Use link in UI which returned a relative url but not html_url which contains an absolute url (#21986)

partially fix #19345

This PR add some `Link` methods for different objects. The `Link`
methods are not different from `HTMLURL`, they are lack of the absolute
URL. And most of UI `HTMLURL` have been replaced to `Link` so that users
can visit them from a different domain or IP.

This PR also introduces a new javascript configuration
`window.config.reqAppUrl` which is different from `appUrl` which is
still an absolute url but the domain has been replaced to the current
requested domain.

3 files changed, 63 insertions, 6 deletions

diff --git a/models/activities/action.go b/models/activities/action.go
index 4baedbfe12..8e7492c008 100644
--- a/models/activities/action.go
+++ b/models/activities/action.go
@@ -223,6 +223,49 @@ func (a *Action) GetRepoAbsoluteLink() string {
 	return setting.AppURL + url.PathEscape(a.GetRepoUserName()) + "/" + url.PathEscape(a.GetRepoName())
 }
 
+// GetCommentHTMLURL returns link to action comment.
+func (a *Action) GetCommentHTMLURL() string {
+	return a.getCommentHTMLURL(db.DefaultContext)
+}
+
+func (a *Action) loadComment(ctx context.Context) (err error) {
+	if a.CommentID == 0 || a.Comment != nil {
+		return nil
+	}
+	a.Comment, err = issues_model.GetCommentByID(ctx, a.CommentID)
+	return err
+}
+
+func (a *Action) getCommentHTMLURL(ctx context.Context) string {
+	if a == nil {
+		return "#"
+	}
+	_ = a.loadComment(ctx)
+	if a.Comment != nil {
+		return a.Comment.HTMLURL()
+	}
+	if len(a.GetIssueInfos()) == 0 {
+		return "#"
+	}
+	// Return link to issue
+	issueIDString := a.GetIssueInfos()[0]
+	issueID, err := strconv.ParseInt(issueIDString, 10, 64)
+	if err != nil {
+		return "#"
+	}
+
+	issue, err := issues_model.GetIssueByID(ctx, issueID)
+	if err != nil {
+		return "#"
+	}
+
+	if err = issue.LoadRepo(ctx); err != nil {
+		return "#"
+	}
+
+	return issue.HTMLURL()
+}
+
 // GetCommentLink returns link to action comment.
 func (a *Action) GetCommentLink() string {
 	return a.getCommentLink(db.DefaultContext)
@@ -232,11 +275,9 @@ func (a *Action) getCommentLink(ctx context.Context) string {
 	if a == nil {
 		return "#"
 	}
-	if a.Comment == nil && a.CommentID != 0 {
-		a.Comment, _ = issues_model.GetCommentByID(ctx, a.CommentID)
-	}
+	_ = a.loadComment(ctx)
 	if a.Comment != nil {
-		return a.Comment.HTMLURL()
+		return a.Comment.Link()
 	}
 	if len(a.GetIssueInfos()) == 0 {
 		return "#"
@@ -257,7 +298,7 @@ func (a *Action) getCommentLink(ctx context.Context) string {
 		return "#"
 	}
 
-	return issue.HTMLURL()
+	return issue.Link()
 }
 
 // GetBranch returns the action's repository branch.
diff --git a/models/activities/action_test.go b/models/activities/action_test.go
index 29312bd482..f37e58f685 100644
--- a/models/activities/action_test.go
+++ b/models/activities/action_test.go
@@ -36,7 +36,7 @@ func TestAction_GetRepoLink(t *testing.T) {
 	expected := path.Join(setting.AppSubURL, owner.Name, repo.Name)
 	assert.Equal(t, expected, action.GetRepoLink())
 	assert.Equal(t, repo.HTMLURL(), action.GetRepoAbsoluteLink())
-	assert.Equal(t, comment.HTMLURL(), action.GetCommentLink())
+	assert.Equal(t, comment.HTMLURL(), action.GetCommentHTMLURL())
 }
 
 func TestGetFeeds(t *testing.T) {
diff --git a/models/activities/notification.go b/models/activities/notification.go
index f153eb0589..75276a0443 100644
--- a/models/activities/notification.go
+++ b/models/activities/notification.go
@@ -459,6 +459,22 @@ func (n *Notification) HTMLURL() string {
 	return ""
 }
 
+// Link formats a relative URL-string to the notification
+func (n *Notification) Link() string {
+	switch n.Source {
+	case NotificationSourceIssue, NotificationSourcePullRequest:
+		if n.Comment != nil {
+			return n.Comment.Link()
+		}
+		return n.Issue.Link()
+	case NotificationSourceCommit:
+		return n.Repository.Link() + "/commit/" + url.PathEscape(n.CommitID)
+	case NotificationSourceRepository:
+		return n.Repository.Link()
+	}
+	return ""
+}
+
 // APIURL formats a URL-string to the notification
 func (n *Notification) APIURL() string {
 	return setting.AppURL + "api/v1/notifications/threads/" + strconv.FormatInt(n.ID, 10)