#!/bin/bash
set -euo pipefail

USERNAME="${1:-kugetsu}"

echo "=== kugetsu SSH Setup ==="
echo "Target user: $USERNAME"
echo ""

detect_os() {
    if [ -f /etc/os-release ]; then
        . /etc/os-release
        case "$ID" in
            debian|ubuntu|"noble"|"jammy"|"focal"|"bionic"|"bullseye"|"bookworm"|"trixie"|"sid")
                echo "debian"
                ;;
            fedora|rhel|centos|rocky|alma)
                echo "fedora"
                ;;
            *)
                echo "unknown"
                ;;
        esac
    else
        echo "unknown"
    fi
}

OS_TYPE=$(detect_os)
echo "Detected OS: $OS_TYPE"

if ! command -v systemctl &> /dev/null; then
    echo "ERROR: systemd not found."
    echo ""
    echo "This script requires systemd to be installed and running inside the container."
    echo "Please install systemd first:"
    case "$OS_TYPE" in
        debian)
            echo "    apt-get update && apt-get install -y systemd"
            ;;
        fedora)
            echo "    dnf install -y systemd"
            ;;
        *)
            echo "    Install systemd using your package manager"
            ;;
    esac
    echo ""
    echo "If you are running in a container that doesn't support systemd, consider:"
    echo "    - Using a container image with systemd support"
    echo "    - Running sshd directly (without systemd) - manual setup required"
    exit 1
fi

echo ""
echo "=== Step 1: Install openssh-server ==="
case "$OS_TYPE" in
    debian)
        echo "Using apt-get (Debian/Ubuntu)..."
        apt-get update -qq
        apt-get install -y -qq openssh-server sudo
        ;;
    fedora)
        echo "Using dnf (Fedora/RHEL)..."
        dnf install -y -q openssh-server sudo
        ;;
    *)
        echo "ERROR: Unsupported OS. Please install openssh-server and sudo manually."
        exit 1
        ;;
esac

echo ""
echo "=== Step 2: Verify installation ==="
if ! command -v sshd &> /dev/null; then
    echo "ERROR: sshd installation failed."
    echo "Please verify openssh-server was installed correctly."
    exit 1
fi
echo "sshd binary: $(which sshd)"
echo "sshd version: $(sshd -V 2>&1 | head -1)"

echo ""
echo "=== Step 3: Create user '$USERNAME' ==="
if ! id "$USERNAME" &> /dev/null; then
    useradd -m -s /bin/bash "$USERNAME"
    echo "User '$USERNAME' created."
else
    echo "User '$USERNAME' already exists."
fi

echo ""
echo "=== Step 4: Configure SSH for key-only authentication ==="
SSHD_CONFIG="/etc/ssh/sshd_config"
sed -i 's/^#*PasswordAuthentication.*/PasswordAuthentication no/' "$SSHD_CONFIG"
sed -i 's/^#*PubkeyAuthentication.*/PubkeyAuthentication yes/' "$SSHD_CONFIG"
sed -i 's/^#*PermitRootLogin.*/PermitRootLogin no/' "$SSHD_CONFIG"
echo "SSH configured: key-only auth, root login disabled."

echo ""
echo "=== Step 5: Configure sudo for passwordless access ==="
SUDOERS_FILE="/etc/sudoers.d/$USERNAME"
echo "$USERNAME ALL=(ALL) NOPASSWD: ALL" > "$SUDOERS_FILE"
chmod 0440 "$SUDOERS_FILE"
echo "Sudo configured: $USERNAME can run sudo without password."

echo ""
echo "=== Step 6: Enable and start sshd ==="
systemctl enable sshd
systemctl restart sshd

sleep 1

echo ""
echo "=== Step 7: Verify sshd is running ==="
if systemctl is-active --quiet sshd; then
    echo "SUCCESS: sshd is running."
    echo "Status:"
    systemctl status sshd --no-pager | head -5
else
    echo "ERROR: sshd is not running."
    echo "Debug info:"
    systemctl status sshd --no-pager
    journalctl -u sshd -n 10 --no-pager
    exit 1
fi

echo ""
echo "=== Setup Complete ==="
echo ""
echo "Next steps:"
echo ""
echo "1. Add your SSH public key to authorized_keys:"
echo "   mkdir -p /home/$USERNAME/.ssh"
echo "   chmod 700 /home/$USERNAME/.ssh"
echo "   echo 'YOUR_PUBLIC_KEY' >> /home/$USERNAME/.ssh/authorized_keys"
echo "   chmod 600 /home/$USERNAME/.ssh/authorized_keys"
echo "   chown -R $USERNAME:$USERNAME /home/$USERNAME/.ssh"
echo ""
echo "2. Connect from remote:"
echo "   ssh -p 2222 $USERNAME@<container-host-ip>"
echo ""
echo "3. Verify SSH access:"
echo "   ssh -p 2222 $USERNAME@<container-host-ip> sudo systemctl status sshd"
echo ""
echo "=== Troubleshooting ==="
echo ""
echo "If SSH connection fails:"
echo "  - Check sshd is running: systemctl status sshd"
echo "  - Check sshd logs: journalctl -u sshd -n 20"
echo "  - Verify user exists: id $USERNAME"
echo "  - Verify SSH key was added: cat /home/$USERNAME/.ssh/authorized_keys"
echo ""