#!/usr/bin/env bash

# Create a new host from a template

FLAKE_DIR="."
TEMPLATE=""
HOSTNAME=""
SYSTEM=""

SEPARATOR="________________________________________"

usage() {
    cat <<EOF
Usage: $(basename "$0") -t TEMPLATE -n HOSTNAME [-s SYSTEM] [-f FLAKE_DIR]

Options:
  -t, --template TEMPLATE   Template to use (mandatory)
  -n, --hostname HOSTNAME   Hostname for the new host (mandatory)
  -s, --system SYSTEM       System architecture (default: derived from template)
  -f, --flake FLAKE_DIR     Path to flake directory (default: .)
  -h, --help                Show this help message

Available templates:
  generic-server    x86_64 server with SSH, Nginx, Headscale client
  raspberry-pi      aarch64 Raspberry Pi 4 with Comin, Tailscale
EOF
}

error() {
  echo "Error: $1" >&2
  exit 1
}

while [[ $# -gt 0 ]]; do
  case "$1" in
    -t|--template)  TEMPLATE="$2"; shift 2 ;;
    -n|--hostname)  HOSTNAME="$2"; shift 2 ;;
    -s|--system)    SYSTEM="$2"; shift 2 ;;
    -f|--flake)     FLAKE_DIR="$2"; shift 2 ;;
    -h|--help)      usage; exit 0 ;;
    *)              error "Unknown option: $1" ;;
  esac
done

# Validate
[[ -z "$TEMPLATE" ]] && error "Template is required (-t)"
[[ -z "$HOSTNAME" ]] && error "Hostname is required (-n)"

TEMPLATE_DIR="$FLAKE_DIR/templates/$TEMPLATE"
HOST_DIR="$FLAKE_DIR/hosts/$HOSTNAME"

[[ ! -d "$TEMPLATE_DIR" ]] && error "Template '$TEMPLATE' not found in $TEMPLATE_DIR"
[[ -d "$HOST_DIR" ]] && error "Host '$HOSTNAME' already exists in $HOST_DIR"

# Derive system from template if not specified
if [[ -z "$SYSTEM" ]]; then
  case "$TEMPLATE" in
    generic-server)  SYSTEM="x86_64-linux" ;;
    raspberry-pi)    SYSTEM="aarch64-linux" ;;
    *)               error "Cannot derive system for template '$TEMPLATE'. Use -s to specify." ;;
  esac
fi

echo "$SEPARATOR"
echo "Creating host '$HOSTNAME' from template '$TEMPLATE'"
echo "  System:    $SYSTEM"
echo "  Target:    $HOST_DIR"
echo "$SEPARATOR"

# Copy template
cp -r "$TEMPLATE_DIR" "$HOST_DIR"

# Remove template flake.nix (not needed in host dir)
rm -f "$HOST_DIR/flake.nix"

# Replace hostname in networking.nix
sed -i "s/networking.hostName = \".*\"/networking.hostName = \"$HOSTNAME\"/" "$HOST_DIR/networking.nix"

# Create empty secrets.yaml placeholder
touch "$HOST_DIR/secrets.yaml"

# Add to git
git -C "$FLAKE_DIR" add "$HOST_DIR"

echo "$SEPARATOR"
echo "Host '$HOSTNAME' created successfully."
echo ""
echo "Next steps:"
echo "  1. Add to flake.nix:"
echo ""
echo "     $HOSTNAME = mkNixosConfiguration \"$SYSTEM\" [ ./hosts/$HOSTNAME ];"
echo ""
echo "  2. Update hardware.nix and disks.sh for your hardware"
echo "  3. Update .sops.yaml with creation rules for hosts/$HOSTNAME/secrets.yaml"
echo "  4. Follow the first-install guide: docs/getting-started/first-install.md"