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

    labelloc="t";
    label="Google Vein - OAuth Flow";
    fontsize=16;

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

        app [label="Application", fillcolor="#C8E6C9"];
        vein [label="Google Vein\n(artery/veins/google)", fillcolor="#A5D6A7"];
        oauth [label="OAuth Handler\n(artery/oauth.py)", fillcolor="#81C784"];
    }

    // OAuth Flow
    subgraph cluster_oauth {
        label="OAuth 2.0";
        style=filled;
        color="#FFF8E1";
        fillcolor="#FFF8E1";

        auth_url [label="1. Authorization URL", fillcolor="#FFECB3"];
        consent [label="2. User Consent", fillcolor="#FFE082"];
        callback [label="3. Callback + Code", fillcolor="#FFD54F"];
        tokens [label="4. Access + Refresh\nTokens", fillcolor="#FFCA28"];
    }

    // Google APIs
    subgraph cluster_google {
        label="Google APIs";
        style=filled;
        color="#E3F2FD";
        fillcolor="#E3F2FD";

        sheets [label="Sheets API", fillcolor="#BBDEFB"];
        calendar [label="Calendar API", fillcolor="#BBDEFB"];
        drive [label="Drive API", fillcolor="#BBDEFB"];
    }

    // Flow
    app -> vein [label="get_sheets()"];
    vein -> oauth [label="ensure_auth"];
    oauth -> auth_url;
    auth_url -> consent;
    consent -> callback;
    callback -> tokens;
    tokens -> oauth [label="store"];

    oauth -> sheets [label="Bearer token"];
    oauth -> calendar [label="Bearer token"];
    oauth -> drive [label="Bearer token"];
}