Implement current subcommand (#28)

* feat: implement current subcommand for displaying active tf version

* refactor: error handling

* refactor: simplify determining current active version

* chore: update error messages

README.md

@@ -115,6 +115,11 @@ tfversion list --pre-release
 tfversion uninstall 1.7.4
 ```
 
+### Display the currently activated version of Terraform
+```sh
+tfversion current
+```
+
 ## Contributing
 
 Contributions are highly appreciated and always welcome.

cmd/current.go

@@ -0,0 +1,26 @@
+package cmd
+
+import (
+	"github.com/spf13/cobra"
+	"github.com/tfversion/tfversion/pkg/current"
+)
+
+const (
+	currentExample = "# Print the current active version of Terraform\n" +
+		"tfversion current"
+)
+
+var (
+	currentCmd = &cobra.Command{
+		Use:     "current",
+		Short:   "Print the current active version of Terraform",
+		Example: currentExample,
+		Run: func(cmd *cobra.Command, args []string) {
+			current.CheckCurrentVersion()
+		},
+	}
+)
+
+func init() {
+	rootCmd.AddCommand(currentCmd)
+}

pkg/current/current.go

@@ -0,0 +1,29 @@
+package current
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/tfversion/tfversion/pkg/download"
+	"github.com/tfversion/tfversion/pkg/helpers"
+	"github.com/tfversion/tfversion/pkg/use"
+)
+
+// CheckCurrentVersion prints the current active version of Terraform.
+func CheckCurrentVersion() {
+
+	symlinkPath := filepath.Join(use.GetUseLocation(), download.TerraformBinaryName)
+	_, err := os.Lstat(symlinkPath)
+	if err != nil {
+		helpers.ExitWithError("no current terraform version found", err)
+	}
+
+	realPath, err := filepath.EvalSymlinks(symlinkPath)
+	if err != nil {
+		helpers.ExitWithError("resolving symlink", err)
+	}
+	_, currentVersion := filepath.Split(filepath.Dir(realPath))
+
+	fmt.Printf("Current active Terraform version: %s\n", helpers.ColoredVersion(currentVersion))
+}

pkg/use/use.go

@@ -30,7 +30,7 @@ func UseVersion(versionOrAlias string) {
 		helpers.ExitWithError("using", err)
 	}
 
-	useLocation := getUseLocation()
+	useLocation := GetUseLocation()
 
 	// inform the user that they need to update their PATH
 	path := os.Getenv("PATH")
@@ -96,7 +96,7 @@ func UseRequiredVersion() {
 	UseVersion(foundVersion)
 }
 
-func getUseLocation() string {
+func GetUseLocation() string {
 	user, err := os.UserHomeDir()
 	if err != nil {
 		helpers.ExitWithError("user home directory", err)