#!/usr/bin/env bash
# ─────────────────────────────────────────────────────────────────────────────
# Arcline OS — live ISO builder
#
#   scripts/build-iso.sh <edition>
#
# Wraps a rootfs into a hybrid (BIOS+UEFI) live ISO:
#   1. ensure the rootfs exists (build it with live-boot support if needed)
#   2. stage kernel + initramfs + squashfs in isofiles/live
#   3. write the grub boot config (live-boot: boot=live)
#   4. grub-mkrescue → build/artifacts/arcline-<edition>-<version>-<arch>.iso
#
# Requires root for the rootfs stage; the ISO assembly itself runs unprivileged.
# ─────────────────────────────────────────────────────────────────────────────
set -euo pipefail
source "$(dirname "${BASH_SOURCE[0]}")/common.sh"

EDITION="${1:?usage: build-iso.sh <edition>}"
validate_edition "$EDITION"

ROOTFS="$ROOTFS_DIR/$EDITION"
ISOFILES="$IMAGE_DIR/$EDITION/isofiles"
ARTIFACT="$ARTIFACT_DIR/arcline-$EDITION-$VERSION-$ARCH.iso"

# ── 1. rootfs ───────────────────────────────────────────────────────────────
if [[ ! -d "$ROOTFS" ]]; then
  log "rootfs missing — building with live-boot support"
  ARCLINE_LIVE=1 "$ROOT/scripts/build-rootfs.sh" "$EDITION"
fi

# live-boot must be present in the rootfs for the ISO to boot
if [[ ! -d "$ROOTFS/lib/live" && ! -d "$ROOTFS/usr/lib/live" ]]; then
  warn "rootfs has no live-boot support; rebuilding with ARCLINE_LIVE=1"
  ARCLINE_LIVE=1 "$ROOT/scripts/build-rootfs.sh" "$EDITION"
fi

# ── 2. stage files ──────────────────────────────────────────────────────────
log "staging ISO files for edition '$EDITION'"
rm -rf "$ISOFILES"
mkdir -p "$ISOFILES/live" "$ISOFILES/boot/grub"

KERNEL="$(find "$ROOTFS/boot" -maxdepth 1 -name 'vmlinuz-*' | sort -V | tail -1)"
INITRD="$(find "$ROOTFS/boot" -maxdepth 1 -name 'initrd.img-*' | sort -V | tail -1)"
[[ -n "$KERNEL" && -n "$INITRD" ]] || die "kernel or initramfs not found in rootfs"
cp -L "$KERNEL" "$ISOFILES/live/vmlinuz"
cp -L "$INITRD" "$ISOFILES/live/initrd.img"

# ── 2b. secure boot (optional: ARCLINE_SIGN=1 + a MOK keypair) ──────────────
if [[ "${ARCLINE_SIGN:-0}" == "1" ]]; then
  log "secure boot: signing boot chain and shipping MOK in the live image"
  [[ -f "$BUILD_DIR/keys/MOK.der" ]] || die "ARCLINE_SIGN=1 but no MOK keypair — run: scripts/secureboot/gen-keys.sh"
  mkdir -p "$ROOTFS/etc/arcline"
  cp "$BUILD_DIR/keys/MOK.der" "$ROOTFS/etc/arcline/MOK.der"
  "$ROOT/scripts/secureboot/sign-image.sh" "$ROOTFS" --keydir "$BUILD_DIR/keys"
  "$ROOT/scripts/secureboot/sign-image.sh" "$ISOFILES" --keydir "$BUILD_DIR/keys"
fi

log "compressing rootfs → squashfs (this takes a while)"
# The squashfs is the live root. Keep it complete — offline man pages and
# docs are a product promise (see the landing page), so nothing is excluded.
mksquashfs "$ROOTFS" "$ISOFILES/live/arcline.squashfs" -noappend -comp zstd -Xcompression-level 15 2>/dev/null || \
mksquashfs "$ROOTFS" "$ISOFILES/live/arcline.squashfs" -noappend -comp xz

# ── 3. grub boot config ─────────────────────────────────────────────────────
log "writing grub config"
KCMD="$(tr '\n' ' ' < "$(edition_dir "$EDITION")/kernel.cmdline" | sed 's/  */ /g')"
cat > "$ISOFILES/boot/grub/grub.cfg" <<EOF
set timeout=5
set default=0

menuentry "Arcline $EDITION ($VERSION)" {
    linux  /live/vmlinuz boot=live config quiet $KCMD
    initrd /live/initrd.img
}

menuentry "Arcline $EDITION ($VERSION) — safe mode (no mitigations)" {
    linux  /live/vmlinuz boot=live config quiet nomodeset
    initrd /live/initrd.img
}
EOF

# ── 4. assemble ─────────────────────────────────────────────────────────────
log "assembling ISO with grub-mkrescue"
command -v grub-mkrescue >/dev/null || die "grub-mkrescue not found (run scripts/check-host-deps.sh --install)"
mkdir -p "$ARTIFACT_DIR"
grub-mkrescue -o "$ARTIFACT" "$ISOFILES" -- \
  -volume-label "ARCLINE_${EDITION^^}" 2>/dev/null || \
grub-mkrescue -o "$ARTIFACT" "$ISOFILES"

# ── 5. verify hybrid boot entries ───────────────────────────────────────────
# grub-mkrescue builds the ISO bootloader from the HOST's GRUB modules. If the
# host lacks the x86_64-efi modules or mtools, the ISO has no UEFI boot entry
# and UEFI firmware shows "make sure there is a bootable uefi x64 image".
# Check the finished ISO instead of trusting the host.
if command -v xorriso >/dev/null 2>&1; then
  log "verifying ISO boot entries"
  ET="$(xorriso -indev "$ARTIFACT" -report_el_torito cmd 2>/dev/null || true)"

  HAS_EFI=0
  echo "$ET" | grep -qiE 'boot_image efi|efi\.img|BOOTX64\.EFI' && HAS_EFI=1
  if [[ $HAS_EFI -eq 0 ]]; then
    # fallback: some xorriso versions name it differently — look in the fs
    xorriso -indev "$ARTIFACT" -find / -name 'efi.img' 2>/dev/null | grep -qi 'efi\.img' && HAS_EFI=1
  fi

  HAS_BIOS=0
  echo "$ET" | grep -qiE 'boot_image isolinux|boot_image grub' && HAS_BIOS=1

  [[ $HAS_EFI  -eq 1 ]] && log "  ✓ EFI boot entry present"  || warn "  ISO has NO EFI boot entry (UEFI will refuse it)"
  [[ $HAS_BIOS -eq 1 ]] && log "  ✓ BIOS boot entry present" || warn "  ISO has NO BIOS boot entry (legacy BIOS will refuse it)"

  if [[ "$BOOT" == "efi" && $HAS_EFI -eq 0 ]]; then
    die "BOOT=efi but the ISO has no EFI boot entry — install grub-efi-amd64-bin + mtools on the build host (scripts/check-host-deps.sh --install), then rebuild"
  fi
fi

log "ISO artifact: $ARTIFACT"
sha256sum "$ARTIFACT" | tee "$ARTIFACT.sha256"