#!/usr/bin/env bash

#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.

# Print manual if no parameters provided or invalid amount of parameters is provided
if [[ ! -n $1 || -n $2 ]]; then
	cat <<- END
	Usage: bttrfs-build [variant]
	Variants:
	  archlinux		Plain Arch Linux TTY image
	  arkanelinux		Arkane Linux GNOME image
	  debian		Plain Debian TTY image

	Variants are loaded based on their directory names, the ones listed here
	 are included by default. For information on the exact configuration of
	 these variants or to create your own see /etc/bttrfs/variants.
	END
	exit 0
fi

## Set common variables
#
declare -r workdir='/var/tmp/arkane-root'
declare -r configs_dir='./bttrfs/'
declare -r variant="$configs_dir/variants/$1"
declare -r type=$(cat $variant/type)
declare -r output_target='./output.img'

## Common functions
#
# Cleanup and quit if error
cleanup_and_quit () {

	# If any paramters are passed we will assume it to be an error
	[[ -n $1 ]] && printf "\e[1;31m<#>\e[0m $*\e[0m\n" >&2

	# Remove temporary btrfs volumes
	[[ ! -n $BTTRFS_NO_CLEANUP ]] && btrfs subvolume delete $workdir 2> /dev/null

	# Quit program if argument provided to function
	[[ -n $1 ]] && exit 1

	# Otherwise just quit, there is no error
	exit 0

}

## Error checking
#
# Quit if not root
[[ ! $EUID -eq 0 ]] &&
	printf '\e[1;31m<#>\e[0m\e[1m This program has to be run as root\n\e[0m' &&
	exit 1

# Check if all dependencies are installed, quit if not
for prog in btrfs pacstrap; do
	if ! command -v $prog > /dev/null; then
		printf "\e[1;31m<#>\e[0m\e[1m Failed to locate $prog, ensure it is installed\e[0m\n"
		exit 1
	fi
done

# Check if requested variant exists
[[ ! -d $variant ]] &&
	printf '\e[1;31m<#>\e[0m\e[1m The requested variant does not exist\e[0m\n' &&
	exit 1

## Variants
#
# Build archlinux type image
if [[ $type -eq 'archlinux' ]]; then

	# Ensure base.list exists, if not error and quit
	[[ ! -e $variant/base.list ]] &&
		printf "\e[1;31m<#>\e[0m\e[1m The required file 'base.list' is not preset in $(readlink -m $variant)\e[0m\n" &&
		exit 1

	# Check if optional packages.list file exists, if not notify and continue
	[[ ! -e $variant/packages.list ]] &&
		printf "\e[1;34m-->\e[0m\e[1m The optional file 'packages.list' is not preset in $(readlink -m $variant), running without it\e[0m\n" &&
		skip_secondary_package_installation=1

	printf '\e[1;34m-->\e[0m\e[1m Started Arch linux image build\e[0m\n'

	# Create temporary Btrfs subvolume
	printf "\e[1;34m-->\e[0m\e[1m Creating temporary Btrfs subvolume at $(readlink $workdir)\e[0m\n"
	btrfs subvolume create $workdir || cleanup_and_quit "Failed to create btrfs subvolume $(readlink $workdir)"

	# Read base package list and install base system
	readarray base_packages < $variant/base.list
	printf "\e[1;34m-->\e[0m\e[1m Installing base packages\e[0m\n"
	pacstrap $workdir ${base_packages[*]} || cleanup_and_quit 'Failed to install secondary package list'

	# Read package list and install secondary system components, skip if not used
	if [[ ! -n skip_secondary_package_installation ]]; then
		printf '\e[1;34m-->\e[0m\e[1m Installing secondary packages...\e[0m\n'
		readarray packages < $variant/packages.list
		arch-chroot $workdir pacman -S --noconfirm ${packages[*]} || cleanup_and_quit 'Failed to install base packages'
	fi

	# If rootfs directory exists in variant copy it to the temporary subvolume
	if [[ -d $variant/rootfs ]]; then
		cp -rv $variant/rootfs/* $workdir/
	fi

	# Remove subvolumes created by systemd
	[[ -d $workdir/var/lib/portables ]] &&
		printf "\e[1;34m-->\e[0m\e[1m Removing systemd subvolume var/lib/portables\e[0m\n" &&
		btrfs subvolume delete $workdir/var/lib/portables
	[[ -d $workdir/var/lib/machines ]] &&
		printf "\e[1;34m-->\e[0m\e[1m Removing systemd subvolume var/lib/machines\e[0m\n" &&
		btrfs subvolume delete $workdir/var/lib/machines

	# Make subvolume read-only
	printf "\e[1;34m-->\e[0m\e[1m Adding read-only property to subvolume\e[0m\n"
	btrfs property set -ts $workdir ro true

	# Write subvolume to image
	printf "\e[1;34m-->\e[0m\e[1m Writing image...\e[0m\n"
	btrfs send -f $output_target $workdir

	cleanup_and_quit
fi