Support creating projects in current directory

src/NewProject.res

@@ -2,18 +2,20 @@ open Node
 
 module P = ClackPrompts
 
-let packageNameRegExp = /^[a-z0-9-]+$/
-
-let validateProjectName = projectName =>
-  if projectName->String.trim->String.length === 0 {
-    Error("Project name must not be empty.")
-  } else if !(packageNameRegExp->RegExp.test(projectName)) {
-    Error("Project name may only contain lower case letters, numbers and hyphens.")
-  } else if Fs.existsSync(Path.join2(Process.cwd(), projectName)) {
-    Error(`The folder ${projectName} already exist in the current directory.`)
-  } else {
-    Ok()
+let installGitignore = async () => {
+  let templateGitignorePath = "_gitignore"
+  let gitignorePath = ".gitignore"
+
+  if Fs.existsSync(templateGitignorePath) {
+    if Fs.existsSync(gitignorePath) {
+      let templateGitignore = await Fs.Promises.readFile(templateGitignorePath)
+      await Fs.Promises.appendFile(gitignorePath, `${Os.eol}${templateGitignore}`)
+      await Fs.Promises.rm(templateGitignorePath, ~options={force: true})
+    } else {
+      await Fs.Promises.rename(templateGitignorePath, gitignorePath)
+    }
   }
+}
 
 let updatePackageJson = async (~projectName, ~versions) =>
   await JsonUtils.updateJsonFile("package.json", json =>
@@ -111,20 +113,27 @@ let promptTemplateName = async () => {
 
 let createProject = async (~templateName, ~projectName, ~versions) => {
   let templatePath = CraPaths.getTemplatePath(~templateName)
-  let projectPath = Path.join2(Process.cwd(), projectName)
+  let packageName = NewProjectLocation.getPackageName(projectName)
+  let projectPath = NewProjectLocation.getProjectPath(projectName)
+  let createInCurrentDirectory = NewProjectLocation.isCurrentDirectoryProject(projectName)
 
   let s = P.spinner()
 
   if !CI.isRunningInCI {
     s->P.Spinner.start("Creating project...")
   }
 
-  await Fs.Promises.cp(templatePath, projectPath, ~options={recursive: true})
+  if createInCurrentDirectory {
+    await Fs.Promises.cp(templatePath, projectPath, ~options={recursive: true, force: false})
+  } else {
+    await Fs.Promises.cp(templatePath, projectPath, ~options={recursive: true})
+  }
+
   Process.chdir(projectPath)
 
-  await Fs.Promises.rename("_gitignore", ".gitignore")
-  await updatePackageJson(~projectName, ~versions)
-  await updateRescriptJson(~projectName, ~versions)
+  await installGitignore()
+  await updatePackageJson(~projectName=packageName, ~versions)
+  await updateRescriptJson(~projectName=packageName, ~versions)
   await updateViteConfig()
 
   await RescriptVersions.installVersions(versions)
@@ -134,12 +143,13 @@ let createProject = async (~templateName, ~projectName, ~versions) => {
     s->P.Spinner.stop("Project created.")
   }
 
-  P.note(
-    ~title="Get started",
-    ~message=`cd ${projectName}
+  let getStartedMessage = createInCurrentDirectory
+    ? "# See the project's README.md for more information."
+    : `cd ${projectName}
 
-# See the project's README.md for more information.`,
-  )
+# See the project's README.md for more information.`
+
+  P.note(~title="Get started", ~message=getStartedMessage)
 }
 
 let createNewProject = async () => {
@@ -159,7 +169,7 @@ let createNewProject = async () => {
     let projectName = switch commandLineArguments.projectName {
     | Some(projectName) if useDefaultVersions =>
       // Note this throws in the some case, which is why we cannot use Option.getOrThrow here.
-      switch validateProjectName(projectName) {
+      switch NewProjectLocation.validateProjectName(projectName) {
       | Error(message) => JsError.throwWithMessage(message)
       | Ok() => projectName
       }
@@ -170,7 +180,7 @@ let createNewProject = async () => {
         placeholder: "my-rescript-app",
         ?initialValue,
         validate: projectName =>
-          switch validateProjectName(projectName) {
+          switch NewProjectLocation.validateProjectName(projectName) {
           | Ok() => None
           | Error(error) => Some(error)
           },

src/NewProjectLocation.res

@@ -0,0 +1,58 @@
+open Node
+
+let currentDirectoryArgument = "."
+let packageNameRegExp = /^[a-z0-9-]+$/
+
+let allowedCurrentDirectoryEntries = [
+  ".git",
+  ".gitattributes",
+  ".gitignore",
+  "licence",
+  "licence.md",
+  "license",
+  "license.md",
+  "readme",
+  "readme.md",
+]
+
+let isCurrentDirectoryProject = projectName => projectName === currentDirectoryArgument
+
+let getPackageName = (~cwd=Process.cwd(), projectName) =>
+  isCurrentDirectoryProject(projectName) ? Path.basename(cwd) : projectName
+
+let getProjectPath = (~cwd=Process.cwd(), projectName) =>
+  isCurrentDirectoryProject(projectName) ? cwd : Path.join2(cwd, projectName)
+
+let isAllowedCurrentDirectoryEntry = entry => {
+  let normalizedEntry = entry->String.toLowerCase
+
+  allowedCurrentDirectoryEntries
+  ->Array.find(allowedEntry => allowedEntry === normalizedEntry)
+  ->Option.isSome
+}
+
+let validateCurrentDirectory = cwd => {
+  let disallowedEntries =
+    Fs.readdirSync(cwd)->Array.filter(entry => !(entry->isAllowedCurrentDirectoryEntry))
+
+  switch disallowedEntries {
+  | [] => Ok()
+  | _ => Error("The current directory contains files that could conflict with project creation.")
+  }
+}
+
+let validateProjectName = (~cwd=Process.cwd(), projectName) => {
+  let packageName = getPackageName(~cwd, projectName)
+
+  if packageName->String.trim->String.length === 0 {
+    Error("Project name must not be empty.")
+  } else if !(packageNameRegExp->RegExp.test(packageName)) {
+    Error("Project name may only contain lower case letters, numbers and hyphens.")
+  } else if isCurrentDirectoryProject(projectName) {
+    validateCurrentDirectory(cwd)
+  } else if Fs.existsSync(getProjectPath(~cwd, projectName)) {
+    Error(`The folder ${projectName} already exist in the current directory.`)
+  } else {
+    Ok()
+  }
+}

src/bindings/Node.res

@@ -1,6 +1,8 @@
 module Fs = {
   @module("node:fs") external existsSync: string => bool = "existsSync"
 
+  @module("node:fs") external readdirSync: string => array<string> = "readdirSync"
+
   @module("node:fs")
   external readFileSync: (string, @as(json`"utf8"`) _) => string = "readFileSync"
 
@@ -14,7 +16,7 @@ module Fs = {
     @module("node:fs") @scope("promises")
     external appendFile: (string, string) => promise<unit> = "appendFile"
 
-    type cpOptions = {recursive?: bool}
+    type cpOptions = {recursive?: bool, force?: bool}
 
     @module("node:fs") @scope("promises")
     external copyFile: (string, string) => promise<unit> = "copyFile"

test/CommandLineArgumentsTest.res

@@ -31,6 +31,14 @@ Test.describe("CommandLineArguments", () => {
     }
   })
 
+  Test.test("parses the current directory as a project name", () => {
+    switch CommandLineArguments.parse(list{"."}) {
+    | Ok(commandLineArguments) =>
+      commandLineArguments->assertCommandLineArguments(~projectName=Some("."), ~templateName=None)
+    | Error(message) => Assert.fail(message)
+    }
+  })
+
   Test.test("parses the template name from the -t flag", () => {
     switch CommandLineArguments.parse(list{"my-app", "-t", "vite"}) {
     | Ok(commandLineArguments) =>

test/NewProjectLocationTest.res

@@ -0,0 +1,65 @@
+open Node
+
+let testRoot = Path.join2(Process.cwd(), ".tmp-new-project-location-test")
+let currentDirectoryConflictMessage = "The current directory contains files that could conflict with project creation."
+
+let cleanupTestRoot = async () =>
+  await Fs.Promises.rm(testRoot, ~options={recursive: true, force: true})
+
+let resetTestRoot = async projectDirectoryName => {
+  await cleanupTestRoot()
+  let projectPath = Path.join2(testRoot, projectDirectoryName)
+  await Fs.Promises.mkdir(projectPath, ~options={recursive: true})
+  projectPath
+}
+
+let assertValidationOk = result =>
+  switch result {
+  | Ok() => ()
+  | Error(message) => Assert.fail(`Expected project name to be valid, got: ${message}`)
+  }
+
+let assertValidationError = (result, expectedMessage) =>
+  switch result {
+  | Error(message) => Assert.strictEqual(message, expectedMessage)
+  | Ok() => Assert.fail(`Expected validation error: ${expectedMessage}`)
+  }
+
+Test.describe("NewProjectLocation", () => {
+  Test.test("uses the current directory basename as the package name", () => {
+    NewProjectLocation.getPackageName(~cwd="/tmp/my-app", ".")->Assert.strictEqual("my-app")
+  })
+
+  Test.test("uses the current directory as the project path", () => {
+    NewProjectLocation.getProjectPath(~cwd="/tmp/my-app", ".")->Assert.strictEqual("/tmp/my-app")
+  })
+
+  Test.testAsync("allows creating in a repository with README and license files", async () => {
+    let projectPath = await resetTestRoot("my-app")
+    await Fs.Promises.mkdir(Path.join2(projectPath, ".git"))
+    await Fs.Promises.writeFile(Path.join2(projectPath, "README.md"), "")
+    await Fs.Promises.writeFile(Path.join2(projectPath, "LICENSE"), "")
+
+    NewProjectLocation.validateProjectName(~cwd=projectPath, ".")->assertValidationOk
+    await cleanupTestRoot()
+  })
+
+  Test.testAsync("rejects creating in a current directory with project files", async () => {
+    let projectPath = await resetTestRoot("my-app")
+    await Fs.Promises.writeFile(Path.join2(projectPath, "src"), "")
+
+    NewProjectLocation.validateProjectName(~cwd=projectPath, ".")->assertValidationError(
+      currentDirectoryConflictMessage,
+    )
+    await cleanupTestRoot()
+  })
+
+  Test.testAsync("rejects creating a nested project that already exists", async () => {
+    let _ = await resetTestRoot("existing-app")
+
+    NewProjectLocation.validateProjectName(~cwd=testRoot, "existing-app")->assertValidationError(
+      "The folder existing-app already exist in the current directory.",
+    )
+    await cleanupTestRoot()
+  })
+})