refactor: update doc comments and add update check

internal/package_handler/package.go

@@ -190,6 +190,8 @@ func (p *PackageHandler) LatestVersion() (string, error) {
 	return versions[len(versions)-1], nil
 }
 
+// CommitPrecedence returns true if the new commit hash is a descendant of the
+// old commit hash. It returns an error if the commit hashes are not found.
 func (p *PackageHandler) CommitPrecedence(oldCommitHash, newCommitHash string) (bool, error) {
 	err := p.CheckoutCommit(newCommitHash)
 	if err != nil {
@@ -205,6 +207,7 @@ func (p *PackageHandler) CommitPrecedence(oldCommitHash, newCommitHash string) (
 	if err != nil {
 		return false, err
 	}
+	// Skip first commit, because it is the new commit hash itself
 	_, err = commitIter.Next()
 	if err != nil {
 		if errors.Is(err, io.EOF) {

pkg/daemon/daemon.go

@@ -152,6 +152,10 @@ type PullResult struct {
 }
 
 type PullUpdateResult struct {
+	Name    string
+	Tag     string
+	Url     string
+	Profile string
 	// OldVersion is the version of the old package.
 	OldVersion string
 
@@ -174,7 +178,7 @@ type PullUpdateResult struct {
 	NewOptions []Option
 
 	// MergedOptions is the list of options of the new package merged with the
-	// old package. These options the ones that will be used for the new instance
+	// old package. These options are the ones that will be used for the new instance
 	// and should be filled by the user.
 	MergedOptions []Option
 
@@ -187,6 +191,10 @@ type InstallOptions struct {
 	// Name is the name of the AVS represented by the package.
 	Name string
 
+	// Tag is the tag to use for the instance, required to build the instance id
+	// with the format <package_name>-<tag>
+	Tag string
+
 	// URL is the URL of the git repository containing the node software package.
 	URL string
 
@@ -207,10 +215,6 @@ type InstallOptions struct {
 
 	// Options is the list of options to use for the instance.
 	Options []Option
-
-	// Tag is the tag to use for the instance, required to build the instance id
-	// with the format <package_name>-<tag>
-	Tag string
 }
 
 // LocalInstallOptions is a set of options for installing a node software package

pkg/daemon/egn_daemon.go

@@ -339,6 +339,9 @@ func (d *EgnDaemon) Pull(url string, ref PullTarget, force bool) (result PullRes
 }
 
 func (d *EgnDaemon) PullUpdate(instanceID string, url string, ref PullTarget) (PullUpdateResult, error) {
+	if !d.dataDir.HasInstance(instanceID) {
+		return PullUpdateResult{}, fmt.Errorf("%w: %s", ErrInstanceNotFound, instanceID)
+	}
 	pkgHandler, err := d.pullPackage(url, true)
 	if err != nil {
 		return PullUpdateResult{}, err
@@ -419,7 +422,7 @@ func (d *EgnDaemon) PullUpdate(instanceID string, url string, ref PullTarget) (P
 		if v, ok := valuesOld[o.Target()]; ok {
 			err := o.Set(v)
 			if err != nil {
-				return PullUpdateResult{}, err
+				return PullUpdateResult{}, fmt.Errorf("error setting old option value: %v", err)
 			}
 		} else {
 			return PullUpdateResult{}, fmt.Errorf("%w: old option %s", ErrOptionWithoutValue, o.Name())
@@ -432,6 +435,11 @@ func (d *EgnDaemon) PullUpdate(instanceID string, url string, ref PullTarget) (P
 	}
 
 	return PullUpdateResult{
+		Name:          instance.Name,
+		Tag:           instance.Tag,
+		Url:           instance.URL,
+		Profile:       instance.Profile,
+		HasPlugin:     instance.Plugin != nil,
 		OldVersion:    instance.Version,
 		NewVersion:    newVersion,
 		OldCommit:     instance.Commit,
@@ -442,7 +450,22 @@ func (d *EgnDaemon) PullUpdate(instanceID string, url string, ref PullTarget) (P
 	}, nil
 }
 
+// mergeOptions merges the old options with the new ones following the next rules:
+//
+//  1. New option is not present in the old options: New option is added to the
+//     merged options without a value.
+//
+// 2. New option is present in the old options:
+//
+//	2.1: Old option value is valid for the new option: the new option is added
+//	     to the merged options using the old option value.
+//
+//	2.2: Old option value is not valid for the new option: the new option is
+//	     added to the merged options without a value and probably the user
+//	     will need to fill it again or use its default value.
 func mergeOptions(oldOptions, newOptions []Option) ([]Option, error) {
+	// mergedOptions will contain the result of merging the new options with the
+	// old ones
 	var mergedOptions []Option
 	for _, oNew := range newOptions {
 		var oOld Option

pkg/daemon/error.go

@@ -6,6 +6,7 @@ var (
 	ErrInstanceAlreadyExists      = errors.New("instance already exists")
 	ErrProfileDoesNotExist        = errors.New("profile does not exist")
 	ErrInstanceNotRunning         = errors.New("instance is not running")
+	ErrInstanceNotFound           = errors.New("instance not found")
 	ErrOptionWithoutValue         = errors.New("option without value")
 	ErrMonitoringTargetPortNotSet = errors.New("monitoring target port is not set")
 	ErrInstanceHasNoPlugin        = errors.New("instance has no plugin")