Add error handling and improve comments

Added fmt.Errorf for better error messages during HTTP and file handling in InstallTerraformVersion. Also fixed indentation in comments to follow Go conventions. Made other small improvements for better readability and maintainability.

versionedTerraform.go

@@ -5,6 +5,7 @@ import (
 	"bufio"
 	"bytes"
 	"errors"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"net/http"
@@ -25,7 +26,7 @@ const (
 	versionedTerraformFolder = "/.versionedTerraform"
 )
 
-//getLatestMajorRelease() returns the latest major release from Version
+// getLatestMajorRelease() returns the latest major release from Version
 func (v *Version) getLatestMajorRelease() {
 	for _, release := range v.availableVersions {
 		if release.majorVersion == v.Version.majorVersion &&
@@ -37,7 +38,7 @@ func (v *Version) getLatestMajorRelease() {
 	}
 }
 
-//getGreatestRelease() returns less than release
+// getGreatestRelease() returns less than release
 func (v *Version) getOneLessRelease() {
 	var vSlice []Version
 
@@ -60,7 +61,7 @@ func (v *Version) getOneLessRelease() {
 	}
 }
 
-//getLatestRelease returns the latest release from Version
+// getLatestRelease returns the latest release from Version
 func (v *Version) getLatestRelease() {
 	for _, release := range v.availableVersions {
 		if release.majorVersion > v.Version.majorVersion &&
@@ -81,8 +82,8 @@ func (v *Version) getLatestRelease() {
 	}
 }
 
-//InstallTerraformVersion installs the defined terraform Version in the application
-//configuration directory
+// InstallTerraformVersion installs the defined terraform Version in the application
+// configuration directory
 func (v *Version) InstallTerraformVersion() error {
 	homeDir, _ := os.UserHomeDir()
 	suffix := fileSuffix
@@ -90,56 +91,59 @@ func (v *Version) InstallTerraformVersion() error {
 	if v.Version.IsLessThan(*minV) {
 		suffix = alternateSuffix
 	}
-	resp, err := http.Get(hashicorpUrl +
+	url := hashicorpUrl +
 		v.Version.ToString() +
 		"/" + terraformPrefix +
 		v.Version.ToString() +
-		suffix)
+		suffix
+
+	resp, err := http.Get(url)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to download Terraform: %v", err)
 	}
 	defer resp.Body.Close()
 
 	body, err := ioutil.ReadAll(resp.Body)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to read response body: %v", err)
 	}
 
 	zipReader, err := zip.NewReader(bytes.NewReader(body), int64(len(body)))
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to create zip reader: %v", err)
 	}
+
 	versionedFileName := homeDir + versionedTerraformFolder + "/" + terraformPrefix + v.Version.ToString()
-	versionedFile, err := os.OpenFile(versionedFileName, os.O_WRONLY, 0755)
-	if os.IsNotExist(err) {
-		versionedFile, err = os.OpenFile(versionedFileName, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0755)
-		if err != nil {
-			return err
-		}
-	}
+	versionedFile, err := os.OpenFile(versionedFileName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to create output file: %v", err)
 	}
 	defer versionedFile.Close()
 
 	for _, zipFile := range zipReader.File {
+		if zipFile.Name != "terraform" {
+			continue
+		}
+
 		zr, err := zipFile.Open()
 		if err != nil {
-			return err
+			return fmt.Errorf("failed to open zip file: %v", err)
 		}
-		unzippedFileBytes, _ := ioutil.ReadAll(zr)
+		defer zr.Close()
 
-		_, err = versionedFile.Write(unzippedFileBytes)
+		_, err = io.Copy(versionedFile, zr)
 		if err != nil {
-			return err
+			return fmt.Errorf("failed to write terraform binary: %v", err)
 		}
-		zr.Close()
+
+		break
 	}
+
 	return nil
 }
 
-//NewVersion creates a new Version using sem versioning for determining the
-//latest release
+// NewVersion creates a new Version using sem versioning for determining the
+// latest release
 func NewVersion(_version string, _vList []string) *Version {
 	v := new(Version)
 	v.Version = *NewSemVersion(_version)
@@ -202,7 +206,7 @@ func NewVersion(_version string, _vList []string) *Version {
 	return v
 }
 
-//GetVersionList returns a list of available versions from hashicorp's release page
+// GetVersionList returns a list of available versions from hashicorp's release page
 func GetVersionList() ([]string, error) {
 	var versionList []string
 	resp, err := http.Get(hashicorpUrl)
@@ -234,7 +238,7 @@ func GetVersionList() ([]string, error) {
 	return versionList, nil
 }
 
-//removeSpacesVersion removes spaces from Version string for parsing
+// removeSpacesVersion removes spaces from Version string for parsing
 func removeSpacesVersion(v string) string {
 	splitV := strings.Split(v, " ")
 	var returnString string
@@ -245,12 +249,12 @@ func removeSpacesVersion(v string) string {
 	return strings.TrimSpace(returnString)
 }
 
-//VersionToString returns string of a Version
+// VersionToString returns string of a Version
 func (v *Version) VersionToString() string {
 	return v.Version.ToString()
 }
 
-//isVersionGreater returns true if v1 is greater than v2
+// isVersionGreater returns true if v1 is greater than v2
 func isVersionGreater(v1 Version, v2 Version) bool {
 	if v1.Version.majorVersion != v2.Version.majorVersion {
 		if v1.Version.majorVersion > v2.Version.majorVersion {