How to do a git checkout branch using git2go

git2go-checkout-branch.go

package main

import (
	"errors"
	"log"
	"github.com/libgit2/git2go"
)

func checkoutBranch(repo *git.Repository, branchName string) error {
	checkoutOpts := &git.CheckoutOpts{
		Strategy: git.CheckoutSafe | git.CheckoutRecreateMissing | git.CheckoutAllowConflicts | git.CheckoutUseTheirs,
	}
	//Getting the reference for the remote branch
	// remoteBranch, err := repo.References.Lookup("refs/remotes/origin/" + branchName)
	remoteBranch, err := repo.LookupBranch("origin/"+branchName, git.BranchRemote)
	if err != nil {
		log.Print("Failed to find remote branch: " + branchName)
		return err
	}
	defer remoteBranch.Free()

	// Lookup for commit from remote branch
	commit, err := repo.LookupCommit(remoteBranch.Target())
	if err != nil {
		log.Print("Failed to find remote branch commit: " + branchName)
		return err
	}
	defer commit.Free()

	localBranch, err := repo.LookupBranch(branchName, git.BranchLocal)
	// No local branch, lets create one
	if localBranch == nil || err != nil {
		// Creating local branch
		localBranch, err = repo.CreateBranch(branchName, commit, false)
		if err != nil {
			log.Print("Failed to create local branch: " + branchName)
			return err
		}

		// Setting upstream to origin branch
		err = localBranch.SetUpstream("origin/" + branchName)
		if err != nil {
			log.Print("Failed to create upstream to origin/" + branchName)
			return err
		}
	}
	if localBranch == nil {
		return errors.New("Error while locating/creating local branch")
	}
	defer localBranch.Free()

	// Getting the tree for the branch
	localCommit, err := repo.LookupCommit(localBranch.Target())
	if err != nil {
		log.Print("Failed to lookup for commit in local branch " + branchName)
		return err
	}
	defer localCommit.Free()

	tree, err := repo.LookupTree(localCommit.TreeId())
	if err != nil {
		log.Print("Failed to lookup for tree " + branchName)
		return err
	}
	defer tree.Free()

	// Checkout the tree
	err = repo.CheckoutTree(tree, checkoutOpts)
	if err != nil {
		log.Print("Failed to checkout tree " + branchName)
		return err
	}
	// Setting the Head to point to our branch
	repo.SetHead("refs/heads/" + branchName)
	return nil
}