[feature] Add List functionality (#1802)

* start working on lists

* further list work

* test list db functions nicely

* more work on lists

* peepoopeepoo

* poke

* start list timeline func

* we're getting there lads

* couldn't be me working on stuff... could it?

* hook up handlers

* fiddling

* weeee

* woah

* screaming, pissing

* fix streaming being a whiny baby

* lint, small test fix, swagger

* tidying up, testing

* fucked! by the linter

* move timelines to state like a boss

* add timeline start to tests using state

* invalidate lists

internal/validate/formvalidation.go

@@ -45,6 +45,7 @@ const (
 	maximumEmojiCategoryLength    = 64
 	maximumProfileFieldLength     = 255
 	maximumProfileFields          = 6
+	maximumListTitleLength        = 200
 )
 
 // NewPassword returns an error if the given password is not sufficiently strong, or nil if it's ok.
@@ -257,3 +258,28 @@ func ProfileFields(fields []*gtsmodel.Field) error {
 
 	return nil
 }
+
+// ListTitle validates the title of a new or updated List.
+func ListTitle(title string) error {
+	if title == "" {
+		return fmt.Errorf("list title must be provided, and must be no more than %d chars", maximumListTitleLength)
+	}
+
+	if length := len([]rune(title)); length > maximumListTitleLength {
+		return fmt.Errorf("list title length must be no more than %d chars, provided title was %d chars", maximumListTitleLength, length)
+	}
+
+	return nil
+}
+
+// ListRepliesPolicy validates the replies_policy of a new or updated list.
+func ListRepliesPolicy(repliesPolicy gtsmodel.RepliesPolicy) error {
+	switch repliesPolicy {
+	case "", gtsmodel.RepliesPolicyFollowed, gtsmodel.RepliesPolicyList, gtsmodel.RepliesPolicyNone:
+		// No problem.
+		return nil
+	default:
+		// Uh oh.
+		return fmt.Errorf("list replies_policy must be either empty or one of 'followed', 'list', 'none'")
+	}
+}