#!/usr/bin/env bash
# nbd-swap: High-speed RAM swap over network (10.0.0.15 bazina -> 10.0.0.18 t520)
set -euo pipefail

SERVER="10.0.0.15"
PORT="10809"
EXPORT="t520_swap"
DEV="/dev/nbd0"

status() {
    echo "=== NBD Network Swap Status ==="
    if swapon --show | grep -q "$DEV"; then
        echo "Swap active on $DEV:"
        swapon --show | grep "$DEV"
    else
        echo "Swap is NOT active on $DEV."
    fi
    if [ -b "$DEV" ] && lsblk "$DEV" | grep -q "$DEV"; then
        lsblk "$DEV"
    fi
}

start() {
    sudo modprobe nbd
    if swapon --show | grep -q "$DEV"; then
        echo "Swap already active on $DEV."
        exit 0
    fi
    # If device is connected, disconnect first
    if lsblk "$DEV" 2>/dev/null | grep -q "nbd0"; then
        sudo nbd-client -d "$DEV" 2>/dev/null || true
        sleep 1
    fi
    echo "Connecting $DEV to $SERVER:$PORT ($EXPORT)..."
    sudo nbd-client "$SERVER" "$PORT" -N "$EXPORT" "$DEV"
    echo "Initializing and activating swap on $DEV (priority 100)..."
    sudo mkswap "$DEV" >/dev/null
    sudo swapon -p 100 "$DEV"
    status
}

stop() {
    echo "Deactivating swap on $DEV..."
    if swapon --show | grep -q "$DEV"; then
        sudo swapoff "$DEV"
    fi
    if lsblk "$DEV" 2>/dev/null | grep -q "nbd0"; then
        echo "Disconnecting NBD client..."
        sudo nbd-client -d "$DEV"
    fi
    echo "NBD swap stopped."
}

case "${1:-status}" in
    start) start ;;
    stop) stop ;;
    status) status ;;
    restart) stop; sleep 1; start ;;
    *) echo "Usage: $0 {start|stop|restart|status}" ; exit 1 ;;
esac