jami-docs/developer/going-further/message-displayed-status.md

Message displayed status
========================

Every client generally must be able to show what peer read what message and get how many unread messages there is.

For this, the daemon provides some APIs:

## Set a message displayed

The Configuration manager provides:

```
<method name="setMessageDisplayed" tp:name-for-bindings="setMessageDisplayed">
    <tp:added version="8.1.0"/>
    <tp:docstring>
        <p>Informs that a message have been read</p>
    </tp:docstring>
    <arg type="s" name="accountId" direction="in">
        <tp:docstring>
        The account ID
        </tp:docstring>
    </arg>
    <arg type="s" name="conversationUri" direction="in">
        <tp:docstring>
        A conversation uri (swarm:xxxx or jami:xxxx)
        </tp:docstring>
    </arg>
    <arg type="s" name="messageId" direction="in">
        <tp:docstring>
        The message ID
        </tp:docstring>
    </arg>
    <arg type="i" name="status" direction="in">
        <tp:docstring>
        The message status, 3 for displayed
        </tp:docstring>
    </arg>
    <arg type="b" name="success" direction="out">
        <tp:docstring>
        True if the message status was set, false if account, contact or message is unknown.
        </tp:docstring>
    </arg>
</method>
```

to set a message as displayed. Should be done when the interaction is shown and the conversation selected.

This sends a SIP messages to connected peers with the following format:

```cpp
std::string
getDisplayed(const std::string& conversationId, const std::string& messageId)
{
    // implementing https://tools.ietf.org/rfc/rfc5438.txt
    return fmt::format(
        "<?xml version=\"1.0\" encoding=\"utf-8\" ?>\n"
        "<imdn><message-id>{}</message-id>\n"
        "{}"
        "<display-notification><status><displayed/></status></display-notification>\n"
        "</imdn>",
        messageId,
        conversationId.empty() ? "" : "<conversation>" + conversationId + "</conversation>");
}
```

Then the peer will know this via `onMessageDisplayed` and emit a signal to the client (`libjami::ConfigurationSignal::AccountMessageStatusChanged` with status 3 (`libjami::Account::MessageStates::DISPLAYED`))

## Get unread messages

By knowing the lastDisplayedMessage for our account, we can use this informations and `ConfigrationManager::countInteractionsSince` which count interaction since last message to a given message (typically last displayed interaction)

To get last displayed message for a member, in `Configuration::getConversationMembers` each member will have the last displayed interaction available via `memberInfo["lastDisplayed"]`

## How this information is stored

In `src/jamidht/conversation.cpp` each conversation store the last displayed messages in a map<string, string> (uri, interactionId) and this structure is serialized in `fileutils::get_data_dir()/getAccountID()/conversation_data/repository_->id()/lastDisplayed`