Add randomString template function

Signed-off-by: Knut Ahlers <knut@ahlers.me>

internal/template/random/random.go

@@ -12,10 +12,19 @@ import (
 )
 
 func Register(args plugins.RegistrationArguments) error {
+	args.RegisterTemplateFunction("randomString", plugins.GenericTemplateFunctionGetter(randomString))
 	args.RegisterTemplateFunction("seededRandom", plugins.GenericTemplateFunctionGetter(stableRandomFromSeed))
 	return nil
 }
 
+func randomString(lst ...string) (string, error) {
+	if len(lst) == 0 {
+		return "", errors.New("empty list given")
+	}
+
+	return lst[rand.Intn(len(lst))], nil
+}
+
 func stableRandomFromSeed(seed string) (float64, error) {
 	seedValue, err := stringToSeed(seed)
 	if err != nil {

wiki/Templating.md

@@ -251,6 +251,19 @@ Example:
 < 10000
 ```
 
+#### `randomString`
+
+Randomly picks a string from a list of strings
+
+Syntax: `randomString "a" [...]`
+
+Example:
+
+```
+# {{ randomString "a" "b" "c" "d" }}
+< a
+```
+
 #### `recentGame`
 
 Returns the last played game name of the specified user (see shoutout example) or the `fallback` if the game could not be fetched. If no fallback was supplied the message will fail and not be sent.