feat: Add Trans component for interpolating JSX in translations (#6534)

* feat: add Trans component

* Add comments

* tweak

* Move brave to trans component

* fix test and tweaks

* remove any

* fix

* fix

* comment

* replace render function type

* Use tags for Trans

* Fix a typo

Co-authored-by: Aakansha Doshi <aakansha1216@gmail.com>

* Cleanup, add comments, add support for kebab case

* tweaks

---------

Co-authored-by: Aakansha Doshi <aakansha1216@gmail.com>
Co-authored-by: dwelle <luzar.david@gmail.com>

src/components/Trans.tsx

@@ -0,0 +1,169 @@
+import React from "react";
+
+import { useI18n } from "../i18n";
+
+// Used for splitting i18nKey into tokens in Trans component
+// Example:
+// "Please <link>click {{location}}</link> to continue.".split(SPLIT_REGEX).filter(Boolean)
+// produces
+// ["Please ", "<link>", "click ", "{{location}}", "</link>", " to continue."]
+const SPLIT_REGEX = /({{[\w-]+}})|(<[\w-]+>)|(<\/[\w-]+>)/g;
+// Used for extracting "location" from "{{location}}"
+const KEY_REGEXP = /{{([\w-]+)}}/;
+// Used for extracting "link" from "<link>"
+const TAG_START_REGEXP = /<([\w-]+)>/;
+// Used for extracting "link" from "</link>"
+const TAG_END_REGEXP = /<\/([\w-]+)>/;
+
+const getTransChildren = (
+  format: string,
+  props: {
+    [key: string]: React.ReactNode | ((el: React.ReactNode) => React.ReactNode);
+  },
+): React.ReactNode[] => {
+  const stack: { name: string; children: React.ReactNode[] }[] = [
+    {
+      name: "",
+      children: [],
+    },
+  ];
+
+  format
+    .split(SPLIT_REGEX)
+    .filter(Boolean)
+    .forEach((match) => {
+      const tagStartMatch = match.match(TAG_START_REGEXP);
+      const tagEndMatch = match.match(TAG_END_REGEXP);
+      const keyMatch = match.match(KEY_REGEXP);
+
+      if (tagStartMatch !== null) {
+        // The match is <tag>. Set the tag name as the name if it's one of the
+        // props, e.g. for "Please <link>click the button</link> to continue"
+        // tagStartMatch[1] = "link" and props contain "link" then it will be
+        // pushed to stack.
+        const name = tagStartMatch[1];
+        if (props.hasOwnProperty(name)) {
+          stack.push({
+            name,
+            children: [],
+          });
+        } else {
+          console.warn(
+            `Trans: missed to pass in prop ${name} for interpolating ${format}`,
+          );
+        }
+      } else if (tagEndMatch !== null) {
+        // If tag end match is found, this means we need to replace the content with
+        // its actual value in prop e.g. format = "Please <link>click the
+        // button</link> to continue", tagEndMatch is for "</link>", stack last item name =
+        // "link" and props.link = (el) => <a
+        // href="https://example.com">{el}</a> then its prop value will be
+        // pushed to "link"'s children so on DOM when rendering it's rendered as
+        // <a href="https://example.com">click the button</a>
+        const name = tagEndMatch[1];
+        if (name === stack[stack.length - 1].name) {
+          const item = stack.pop()!;
+          const itemChildren = React.createElement(
+            React.Fragment,
+            {},
+            ...item.children,
+          );
+          const fn = props[item.name];
+          if (typeof fn === "function") {
+            stack[stack.length - 1].children.push(fn(itemChildren));
+          }
+        } else {
+          console.warn(
+            `Trans: unexpected end tag ${match} for interpolating ${format}`,
+          );
+        }
+      } else if (keyMatch !== null) {
+        // The match is for {{key}}. Check if the key is present in props and set
+        // the prop value as children of last stack item e.g. format = "Hello
+        // {{name}}", key = "name" and props.name = "Excalidraw" then its prop
+        // value will be pushed to "name"'s children so it's rendered on DOM as
+        // "Hello Excalidraw"
+        const name = keyMatch[1];
+        if (props.hasOwnProperty(name)) {
+          stack[stack.length - 1].children.push(props[name] as React.ReactNode);
+        } else {
+          console.warn(
+            `Trans: key ${name} not in props for interpolating ${format}`,
+          );
+        }
+      } else {
+        // If none of cases match means we just need to push the string
+        // to stack eg - "Hello {{name}} Whats up?" "Hello", "Whats up" will be pushed
+        stack[stack.length - 1].children.push(match);
+      }
+    });
+
+  if (stack.length !== 1) {
+    console.warn(`Trans: stack not empty for interpolating ${format}`);
+  }
+
+  return stack[0].children;
+};
+
+/*
+Trans component is used for translating JSX.
+
+```json
+{
+  "example1": "Hello {{audience}}",
+  "example2": "Please <link>click the button</link> to continue.",
+  "example3": "Please <link>click {{location}}</link> to continue.",
+  "example4": "Please <link>click <bold>{{location}}</bold></link> to continue.",
+}
+```
+
+```jsx
+<Trans i18nKey="example1" audience="world" />
+
+<Trans
+  i18nKey="example2"
+  connectLink={(el) => <a href="https://example.com">{el}</a>}
+/>
+
+<Trans
+  i18nKey="example3"
+  connectLink={(el) => <a href="https://example.com">{el}</a>}
+  location="the button"
+/>
+
+<Trans
+  i18nKey="example4"
+  connectLink={(el) => <a href="https://example.com">{el}</a>}
+  location="the button"
+  bold={(el) => <strong>{el}</strong>}
+/>
+```
+
+Output:
+
+```html
+Hello world
+Please <a href="https://example.com">click the button</a> to continue.
+Please <a href="https://example.com">click the button</a> to continue.
+Please <a href="https://example.com">click <strong>the button</strong></a> to continue.
+```
+*/
+const Trans = ({
+  i18nKey,
+  children,
+  ...props
+}: {
+  i18nKey: string;
+  [key: string]: React.ReactNode | ((el: React.ReactNode) => React.ReactNode);
+}) => {
+  const { t } = useI18n();
+
+  // This is needed to avoid unique key error in list which gets rendered from getTransChildren
+  return React.createElement(
+    React.Fragment,
+    {},
+    ...getTransChildren(t(i18nKey), props),
+  );
+};
+
+export default Trans;