fix: call strconv.Atoi() and strconv.Itoa() properly

Reviewed-on: coop-cloud/tagcmp#3

.drone.yml

@@ -0,0 +1,34 @@
+---
+kind: pipeline
+name: coopcloud.tech/tagcmp
+steps:
+  - name: make check
+    image: golang:1.17
+    commands:
+      - make check
+
+  - name: make build
+    image: golang:1.17
+    commands:
+      - make build
+
+  - name: make test
+    image: golang:1.17
+    commands:
+      - make test
+
+  - name: notify on failure
+    image: plugins/matrix
+    settings:
+      homeserver: https://matrix.autonomic.zone
+      roomid: "IFazIpLtxiScqbHqoa:autonomic.zone"
+      userid: "@autono-bot:autonomic.zone"
+      accesstoken:
+        from_secret: autono_bot_access_token
+    depends_on:
+      - make check
+      - make build
+      - make test
+    when:
+      status:
+        - failure

Makefile

@@ -0,0 +1,8 @@
+build:
+	@go build .
+
+check:
+	@test -z $$(gofmt -l .) || (echo "gofmt: formatting issue - run 'make format' to resolve" && exit 1)
+
+test:
+	@go test . -cover

README.md

@@ -1,5 +1,6 @@
 # tagcmp
 
+[![Build Status](https://build.coopcloud.tech/api/badges/coop-cloud/tagcmp/status.svg?ref=refs/heads/main)](https://build.coopcloud.tech/coop-cloud/tagcmp)
 [![Go Report Card](https://goreportcard.com/badge/git.coopcloud.tech/coop-cloud/tagcmp)](https://goreportcard.com/report/git.coopcloud.tech/coop-cloud/tagcmp)
 
 Comparison operations for image tags. Because registries aren't doing this for

godoc.md

@@ -12,6 +12,7 @@ Package tagcmp provides image tag comparison operations\.
 
 - [Variables](<#variables>)
 - [func IsParsable(tag string) bool](<#func-isparsable>)
+- [func UpgradeType(t Tag) int](<#func-upgradetype>)
 - [type ByTagAsc](<#type-bytagasc>)
   - [func (t ByTagAsc) Len() int](<#func-bytagasc-len>)
   - [func (t ByTagAsc) Less(i, j int) bool](<#func-bytagasc-less>)
@@ -27,6 +28,7 @@ Package tagcmp provides image tag comparison operations\.
   - [func (t Tag) IsGreaterThan(tag Tag) bool](<#func-tag-isgreaterthan>)
   - [func (t Tag) IsLessThan(tag Tag) bool](<#func-tag-islessthan>)
   - [func (t Tag) String() string](<#func-tag-string>)
+  - [func (curTag Tag) UpgradeElement(newTag Tag) (Tag, error)](<#func-tag-upgradeelement>)
 
 
 ## Variables
@@ -69,6 +71,14 @@ func IsParsable(tag string) bool
 
 IsParsable determines if a tag is supported by this library
 
+## func UpgradeType
+
+```go
+func UpgradeType(t Tag) int
+```
+
+UpgradeType takes exit from UpgradeElemene and returns a numeric representation of upgrade or downgrade 1/\-1: patch 2/\-2: minor 4/\-4: major 0: no change
+
 ## type ByTagAsc
 
 ByTagAsc sorts tags in ascending order where the last element is the latest tag\.
@@ -183,6 +193,14 @@ func (t Tag) String() string
 
 String formats a Tag correctly in string representation
 
+### func \(Tag\) UpgradeElement
+
+```go
+func (curTag Tag) UpgradeElement(newTag Tag) (Tag, error)
+```
+
+UpgradeElement returns a Tag object which is the difference between an old and new tag It can contain negative numbers if comparing with an older tag\.
+
 
 
 Generated by [gomarkdoc](<https://github.com/princjef/gomarkdoc>)

tagcmp.go

@@ -173,12 +173,36 @@ func (curTag Tag) UpgradeElement(newTag Tag) (Tag, error) {
 		return Tag{}, fmt.Errorf("%s and %s are not compatible with each other", curTag.String(), newTag.String())
 	}
 	diff := curTag
-	diff.Major(strconv.Itoa(strconv.Atoi(newTag.Major) - strconv.Atoi(curTag.Major)))
+	curMajor, err := strconv.Atoi(curTag.Major)
+	if err != nil {
+		return Tag{}, err
+	}
+	curMinor, err := strconv.Atoi(curTag.Minor)
+	if err != nil {
+		return Tag{}, err
+	}
+	curPatch, err := strconv.Atoi(curTag.Patch)
+	if err != nil {
+		return Tag{}, err
+	}
+	newMajor, err := strconv.Atoi(newTag.Major)
+	if err != nil {
+		return Tag{}, err
+	}
+	newMinor, err := strconv.Atoi(newTag.Minor)
+	if err != nil {
+		return Tag{}, err
+	}
+	newPatch, err := strconv.Atoi(newTag.Patch)
+	if err != nil {
+		return Tag{}, err
+	}
+	diff.Major = strconv.Itoa(newMajor - curMajor)
 	if !curTag.MissingMinor {
-		diff.Minor(strconv.Itoa(strconv.Atoi(newTag.Minor) - strconv.Atoi(curTag.Minor)))
+		diff.Minor = strconv.Itoa(newMinor - curMinor)
 	}
 	if !curTag.MissingPatch {
-		diff.Patch(strconv.Itoa(strconv.Atoi(newTag.Patch) - strconv.Atoi(curTag.Patch)))
+		diff.Patch = strconv.Itoa(newPatch - curPatch)
 	}
 
 	return diff, nil
@@ -188,16 +212,16 @@ func (curTag Tag) UpgradeElement(newTag Tag) (Tag, error) {
 // 1/-1: patch 2/-2: minor 4/-4: major 0: no change
 func UpgradeType(t Tag) int {
 	var major, minor, patch int
-	major = strconv.Atoi(t.Major)
+	major, _ = strconv.Atoi(t.Major)
 	if t.MissingMinor {
 		minor = 0
 	} else {
-		minor = strconv.Atoi(t.Minor)
+		minor, _ = strconv.Atoi(t.Minor)
 	}
 	if t.MissingPatch {
 		patch = 0
 	} else {
-		patch := strconv.Atoi(t.Patch)
+		patch, _ = strconv.Atoi(t.Patch)
 	}
 	if major > 0 {
 		return 4