feat(frontend): Add copy button to code blocks (#13458)

Co-authored-by: openhands <openhands@all-hands.dev>

frontend/__tests__/components/buttons/copyable-content-wrapper.test.tsx

@@ -0,0 +1,60 @@
+import { render, screen, waitFor } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import { describe, it, expect } from "vitest";
+import { CopyableContentWrapper } from "#/components/shared/buttons/copyable-content-wrapper";
+
+describe("CopyableContentWrapper", () => {
+  it("should hide the copy button by default", () => {
+    render(
+      <CopyableContentWrapper text="hello">
+        <p>content</p>
+      </CopyableContentWrapper>,
+    );
+
+    expect(screen.getByTestId("copy-to-clipboard")).not.toBeVisible();
+  });
+
+  it("should show the copy button on hover", async () => {
+    const user = userEvent.setup();
+    render(
+      <CopyableContentWrapper text="hello">
+        <p>content</p>
+      </CopyableContentWrapper>,
+    );
+
+    await user.hover(screen.getByText("content"));
+
+    expect(screen.getByTestId("copy-to-clipboard")).toBeVisible();
+  });
+
+  it("should copy text to clipboard on click", async () => {
+    const user = userEvent.setup();
+    render(
+      <CopyableContentWrapper text="copy me">
+        <p>content</p>
+      </CopyableContentWrapper>,
+    );
+
+    await user.click(screen.getByTestId("copy-to-clipboard"));
+
+    await waitFor(() =>
+      expect(navigator.clipboard.readText()).resolves.toBe("copy me"),
+    );
+  });
+
+  it("should show copied state after clicking", async () => {
+    const user = userEvent.setup();
+    render(
+      <CopyableContentWrapper text="hello">
+        <p>content</p>
+      </CopyableContentWrapper>,
+    );
+
+    await user.click(screen.getByTestId("copy-to-clipboard"));
+
+    expect(screen.getByTestId("copy-to-clipboard")).toHaveAttribute(
+      "aria-label",
+      "BUTTON$COPIED",
+    );
+  });
+});

frontend/__tests__/components/features/markdown/code.test.tsx

@@ -0,0 +1,37 @@
+import { render, screen, waitFor } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import { describe, it, expect } from "vitest";
+import { code as Code } from "#/components/features/markdown/code";
+
+describe("code (markdown)", () => {
+  it("should render inline code without a copy button", () => {
+    render(<Code>inline snippet</Code>);
+
+    expect(screen.getByText("inline snippet")).toBeInTheDocument();
+    expect(screen.queryByTestId("copy-to-clipboard")).not.toBeInTheDocument();
+  });
+
+  it("should render a multiline code block with a copy button", () => {
+    render(<Code>{"line1\nline2"}</Code>);
+
+    expect(screen.getByText("line1 line2")).toBeInTheDocument();
+    expect(screen.getByTestId("copy-to-clipboard")).toBeInTheDocument();
+  });
+
+  it("should render a syntax-highlighted block with a copy button", () => {
+    render(<Code className="language-js">{"console.log('hi')"}</Code>);
+
+    expect(screen.getByTestId("copy-to-clipboard")).toBeInTheDocument();
+  });
+
+  it("should copy code block content to clipboard", async () => {
+    const user = userEvent.setup();
+    render(<Code>{"line1\nline2"}</Code>);
+
+    await user.click(screen.getByTestId("copy-to-clipboard"));
+
+    await waitFor(() =>
+      expect(navigator.clipboard.readText()).resolves.toBe("line1\nline2"),
+    );
+  });
+});

frontend/src/components/features/markdown/code.tsx

@@ -2,6 +2,7 @@ import React from "react";
 import { ExtraProps } from "react-markdown";
 import { Prism as SyntaxHighlighter } from "react-syntax-highlighter";
 import { vscDarkPlus } from "react-syntax-highlighter/dist/esm/styles/prism";
+import { CopyableContentWrapper } from "#/components/shared/buttons/copyable-content-wrapper";
 
 // See https://github.com/remarkjs/react-markdown?tab=readme-ov-file#use-custom-components-syntax-highlight
 
@@ -15,6 +16,7 @@ export function code({
   React.HTMLAttributes<HTMLElement> &
   ExtraProps) {
   const match = /language-(\w+)/.exec(className || ""); // get the language
+  const codeString = String(children).replace(/\n$/, "");
 
   if (!match) {
     const isMultiline = String(children).includes("\n");
@@ -37,29 +39,33 @@ export function code({
     }
 
     return (
-      <pre
-        style={{
-          backgroundColor: "#2a3038",
-          padding: "1em",
-          borderRadius: "4px",
-          color: "#e6edf3",
-          border: "1px solid #30363d",
-          overflow: "auto",
-        }}
-      >
-        <code className={className}>{String(children).replace(/\n$/, "")}</code>
-      </pre>
+      <CopyableContentWrapper text={codeString}>
+        <pre
+          style={{
+            backgroundColor: "#2a3038",
+            padding: "1em",
+            borderRadius: "4px",
+            color: "#e6edf3",
+            border: "1px solid #30363d",
+            overflow: "auto",
+          }}
+        >
+          <code className={className}>{codeString}</code>
+        </pre>
+      </CopyableContentWrapper>
     );
   }
 
   return (
-    <SyntaxHighlighter
-      className="rounded-lg"
-      style={vscDarkPlus}
-      language={match?.[1]}
-      PreTag="div"
-    >
-      {String(children).replace(/\n$/, "")}
-    </SyntaxHighlighter>
+    <CopyableContentWrapper text={codeString}>
+      <SyntaxHighlighter
+        className="rounded-lg"
+        style={vscDarkPlus}
+        language={match?.[1]}
+        PreTag="div"
+      >
+        {codeString}
+      </SyntaxHighlighter>
+    </CopyableContentWrapper>
   );
 }

frontend/src/components/shared/buttons/copyable-content-wrapper.tsx

@@ -0,0 +1,44 @@
+import React from "react";
+import { CopyToClipboardButton } from "./copy-to-clipboard-button";
+
+export function CopyableContentWrapper({
+  text,
+  children,
+}: {
+  text: string;
+  children: React.ReactNode;
+}) {
+  const [isHovering, setIsHovering] = React.useState(false);
+  const [isCopied, setIsCopied] = React.useState(false);
+
+  const handleCopy = async () => {
+    await navigator.clipboard.writeText(text);
+    setIsCopied(true);
+  };
+
+  React.useEffect(() => {
+    let timeout: NodeJS.Timeout;
+    if (isCopied) {
+      timeout = setTimeout(() => setIsCopied(false), 2000);
+    }
+    return () => clearTimeout(timeout);
+  }, [isCopied]);
+
+  return (
+    <div
+      className="relative"
+      onMouseEnter={() => setIsHovering(true)}
+      onMouseLeave={() => setIsHovering(false)}
+    >
+      <div className="absolute top-2 right-2 z-10">
+        <CopyToClipboardButton
+          isHidden={!isHovering}
+          isDisabled={isCopied}
+          onClick={handleCopy}
+          mode={isCopied ? "copied" : "copy"}
+        />
+      </div>
+      {children}
+    </div>
+  );
+}