Global code ovehaul - remove CAS and other, add 15 minute greet check

- Remove CAS, as it no longer works for us
- Remove other checks
- Implement 15 minute greet timeout check
- Fix chat logos
- Ditch thirdparty logger, use stdlib log facility wrapper for logging

internal/moon/retractGreeting.go

@@ -0,0 +1,119 @@
+package moon
+
+import (
+	"bunny-bot/internal/elog"
+	"bunny-bot/internal/mylog"
+
+	"github.com/NicoNex/echotron/v3"
+)
+
+// retractGreetings deletes the greetings we sent to a member who has just been
+// banned for never answering them, so the room is not left asking a question of
+// someone who no longer has access.
+//
+// Ids <= 0 mean "no greeting was ever sent for that join" and are skipped
+// silently. A deletion Telegram refuses is logged and the pass continues: the
+// greeting is not worth abandoning the rest over, and a failed retraction never
+// changes the ban that has already landed.
+func retractGreetings(chat *echotron.Chat, user *echotron.User, greetingIDs []int) retractOutcome {
+	retracted, failed := 0, 0
+
+	for _, id := range greetingIDs {
+		if id <= 0 {
+			continue
+		}
+
+		if _, err := Tg.DeleteMessage(chat.ID, id); err != nil {
+			failed++
+
+			reportRetractFailure(chat, user, id, err)
+
+			continue
+		}
+
+		retracted++
+
+		elog.LogGreetingRetracted(chat, user, id)
+	}
+
+	return retractOutcomeFor(retracted, failed)
+}
+
+// reportRetractFailure logs a refused deletion. It is a WARN rather than an ERROR
+// because the ban it followed already succeeded and nothing depends on the
+// greeting being gone.
+func reportRetractFailure(chat *echotron.Chat, user *echotron.User, id int, err error) {
+	mylog.Warnf(
+		"Left an unanswered greeting in place: cannot delete message %d in chat %d for user %d: %s",
+		id,
+		chat.ID,
+		userIDOf(user),
+		err,
+	)
+}
+
+// retractAskedGreetings takes down the questions this member was asked and never
+// answered. One id per recorded join, so a member who joined twice had two
+// greetings and both go.
+func retractAskedGreetings(refs []joinRef) {
+	ids := make([]int, 0, len(refs))
+	for _, ref := range refs {
+		ids = append(ids, ref.greetingID)
+	}
+
+	chat, user := refs[0].chat, refs[0].user
+
+	switch retractGreetings(&chat, user, ids) {
+	case greetingRetracted:
+		mylog.Debugf(
+			"Deleted %d unanswered greeting(s) asked of user %d in chat %d",
+			countNamedGreetings(ids),
+			user.ID,
+			chat.ID,
+		)
+	case greetingRetractFailed:
+		mylog.Warnf(
+			"Banned user %d in chat %d, but could not delete every greeting we asked them",
+			user.ID,
+			chat.ID,
+		)
+	case nothingToRetract:
+	}
+}
+
+// countNamedGreetings counts the ids that actually named a message; the rest
+// mean no greeting was ever delivered.
+func countNamedGreetings(ids []int) int {
+	n := 0
+
+	for _, id := range ids {
+		if id > 0 {
+			n++
+		}
+	}
+
+	return n
+}
+
+// retractOutcomeFor collapses the two counts into the single value callers act on.
+func retractOutcomeFor(retracted int, failed int) retractOutcome {
+	switch {
+	case retracted > 0 && failed == 0:
+		return greetingRetracted
+	case failed > 0:
+		return greetingRetractFailed
+	default:
+		return nothingToRetract
+	}
+}
+
+// userIDOf names a user in a log line without dereferencing a possibly nil one.
+func userIDOf(user *echotron.User) int64 {
+	if user == nil {
+		return 0
+	}
+
+	return user.ID
+}
+
+/* vim: set ft=go noet ai ts=4 sw=4 sts=4: */