#!/usr/bin/env bash
set -euo pipefail

# Update system
sudo pacman -Syu --noconfirm

# Switch from legacy iptables to nft backend if needed
if pacman -Q iptables >/dev/null 2>&1; then
  sudo pacman -Rns --noconfirm iptables || true
fi

# Install Kubernetes prerequisites and container runtime
sudo pacman -S --needed --noconfirm \
  ca-certificates \
  curl \
  wget \
  containerd \
  crictl \
  kubelet \
  kubeadm \
  kubectl \
  conntrack-tools \
  socat \
  ethtool \
  iptables-nft \
  cni-plugins

# Enable and start containerd
sudo systemctl enable --now containerd.service

# Generate default containerd config if missing
if [[ ! -f /etc/containerd/config.toml ]]; then
  sudo mkdir -p /etc/containerd
  containerd config default | sudo tee /etc/containerd/config.toml >/dev/null
fi

# Set SystemdCgroup = true for kubelet compatibility
sudo sed -i 's/SystemdCgroup = false/SystemdCgroup = true/' /etc/containerd/config.toml
sudo systemctl restart containerd

# Kernel modules for Kubernetes networking
sudo tee /etc/modules-load.d/k8s.conf >/dev/null <<'EOF'
overlay
br_netfilter
EOF

sudo modprobe overlay
sudo modprobe br_netfilter

# Sysctl settings required by Kubernetes
sudo tee /etc/sysctl.d/k8s.conf >/dev/null <<'EOF'
net.bridge.bridge-nf-call-iptables = 1
net.bridge.bridge-nf-call-ip6tables = 1
net.ipv4.ip_forward = 1
EOF

sudo sysctl --system

# Disable swap now
sudo swapoff -a

# Disable swap on boot by commenting swap lines in /etc/fstab
sudo sed -i.bak '/\sswap\s/s/^/#/' /etc/fstab

# Enable kubelet
sudo systemctl enable --now kubelet.service

echo
echo "Base Kubernetes packages are installed."
echo "Next step:"
echo "  sudo kubeadm init --pod-network-cidr=10.244.0.0/16"
echo
echo "Then set up kubectl for your user:"
echo "  mkdir -p \$HOME/.kube"
echo "  sudo cp -i /etc/kubernetes/admin.conf \$HOME/.kube/config"
echo "  sudo chown \$(id -u):\$(id -g) \$HOME/.kube/config"
echo
echo "Then install Flannel:"
echo "  kubectl apply -f https://raw.githubusercontent.com/flannel-io/flannel/master/Documentation/kube-flannel.yml"
echo
echo "Check status with:"
echo "  systemctl status containerd kubelet --no-pager"
echo "  crictl info"