Fix > 250 char Branch name issue (#188)

* Fix > 250 char Branch name issue

Move brnach name generation to a function.
Limit original branch substing to 200 charts
Switch target paths substring to sha1 of the target paths.
Tests

* Address isssus raised in PR reivew

Rename a var
Used Repeat to avoid hardcoding long string
Made some test input **a bit** more realistic

internal/pkg/githubapi/github.go

@@ -3,7 +3,9 @@ package githubapi
 import (
 	"bytes"
 	"context"
+	"crypto/sha1" //nolint:gosec // G505: Blocklisted import crypto/sha1: weak cryptographic primitive (gosec), this is not a cryptographic use case
 	"encoding/base64"
+	"encoding/hex"
 	"encoding/json"
 	"fmt"
 	"net/http"
@@ -353,7 +355,7 @@ func handleMergedPrEvent(ghPrClientDetails GhPrClientDetails, prApproverGithubCl
 				return err
 			}
 
-			newBranchName := fmt.Sprintf("promotions/%v-%v-%v8", ghPrClientDetails.PrNumber, strings.Replace(ghPrClientDetails.Ref, "/", "-", -1), strings.Replace(strings.Join(promotion.Metadata.TargetPaths, "_"), "/", "-", -1)) // TODO max branch name length is 250 - make sure this fit
+			newBranchName := generateSafePromotionBranchName(ghPrClientDetails.PrNumber, ghPrClientDetails.Ref, promotion.Metadata.TargetPaths)
 
 			newBranchRef, err := createBranch(ghPrClientDetails, commit, newBranchName)
 			if err != nil {
@@ -414,6 +416,25 @@ func handleMergedPrEvent(ghPrClientDetails GhPrClientDetails, prApproverGithubCl
 	return nil
 }
 
+// Creating a unique branch name based on the PR number, PR ref and the promotion target paths
+// Max length of branch name is 250 characters
+func generateSafePromotionBranchName(prNumber int, originalBranchName string, targetPaths []string) string {
+	targetPathsBa := []byte(strings.Join(targetPaths, "_"))
+	hasher := sha1.New() //nolint:gosec // G505: Blocklisted import crypto/sha1: weak cryptographic primitive (gosec), this is not a cryptographic use case
+	hasher.Write(targetPathsBa)
+	uniqBranchNameSuffix := firstN(hex.EncodeToString(hasher.Sum(nil)), 12)
+	safeOriginalBranchName := firstN(strings.Replace(originalBranchName, "/", "-", -1), 200)
+	return fmt.Sprintf("promotions/%v-%v-%v", prNumber, safeOriginalBranchName, uniqBranchNameSuffix)
+}
+
+func firstN(str string, n int) string {
+	v := []rune(str)
+	if n >= len(v) {
+		return str
+	}
+	return string(v[:n])
+}
+
 func MergePr(details GhPrClientDetails, number *int) error {
 	operation := func() error {
 		err := tryMergePR(details, number)

internal/pkg/githubapi/github_test.go

@@ -0,0 +1,64 @@
+package githubapi
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestGenerateSafePromotionBranchName(t *testing.T) {
+	t.Parallel()
+	prNumber := 11
+	originBranch := "originBranch"
+	targetPaths := []string{"targetPath1", "targetPath2"}
+	result := generateSafePromotionBranchName(prNumber, originBranch, targetPaths)
+	expectedResult := "promotions/11-originBranch-676f02019f18"
+	if result != expectedResult {
+		t.Errorf("Expected %s, got %s", expectedResult, result)
+	}
+}
+
+// TestGenerateSafePromotionBranchNameLongBranchName tests the case where the original  branch name is longer than 250 characters
+func TestGenerateSafePromotionBranchNameLongBranchName(t *testing.T) {
+	t.Parallel()
+	prNumber := 11
+
+	originBranch := string(bytes.Repeat([]byte("originBranch"), 100))
+	targetPaths := []string{"targetPath1", "targetPath2"}
+	result := generateSafePromotionBranchName(prNumber, originBranch, targetPaths)
+	if len(result) > 250 {
+		t.Errorf("Expected branch name to be less than 250 characters, got %d", len(result))
+	}
+}
+
+// TestGenerateSafePromotionBranchNameLongTargets tests the case where the target paths are longer than 250 characters
+func TestGenerateSafePromotionBranchNameLongTargets(t *testing.T) {
+	t.Parallel()
+	prNumber := 11
+	originBranch := "originBranch"
+	targetPaths := []string{
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/1",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/2",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/3",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/4",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/5",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/6",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/7",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/8",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/9",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/10",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/11",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/12",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/13",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/14",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/15",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/16",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/17",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/18",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/19",
+		"loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong/target/path/20",
+	}
+	result := generateSafePromotionBranchName(prNumber, originBranch, targetPaths)
+	if len(result) > 250 {
+		t.Errorf("Expected branch name to be less than 250 characters, got %d", len(result))
+	}
+}