feat: add file copying function into new directory

Author: archandatta

cmd/create.go

@@ -2,8 +2,11 @@ package cmd
 
 import (
 	"fmt"
+	"os"
+	"path/filepath"
 
 	"github.com/onkernel/cli/pkg/create"
+	"github.com/pterm/pterm"
 	"github.com/spf13/cobra"
 )
 
@@ -40,28 +43,46 @@ func runCreateApp(cmd *cobra.Command, args []string) error {
 		return fmt.Errorf("failed to get template: %w", err)
 	}
 
-	fmt.Printf("Creating application '%s' with language '%s' and template '%s'...\n", appName, language, template)
+	// Get absolute path for the app directory
+	appPath, err := filepath.Abs(appName)
+	if err != nil {
+		return fmt.Errorf("failed to resolve app path: %w", err)
+	}
 
-	// TODO: create the project structure
+	// Check if directory already exists
+	if _, err := os.Stat(appPath); err == nil {
+		return fmt.Errorf("directory %s already exists", appName)
+	}
 
-	// print "Creating a new TypeScript Sample App" or similar. Essentially the language and template name combined.
+	// Create the app directory
+	if err := os.MkdirAll(appPath, 0755); err != nil {
+		return fmt.Errorf("failed to create directory: %w", err)
+	}
 
-	/*
-		Print the following:
-				✔ TypeScript environment set up successfully
+	fmt.Printf("\nCreating a new %s %s\n\n", language, template)
+
+	spinner, _ := pterm.DefaultSpinner.Start("Copying template files...")
+
+	if err := create.CopyTemplateFiles(appPath, language, template); err != nil {
+		spinner.Fail("Failed to copy template files")
+		return fmt.Errorf("failed to copy template files: %w", err)
+	}
+	spinner.Success("✔ TypeScript environment set up successfully")
 
-				🎉 Kernel app created successfully!
+	nextSteps := fmt.Sprintf(`Next steps:
+  brew install onkernel/tap/kernel
+  cd %s
+  kernel login  # or: export KERNEL_API_KEY=<YOUR_API_KEY>
+  kernel deploy index.ts
+  kernel invoke ts-basic get-page-title --payload '{"url": "https://www.google.com"}'
+  # Do this in a separate tab
+  kernel login  # or: export KERNEL_API_KEY=<YOUR_API_KEY>
+  kernel logs ts-basic --follow
+`, appName)
 
-				Next steps:
-				  brew install onkernel/tap/kernel
-				  cd my-kernel-app
-				  kernel login  # or: export KERNEL_API_KEY=<YOUR_API_KEY>
-				  kernel deploy index.ts
-				  kernel invoke ts-basic get-page-title --payload '{"url": "https://www.google.com"}'
-				  # Do this in a separate tab
-				  kernel login  # or: export KERNEL_API_KEY=<YOUR_API_KEY>
-				  kernel logs ts-basic --follow
-	*/
+	pterm.Success.Println("🎉 Kernel app created successfully!")
+	pterm.Println()
+	pterm.FgYellow.Println(nextSteps)
 
 	return nil
 }

pkg/create/copy.go

@@ -0,0 +1,84 @@
+package create
+
+import (
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+
+	"github.com/onkernel/cli/pkg/templates"
+)
+
+const (
+	DIR_PERM  = 0755 // rwxr-xr-x
+	FILE_PERM = 0644 // rw-r--r--
+)
+
+// CopyTemplateFiles copies all files and directories from the specified embedded template
+// into the target application path. It uses the given language and template names
+// to locate the template inside the embedded filesystem.
+//
+//   - appPath: filesystem path where the files should be written (the project directory)
+//   - language: language subdirectory (e.g., "typescript")
+//   - template: template subdirectory (e.g., "sample-app")
+//
+// The function will recursively walk through the embedded template directory and
+// replicate all files and folders in appPath. If a file named "_gitignore" is encountered,
+// it is renamed to ".gitignore" in the output, to work around file embedding limitations.
+//
+// Returns an error if the template path is invalid, empty, or if any file operations fail.
+func CopyTemplateFiles(appPath, language, template string) error {
+	// Build the template path within the embedded FS (e.g., "typescript/sample-app")
+	templatePath := filepath.Join(language, template)
+
+	// Check if the template exists and is non-empty
+	entries, err := fs.ReadDir(templates.FS, templatePath)
+	if err != nil {
+		return fmt.Errorf("template not found: %s/%s", language, template)
+	}
+	if len(entries) == 0 {
+		return fmt.Errorf("template directory is empty: %s/%s", language, template)
+	}
+
+	// Walk through the embedded template directory and copy contents
+	return fs.WalkDir(templates.FS, templatePath, func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+
+		// Determine the path relative to the root of the template
+		relPath, err := filepath.Rel(templatePath, path)
+		if err != nil {
+			return err
+		}
+
+		// Skip the template root directory itself
+		if relPath == "." {
+			return nil
+		}
+
+		destPath := filepath.Join(appPath, relPath)
+
+		if d.IsDir() {
+			return os.MkdirAll(destPath, DIR_PERM)
+		}
+
+		// Read the file content from the embedded filesystem
+		content, err := fs.ReadFile(templates.FS, path)
+		if err != nil {
+			return fmt.Errorf("failed to read template file %s: %w", path, err)
+		}
+
+		// Rename _gitignore to .gitignore in the destination
+		if filepath.Base(destPath) == "_gitignore" {
+			destPath = filepath.Join(filepath.Dir(destPath), ".gitignore")
+		}
+
+		// Write the file to disk in the target project directory
+		if err := os.WriteFile(destPath, content, FILE_PERM); err != nil {
+			return fmt.Errorf("failed to write file %s: %w", destPath, err)
+		}
+
+		return nil
+	})
+}