#!/usr/bin/env bash
# Quick rebuild: extract existing ISO, update files, repack
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
PROJECT_DIR="$(cd "$SCRIPT_DIR/.." && pwd)"
BUILD_DIR="$PROJECT_DIR/build"
EXISTING_ISO="$BUILD_DIR/output/hermes-rescue.iso"
OUTPUT_DIR="$BUILD_DIR/output"
WORKDIR="${WORKDIR:-/tmp/hermes-iso-quick}"
SOURCE_DIR="$PROJECT_DIR/src"

info()  { echo -e "\033[0;34m[INFO]\033[0m  $*"; }
ok()    { echo -e "\033[0;32m[OK]\033[0m    $*"; }
die()   { echo -e "\033[0;31m[ERROR]\033[0m $*"; exit 1; }

# Check prerequisites
for cmd in unsquashfs mksquashfs xorriso rsync; do
    command -v "$cmd" &>/dev/null || die "$cmd not found"
done

[[ -f "$EXISTING_ISO" ]] || die "Existing ISO not found: $EXISTING_ISO"

# Clean workdir contents (handles bind mounts safely)
rm -rf "$WORKDIR" 2>/dev/null || (rm -rf "$WORKDIR"/* 2>/dev/null; true)
mkdir -p "$WORKDIR/iso-contents" "$WORKDIR/squashfs-root"

info "Mounting existing ISO..."
mkdir -p /mnt/hermes-iso-source
mount -o loop "$EXISTING_ISO" /mnt/hermes-iso-source 2>/dev/null || die "Failed to mount ISO"

info "Copying ISO contents (excluding squashfs)..."
rsync -a --exclude="casper/filesystem.squashfs" \
    /mnt/hermes-iso-source/ "$WORKDIR/iso-contents/" 2>/dev/null

info "Extracting squashfs..."
cp /mnt/hermes-iso-source/casper/filesystem.squashfs "$WORKDIR/filesystem.squashfs"
umount /mnt/hermes-iso-source 2>/dev/null || true

unsquashfs -d "$WORKDIR/squashfs-root" -f "$WORKDIR/filesystem.squashfs" 2>&1 | tail -3
ok "Squashfs extracted ($(du -sh "$WORKDIR/squashfs-root" | cut -f1))"

info "Updating config.yaml..."
cp "$SOURCE_DIR/hermes/config.yaml" "$WORKDIR/squashfs-root/opt/hermes/config.yaml"
ok "config.yaml updated"

info "Updating auth.json..."
cp "$SOURCE_DIR/hermes/auth.json" "$WORKDIR/squashfs-root/opt/hermes/auth.json"
ok "auth.json updated"

info "Updating autorun.sh..."
cp "$SOURCE_DIR/hermes/autorun.sh" "$WORKDIR/squashfs-root/opt/hermes/autorun.sh"
ok "autorun.sh updated"

info "Re-packing squashfs..."
mksquashfs "$WORKDIR/squashfs-root" "$WORKDIR/iso-contents/casper/filesystem.squashfs" \
    -comp lz4 -b 1M -noappend -processors 1 2>&1 | tail -5
ok "Squashfs repacked ($(du -sh "$WORKDIR/iso-contents/casper/filesystem.squashfs" | cut -f1))"

# Update filesystem.size
fs_size=$(du -sx --block-size=1 "$WORKDIR/squashfs-root" 2>/dev/null | cut -f1)
echo "$fs_size" > "$WORKDIR/iso-contents/casper/filesystem.size"
ok "filesystem.size updated"

info "Generating ISO..."
OUTPUT_ISO="$OUTPUT_DIR/hermes-rescue.iso"
EFI_IMG=$(find "$WORKDIR/iso-contents" -name "efi.img" -o -name "eltorito.img" 2>/dev/null | head -1 | sed "s|$WORKDIR/iso-contents/||")

if [[ -n "$EFI_IMG" ]]; then
    xorriso -as mkisofs -r -V "HERMES_RESCUE" \
        -J -joliet-long \
        -isohybrid-mbr "$WORKDIR/iso-contents/isohdpfx.bin" \
        -b isolinux/isolinux.bin \
        -c isolinux/boot.cat \
        -no-emul-boot -boot-load-size 4 -boot-info-table \
        -eltorito-alt-boot -e "$EFI_IMG" -no-emul-boot \
        -isohybrid-gpt-basdat \
        -isohybrid-apm-hfsplus \
        -o "$OUTPUT_ISO" \
        "$WORKDIR/iso-contents" 2>&1 | tail -5
else
    xorriso -as mkisofs -r -V "HERMES_RESCUE" \
        -J -joliet-long \
        -isohybrid-mbr "$WORKDIR/iso-contents/isohdpfx.bin" \
        -b isolinux/isolinux.bin \
        -c isolinux/boot.cat \
        -no-emul-boot -boot-load-size 4 -boot-info-table \
        -o "$OUTPUT_ISO" \
        "$WORKDIR/iso-contents" 2>&1 | tail -5
fi

iso_size=$(du -h "$OUTPUT_ISO" | cut -f1)
ok "ISO generated: $OUTPUT_ISO ($iso_size)"

info "Cleaning up..."
# rm -rf workdir (skip - bind mount)
ok "Done!"