feat: adds tagging functionality

Signed-off-by: ChrisJBurns <29541485+ChrisJBurns@users.noreply.github.com>

Author: ChrisJBurns

.gitignore

@@ -24,4 +24,6 @@ go.work
 create-cli
 
 # exclude the folders created by the download command
-create-repositories
+create-repositories
+
+.DS_Store

internal/download/download.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 
 	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/transport/http"
 	"github.com/spf13/viper"
 )
@@ -42,8 +43,10 @@ func ReturnRepoListWithCloudProviderTemplate(cloudProvider string) map[string]st
 }
 
 func Download() {
+
 	cloudProvider := viper.GetString("cloud-provider")
 	personalAccessToken := viper.GetString("pat")
+	tag := "1.0.0.0"
 
 	ReturnRepoListWithCloudProviderTemplate(cloudProvider)
 
@@ -55,7 +58,7 @@ func Download() {
 
 	for repoName, repoUrl := range ReposToClone {
 		log.Printf("Cloning %s into %s", repoName, CreateRepositoryDirectory)
-		_, err := git.PlainClone(CreateRepositoryDirectory+repoName, false, &git.CloneOptions{
+		r, err := git.PlainClone(CreateRepositoryDirectory+repoName, false, &git.CloneOptions{
 			// The intended use of a GitHub personal access token is in replace of your password
 			// because access tokens can easily be revoked.
 			// https://help.github.com/articles/creating-a-personal-access-token-for-the-command-line/
@@ -66,10 +69,66 @@ func Download() {
 			URL:      repoUrl,
 			Progress: os.Stdout,
 		})
+		if err != nil {
+			panic(err)
+		}
 
+		// get work tree for cloned repo
+		tree, err := r.Worktree()
 		if err != nil {
 			panic(err)
 		}
+
+		checkoutTag(tag, tree)
+		deletesMainBranch(r)
+		createAndCheckoutMainBranchOffTag(tag, r, tree)
+	}
+}
+
+// checkoutTag checks out the passed tag
+func checkoutTag(tag string, tree *git.Worktree) {
+	err := tree.Checkout(&git.CheckoutOptions{
+		Branch: plumbing.ReferenceName("refs/tags/" + tag),
+	})
+	if err != nil {
+		panic(err)
 	}
+}
 
+// deletesMainBranch deletes the main branch because we want to create a new
+// main branch off the specific tag. otherwise, the main branch will have the entire
+// history of the repository which in this case we don't want. just the specific version
+func deletesMainBranch(r *git.Repository) {
+	err := r.Storer.RemoveReference("refs/heads/main")
+	if err != nil {
+		panic(err)
+	}
+}
+
+// createAndCheckpoutMainBranchOffTag will create and checkout a main branch off the commit hash reference
+// of the tag that is passed in. this is to ensure that the main branch only has the code on the tag.
+// otherwise, if you want the code on the 1.0.0.0 tag, without deleting and creating a new main
+// branch off the tag, the main branch will have all of the latest code - which in this case is not
+// what you want.
+func createAndCheckoutMainBranchOffTag(tag string, r *git.Repository, tree *git.Worktree) {
+	// we get the commit reference that is at the tip of the tag
+	headRef, err := r.Reference(plumbing.ReferenceName("refs/tags/"+tag), false)
+	if err != nil {
+		panic(err)
+	}
+
+	// we create a new branch called `main` off the commit hash from the tag
+	ref := plumbing.NewHashReference("refs/heads/main", headRef.Hash())
+	err = r.Storer.SetReference(ref)
+	if err != nil {
+		panic(err)
+	}
+
+	// we checkout the `main` branch just created.
+	err = tree.Checkout(&git.CheckoutOptions{
+		Branch: plumbing.ReferenceName("refs/heads/main"),
+	})
+	if err != nil {
+		panic(err)
+	}
 }