Function post

src/OpenLoco/src/MessageManager.cpp:45–437

    void setActiveIndex(const MessageId newIndex) { getGameState().activeMessageIndex = newIndex; }

    void post(
        MessageType type,
        CompanyId companyId,
        uint16_t subjectIdA,
        uint16_t subjectIdB,
        uint16_t subjectIdC)
    {
        Message newMessage{};
        newMessage.companyId = companyId;
        newMessage.type = type;
        newMessage.date = getCurrentDay();
        newMessage.itemSubjects[0] = subjectIdA;
        newMessage.itemSubjects[1] = subjectIdB;
        newMessage.itemSubjects[2] = subjectIdC;

        // Don't add the message if a seemingly identical message is present
        // Note that Message::operator== isn't quite structural equality, company id is ignored
        if (getMessageTypeDescriptor(type).hasFlag(MessageTypeFlags::shouldDedup))
        {
            for (auto i = 0; i < getNumMessages(); ++i)
            {
                auto& message = rawMessages()[i];
                if (message == newMessage)
                {
                    return;
                }
            }
        }

        if (getNumMessages() >= Limits::kMaxMessages)
        {
            MessageId oldestMessage = MessageId::null;
            int32_t oldest = -1;
            for (auto i = 0; i < getNumMessages(); ++i)
            {
                auto& message = rawMessages()[i];
                if (message.timeActive != 0)
                {
                    const int32_t age = getMessageTypeDescriptor(message.type).duration + message.date - getCurrentDay();
                    if (age > oldest)
                    {
                        oldest = age;
                        oldestMessage = static_cast<MessageId>(i);
                    }
                }
            }
            // Nothing found so now search for messages that are active
            if (oldest == -1)
            {
                for (auto i = 0; i < getNumMessages(); ++i)
                {
                    auto& message = rawMessages()[i];

                    const int32_t age = getMessageTypeDescriptor(message.type).duration + message.date - getCurrentDay();
                    if (age > oldest)
                    {
                        oldest = age;
                        oldestMessage = static_cast<MessageId>(i);