7 files changed, 343 insertions, 0 deletions
diff --git a/packages/create-turbo/src/utils/examples.ts b/packages/create-turbo/src/utils/examples.ts
new file mode 100644
index 0000000..b7c4812
--- /dev/null
+++ b/packages/create-turbo/src/utils/examples.ts
@@ -0,0 +1,139 @@
+import got from "got";
+import tar from "tar";
+import { Stream } from "stream";
+import { promisify } from "util";
+import { join } from "path";
+import { tmpdir } from "os";
+import { createWriteStream, promises as fs } from "fs";
+
+const pipeline = promisify(Stream.pipeline);
+
+export type RepoInfo = {
+  username: string;
+  name: string;
+  branch: string;
+  filePath: string;
+};
+
+export async function isUrlOk(url: string): Promise<boolean> {
+  try {
+    const res = await got.head(url);
+    return res.statusCode === 200;
+  } catch (err) {
+    return false;
+  }
+}
+
+export async function getRepoInfo(
+  url: URL,
+  examplePath?: string
+): Promise<RepoInfo | undefined> {
+  const [, username, name, tree, sourceBranch, ...file] =
+    url.pathname.split("/");
+  const filePath = examplePath
+    ? examplePath.replace(/^\//, "")
+    : file.join("/");
+
+  if (
+    // Support repos whose entire purpose is to be a Turborepo example, e.g.
+    // https://github.com/:username/:my-cool-turborepo-example-repo-name.
+    tree === undefined ||
+    // Support GitHub URL that ends with a trailing slash, e.g.
+    // https://github.com/:username/:my-cool-turborepo-example-repo-name/
+    // In this case "t" will be an empty string while the turbo part "_branch" will be undefined
+    (tree === "" && sourceBranch === undefined)
+  ) {
+    try {
+      const infoResponse = await got(
+        `https://api.github.com/repos/${username}/${name}`
+      );
+      const info = JSON.parse(infoResponse.body);
+      return { username, name, branch: info["default_branch"], filePath };
+    } catch (err) {
+      return;
+    }
+  }
+
+  // If examplePath is available, the branch name takes the entire path
+  const branch = examplePath
+    ? `${sourceBranch}/${file.join("/")}`.replace(
+        new RegExp(`/${filePath}|/$`),
+        ""
+      )
+    : sourceBranch;
+
+  if (username && name && branch && tree === "tree") {
+    return { username, name, branch, filePath };
+  }
+}
+
+export function hasRepo({
+  username,
+  name,
+  branch,
+  filePath,
+}: RepoInfo): Promise<boolean> {
+  const contentsUrl = `https://api.github.com/repos/${username}/${name}/contents`;
+  const packagePath = `${filePath ? `/${filePath}` : ""}/package.json`;
+
+  return isUrlOk(contentsUrl + packagePath + `?ref=${branch}`);
+}
+
+export function existsInRepo(nameOrUrl: string): Promise<boolean> {
+  try {
+    const url = new URL(nameOrUrl);
+    return isUrlOk(url.href);
+  } catch {
+    return isUrlOk(
+      `https://api.github.com/repos/vercel/turbo/contents/examples/${encodeURIComponent(
+        nameOrUrl
+      )}`
+    );
+  }
+}
+
+async function downloadTar(url: string, name: string) {
+  const tempFile = join(tmpdir(), `${name}.temp-${Date.now()}`);
+  await pipeline(got.stream(url), createWriteStream(tempFile));
+  return tempFile;
+}
+
+export async function downloadAndExtractRepo(
+  root: string,
+  { username, name, branch, filePath }: RepoInfo
+) {
+  const tempFile = await downloadTar(
+    `https://codeload.github.com/${username}/${name}/tar.gz/${branch}`,
+    `turbo-ct-example`
+  );
+
+  await tar.x({
+    file: tempFile,
+    cwd: root,
+    strip: filePath ? filePath.split("/").length + 1 : 1,
+    filter: (p: string) =>
+      p.startsWith(
+        `${name}-${branch.replace(/\//g, "-")}${
+          filePath ? `/${filePath}/` : "/"
+        }`
+      ),
+  });
+
+  await fs.unlink(tempFile);
+}
+
+export async function downloadAndExtractExample(root: string, name: string) {
+  const tempFile = await downloadTar(
+    `https://codeload.github.com/vercel/turbo/tar.gz/main`,
+    `turbo-ct-example`
+  );
+
+  await tar.x({
+    file: tempFile,
+    cwd: root,
+    strip: 2 + name.split("/").length,
+    filter: (p: string) => p.includes(`turbo-main/examples/${name}/`),
+  });
+
+  await fs.unlink(tempFile);
+}
diff --git a/packages/create-turbo/src/utils/git.ts b/packages/create-turbo/src/utils/git.ts
new file mode 100644
index 0000000..593e7ea
--- /dev/null
+++ b/packages/create-turbo/src/utils/git.ts
@@ -0,0 +1,90 @@
+import fs from "fs-extra";
+import { execSync } from "child_process";
+import path from "path";
+import rimraf from "rimraf";
+
+export const DEFAULT_IGNORE = `
+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+node_modules
+.pnp
+.pnp.js
+
+# testing
+coverage
+
+# misc
+.DS_Store
+*.pem
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# turbo
+.turbo
+
+# vercel
+.vercel
+`;
+
+export const GIT_REPO_COMMAND = "git rev-parse --is-inside-work-tree";
+export const HG_REPO_COMMAND = "hg --cwd . root";
+
+export function isInGitRepository(): boolean {
+  try {
+    execSync(GIT_REPO_COMMAND, { stdio: "ignore" });
+    return true;
+  } catch (_) {}
+  return false;
+}
+
+export function isInMercurialRepository(): boolean {
+  try {
+    execSync(HG_REPO_COMMAND, { stdio: "ignore" });
+    return true;
+  } catch (_) {}
+  return false;
+}
+
+export function tryGitInit(root: string, message: string): boolean {
+  let didInit = false;
+  try {
+    execSync("git --version", { stdio: "ignore" });
+    if (isInGitRepository() || isInMercurialRepository()) {
+      return false;
+    }
+
+    execSync("git init", { stdio: "ignore" });
+    didInit = true;
+
+    execSync("git checkout -b main", { stdio: "ignore" });
+
+    execSync("git add -A", { stdio: "ignore" });
+    execSync(`git commit -m "${message}"`, {
+      stdio: "ignore",
+    });
+    return true;
+  } catch (err) {
+    if (didInit) {
+      try {
+        rimraf.sync(path.join(root, ".git"));
+      } catch (_) {}
+    }
+    return false;
+  }
+}
+
+export function tryGitCommit(message: string): boolean {
+  try {
+    execSync("git add -A", { stdio: "ignore" });
+    execSync(`git commit -m "${message}"`, {
+      stdio: "ignore",
+    });
+    return true;
+  } catch (err) {
+    return false;
+  }
+}
diff --git a/packages/create-turbo/src/utils/isDefaultExample.ts b/packages/create-turbo/src/utils/isDefaultExample.ts
new file mode 100644
index 0000000..9fb2ef2
--- /dev/null
+++ b/packages/create-turbo/src/utils/isDefaultExample.ts
@@ -0,0 +1,5 @@
+export const DEFAULT_EXAMPLES = new Set(["basic", "default"]);
+
+export function isDefaultExample(example: string): boolean {
+  return DEFAULT_EXAMPLES.has(example);
+}
diff --git a/packages/create-turbo/src/utils/isFolderEmpty.ts b/packages/create-turbo/src/utils/isFolderEmpty.ts
new file mode 100644
index 0000000..4de2d58
--- /dev/null
+++ b/packages/create-turbo/src/utils/isFolderEmpty.ts
@@ -0,0 +1,37 @@
+import fs from "fs-extra";
+
+const VALID_FILES = [
+  ".DS_Store",
+  ".git",
+  ".gitattributes",
+  ".gitignore",
+  ".gitlab-ci.yml",
+  ".hg",
+  ".hgcheck",
+  ".hgignore",
+  ".idea",
+  ".npmignore",
+  ".travis.yml",
+  "LICENSE",
+  "Thumbs.db",
+  "docs",
+  "mkdocs.yml",
+  "npm-debug.log",
+  "yarn-debug.log",
+  "yarn-error.log",
+  "yarnrc.yml",
+  ".yarn",
+];
+
+export function isFolderEmpty(root: string): {
+  isEmpty: boolean;
+  conflicts: Array<string>;
+} {
+  const conflicts = fs
+    .readdirSync(root)
+    .filter((file) => !VALID_FILES.includes(file))
+    // Support IntelliJ IDEA-based editors
+    .filter((file) => !/\.iml$/.test(file));
+
+  return { isEmpty: conflicts.length === 0, conflicts };
+}
diff --git a/packages/create-turbo/src/utils/isOnline.ts b/packages/create-turbo/src/utils/isOnline.ts
new file mode 100644
index 0000000..f02b2e6
--- /dev/null
+++ b/packages/create-turbo/src/utils/isOnline.ts
@@ -0,0 +1,40 @@
+import { execSync } from "child_process";
+import dns from "dns";
+import url from "url";
+
+function getProxy(): string | undefined {
+  if (process.env.https_proxy) {
+    return process.env.https_proxy;
+  }
+
+  try {
+    const httpsProxy = execSync("npm config get https-proxy").toString().trim();
+    return httpsProxy !== "null" ? httpsProxy : undefined;
+  } catch (e) {
+    return;
+  }
+}
+
+export function isOnline(): Promise<boolean> {
+  return new Promise((resolve) => {
+    dns.lookup("registry.yarnpkg.com", (registryErr) => {
+      if (!registryErr) {
+        return resolve(true);
+      }
+
+      const proxy = getProxy();
+      if (!proxy) {
+        return resolve(false);
+      }
+
+      const { hostname } = url.parse(proxy);
+      if (!hostname) {
+        return resolve(false);
+      }
+
+      dns.lookup(hostname, (proxyErr) => {
+        resolve(proxyErr == null);
+      });
+    });
+  });
+}
diff --git a/packages/create-turbo/src/utils/isWriteable.ts b/packages/create-turbo/src/utils/isWriteable.ts
new file mode 100644
index 0000000..132c42a
--- /dev/null
+++ b/packages/create-turbo/src/utils/isWriteable.ts
@@ -0,0 +1,10 @@
+import fs from "fs-extra";
+
+export async function isWriteable(directory: string): Promise<boolean> {
+  try {
+    await fs.access(directory, (fs.constants || fs).W_OK);
+    return true;
+  } catch (err) {
+    return false;
+  }
+}
diff --git a/packages/create-turbo/src/utils/notifyUpdate.ts b/packages/create-turbo/src/utils/notifyUpdate.ts
new file mode 100644
index 0000000..e1dadc0
--- /dev/null
+++ b/packages/create-turbo/src/utils/notifyUpdate.ts
@@ -0,0 +1,22 @@
+import chalk from "chalk";
+import checkForUpdate from "update-check";
+
+import cliPkgJson from "../../package.json";
+
+const update = checkForUpdate(cliPkgJson).catch(() => null);
+
+export default async function notifyUpdate(): Promise<void> {
+  try {
+    const res = await update;
+    if (res?.latest) {
+      console.log();
+      console.log(
+        chalk.yellow.bold("A new version of `create-turbo` is available!")
+      );
+      console.log();
+    }
+    process.exit();
+  } catch (_e: any) {
+    // ignore error
+  }
+}