#!/bin/sh
# Shell script to install Nameless to a disk.

BINARIES=( boot/x86/mbr boot/x86/vbr-fat32 boot/x86/stage3/LOADER.BIN kernel/kernel.bin )

check_binaries() {
	for i in "${BINARIES[@]}"; do
		if ! [ -e $i ]; then
			echo $i does not exist, have you compiled Nameless?
			exit 1
		fi
	done
}

install_blkdev() {
	# Ask the user are they sure they want to install.
	local prompt
	echo About to install Nameless to real disk $target.
	echo This will WIPE ALL DATA on $target, type YES if you want to continue.
	read -r prompt
	if [ $prompt != "YES" ]; then
		echo -e "Aborting."
		exit 1
	fi

	echo OK, installing Nameless to $target.
	echo Creating partition table on $target...

	# Create a partition table on the disk.
	fdisk $target <<- END > /dev/null
	o
	n
	p
	1


	a
	t
	0c
	w
	END
	if ! [ $? -eq 0 ]; then
		echo An error occurred!
		exit 1
	fi
	# Create a FAT32 filesystem on the disk.
	echo Formatting $target...
	mkfs.fat -F 32 "$target"1
	if ! [ $? -eq 0 ]; then
		echo An error occurred!
		exit 1
	fi
	# Write MBR and VBR to the disk.
	# TODO: write VBR to the backup BPB as well?
	echo Writing bootsectors to $target...
	dd 'if=boot/x86/mbr' "of=$target" 'bs=440' 'count=1'
	if ! [ $? -eq 0 ]; then
		echo An error occurred!
		exit 1
	fi
	dd 'if=boot/x86/vbr-fat32' 'of='"$target"1 'bs=1' 'skip=90' 'seek=90'
	if ! [ $? -eq 0 ]; then
		echo An error occurred!
		exit 1
	fi
	# Mount the partition and copy stage3 and kernel to it.
	echo Copying files to $target...
	local mountpoint=$(mktemp -d)
	mount "$target"1 $mountpoint
	if ! [ $? -eq 0 ]; then
		echo An error occurred!
		exit 1
	fi
	cp boot/x86/stage3/LOADER.BIN $mountpoint/LOADER.BIN
	cp kernel/kernel.bin $mountpoint/KERNEL.BIN
	if ! [ $? -eq 0 ]; then
		echo An error occurred!
		exit 1
	fi
	# Unmount the partition and flush write cache to make sure the OS
	# binaries have actually been written to the disk.
	echo Unmounting $target...
	umount $mountpoint
	rm -rf $mountpoint
	echo Flushing cache...
	sync
	echo Nameless has been successfully installed to $target!
	return
}

# Check if all the required tools are installed.
[ -z $(command -v fdisk) ] && echo fdisk not found, is util-linux installed? && exit 127
[ -z $(command -v mkfs.fat) ] && echo mkfs.fat not found, is dosfstools installed? && exit 127

# Make sure that Nameless has been compiled.
check_binaries

# cd to the directory we're in.
cd $(dirname $(realpath $0))

# For convenience, list all connected disks.
fdisk -l

# Ask the user where to install.
echo -n "Choose the disk you want to install to: "
read -r target

# If the target does not exist or is not a blkdev, exit.
[ -b $target ] || echo $target does not exist or is not a block device! || exit 1
install_blkdev
exit 0