added twitch draw command

config.yaml

@@ -43,6 +43,8 @@ event:
   twitch_giveaway:
     # The amount of points a single giveaway ticket costs.
     ticket_cost: 1000
+    # the filepath for of the json giveaway prizes
+    prizes: twitch/prizes.json
 
 webserver:
   favicon: webserver/favicon.png

data/lang/de.yaml

@@ -147,4 +147,9 @@ twitch.command:
 
   join:
     msg.too_few_points: "@%s du nicht genügend Punkte(%d)! Du brauchst noch %d mehr um den Preis von %d zu bezahlen." 
-    msg.success: "@%s Du hast dir erfolgreich ein Ticket für %d Punkte gekauft. Du hast nun %d Tickets und noch %d Punkte über."
+    msg.success: "@%s du hast dir erfolgreich ein Ticket für %d Punkte gekauft. Du hast nun %d Tickets und noch %d Punkte über."
+
+  draw:
+    msg.no_prizes: "@%s es gibt momentan keine Preise zu gewinnen. Du kannst diesen Befehl momentan nicht ausführen."
+    msg.no_entries: "@%s es gibt momentan keine Einträge und somit kann kein Gewinner gezogen werden."
+    msg.winner: Glückwunsch! @%s hat %s gewonnen. Du hattest %d/10 Tickets und eine Gewinnchance von %.2f%%.

data/lang/en.yaml

@@ -147,4 +147,9 @@ twitch.command:
 
   join:
     msg.too_few_points: "@%s you don't have enough points (%d)! You need %d more to pay the costs of %d points." 
-    msg.success: "@%s You successfully bought a ticket for %d points. Now you have %d tickets and still %d points."
+    msg.success: "@%s you successfully bought a ticket for %d points. Now you have %d tickets and still %d points."
+
+  draw:
+    msg.no_prizes: "@%s There're currently no prizes available. You can't perfrom this command now."
+    msg.no_entries: "@%s There're currently no entries and therefore no winner can be drawn."
+    msg.winner: Congratulations! @%s won %s. You had %d/10 tickets and a win probability of %.2f%%.

database/giveaway.go

@@ -90,6 +90,19 @@ func GetGiveawayEntry(prefix, userID string) GiveawayEntry {
 	return GiveawayEntry{userID, weight, lastEntry}
 }
 
+// DeleteGiveawayEntry deletes the giveaway entry for the given user identifier from the database.
+//
+// If an error occours it will be returned. However if no datbase entry matched it returns err ==
+// nil, not err == sql.ErrNoRows. Because sql.ErrNoRows also results in the non-existence of the
+// requested row and therefore is treated as a successful call.
+func DeleteGiveawayEntry(userID string) error {
+	_, err := Exec("DELETE FROM giveaway WHERE id=?", userID)
+	if err == sql.ErrNoRows {
+		return nil
+	}
+	return err
+}
+
 // AddGiveawayWeight adds amount to the given user identifier.
 //
 // However if their last entry wasn't prefixed with prefix, their weight will be resetted and starts
@@ -182,6 +195,11 @@ func GetAllGiveawayEntries(prefix string) []GiveawayEntry {
 // DrawGiveawayWinner takes one of the given entries and draw one winner of them. The probability
 // is based on their Weight value. A higher Weight means a higher probability.
 func DrawGiveawayWinner(e []GiveawayEntry) (winner GiveawayEntry, totalTickets int) {
+	// skip randomizing when there is only one entry
+	if len(e) == 1 {
+		return e[0], e[0].Weight
+	}
+
 	var entries []GiveawayEntry
 	for _, e := range e {
 		for i := 0; i < e.Weight; i++ {

main.go

@@ -95,6 +95,7 @@ func main() {
 
 	client := twitchgo.New(viper.GetString("twitch.name"), viper.GetString("twitch.token"))
 	client.OnChannelCommandMessage("join", twitch.HandleCmdJoin)
+	client.OnChannelCommandMessage("draw", twitch.HandleCmdDraw)
 	client.OnChannelMessage(twitch.MessageHandler)
 	err = client.Connect()
 	if err != nil {

twitch/messageHandler.go

@@ -25,7 +25,7 @@ import (
 	"github.com/spf13/viper"
 )
 
-const tp string = "twitch.command.join."
+const tp string = "twitch.command."
 
 var log logger.Logger = *logger.New(logger.Writer(), "[Twitch] ", logger.LstdFlags|logger.Lmsgprefix)
 var se *streamelements.Streamelements
@@ -40,6 +40,8 @@ func MessageHandler(t *twitchgo.Twitch, channel string, user *twitchgo.User, mes
 // and removes the configured cost amount for a ticket.
 func HandleCmdJoin(t *twitchgo.Twitch, channel string, user *twitchgo.User, args []string) {
 	channel, _ = strings.CutPrefix(channel, "#")
+	const tp = tp + "join."
+
 	log.Printf("[%s@%s] executed join command with %d args: %v", user.Nickname, channel, len(args), args)
 	seChannel, err := se.GetChannel(channel)
 	if err != nil {
@@ -73,3 +75,50 @@ func HandleCmdJoin(t *twitchgo.Twitch, channel string, user *twitchgo.User, args
 	}
 	t.SendMessagef(channel, lang.GetDefault(tp+"msg.success"), user.Nickname, joinCost, entry.Weight, sePoints.Points-joinCost)
 }
+
+// HandleCmdDraw is the handler for the draw command in a twitch chat. This handler selects a random
+// winner and removes their tickets.
+func HandleCmdDraw(t *twitchgo.Twitch, channel string, user *twitchgo.User, args []string) {
+	channel, _ = strings.CutPrefix(channel, "#")
+	const tp = tp + "draw."
+
+	//only accept broadcaster
+	if channel != user.Nickname {
+		return
+	}
+
+	p, err := database.NewGiveawayPrize(viper.GetString("event.twitch_giveaway.prizes"))
+	if err != nil {
+		log.Printf("Error reading prizes file: %v", err)
+		t.SendMessagef(channel, lang.GetDefault("twitch.command.generic.error"))
+		return
+	}
+	prize, ok := p.GetNextPrize()
+	if !ok {
+		t.SendMessagef(channel, lang.GetDefault(tp+"msg.no_prizes"), user.Nickname)
+		return
+	}
+
+	winner, totalTickets := database.DrawGiveawayWinner(database.GetAllGiveawayEntries("tw11"))
+	if totalTickets == 0 {
+		t.SendMessagef(channel, lang.GetDefault(tp+"msg.no_entries"), user.Nickname)
+		return
+	}
+
+	t.SendMessagef(channel, lang.GetDefault(tp+"msg.winner"), winner.UserID, prize.Name, winner.Weight, float64(winner.Weight*100)/float64(totalTickets))
+
+	err = database.DeleteGiveawayEntry(winner.UserID)
+	if err != nil {
+		log.Printf("Error deleting database giveaway entry: %v", err)
+		t.SendMessagef(channel, lang.GetDefault("twitch.command.generic.error"))
+		return
+	}
+
+	prize.Winner = winner.UserID
+	err = p.SaveFile()
+	if err != nil {
+		log.Printf("Error saving prizes file: %v", err)
+		t.SendMessagef(channel, lang.GetDefault("twitch.command.generic.error"))
+		return
+	}
+}