#!/bin/bash

set -e

echo "=== Checking Prerequisites ==="

# Check if running as root
if [ "$(id -u)" -ne 0 ]; then
    echo "Error: This script must be run as root."
    exit 1
fi
echo "✔ Running as root."

# Check if disk /dev/vda exists
if [ ! -b /dev/vda ]; then
    echo "Error: /dev/vda not found. Ensure this is a Proxmox host using the default LVM layout."
    exit 1
fi
echo "✔ /dev/vda detected."

# Check if LVM is installed
if ! command -v pvdisplay >/dev/null 2>&1; then
    echo "Error: LVM tools not found. Please install lvm2."
    exit 1
fi
echo "✔ LVM tools detected."

# Check if /dev/vda3 exists
if [ ! -b /dev/vda3 ]; then
    echo "Error: Partition /dev/vda3 not found. Ensure the system uses the default Proxmox LVM layout."
    exit 1
fi
echo "✔ /dev/vda3 detected."

echo "=== All prerequisites met ==="

echo "=== Checking for 'growpart' Utility ==="
if ! command -v growpart >/dev/null 2>&1; then
    echo "'growpart' is not installed. Installing required package..."
    apt update && apt install -y cloud-guest-utils
else
    echo "'growpart' is already installed."
fi


echo "=== Expanding Partition /dev/vda3 ==="
GROW_OUTPUT=$(growpart /dev/vda 3 2>&1) || true
if echo "$GROW_OUTPUT" | grep -q "NOCHANGE"; then
    echo "✔ /dev/vda3 is already at maximum size. No expansion needed."
else
    echo "$GROW_OUTPUT"
    echo "✔ Partition /dev/vda3 expanded successfully."
fi

echo "=== Resizing the Physical Volume ==="
pvresize /dev/vda3


echo "=== Extending the Logical Volume to Use All Available Free Space ==="
LV_OUTPUT=$(lvextend -l +100%FREE /dev/pve/root 2>&1) || true
if echo "$LV_OUTPUT" | grep -q "No size change"; then
    echo "✔ Logical volume /dev/pve/root is already using all available free space. No extension needed."
else
    echo "$LV_OUTPUT"
    echo "✔ Logical volume /dev/pve/root extended successfully."
fi

echo "=== Resizing the Filesystem ==="
resize2fs /dev/pve/root

echo "=== Disk Expansion Completed Successfully ==="