Include username in email headers (#28981)

Emails from Gitea comments do not contain the username of the commenter
anywhere, only their display name, so it is not possible to verify who
made a comment from the email itself:

	From: "Alice" <email@gitea>
	X-Gitea-Sender: Alice
	X-Gitea-Recipient: Bob
	X-GitHub-Sender: Alice
	X-GitHub-Recipient: Bob

	This comment looks like it's from @alice.

The X-Gitea/X-GitHub headers also use display names, which is not very
reliable for filtering, and inconsistent with GitHub's behavior:

	X-GitHub-Sender: lunny
	X-GitHub-Recipient: gwymor

This change includes both the display name and username in the From
header, and switches the other headers from display name to username:

	From: "Alice (@fakealice)" <email@gitea>
	X-Gitea-Sender: fakealice
	X-Gitea-Recipient: bob
	X-GitHub-Sender: fakealice
	X-GitHub-Recipient: bob

	This comment looks like it's from @alice.

1 files changed, 11 insertions, 0 deletions

diff --git a/models/user/user.go b/models/user/user.go
index 6d1b1aef18..269a1be725 100644
--- a/models/user/user.go
+++ b/models/user/user.go
@@ -443,6 +443,17 @@ func (u *User) GetDisplayName() string {
 	return u.Name
 }
 
+// GetCompleteName returns the the full name and username in the form of
+// "Full Name (@username)" if full name is not empty, otherwise it returns
+// "@username".
+func (u *User) GetCompleteName() string {
+	trimmedFullName := strings.TrimSpace(u.FullName)
+	if len(trimmedFullName) > 0 {
+		return fmt.Sprintf("%s (@%s)", trimmedFullName, u.Name)
+	}
+	return fmt.Sprintf("@%s", u.Name)
+}
+
 func gitSafeName(name string) string {
 	return strings.TrimSpace(strings.NewReplacer("\n", "", "<", "", ">", "").Replace(name))
 }