#!/bin/bash
# NAME: Script to transition from systemd-boot to Limine bootloader
# REQUIRES: sudo

set -euo pipefail

echo "do you confirm this transition?"

read -r -p "Are you sure? [y/N] " response

if [[ "$response" != "y" ]]; then
	exit 0
fi

RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m'

print_status() { echo -e "${BLUE}[INFO]${NC} $1"; }
print_success() { echo -e "${GREEN}[SUCCESS]${NC} $1"; }
print_warning() { echo -e "${YELLOW}[WARNING]${NC} $1"; }
print_error() { echo -e "${RED}[ERROR]${NC} $1"; }

if [[ $EUID -ne 0 ]]; then
	print_error "This script must be run as root (use sudo)"
	exit 1
fi

if ! command -v pacman &>/dev/null; then
	print_error "This script is designed for Arch Linux / CachyOS systems"
	exit 1
fi

print_status "Starting transition from systemd-boot to Limine..."

ESP_PATH=""
if command -v bootctl &>/dev/null; then
	ESP_PATH=$(bootctl --print-esp-path 2>/dev/null || echo "")
fi

if [[ -z "$ESP_PATH" ]]; then
	if [[ -d "/boot/EFI" ]]; then
		ESP_PATH="/boot"
	elif [[ -d "/efi/EFI" ]]; then
		ESP_PATH="/efi"
	else
		print_error "Could not detect ESP path"
		exit 1
	fi
fi

print_success "ESP detected at: $ESP_PATH"

BACKUP_DIR="/root/bootloader-backup-$(date +%Y%m%d-%H%M%S)"
mkdir -p "$BACKUP_DIR"

[[ -d "$ESP_PATH/loader" ]] && cp -r "$ESP_PATH/loader" "$BACKUP_DIR/" 2>/dev/null || true
[[ -d "$ESP_PATH/EFI/systemd" ]] && cp -r "$ESP_PATH/EFI/systemd" "$BACKUP_DIR/" 2>/dev/null || true
efibootmgr -v >"$BACKUP_DIR/efibootmgr-backup.txt" 2>/dev/null || true

print_success "Backup created at: $BACKUP_DIR"

CURRENT_CMDLINE=""
if [[ -f "/etc/kernel/cmdline" ]]; then
	CURRENT_CMDLINE=$(cat /etc/kernel/cmdline)
	print_status "Found existing /etc/kernel/cmdline: $CURRENT_CMDLINE"
else
	CURRENT_CMDLINE=$(cat /proc/cmdline | sed 's/BOOT_IMAGE=[^ ]* //')
	print_status "Using current /proc/cmdline: $CURRENT_CMDLINE"
fi

print_status "Installing Limine and related packages..."
pacman -S --needed --noconfirm limine limine-snapper-sync limine-mkinitcpio-hook
print_success "Limine packages installed"

print_status "Installing Limine bootloader to ESP..."
mkdir -p "$ESP_PATH/EFI/Limine"

if [[ -f "/usr/share/limine/limine_x64.efi" ]]; then
	cp /usr/share/limine/limine_x64.efi "$ESP_PATH/EFI/Limine/"
elif [[ -f "/usr/share/limine/BOOTX64.EFI" ]]; then
	cp /usr/share/limine/BOOTX64.EFI "$ESP_PATH/EFI/Limine/limine_x64.efi"
else
	print_error "Could not find Limine EFI files"
	exit 1
fi

print_success "Limine files installed to ESP"

print_status "Creating UEFI boot entry for Limine..."
ESP_DEVICE=$(df "$ESP_PATH" | tail -1 | awk '{print $1}')
ESP_DISK=$(echo "$ESP_DEVICE" | sed 's/[0-9]*$//')
ESP_PART_NUM=$(echo "$ESP_DEVICE" | sed 's/.*[^0-9]//')

efibootmgr -c -d "$ESP_DISK" -p "$ESP_PART_NUM" -L "Limine" -l "\\EFI\\Limine\\limine_x64.efi" || {
	print_warning "Could not create UEFI boot entry automatically"
}

print_success "Limine UEFI boot entry created"

print_status "Configuring kernel command line..."
echo "$CURRENT_CMDLINE" >/etc/kernel/cmdline
print_success "Kernel command line configured: $CURRENT_CMDLINE"

print_status "Configuring Limine..."
[[ ! -f "/etc/default/limine" ]] && cat >/etc/default/limine <<EOF
SPACE_NUMBER=2
ENABLE_VERIFICATION=yes
BACKUP_THRESHOLD=8
BOOT_ORDER="*, *fallback, Snapshots"
ENABLE_SORT=no
ENABLE_LIMINE_FALLBACK=no
FIND_BOOTLOADERS=yes
ROOT_SNAPSHOTS_PATH="/@snapshots"
EOF

print_status "Creating custom Limine configuration..."
cat >"$ESP_PATH/limine.conf" <<'EOF'
### Read more at config document: https://github.com/limine-bootloader/limine/blob/trunk/CONFIG.md
timeout: 1
### Note: For "default_entry" to select a sub-entry within an OS menu, modify "/OS name" to "/+OS name" to keep its submenus visible.
default_entry: 2
#interface_branding_color: 3
interface_branding:
hash_mismatch_panic: no
term_palette: 1e1e2e;f38ba8;a6e3a1;f9e2af;89b4fa;f5c2e7;94e2d5;cdd6f4
term_palette_bright: 585b70;f38ba8;a6e3a1;f9e2af;89b4fa;f5c2e7;94e2d5;cdd6f4
term_background: 1e1e2e
term_foreground: cdd6f4
term_background_bright: 585b70
term_foreground_bright: cdd6f4

EOF

print_status "Generating Limine boot entries..."
limine-update
print_success "Limine configuration created"

print_status "Setting Limine as default boot option..."
LIMINE_ENTRY=$(efibootmgr | grep "Limine" | head -1 | cut -c5-8)

if [[ -n "$LIMINE_ENTRY" ]]; then
	CURRENT_ORDER=$(efibootmgr | grep "BootOrder" | cut -d' ' -f2)
	NEW_ORDER=$(echo "$CURRENT_ORDER" | sed "s/$LIMINE_ENTRY,//g" | sed "s/,$LIMINE_ENTRY//g" | sed "s/^$LIMINE_ENTRY$//g")

	if [[ -n "$NEW_ORDER" ]]; then
		efibootmgr -o "$LIMINE_ENTRY,$NEW_ORDER"
	else
		efibootmgr -o "$LIMINE_ENTRY"
	fi

	print_success "Limine set as default boot option"
else
	print_warning "Could not find Limine boot entry to set as default"
fi

print_status "Removing systemd-boot components..."

# Remove systemd-boot UEFI entries
SYSTEMD_ENTRIES=$(efibootmgr | grep -i "Linux Boot Manager\|systemd" | cut -c5-8 || true)
if [[ -n "$SYSTEMD_ENTRIES" ]]; then
	for entry in $SYSTEMD_ENTRIES; do
		print_status "Removing UEFI boot entry: Boot$entry"
		efibootmgr -b "$entry" -B || print_warning "Failed to remove boot entry $entry"
	done
fi

# Remove systemd-boot files from ESP
if [[ -d "$ESP_PATH/EFI/systemd" ]]; then
	print_status "Removing systemd-boot EFI files..."
	rm -rf "$ESP_PATH/EFI/systemd"
	print_success "systemd-boot EFI files removed"
fi

if [[ -d "$ESP_PATH/loader" ]]; then
	print_status "Removing systemd-boot configuration..."
	rm -rf "$ESP_PATH/loader"
	print_success "systemd-boot configuration removed"
fi

if [[ -f "$ESP_PATH/limine.conf" ]]; then
	print_success "Limine configuration file exists"
else
	print_error "Limine configuration file missing!"
fi

if [[ -f "$ESP_PATH/EFI/Limine/limine_x64.efi" ]]; then
	print_success "Limine EFI bootloader exists"
else
	print_error "Limine EFI bootloader missing!"
fi

sudo pacman -S snap-pac
sudo systemctl enable --now limine-snapper-sync.service

echo
print_success "TRANSITION COMPLETED SUCCESSFULLY!"
echo
print_status "Summary:"
echo "  • Limine bootloader installed to: $ESP_PATH/EFI/Limine/"
echo "  • Configuration file: $ESP_PATH/limine.conf"
echo "  • Kernel command line: /etc/kernel/cmdline"
echo "  • Backup created at: $BACKUP_DIR"
echo "  • Boot order updated"
echo "  • systemd-boot completely removed"
echo
print_warning "IMPORTANT: Reboot to test the new Limine setup!"
print_warning "systemd-boot has been completely removed - ensure Limine works before removing backup!"
print_success "Script completed. Please reboot when ready."