1 files changed, 214 insertions, 0 deletions
diff --git a/modules/git/ref.go b/modules/git/ref.go
new file mode 100644
index 00000000..2db630e2
--- /dev/null
+++ b/modules/git/ref.go
@@ -0,0 +1,214 @@
+// Copyright 2018 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package git
+
+import (
+	"regexp"
+	"strings"
+
+	"code.gitea.io/gitea/modules/util"
+)
+
+const (
+	// RemotePrefix is the base directory of the remotes information of git.
+	RemotePrefix = "refs/remotes/"
+	// PullPrefix is the base directory of the pull information of git.
+	PullPrefix = "refs/pull/"
+)
+
+// refNamePatternInvalid is regular expression with unallowed characters in git reference name
+// They cannot have ASCII control characters (i.e. bytes whose values are lower than \040, or \177 DEL), space, tilde ~, caret ^, or colon : anywhere.
+// They cannot have question-mark ?, asterisk *, or open bracket [ anywhere
+var refNamePatternInvalid = regexp.MustCompile(
+	`[\000-\037\177 \\~^:?*[]|` + // No absolutely invalid characters
+		`(?:^[/.])|` + // Not HasPrefix("/") or "."
+		`(?:/\.)|` + // no "/."
+		`(?:\.lock$)|(?:\.lock/)|` + // No ".lock/"" or ".lock" at the end
+		`(?:\.\.)|` + // no ".." anywhere
+		`(?://)|` + // no "//" anywhere
+		`(?:@{)|` + // no "@{"
+		`(?:[/.]$)|` + // no terminal '/' or '.'
+		`(?:^@$)`) // Not "@"
+
+// IsValidRefPattern ensures that the provided string could be a valid reference
+func IsValidRefPattern(name string) bool {
+	return !refNamePatternInvalid.MatchString(name)
+}
+
+func SanitizeRefPattern(name string) string {
+	return refNamePatternInvalid.ReplaceAllString(name, "_")
+}
+
+// Reference represents a Git ref.
+type Reference struct {
+	Name   string
+	repo   *Repository
+	Object ObjectID // The id of this commit object
+	Type   string
+}
+
+// Commit return the commit of the reference
+func (ref *Reference) Commit() (*Commit, error) {
+	return ref.repo.getCommit(ref.Object)
+}
+
+// ShortName returns the short name of the reference
+func (ref *Reference) ShortName() string {
+	return RefName(ref.Name).ShortName()
+}
+
+// RefGroup returns the group type of the reference
+func (ref *Reference) RefGroup() string {
+	return RefName(ref.Name).RefGroup()
+}
+
+// ForPrefix special ref to create a pull request: refs/for/<target-branch>/<topic-branch>
+// or refs/for/<targe-branch> -o topic='<topic-branch>'
+const ForPrefix = "refs/for/"
+
+// TODO: /refs/for-review for suggest change interface
+
+// RefName represents a full git reference name
+type RefName string
+
+func RefNameFromBranch(shortName string) RefName {
+	return RefName(BranchPrefix + shortName)
+}
+
+func RefNameFromTag(shortName string) RefName {
+	return RefName(TagPrefix + shortName)
+}
+
+func (ref RefName) String() string {
+	return string(ref)
+}
+
+func (ref RefName) IsBranch() bool {
+	return strings.HasPrefix(string(ref), BranchPrefix)
+}
+
+func (ref RefName) IsTag() bool {
+	return strings.HasPrefix(string(ref), TagPrefix)
+}
+
+func (ref RefName) IsRemote() bool {
+	return strings.HasPrefix(string(ref), RemotePrefix)
+}
+
+func (ref RefName) IsPull() bool {
+	return strings.HasPrefix(string(ref), PullPrefix) && strings.IndexByte(string(ref)[len(PullPrefix):], '/') > -1
+}
+
+func (ref RefName) IsFor() bool {
+	return strings.HasPrefix(string(ref), ForPrefix)
+}
+
+func (ref RefName) nameWithoutPrefix(prefix string) string {
+	if strings.HasPrefix(string(ref), prefix) {
+		return strings.TrimPrefix(string(ref), prefix)
+	}
+	return ""
+}
+
+// TagName returns simple tag name if it's an operation to a tag
+func (ref RefName) TagName() string {
+	return ref.nameWithoutPrefix(TagPrefix)
+}
+
+// BranchName returns simple branch name if it's an operation to branch
+func (ref RefName) BranchName() string {
+	return ref.nameWithoutPrefix(BranchPrefix)
+}
+
+// PullName returns the pull request name part of refs like refs/pull/<pull_name>/head
+func (ref RefName) PullName() string {
+	refName := string(ref)
+	lastIdx := strings.LastIndexByte(refName[len(PullPrefix):], '/')
+	if strings.HasPrefix(refName, PullPrefix) && lastIdx > -1 {
+		return refName[len(PullPrefix) : lastIdx+len(PullPrefix)]
+	}
+	return ""
+}
+
+// ForBranchName returns the branch name part of refs like refs/for/<branch_name>
+func (ref RefName) ForBranchName() string {
+	return ref.nameWithoutPrefix(ForPrefix)
+}
+
+func (ref RefName) RemoteName() string {
+	return ref.nameWithoutPrefix(RemotePrefix)
+}
+
+// ShortName returns the short name of the reference name
+func (ref RefName) ShortName() string {
+	refName := string(ref)
+	if ref.IsBranch() {
+		return ref.BranchName()
+	}
+	if ref.IsTag() {
+		return ref.TagName()
+	}
+	if ref.IsRemote() {
+		return ref.RemoteName()
+	}
+	if ref.IsPull() {
+		return ref.PullName()
+	}
+	if ref.IsFor() {
+		return ref.ForBranchName()
+	}
+
+	return refName
+}
+
+// RefGroup returns the group type of the reference
+// Using the name of the directory under .git/refs
+func (ref RefName) RefGroup() string {
+	if ref.IsBranch() {
+		return "heads"
+	}
+	if ref.IsTag() {
+		return "tags"
+	}
+	if ref.IsRemote() {
+		return "remotes"
+	}
+	if ref.IsPull() {
+		return "pull"
+	}
+	if ref.IsFor() {
+		return "for"
+	}
+	return ""
+}
+
+// RefType returns the simple ref type of the reference, e.g. branch, tag
+// It's different from RefGroup, which is using the name of the directory under .git/refs
+// Here we using branch but not heads, using tag but not tags
+func (ref RefName) RefType() string {
+	var refType string
+	if ref.IsBranch() {
+		refType = "branch"
+	} else if ref.IsTag() {
+		refType = "tag"
+	}
+	return refType
+}
+
+// RefURL returns the absolute URL for a ref in a repository
+func RefURL(repoURL, ref string) string {
+	refFullName := RefName(ref)
+	refName := util.PathEscapeSegments(refFullName.ShortName())
+	switch {
+	case refFullName.IsBranch():
+		return repoURL + "/src/branch/" + refName
+	case refFullName.IsTag():
+		return repoURL + "/src/tag/" + refName
+	case !Sha1ObjectFormat.IsValid(ref):
+		// assume they mean a branch
+		return repoURL + "/src/branch/" + refName
+	default:
+		return repoURL + "/src/commit/" + refName
+	}
+}