#! /bin/sh

usage() {
    echo "EXAMPLE (whole tree)   : $0 | neato -T png > ps.png && open ps.png"
    echo "EXAMPLE (user clusters): $0 | sdp   -T png > ps.png && open ps.png"
}


compile() {
    awk -v kernel="$(uname -v)" -v whoami="$(whoami)" \
    '
        BEGIN {
            p2cmd[0] = "swapper/sched"
            color_base = 20
            color_incr = 30
            color_hi  = sprintf("grey%d", (color_base + (color_incr * 0)))
            color_mid = sprintf("grey%d", (color_base + (color_incr * 1)))
            color_low = sprintf("grey%d", (color_base + (color_incr * 2)))
        }

        NR > 1 {
            p2pp[$1]=$2;
            p2user_id[$1]=$3
            p2user_name[$1]=$4
            p2cmd[$1]=$5
            user_names[$4]=1
        }

        END {
            print "strict digraph G {";

            print "start=0;";
            print "colorscheme=brewer;";
            print "fontsize=8;";
            print "fontname=Helvetica;";
            print "label=\"" kernel "\";";

            printf(\
                "edge [ fontsize=8 \
                      , fontname=Helvetica \
                      , len=2.0 \
                      , color=%s \
                      ];",
                color_low\
            )

            print "node [ fontsize=8 \
                        , fontname=Helvetica \
                        , shape=ellipse \
                        ]; \
                    ";

            ##### Vertices (clustered by user)
            for (user in user_names) {
                printf "subgraph \"cluster_%s\" {\n", user
                printf "label=\"%s\"\n", user
                for (p in p2pp) {
                    if (p2user_name[p] == user) {
                        color     = p2user_name[p] == whoami ? color_hi : color_low
                        fontcolor = p2user_name[p] == whoami ? color_hi : color_mid
                        printf(\
                            "\"%d\"\
                            [ fontsize=8 \
                            , fontname=Helvetica \
                            , shape=ellipse \
                            , label=\"%s\n%d\" \
                            , color=\"%s\" \
                            , fontcolor=\"%s\" \
                            ];",
                            p,
                            p2cmd[p],
                            p,
                            color,
                            fontcolor\
                        )
                    }
                }
                print "}"
            }

            ##### Vertices (without a user)
            for (p in p2cmd) {
                if (!p2user_name[p]) {
                    printf(\
                        "\"%d\"\
                        [ fontsize=8 \
                        , fontname=Helvetica \
                        , shape=ellipse \
                        , label=\"%s\n%d\" \
                        , color=\"%s\" \
                        , fontcolor=\"%s\" \
                        ];",
                        p,
                        p2cmd[p],
                        p,
                        color_low,
                        color_mid\
                    )
                }
            }

            ##### Edges (across clusters)
            for (p in p2pp) {
                printf "\"%d\" -> \"%d\";\n",  p2pp[p], p, p
            }

            print "}";
        }
    '
}


procs() {
    if [ "$(uname)" = 'Linux' ]; then
        ps -eo pid,ppid,euid,euser,comm
    else
        ps -eco pid,ppid,euid,euser,comm
    fi
}


main() {
    case "$1" in
        '--help') usage
        ;;
        *) procs | grep "$1" | compile
        ;;
    esac
}


main "$1"