digraph SlackVein {
    rankdir=LR;
    compound=true;
    fontname="Helvetica";
    node [fontname="Helvetica", fontsize=11, shape=box, style="rounded,filled"];
    edge [fontname="Helvetica", fontsize=10];

    labelloc="t";
    label="Slack Vein - API Flow";
    fontsize=16;

    // Client
    subgraph cluster_client {
        label="Soleprint";
        style=filled;
        color="#E8F5E9";
        fillcolor="#E8F5E9";

        app [label="Application", fillcolor="#C8E6C9"];
        vein [label="Slack Vein\n(artery/veins/slack)", fillcolor="#A5D6A7"];
    }

    // Auth
    subgraph cluster_auth {
        label="Authentication";
        style=filled;
        color="#FFF8E1";
        fillcolor="#FFF8E1";

        token [label="Bot Token\n(Bearer)", fillcolor="#FFECB3"];
    }

    // Slack API
    subgraph cluster_slack {
        label="Slack API";
        style=filled;
        color="#E3F2FD";
        fillcolor="#E3F2FD";

        chat [label="chat.postMessage", fillcolor="#BBDEFB"];
        channels [label="conversations.list", fillcolor="#BBDEFB"];
        users [label="users.list", fillcolor="#BBDEFB"];
        files [label="files.upload", fillcolor="#BBDEFB"];
    }

    // Webhooks
    subgraph cluster_webhooks {
        label="Incoming";
        style=dashed;
        color=gray;

        webhook [label="Webhook URL", fillcolor="#F5F5F5"];
    }

    // Flow
    app -> vein [label="send_message()"];
    vein -> token [label="auth"];
    token -> chat [label="POST"];
    token -> channels [label="GET"];
    token -> users [label="GET"];
    token -> files [label="POST"];

    vein -> webhook [label="simple post", style=dashed];
}