Multiplatform Kotlin library for working with the Mattermost API. It helps you build bots and integrations that can receive direct messages, detect new chats, and send messages back to channels/users.

• JVM – for server applications and Android
• JavaScript – for the browser and Node.js
• Wasm – for the browser and Node.js
• Native (Linux) – for native applications on Linux

• mattermost-client — core client with a simple high-level API.

Coordinates (published to Maven Central):

• Group: dev.limebeck.libs
• Artifact: mattermost-client
• Version: 1.0.0

Gradle Kotlin DSL (build.gradle.kts):

repositories {
    mavenCentral()
}

dependencies {
    implementation("dev.limebeck.libs:mattermost-client:1.0.0")
}

Gradle Groovy DSL (build.gradle):

repositories {
    mavenCentral()
}

dependencies {
    implementation 'dev.limebeck.libs:mattermost-client:1.0.0'
}

Maven (pom.xml):

<dependencies>
  <dependency>
    <groupId>dev.limebeck.libs</groupId>
    <artifactId>mattermost-client</artifactId>
    <version>1.0.0</version>
  </dependency>
</dependencies>

Note: This is a Kotlin Multiplatform library. Gradle will pick the right variant for your target (JVM, JS, Linux) automatically.

• Create a personal access token in your Mattermost server.
• Instantiate a client and send a message.

suspend fun main() {
    val baseUrl = "https://your.mattermost.server"
    val token = "MM_PERSONAL_ACCESS_TOKEN"
    val client = MattermostClientImpl(baseUrl, token)

    client.sendMessage(ChannelId("channel-id"), "Hello from Kotlin!")
}

Below is a real-world example that:

• Receive the incoming user request.
• Builds a message for an LLM.
• Sends the LLM response back to Mattermost, reporting token usage.

mattermostClient.receiveDirectMessages().collect { message ->
    logger.info("<173c4c43> Processing client request ${message.userName}")

    val response = gptClient.getCompletion(message.text)

    response.onSuccess { r ->
        mattermostClient.sendMessage(message.channelId, r.text)
    }.onFailure { t ->
        val requestUuid = Uuid.random().toString()
        logger.error("<ea88cf0c> An error occurred while processing the request $requestUuid", t)
        mattermostClient.sendMessage(
            message.channelId,
            "An error occurred while processing the request. Error code $requestUuid.\n${t.message}",
        )
    }
}

Notes:

• mattermostClient.sendMessage(ChannelId, String) is provided by this library.
• DirectMessage objects you receive from Mattermost include attachments with id, name, mimeType, and raw bytes (data).
• For long responses, consider splitting large Markdown into chunks before sending. This project already includes a helper splitMarkdown in mattermost-client/utils.

This project is distributed under the terms specified in the LICENCE file.