wifi() {
    local interface=wlan0;
    local dir="/etc/network/interfaces.d";
    local symlink="${dir}/${interface}";

    export WIFI_DEFAULT_NETWORK="${WIFI_DEFAULT_NETWORK:-tiny-bronco}";
    export WIFI_NETWORK_PATH="${WIFI_NETWORK_PATH:-$HOME/.network.wlan0}";

    local current="$(cat "$WIFI_NETWORK_PATH")";

    case "$1" in
        connect|on|up)
            sudo /sbin/ifup "$interface";
            ;;
        disconnect|down|off)
            sudo /sbin/ifdown "$interface";
            ;;
        goto|switch|use)
            local network="${2:-WIFI_DEFAULT_NETWORK}";
            local path="${dir}/${network}.${interface}";

            sudo ln -fs "$path" "$symlink" || return 1;

            if [[ $network != $current ]]; then
                echo "Changing to $network.";
                echo -n "$network" > "$WIFI_NETWORK_PATH";
                wifi off;
                wifi on;
            fi;
            ;;
        list|ls)
            sudo ls "${dir}/" | sed -e 's/\.wlan0\b//g';
            ;;
        query|which)
            echo "$current";
            ;;
        re|restart|reup)
            wifi off && wifi on;
            ;;
        st|status)
            /sbin/ifconfig "$interface";
            ;;
        *|'?'|help)
            cat <<USAGE | "${PAGER:-less}";
wifi [SUBCOMMAND] [ARG...]

Subcommands:

    connect (alias: on, up)

        Args: none.

        Attempt to connect the wireless interface using
        the selected configuration.

    disconnect (alias: down, off)

        Args: none.

        Attempt to disconnect the wireless interface.

    goto (alias: switch, use)

        Args: configuration file name (excluding the extension).

        Change the selected configuration. Configurations
        must already exist within the configuration
        directory ($dir).

        If the configuration is changed then we
        automatically attempt to disconnect from an
        existing interface and connect using the new
        configuration.

    help (alias: ?) (default)

        Args: none.

        Print this message to the pager (default pager:
        less).

    list (alias: ls)

        Args: none.

        List available configurations.

    query (alias: which)

        Args: none.

        Print the name of the currently selected
        configuration (if known).

    restart (alias: re, reup)

        Args: none.

        Disconnect and connect.

    status (alias: st)

        Args: none.

        Print the ifconfig(1) of the network interface.
        The format is not defined by this command. It is a
        simple shell-out (as are most commands).
USAGE
            ;;
    esac;
};