;
+      if (escaped) {
+        escaped = false;
+        continue;
+      }
+      if (ch === '\\') {
+        escaped = true;
+        continue;
+      }
+      if (stringQuote && ch === stringQuote) {
+        inString = false;
+        stringQuote = null;
+      }
+      continue;
+    }
+
+    if (ch === '/' && next === '/') {
+      inLineComment = true;
+      i++;
+      continue;
+    }
+
+    if (ch === '/' && next === '*') {
+      inBlockComment = true;
+      i++;
+      continue;
+    }
+
+    if (ch === '"' || ch === '\'') {
+      inString = true;
+      stringQuote = ch;
+      output += ch;
+      continue;
+    }
+
+    output += ch;
+  }
+
+  return output;
+};
+
+const stripTrailingCommas = (input: string): string => {
+  let output = '';
+  let inString = false;
+  let stringQuote: '"' | '\'' | null = null;
+  let escaped = false;
+
+  for (let i = 0; i < input.length; i++) {
+    const ch = input[i];
+
+    if (inString) {
+      output += ch;
+      if (escaped) {
+        escaped = false;
+        continue;
+      }
+      if (ch === '\\') {
+        escaped = true;
+        continue;
+      }
+      if (stringQuote && ch === stringQuote) {
+        inString = false;
+        stringQuote = null;
+      }
+      continue;
+    }
+
+    if (ch === '"' || ch === '\'') {
+      inString = true;
+      stringQuote = ch;
+      output += ch;
+      continue;
+    }
+
+    if (ch === ',') {
+      // If the next non-whitespace character is a closing brace/bracket, drop this comma.
+      let j = i + 1;
+      while (j < input.length && /\s/.test(input[j] ?? '')) j++;
+      const nextNonWs = input[j];
+      if (nextNonWs === '}' || nextNonWs === ']') {
+        continue;
+      }
+    }
+
+    output += ch;
+  }
+
+  return output;
+};
+
+const parseJsoncLoose = (input: string): Record<string, unknown> | null => {
+  try {
+    const noComments = stripJsonc(input);
+    const noTrailingCommas = stripTrailingCommas(noComments);
+    const parsed = JSON.parse(noTrailingCommas) as unknown;
+    if (parsed && typeof parsed === 'object' && !Array.isArray(parsed)) {
+      return parsed as Record<string, unknown>;
+    }
+    return null;
+  } catch {
+    return null;
+  }
+};
+
+const getThemeLabelFromConfig = (key: string): string | undefined => {
+  return vscode.workspace.getConfiguration('workbench').get<string>(key) || undefined;
+};
+
+const normalizeLabel = (value: string): string => value.trim().replace(/\s+/g, ' ').toLowerCase();
+
+const labelVariants = (label: string): string[] => {
+  const trimmed = label.trim();
+  const variants = new Set<string>([trimmed]);
+
+  // VS Code sometimes uses "Default …" in settings while theme contributions omit it.
+  if (trimmed.toLowerCase().startsWith('default ')) {
+    variants.add(trimmed.slice('default '.length));
+  }
+
+  return Array.from(variants);
+};
+
+const findContributedTheme = (label: string): { extension: vscode.Extension<unknown>; theme: VSCodeThemeContribution } | null => {
+  const targets = labelVariants(label).map(normalizeLabel);
+  for (const extension of vscode.extensions.all) {
+    const contributes = (extension.packageJSON as { contributes?: { themes?: VSCodeThemeContribution[] } } | undefined)?.contributes;
+    const themes = contributes?.themes;
+    if (!Array.isArray(themes)) continue;
+
+    const match = themes.find((theme) => theme?.label && targets.includes(normalizeLabel(theme.label)));
+    if (match?.path) {
+      return { extension, theme: match };
+    }
+  }
+  return null;
+};
+
+const readThemeJsonByLabel = async (label: string): Promise<Record<string, unknown> | null> => {
+  const resolved = findContributedTheme(label);
+  if (!resolved) return null;
+
+  try {
+    const uri = vscode.Uri.joinPath(resolved.extension.extensionUri, resolved.theme.path as string);
+    const bytes = await vscode.workspace.fs.readFile(uri);
+    const text = new TextDecoder('utf-8').decode(bytes);
+    return parseJsoncLoose(text);
+  } catch {
+    return null;
+  }
+};
+
+const ensureUniqueThemeName = (raw: Record<string, unknown>, suffix: string): Record<string, unknown> => {
+  const originalName = typeof raw.name === 'string' && raw.name.length > 0 ? raw.name : 'VSCode Theme';
+  return { ...raw, name: `${originalName} (${suffix})` };
+};
+
+export async function getWebviewShikiThemes(): Promise<WebviewShikiThemePayload | null> {
+  const current = getThemeLabelFromConfig('colorTheme');
+  const preferredLight = getThemeLabelFromConfig('preferredLightColorTheme') || current;
+  const preferredDark = getThemeLabelFromConfig('preferredDarkColorTheme') || current;
+
+  const themeVariant =
+    vscode.window.activeColorTheme.kind === vscode.ColorThemeKind.Light ||
+    vscode.window.activeColorTheme.kind === vscode.ColorThemeKind.HighContrastLight
+      ? 'light'
+      : 'dark';
+
+  // Use the actively selected theme for the current variant, and only fall back to preferred
+  // themes for the opposite variant (so we actually pick up user-selected theme changes).
+  const lightLabel = themeVariant === 'light' ? current : preferredLight;
+  const darkLabel = themeVariant === 'dark' ? current : preferredDark;
+
+  const [lightRaw, darkRaw] = await Promise.all([
+    lightLabel ? readThemeJsonByLabel(lightLabel) : Promise.resolve(null),
+    darkLabel ? readThemeJsonByLabel(darkLabel) : Promise.resolve(null),
+  ]);
+
+  // If we only managed to resolve one side, use it for both. This still gives correct highlighting
+  // for the currently active VS Code theme, and avoids falling back to Flexoki.
+  const fallbackOneSide = lightRaw ?? darkRaw;
+  const effectiveLight = lightRaw ?? fallbackOneSide;
+  const effectiveDark = darkRaw ?? fallbackOneSide;
+
+  return !effectiveLight && !effectiveDark
+    ? null
+    : {
+        light: effectiveLight ? ensureUniqueThemeName(effectiveLight, 'Light') : undefined,
+        dark: effectiveDark ? ensureUniqueThemeName(effectiveDark, 'Dark') : undefined,
+      };
+}