language switcher

compiler/src/cli/cli.ts

@@ -82,6 +82,10 @@ const args = {
     type: 'string',
     description: 'Specify which environment program to display',
   },
+  envLanguage: {
+    type: 'string',
+    description: 'Specify which environment language to display',
+  },
   fileName: {
     type: 'string',
     description: 'Specify name of output file',
@@ -116,6 +120,7 @@ const options: Options = {
   verbose: argv.verbose,
   envPlatform: argv.envPlatform,
   envProgram: argv.envProgram,
+  envLanguage: argv.envLanguage,
   fileName: argv.fileName,
   output: argv.output as 'md' | 'html',
 };

compiler/src/context.ts

@@ -25,6 +25,7 @@ export type Options = {
   verbose?: boolean;
   envPlatform?: string;
   envProgram?: string;
+  envLanguage?: string;
   fileName?: string;
   output?: 'md' | 'html';
 };

compiler/src/mdast/__test__/language-switcher.test.ts

@@ -0,0 +1,64 @@
+import {
+  testProcessor,
+  unindentString,
+} from '../../test-utils/test-processor';
+
+describe('program switcher', () => {
+  it('should show the program switcher correctly', async () => {
+    const { html } = await testProcessor(`
+      ::::language-switcher
+      :::r
+      I am R
+      :::
+
+      :::python
+      I am Python
+      :::
+      ::::
+    `);
+
+    const expected = unindentString(`
+      <div class="language-switcher">
+        <ul>
+          <li data-language="r">R</li>
+          <li data-language="python">Python</li>
+        </ul>
+        <div data-language="r" class="language">
+          <p>I am R</p>
+        </div>
+        <div data-language="python" class="language">
+          <p>I am Python</p>
+        </div>
+      </div>
+    `);
+
+    expect(html).toBe(expected);
+  });
+
+  it('should only show cli', async () => {
+    const md = `
+      ::::language-switcher
+      :::r
+      I am R
+      :::
+
+      :::python
+      I am Python
+      :::
+      ::::
+    `;
+    const { html } = await testProcessor(md, {
+      envLanguage: 'r',
+    });
+
+    const expected = unindentString(`
+      <div class="language-switcher">
+        <div data-language="r" class="language show">
+          <p>I am R</p>
+        </div>
+      </div>
+    `);
+
+    expect(html).toBe(expected);
+  });
+});

compiler/src/mdast/__test__/program-switcher.test.ts

@@ -5,21 +5,17 @@ import {
 
 describe('program switcher', () => {
   it('should show the program switcher correctly', async () => {
-    const { html } = await testProcessor(
-      `
+    const { html } = await testProcessor(`
       ::::program-switcher
-
       :::command-line
       I am cli
       :::
 
       :::github-desktop
       I am github desktop
       :::
-
       ::::
-    `
-    );
+    `);
 
     const expected = unindentString(`
       <div class="program-switcher">
@@ -40,24 +36,20 @@ describe('program switcher', () => {
   });
 
   it('should only show cli', async () => {
-    const { html } = await testProcessor(
-      `
+    const md = `
       ::::program-switcher
-
       :::command-line
       I am cli
       :::
 
       :::github-desktop
       I am github desktop
       :::
-
       ::::
-    `,
-      {
-        envProgram: 'command-line',
-      }
-    );
+    `;
+    const { html } = await testProcessor(md, {
+      envProgram: 'command-line',
+    });
 
     const expected = unindentString(`
       <div class="program-switcher">

compiler/src/mdast/combined.ts

@@ -6,15 +6,17 @@ import { Context } from '../context';
 import { boxouts } from './boxouts';
 import { moveAnswersToEnd } from './move-answers-to-end';
 import { programSwitcher } from './program-switcher';
+import { languageSwitcher } from './language-switcher';
 
 export async function combinedMdastPhase(
   mdast: Root,
   ctx: Context,
   file: VFile,
-  targetPdf?: boolean
+  targetPdf?: boolean,
 ) {
   const processor = unified()
     .use(programSwitcher, ctx)
+    .use(languageSwitcher, ctx)
     .use(boxouts, ctx.refStore);
 
   if (targetPdf) {

compiler/src/mdast/language-switcher.ts

@@ -0,0 +1,99 @@
+import { Element, ElementContent } from 'hast';
+import { ContainerDirective } from 'mdast-util-directive';
+import { toHast } from 'mdast-util-to-hast';
+import { Node } from 'unist';
+import { visit } from 'unist-util-visit';
+
+import { Context } from '../context';
+
+const languages = ['r', 'python'];
+const titleCase = ['R', 'Python'];
+
+export function languageSwitcher(ctx: Context) {
+  const languageFlag = ctx.options.envLanguage;
+  if (languageFlag !== undefined && !languages.includes(languageFlag)) {
+    throw new Error(
+      `[environment]: envLanguage ${languageFlag} should be one of ${languages}`,
+    );
+  }
+
+  return (tree: Node) => {
+    visit(tree, 'containerDirective', (node: ContainerDirective) => {
+      if (node.name === 'language-switcher') {
+        const children = [];
+        if (languageFlag === undefined) {
+          children.push(processMenu(node));
+        }
+        children.push(...processChildren(node, languageFlag));
+
+        node.data = {
+          hProperties: {
+            className: 'language-switcher',
+          },
+          hChildren: children,
+        };
+      }
+    });
+  };
+}
+
+function processMenu(parent: ContainerDirective): ElementContent {
+  const children = parent.children as ContainerDirective[];
+  return {
+    type: 'element',
+    tagName: 'ul',
+    properties: {},
+    children: children.map((node) => {
+      const element: ElementContent = {
+        type: 'element',
+        tagName: 'li',
+        properties: {
+          'data-language': node.name,
+        },
+        children: [
+          {
+            type: 'text',
+            value: titleCase[languages.indexOf(node.name)],
+          },
+        ],
+      };
+      return element;
+    }),
+  };
+}
+
+function processChildren(
+  parent: ContainerDirective,
+  languageFlag: string | undefined,
+): ElementContent[] {
+  const children = parent.children.map((node) => {
+    const parent = node as ContainerDirective;
+    if (languages.includes(parent.name)) {
+      node.data = {
+        hProperties: {
+          'data-language': parent.name,
+          className: [
+            'language',
+            languageFlag === parent.name ? 'show' : '',
+          ],
+        },
+      };
+    }
+    return node;
+  });
+
+  let filtered = children;
+  if (languageFlag !== undefined) {
+    filtered = filtered.filter((node) => {
+      const parent = node as ContainerDirective;
+      return languageFlag === parent.name;
+    });
+  }
+
+  const parentHast = toHast({
+    type: 'root',
+    children: filtered,
+  }) as Element;
+
+  return parentHast.children;
+}