#!/bin/bash
set -e

# SeniorNet Kiosk ISO Builder
# Takes the official Debian Trixie netinstall ISO and repacks it with:
#   - preseed.cfg embedded for silent auto-install
#   - GRUB + isolinux configured for auto-boot (UEFI + BIOS)
#
# The kiosk app itself is NOT bundled — it's downloaded from Gitea at
# first-boot time. Rebuild the ISO only when changing Debian base or preseed.
#
# Run: sudo ./build-iso.sh
# Output: iso-output/seniornet-kiosk.iso

if [ "$EUID" -ne 0 ]; then
  echo "ERROR: Run as root: sudo ./build-iso.sh"; exit 1
fi

REPO_DIR="$(cd "$(dirname "$0")" && pwd)"
OUTPUT_DIR="$REPO_DIR/iso-output"
WORK_DIR="$(mktemp -d /tmp/kiosk-iso-XXXX)"
trap 'rm -rf "$WORK_DIR"' EXIT

DEBIAN_ISO_URL="https://cdimage.debian.org/cdimage/daily-builds/daily/arch-latest/amd64/iso-cd/debian-testing-amd64-netinst.iso"
ISO_CACHE="$OUTPUT_DIR/debian-netinst.iso"
OUTPUT_ISO="$OUTPUT_DIR/seniornet-kiosk.iso"

mkdir -p "$OUTPUT_DIR"

# ── Dependencies ───────────────────────────────────────────────────
echo "==> Checking dependencies..."
MISSING=""
for pkg in xorriso isolinux curl; do
  dpkg -l "$pkg" &>/dev/null || MISSING="$MISSING $pkg"
done
if [ -n "$MISSING" ]; then
  apt-get install -y $MISSING
fi

# ── Download Debian netinstall ISO (cached) ────────────────────────
if [ -f "$ISO_CACHE" ]; then
  echo "==> Using cached Debian ISO: $ISO_CACHE"
else
  echo "==> Downloading Debian Trixie netinstall (~700 MB)..."
  curl -L --progress-bar "$DEBIAN_ISO_URL" -o "$ISO_CACHE"
fi

# ── Extract ISO ────────────────────────────────────────────────────
echo "==> Extracting ISO..."
mkdir -p "$WORK_DIR/iso"
xorriso -osirrox on -indev "$ISO_CACHE" -extract / "$WORK_DIR/iso" 2>/dev/null
chmod -R u+w "$WORK_DIR/iso"

# ── Add preseed to ISO root ────────────────────────────────────────
# Accessible during install as /cdrom/preseed.cfg
cp "$REPO_DIR/preseed.cfg" "$WORK_DIR/iso/preseed.cfg"

# ── Auto-boot: GRUB (UEFI) ────────────────────────────────────────
echo "==> Configuring auto-boot..."
cat > "$WORK_DIR/iso/boot/grub/grub.cfg" << 'GRUBEOF'
set default=0
set timeout=5

menuentry "SeniorNet Kiosk — Automatic Install" {
    linux  /install.amd/vmlinuz preseed/file=/cdrom/preseed.cfg auto=true priority=critical quiet ---
    initrd /install.amd/initrd.gz
}

menuentry "SeniorNet Kiosk — Install (verbose)" {
    linux  /install.amd/vmlinuz preseed/file=/cdrom/preseed.cfg auto=true priority=critical ---
    initrd /install.amd/initrd.gz
}
GRUBEOF

# ── Auto-boot: isolinux (BIOS legacy) ─────────────────────────────
if [ -f "$WORK_DIR/iso/isolinux/isolinux.cfg" ]; then
  cat > "$WORK_DIR/iso/isolinux/isolinux.cfg" << 'ISOEOF'
default install
timeout 50

label install
  menu label SeniorNet Kiosk - Automatic Install
  kernel /install.amd/vmlinuz
  append initrd=/install.amd/initrd.gz preseed/file=/cdrom/preseed.cfg auto=true priority=critical quiet ---

label verbose
  menu label SeniorNet Kiosk - Install (verbose)
  kernel /install.amd/vmlinuz
  append initrd=/install.amd/initrd.gz preseed/file=/cdrom/preseed.cfg auto=true priority=critical ---
ISOEOF
fi

# ── Repack ISO (UEFI + BIOS hybrid) ───────────────────────────────
echo "==> Building final ISO..."
cd "$WORK_DIR/iso"

xorriso -as mkisofs \
  -r -J -joliet-long \
  -V "SeniorNet Kiosk" \
  --grub2-mbr boot/grub/i386-pc/boot_hybrid.img \
  -partition_offset 16 \
  --mbr-force-bootable \
  -append_partition 2 28732ac11ff8d211ba4b00a0c93ec93b boot/grub/efi.img \
  -appended_part_as_gpt \
  -iso_mbr_part_type a2a0d0ebe5b9334487c068b6b72699c7 \
  -c '/boot/boot.cat' \
  -b '/boot/grub/i386-pc/eltorito.img' \
  -no-emul-boot -boot-load-size 4 -boot-info-table --grub2-boot-info \
  -eltorito-alt-boot \
  -e '--interval:appended_partition_2:::' \
  -no-emul-boot \
  -o "$OUTPUT_ISO" \
  . 2>&1 | tail -5

echo
SIZE=$(du -sh "$OUTPUT_ISO" | cut -f1)
echo "==> ✓ ISO complete: $OUTPUT_ISO ($SIZE)"
echo
echo "Write to USB:"
echo "  sudo dd if=\"$OUTPUT_ISO\" of=/dev/sdX bs=4M status=progress && sync"
echo
echo "Boot from USB — Debian installs silently (~10 min) then reboots."
echo "On first reboot: setup wizard prompts for username and senior's name."
echo "Second reboot: kiosk is running."