6 files changed, 189 insertions, 0 deletions

diff --git a/packages/create-turbo/src/transforms/errors.ts b/packages/create-turbo/src/transforms/errors.ts
new file mode 100644
index 0000000..a5b8a7a
--- /dev/null
+++ b/packages/create-turbo/src/transforms/errors.ts
@@ -0,0 +1,17 @@
+export type TransformErrorOptions = {
+  transform?: string;
+  fatal?: boolean;
+};
+
+export class TransformError extends Error {
+  public transform: string;
+  public fatal: boolean;
+
+  constructor(message: string, opts?: TransformErrorOptions) {
+    super(message);
+    this.name = "TransformError";
+    this.transform = opts?.transform ?? "unknown";
+    this.fatal = opts?.fatal ?? true;
+    Error.captureStackTrace(this, TransformError);
+  }
+}
diff --git a/packages/create-turbo/src/transforms/git-ignore.ts b/packages/create-turbo/src/transforms/git-ignore.ts
new file mode 100644
index 0000000..bb61ca7
--- /dev/null
+++ b/packages/create-turbo/src/transforms/git-ignore.ts
@@ -0,0 +1,30 @@
+import path from "path";
+import fs from "fs-extra";
+import { DEFAULT_IGNORE } from "../utils/git";
+import { TransformInput, TransformResult } from "./types";
+import { TransformError } from "./errors";
+
+const meta = {
+  name: "git-ignore",
+};
+
+export async function transform(args: TransformInput): TransformResult {
+  const { prompts } = args;
+  const ignorePath = path.join(prompts.root, ".gitignore");
+  try {
+    if (!fs.existsSync(ignorePath)) {
+      fs.writeFileSync(ignorePath, DEFAULT_IGNORE);
+    } else {
+      return { result: "not-applicable", ...meta };
+    }
+  } catch (err) {
+    // existsSync cannot throw, so we don't need to narrow here and can
+    // assume this came from writeFileSync
+    throw new TransformError("Unable to write .gitignore", {
+      transform: meta.name,
+      fatal: false,
+    });
+  }
+
+  return { result: "success", ...meta };
+}
diff --git a/packages/create-turbo/src/transforms/index.ts b/packages/create-turbo/src/transforms/index.ts
new file mode 100644
index 0000000..1918ecc
--- /dev/null
+++ b/packages/create-turbo/src/transforms/index.ts
@@ -0,0 +1,13 @@
+import { transform as packageManagerTransform } from "./package-manager";
+import { transform as officialStarter } from "./official-starter";
+import { transform as gitIgnoreTransform } from "./git-ignore";
+import type { TransformInput, TransformResult } from "./types";
+
+/**
+ * In the future, we may want to support sourcing additional transforms from the templates themselves.
+ */
+export const transforms: Array<(args: TransformInput) => TransformResult> = [
+  officialStarter,
+  gitIgnoreTransform,
+  packageManagerTransform,
+];
diff --git a/packages/create-turbo/src/transforms/official-starter.ts b/packages/create-turbo/src/transforms/official-starter.ts
new file mode 100644
index 0000000..1d71909
--- /dev/null
+++ b/packages/create-turbo/src/transforms/official-starter.ts
@@ -0,0 +1,73 @@
+import path from "path";
+import fs from "fs-extra";
+import semverPrerelease from "semver/functions/prerelease";
+import cliPkgJson from "../../package.json";
+import { isDefaultExample } from "../utils/isDefaultExample";
+import { TransformInput, TransformResult } from "./types";
+import { TransformError } from "./errors";
+
+const meta = {
+  name: "official-starter",
+};
+
+// applied to "official starter" examples (those hosted within vercel/turbo/examples)
+export async function transform(args: TransformInput): TransformResult {
+  const { prompts, example } = args;
+
+  const defaultExample = isDefaultExample(example.name);
+  const isOfficialStarter =
+    !example.repo ||
+    (example.repo?.username === "vercel" && example.repo?.name === "turbo");
+
+  if (!isOfficialStarter) {
+    return { result: "not-applicable", ...meta };
+  }
+
+  // paths
+  const rootPackageJsonPath = path.join(prompts.root, "package.json");
+  const rootMetaJsonPath = path.join(prompts.root, "meta.json");
+  const hasPackageJson = fs.existsSync(rootPackageJsonPath);
+
+  // 1. remove meta file (used for generating the examples page on turbo.build)
+  try {
+    fs.rmSync(rootMetaJsonPath, { force: true });
+  } catch (_err) {}
+
+  if (hasPackageJson) {
+    let packageJsonContent;
+    try {
+      packageJsonContent = fs.readJsonSync(rootPackageJsonPath);
+    } catch {
+      throw new TransformError("Unable to read package.json", {
+        transform: meta.name,
+        fatal: false,
+      });
+    }
+
+    // if using the basic example, set the name to the project name (legacy behavior)
+    if (packageJsonContent) {
+      if (defaultExample) {
+        packageJsonContent.name = prompts.projectName;
+      }
+
+      // if we're using a pre-release version of create-turbo, install turbo canary instead of latest
+      const shouldUsePreRelease = semverPrerelease(cliPkgJson.version) !== null;
+      if (shouldUsePreRelease && packageJsonContent?.devDependencies?.turbo) {
+        packageJsonContent.devDependencies.turbo = "canary";
+      }
+
+      try {
+        fs.writeJsonSync(rootPackageJsonPath, packageJsonContent, {
+          spaces: 2,
+        });
+      } catch (err) {
+        throw new TransformError("Unable to write package.json", {
+          transform: meta.name,
+          fatal: false,
+        });
+      }
+    }
+  }
+
+  return { result: "success", ...meta };
+}
diff --git a/packages/create-turbo/src/transforms/package-manager.ts b/packages/create-turbo/src/transforms/package-manager.ts
new file mode 100644
index 0000000..9c0af24
--- /dev/null
+++ b/packages/create-turbo/src/transforms/package-manager.ts
@@ -0,0 +1,26 @@
+import { convert } from "@turbo/workspaces";
+import { TransformInput, TransformResult } from "./types";
+
+const meta = {
+  name: "package-manager",
+};
+
+export async function transform(args: TransformInput): TransformResult {
+  const { project, prompts } = args;
+  const { root, packageManager } = prompts;
+
+  if (packageManager && project.packageManager !== packageManager.name) {
+    await convert({
+      root,
+      to: packageManager.name,
+      options: {
+        // skip install after conversion- we will do it later
+        skipInstall: true,
+      },
+    });
+  } else {
+    return { result: "not-applicable", ...meta };
+  }
+
+  return { result: "success", ...meta };
+}
diff --git a/packages/create-turbo/src/transforms/types.ts b/packages/create-turbo/src/transforms/types.ts
new file mode 100644
index 0000000..6a8e141
--- /dev/null
+++ b/packages/create-turbo/src/transforms/types.ts
@@ -0,0 +1,30 @@
+import { CreateCommandOptions } from "../commands/create/types";
+import { RepoInfo } from "../utils/examples";
+import type { Project, PackageManager } from "@turbo/workspaces";
+
+export interface TransformInput {
+  example: {
+    repo: RepoInfo | undefined;
+    name: string;
+  };
+  project: Project;
+  prompts: {
+    projectName: string;
+    root: string;
+    packageManager:
+      | {
+          name: PackageManager;
+          version: string | undefined;
+        }
+      | undefined;
+  };
+  opts: CreateCommandOptions;
+}
+
+export interface TransformResponse {
+  // errors should be thrown as instances of TransformError
+  result: "not-applicable" | "success";
+  name: string;
+}
+
+export type TransformResult = Promise<TransformResponse>;