#!/usr/bin/env bash
#
# scripts/mksystem.sh — assemble the single dd-able rs-dos system image
#
# Replaces the old two-source setup (vvfat `esp/` directory for boot +
# separate /tmp/disk.img for data).  One FAT32 image holds EVERYTHING:
#
#   \bzImage                 kernel (rsbl requires this exact path)
#   \initramfs.cpio.gz       empty initramfs (rsbl requires it)
#   \EFI\BOOT\BOOTX64.EFI    boot entry: the kernel (default) or rsboot
#   \etc\motd.txt            seed config
#   \bin\cli\  \bin\gui\     binary tree (empty until Phase 2/4 migrate tools)
#   \*.txt                   seed files (seed/)
#
# The firmware boots from this image and the kernel mounts the same
# volume at /disk/<UID>/ — boot medium and data medium are one disk.
#
# Usage:
#   ./scripts/mksystem.sh [options] [output.img]     # default /tmp/system.img
#
# Options:
#   --force        rebuild even if the image exists (Makefile stamps handle
#                  normal freshness; without --force an existing image is kept,
#                  so user files survive across reboots)
#   --size NM      image size in MB (default 64)
#   --chain        \EFI\BOOT\BOOTX64.EFI = rsboot bootloader (full chain:
#                  firmware → rsboot → rsnix).  Default is the kernel itself
#                  (direct: firmware → rsnix), matching the old dev loop.
#   --gpt          wrap the FAT volume in a GPT partition table (for dd-ing
#                  to real USB sticks whose firmware refuses superfloppies)
#   --label NAME   FAT volume label (default RSDOS)
#
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
PROJECT_DIR="$(dirname "$SCRIPT_DIR")"
cd "$PROJECT_DIR"

IMG="/tmp/system.img"
SIZE_MB=64
FORCE=0
CHAIN=0
GPT=0
LABEL="RSDOS"

while [ $# -gt 0 ]; do
	case "$1" in
	--force | --fresh)
		FORCE=1
		;;
	--size)
		shift
		SIZE_MB="$1"
		;;
	--chain)
		CHAIN=1
		;;
	--gpt)
		GPT=1
		;;
	--label)
		shift
		LABEL="$1"
		;;
	--help | -h)
		head -30 "$0" | grep "^#" | sed 's/^# \?//'
		exit 0
		;;
	-*)
		echo "mksystem: unknown option: $1" >&2
		exit 1
		;;
	*)
		IMG="$1"
		;;
	esac
	shift
done

TARGET=x86_64-unknown-uefi
PROFILE=debug
OUT_DIR="target/$TARGET/$PROFILE"
KERNEL="$OUT_DIR/rsdos.efi"
BZIMAGE="esp/bzImage"
INITRD="esp/initramfs.cpio.gz"
BOOTLOADER="build/bootloader/BOOTX64.EFI"

# ---- checks ----
for cmd in mkfs.fat mcopy mmd; do
	if ! command -v "$cmd" >/dev/null 2>&1; then
		echo "mksystem: $cmd not found (install dosfstools + mtools)" >&2
		exit 1
	fi
done
if [ "$GPT" -eq 1 ]; then
	for cmd in sfdisk truncate dd; do
		if ! command -v "$cmd" >/dev/null 2>&1; then
			echo "mksystem: --gpt needs $cmd" >&2
			exit 1
		fi
	done
fi

if [ -f "$IMG" ] && [ "$FORCE" -eq 0 ]; then
	echo "mksystem: $IMG already exists (use --force to re-create)"
	exit 0
fi

# ---- build kernel ----
if [ ! -f "$KERNEL" ]; then
	echo "mksystem: building kernel..."
	cargo build --package rsdos --target "$TARGET"
fi

# ---- build bootloader (chain mode only) ----
if [ "$CHAIN" -eq 1 ] && [ ! -f "$BOOTLOADER" ]; then
	echo "mksystem: building bootloader..."
	"$SCRIPT_DIR/build-bootloader.sh"
fi

# ---- deploy kernel artifacts to esp/ (shared with the old layout) ----
mkdir -p esp/EFI/BOOT
cp "$KERNEL" "$BZIMAGE"
[ -f "$INITRD" ] || printf '' | gzip >"$INITRD"

# ---- create the FAT volume ----
rm -f "$IMG"
SIZE_BLOCKS=$((SIZE_MB * 1024)) # mkfs.fat counts 1024-byte blocks
echo "mksystem: creating $IMG (${SIZE_MB}M FAT32, label $LABEL)"
mkfs.fat -C -F 32 -n "$LABEL" "$IMG" "$SIZE_BLOCKS" >/dev/null

echo "mksystem: staging system tree"
mmd -i "$IMG" ::/EFI ::/EFI/BOOT ::/etc ::/bin ::/bin/cli ::/bin/gui
mcopy -i "$IMG" "$BZIMAGE" ::/bzImage
mcopy -i "$IMG" "$INITRD" ::/initramfs.cpio.gz
if [ "$CHAIN" -eq 1 ]; then
	mcopy -i "$IMG" "$BOOTLOADER" ::/EFI/BOOT/BOOTX64.EFI
	echo "  \\EFI\\BOOT\\BOOTX64.EFI  <- rsboot (full chain)"
else
	mcopy -i "$IMG" "$KERNEL" ::/EFI/BOOT/BOOTX64.EFI
	echo "  \\EFI\\BOOT\\BOOTX64.EFI  <- kernel (direct)"
fi
echo "  \\bzImage  \\initramfs.cpio.gz  \\bin{\\cli,\\gui}  \\etc"

# Seed files: motd lives in \etc, everything else at the volume root.
SEED_DIR="$PROJECT_DIR/seed"
if [ -d "$SEED_DIR" ]; then
	for f in "$SEED_DIR"/*; do
		[ -f "$f" ] || continue
		name="$(basename "$f")"
		if [ "$name" = "motd.txt" ]; then
			mcopy -i "$IMG" "$f" ::/etc/"$name"
			echo "  \\etc\\$name"
		else
			mcopy -i "$IMG" "$f" ::/"$name"
			echo "  \\$name"
		fi
	done
fi

# ---- optional GPT wrapper (real-hardware dd target) ----
if [ "$GPT" -eq 1 ]; then
	GPT_START=2048 # 1 MiB offset (standard alignment)
	GPT_IMG="$(mktemp)"
	truncate -s "${SIZE_MB}M" "$GPT_IMG"
	dd if="$IMG" of="$GPT_IMG" bs=512 seek="$GPT_START" conv=notrunc 2>/dev/null
	FINAL="$(mktemp)"
	truncate -s "$((SIZE_MB + 2))M" "$FINAL"
	sfdisk --quiet "$FINAL" <<EOF
label: gpt
type=U, start=$GPT_START, size=
EOF
	dd if="$GPT_IMG" of="$FINAL" bs=512 seek="$GPT_START" conv=notrunc 2>/dev/null
	rm -f "$GPT_IMG"
	mv "$FINAL" "$IMG"
	echo "mksystem: wrapped in GPT (partition at LBA $GPT_START)"
fi

echo ""
echo "=== Done: $IMG ==="
ls -lh "$IMG"
echo "Boot with:  make run   (or: make boot-image)"
[ "$GPT" -eq 0 ] && echo "USB dd tip: add --gpt for firmwares that refuse superfloppies"
exit 0