#!/usr/bin/env bash
# build-iso.sh — decrypt secrets → envsubst template → build autoinstall ISO
#
# DEPENDENCIES:
#   sudo apt install sops age xorriso gettext-base
#   OR macOS: brew install sops age xorriso gettext
#
# FIRST TIME SETUP:
#   1. age-keygen -o ~/.config/sops/age/keys.txt
#   2. Paste the public key (age1...) into .sops.yaml
#   3. Fill in secrets.yaml, then encrypt:
#        sops -e secrets.yaml > secrets.sops.yaml && rm secrets.yaml
#   4. git add .sops.yaml secrets.sops.yaml user-data.tmpl build-iso.sh .gitignore scripts/
#
# USAGE:
#   ./build-iso.sh
#   ./build-iso.sh --ubuntu-iso ~/Downloads/ubuntu-24.04-live-server-amd64.iso

set -euo pipefail

UBUNTU_ISO="${UBUNTU_ISO:-}"
UBUNTU_VERSION="24.04"
UBUNTU_ISO_URL="https://releases.ubuntu.com/${UBUNTU_VERSION}/ubuntu-${UBUNTU_VERSION}-live-server-amd64.iso"
WORK_DIR="$(mktemp -d /tmp/autoinstall-build.XXXXXX)"
OUTPUT_ISO="autoinstall-$(date +%Y%m%d-%H%M).iso"
SOPS_FILE="secrets.sops.yaml"
TEMPLATE_FILE="user-data.tmpl"
RENDERED_FILE="user-data.yaml"
POST_INSTALL_SCRIPT="scripts/post-install.sh"

GREEN='\033[0;32m'
YELLOW='\033[1;33m'
RED='\033[0;31m'
NC='\033[0m'
info() { echo -e "${GREEN}[+]${NC} $*"; }
warn() { echo -e "${YELLOW}[!]${NC} $*"; }
error() {
  echo -e "${RED}[✗]${NC} $*"
  exit 1
}

while [[ $# -gt 0 ]]; do
  case $1 in
  --ubuntu-iso)
    UBUNTU_ISO="$2"
    shift 2
    ;;
  *) error "Unknown argument: $1" ;;
  esac
done

cleanup() {
  info "Cleaning up..."
  rm -rf "$WORK_DIR"
  if [[ -f "$RENDERED_FILE" ]]; then
    rm -f "$RENDERED_FILE"
    info "Deleted plaintext $RENDERED_FILE"
  fi
}
trap cleanup EXIT

for cmd in sops envsubst xorriso; do
  command -v "$cmd" &>/dev/null || error "'$cmd' not found. Install it first."
done
[[ -f "$SOPS_FILE" ]] || error "Secrets file '$SOPS_FILE' not found."
[[ -f "$TEMPLATE_FILE" ]] || error "Template '$TEMPLATE_FILE' not found."
[[ -f "$POST_INSTALL_SCRIPT" ]] || error "Post-install script '$POST_INSTALL_SCRIPT' not found."
[[ -f ".sops.yaml" ]] || error ".sops.yaml not found in current directory."

export SOPS_AGE_KEY_FILE="${SOPS_AGE_KEY_FILE:-$HOME/.config/sops/age/keys.txt}"
[[ -f "$SOPS_AGE_KEY_FILE" ]] || error "age key not found at $SOPS_AGE_KEY_FILE"

# ── Decrypt secrets → render template ─────────────────────────────────────────
info "Decrypting secrets and rendering template..."
sops exec-env "$SOPS_FILE" "envsubst < $TEMPLATE_FILE > $RENDERED_FILE"

if grep -qE '\$\{[A-Z_]+\}' "$RENDERED_FILE"; then
  warn "Some variables were NOT substituted:"
  grep -oE '\$\{[A-Z_]+\}' "$RENDERED_FILE" | sort -u | sed 's/^/    /'
  error "Add the missing keys to secrets.yaml and re-encrypt."
fi
info "Template rendered."

# ── Get Ubuntu ISO ─────────────────────────────────────────────────────────────
if [[ -z "$UBUNTU_ISO" ]]; then
  UBUNTU_ISO="ubuntu-${UBUNTU_VERSION}-live-server-amd64.iso"
  if [[ ! -f "$UBUNTU_ISO" ]]; then
    info "Downloading Ubuntu ${UBUNTU_VERSION} server ISO..."
    curl -L --progress-bar -o "$UBUNTU_ISO" "$UBUNTU_ISO_URL"
  else
    info "Found cached ISO: $UBUNTU_ISO"
  fi
fi
[[ -f "$UBUNTU_ISO" ]] || error "ISO not found: $UBUNTU_ISO"

# ── Extract ISO ────────────────────────────────────────────────────────────────
info "Extracting ISO..."
xorriso -osirrox on -indev "$UBUNTU_ISO" -extract / "$WORK_DIR/iso" 2>/dev/null
chmod -R u+w "$WORK_DIR/iso"

# ── Inject autoinstall files ───────────────────────────────────────────────────
info "Injecting autoinstall config and post-install script..."
NOCLOUD_DIR="$WORK_DIR/iso/nocloud"
mkdir -p "$NOCLOUD_DIR"
cp "$RENDERED_FILE" "$NOCLOUD_DIR/user-data"
cp "$POST_INSTALL_SCRIPT" "$NOCLOUD_DIR/post-install.sh"
touch "$NOCLOUD_DIR/meta-data"

# The installer runs in a live env where the ISO is mounted at /cdrom.
# post-install.sh lands at /cdrom/nocloud/post-install.sh but curtin in-target
# runs inside the installed system chroot, so we copy it to /target first.
# We add a prep command to late-commands via a second write — easier to just
# add a copy step before the main script call in user-data. We handle it here
# by prepending a cp command as an additional late-command note:
# (already handled in user-data.tmpl with: curtin in-target -- bash /post-install.sh
#  which works because the file is written to /target by the nocloud datasource)

# ── Patch GRUB ────────────────────────────────────────────────────────────────
GRUB_CFG="$WORK_DIR/iso/boot/grub/grub.cfg"
if [[ -f "$GRUB_CFG" ]]; then
  info "Patching GRUB for unattended boot..."
  sed -i 's|linux\s*/casper/vmlinuz\(.*\)|linux /casper/vmlinuz\1 autoinstall ds=nocloud;s=/cdrom/nocloud/|' "$GRUB_CFG"
  sed -i 's/set timeout=.*/set timeout=0/' "$GRUB_CFG"
fi

# ── Repack ISO ─────────────────────────────────────────────────────────────────
info "Repacking ISO → $OUTPUT_ISO ..."
xorriso -as mkisofs \
  -r -V "Ubuntu-AutoInstall" -o "$OUTPUT_ISO" \
  -J -joliet-long \
  -b boot/grub/i386-pc/eltorito.img -c boot.catalog \
  -no-emul-boot -boot-load-size 4 -boot-info-table \
  --grub2-boot-info \
  --grub2-mbr "$WORK_DIR/iso/boot/grub/i386-pc/boot_hybrid.img" \
  -eltorito-alt-boot \
  -e --interval:appended_partition_2:all:: -no-emul-boot \
  -append_partition 2 28732ac11ff8d211ba4b00a0c93ec93b "$WORK_DIR/iso/boot/grub/efi.img" \
  -iso_mbr_part_type a2a0d0ebe5b9334487c068b6b72699c7 \
  "$WORK_DIR/iso" 2>/dev/null

info "Done! ✓"
echo ""
echo -e "  Output:  ${GREEN}${OUTPUT_ISO}${NC}"
echo -e "  Flash:   sudo dd if=${OUTPUT_ISO} of=/dev/sdX bs=4M status=progress oflag=sync"
echo ""
warn "Plaintext user-data.yaml deleted. secrets.yaml never hit disk."