From f1f7c4e10c66573fe0c0686cc9eaa46f1ef47370 Mon Sep 17 00:00:00 2001
From: Thomas Meckel <tmeckel@noreply.github.com>
Date: Sat, 23 Mar 2019 22:02:36 +0100
Subject: [PATCH] * added function ParseSnapshotData to parse a string
 representation of a VBox snapshot tree * fixed bugs

---
 builder/virtualbox/common/snapshot.go | 74 +++++++++++++++++++++++++--
 1 file changed, 69 insertions(+), 5 deletions(-)

diff --git a/builder/virtualbox/common/snapshot.go b/builder/virtualbox/common/snapshot.go
index cd5449f78..cc7a3499d 100644
--- a/builder/virtualbox/common/snapshot.go
+++ b/builder/virtualbox/common/snapshot.go
@@ -1,7 +1,12 @@
 package common
 
 import (
+	"bufio"
+	"log"
+	"regexp"
 	"strings"
+
+	"github.com/golang-collections/collections/stack"
 )
 
 // VBoxSnapshot stores the hierarchy of snapshots for a VM instance
@@ -13,6 +18,66 @@ type VBoxSnapshot struct {
 	Children  []*VBoxSnapshot
 }
 
+// ParseSnapshotData parses the machinereadable representation of a virtualbox snapshot tree
+func ParseSnapshotData(snapshotData string) (*VBoxSnapshot, error) {
+	scanner := bufio.NewScanner(strings.NewReader(snapshotData))
+	SnapshotNamePartsRe := regexp.MustCompile("Snapshot(?P<Type>Name|UUID)(?P<Path>(-[1-9]+)*)=\"(?P<Value>[^\"]*)\"")
+	var currentIndicator string
+	parentStack := stack.New()
+	var node *VBoxSnapshot
+	var rootNode *VBoxSnapshot
+
+	for scanner.Scan() {
+		txt := scanner.Text()
+		idx := strings.Index(txt, "=")
+		if idx > 0 {
+			if strings.HasPrefix(txt, "Current") {
+				node.IsCurrent = true
+			} else {
+				matches := SnapshotNamePartsRe.FindStringSubmatch(txt)
+				log.Printf("************ Snapshot %s name parts", txt)
+				log.Printf("Matches %#v\n", matches)
+				log.Printf("Node %s\n", matches[0])
+				log.Printf("Type %s\n", matches[1])
+				log.Printf("Path %s\n", matches[2])
+				log.Printf("Leaf %s\n", matches[3])
+				log.Printf("Value %s\n", matches[4])
+				if matches[1] == "Name" {
+					if nil == rootNode {
+						node = new(VBoxSnapshot)
+						rootNode = node
+						currentIndicator = matches[2]
+					} else {
+						pathLenCur := strings.Count(currentIndicator, "-")
+						pathLen := strings.Count(matches[2], "-")
+						if pathLen > pathLenCur {
+							currentIndicator = matches[2]
+							parentStack.Push(node)
+						} else if pathLen < pathLenCur {
+							currentIndicator = matches[2]
+							for i := 0; i < pathLenCur-1; i++ {
+								parentStack.Pop()
+							}
+						}
+						node = new(VBoxSnapshot)
+						parent := parentStack.Peek().(*VBoxSnapshot)
+						if nil != parent {
+							node.Parent = parent
+							parent.Children = append(parent.Children, node)
+						}
+					}
+					node.Name = matches[4]
+				} else if matches[1] == "UUID" {
+					node.UUID = matches[4]
+				}
+			}
+		} else {
+			log.Printf("Invalid key,value pair [%s]", txt)
+		}
+	}
+	return rootNode, nil
+}
+
 // IsChildOf verifies if the current snaphot is a child of the passed as argument
 func (sn *VBoxSnapshot) IsChildOf(candidate *VBoxSnapshot) bool {
 	if nil == candidate {
@@ -37,9 +102,8 @@ func walk(sn *VBoxSnapshot, ch chan *VBoxSnapshot) {
 		for _, child := range sn.Children {
 			walk(child, ch)
 		}
-	} else {
-		ch <- sn
 	}
+	ch <- sn
 }
 
 func walker(sn *VBoxSnapshot) <-chan *VBoxSnapshot {
@@ -76,7 +140,7 @@ func (sn *VBoxSnapshot) GetSnapshotsByName(name string) []*VBoxSnapshot {
 	for {
 		node, ok := <-ch
 		if !ok {
-			panic("Internal channel error while traversing the snapshot tree")
+			break
 		}
 		if strings.EqualFold(node.Name, name) {
 			result = append(result, node)
@@ -92,7 +156,7 @@ func (sn *VBoxSnapshot) GetSnapshotByUUID(uuid string) *VBoxSnapshot {
 	for {
 		node, ok := <-ch
 		if !ok {
-			panic("Internal channel error while traversing the snapshot tree")
+			break
 		}
 		if strings.EqualFold(node.UUID, uuid) {
 			return node
@@ -108,7 +172,7 @@ func (sn *VBoxSnapshot) GetCurrentSnapshot() *VBoxSnapshot {
 	for {
 		node, ok := <-ch
 		if !ok {
-			panic("Internal channel error while traversing the snapshot tree")
+			break
 		}
 		if node.IsCurrent {
 			return node