require 'to_lvm_xfs'

class Raspbian < Base
	Sizes = {
		''  => 1,
		'b' => 1,
		's' => 512,
		'k' => 1024,
		'm' => 1024*1024,
		'g' => 1024*1024*1024,
		't' => 1024*1024*1024*1024,
		'p' => 1024*1024*1024*1024*1024,
		'e' => 1024*1024*1024*1024*1024*1024,
	}

	Volume = Struct.new :sh, :name, :device, :mountpoint, :builder_mp, :size do
		def uuid()  sh.fs_uuid device  end
		def type()  sh.fs_type device  end

		def to_fstab_entry
			FSTabMountEntry.new "UUID=#{uuid}", mountpoint, type, 'defaults,noatime', nil, nil
		end
	end

	def initialize *args
		@vgname = "raspi_#{SecureRandom.urlsafe_base64 5}"
		@volumes = { root: ['/', '4.2G'], home: ['/home', '100M'] }
		super *args
		@vgpath = XPathname.new( '/dev') + @vgname

		STDERR.printf "Volumes:\n"
		vols = {}
		@volumes.each do |name, (mp, size)|
			mp = XPathname.new( mp).cleanpath
			vols[mp.to_s] = Volume.new sh, name.to_s, @vgpath+name.to_s, mp, dest.root + mp.to_s[1..-1], size
			STDERR.printf "%13s: %s (%s)\n", name, mp, size
		end
		@volumes = vols
	end

	def getopts opts
		super opts
		opts.on '-vNAME', '--volume=NAME', 'Creates additional volume name:mountpoint=size or overwrites defaults.' do |v|
			m = %r<\A([0-9a-z_-]+):(/[0-9a-z/_-]*)=([0-9.]+[%a-z]?)\z>i.match v
			fail "Volume expected in format: \"name:mountpoint=size\""  unless m
			@volumes[m[1].to_sym] = [XPathname.new( m[2]).cleanpath, m[3]]
		end
	end

	def build
		ENV['LANG'] = 'C'
		mkmppaths

		case
		when !dest.image.exist?
		when dest.image.file?
			r = sh.losetup_list
			unless r.empty? or r['loopdevices']
				r['loopdevices'].each do |lo|
					fail "File #{dest.image} used as loop-device back-file"  if +dest.image == +XPathname.new( lo['back-file'])
				end
			end
		when dest.image.blockdev?, dest.image.chardev?
			lsblk( dest.image).each do |l|
				fail "Device #{l[:name]} mounted at #{l[:mountpoint]}"  if l[:mountpoint]
			end
		end

		task "Mount base image #{base.image}" do
			sh.partx -:u, base.image  if base.image.blockdev?

			fail "Base image does not exist"  unless base.image.exist?
			base_parts = kpartx base.image
			fail "two partitions in base expected, got: #{base_parts.inspect}"  unless 2 == base_parts.length
			mount base_parts[1], base.root, -:oro
			mount base_parts[0], base.root+'boot', -:oro
		end

		dest.image.open 'w' do |f|
			size =
				@volumes.inject 136*1024*1024 do |s, (_n, vol)|
					m = /\A([0-9.]+)([bBsSkKmMgGtTpPeE]?)\z/i.match vol.size
					fail "invalid size: #{vol.size}"  unless m
					s + m[1].to_f * Sizes[m[2].downcase]
				end
			f << 0.chr*4096
			f.pos = size - 1
			f.putc 0.chr
		end
		task "Partitioning destination image #{dest.image}" do
			sh.parted dest.image, *%w[--
				mklabel msdos
				mkpart primary fat32   4MB 132MB
				mkpart primary ext2  132MB   -1s
				set 2 LVM on
				print]
			sh.partx -:u, dest.image  if dest.image.blockdev?
		end
		
		*dest_parts =
			begin
				lsblk( dest.image).select do |l|
					sh.dmsetup :remove, File.basename(l[:name])  if 'lvm' == l[:type]
					l[:name].start_with?( dest.image.to_s) and 'part' == l[:type]
				end.map {|l| XPathname.new l[:name] }.sort
			rescue Sh::ProcessError
				kpartx dest.image
			end
		fail "two partitions in destination expected"  unless 2 == dest_parts.length
		task "Prepare boot-partition #{dest_parts[0]} and lvm #{dest_parts[1]}" do
			dest_parts[0].open( 'w') {|f| f << 0.chr*4*1024*1024 }
			dest_parts[1].open( 'w') {|f| f << 0.chr*4*1024*1024 }
			sh.vgscan '--cache'
			sh.pvcreate -:ff, dest_parts[1]
			sh.vgcreate vgname, dest_parts[1]
			@volumes.each {|_name, vol| sh.lvcreate "-n#{vol.name}", "-L#{vol.size}", vgname }
			sh.vgchange -:ae, vgname
			sh.mkvfat -:nboot, dest_parts[0]
			@volumes.each {|_name, vol| sh.mkxfs "-mreflink=1", "-L#{vol.name}", vol.device }
		end

		addmp = {run_udev: dest.root+'run/udev'}
		task "Mount all filesystems" do
			mount @vgpath+'root', dest.root
			(%i[boot]).each do |n|
				d = addmp[n] = dest.root+n.to_s
				d.mkdir  unless d.exist?
			end
			mount dest_parts[0], addmp[:boot]

			@volumes.each do |_name, vol|
				path = vol.builder_mp
				next  if dest.root == path || addmp.values.include?( path)
				path.mkdir  unless path.exist?
				mount @vgpath+vol.name, path
			end
		end

		task "Copy raspbian from base to dest" do
			sh.rsync_all "#{base.root}/", dest.root
		end

		task "Mount all special filesystems" do
			(%i[dev proc sys]).each do |n|
				d = addmp[n] = dest.root+n.to_s
				d.mkdir  unless d.exist?
			end
			mount '/dev',  addmp[:dev],  --:bind
			mount 'proc',  addmp[:proc], -:tproc
			mount 'sysfs', addmp[:sys],  -:tsysfs
		end

		task "Prepare users" do
			install_authorized_keys
			rename_user
		end

		task "Prepare /etc and /boot" do
			update_fstab @volumes.map { |_name, vol| vol.to_fstab_entry } +
				[ FSTabMountEntry.new( "UUID=#{sh.fs_uuid( dest_parts[0])}", '/boot', 'vfat', 'defaults', 1, 1)]

			addmp[:boot].join( 'config.txt').replace_i do |f|
				replace = {
					'pi4' => { initramfs: 'initramfs initrd8.img followkernel', arm_64bit: 'arm_64bit=1' },
					'pi3' => { initramfs: 'initramfs initrd8.img followkernel', arm_64bit: 'arm_64bit=1' },
					'pi2' => { initramfs: 'initramfs initrd7.img followkernel', },
					'pi1' => { initramfs: 'initramfs initrd.img followkernel', },
					'pi0' => { initramfs: 'initramfs initrd.img followkernel', },
				}
				blocks = [nil]
				content = Hash.new {|h,block| h[block] = [] }
				block = nil
				f.each_line do |l|
					l.chomp!
					case l
					when /\A\[([^\]]*)\]\z/
						block = $1
						blocks.push block
					when /\Ainitramfs /
						l = replace[block].delete :initramfs
					end
					content[block].push l
				end
				replace.each {|block, rpl| content[block] += rpl.values + ['']  unless rpl.empty? }
				blocks.flat_map {|block| content[block] }
			end

			addmp[:boot].join( 'ssh').write ''

			addmp[:boot].join( 'cmdline.txt').replace_i do |f|
				lines = f.readlines
				fail "Only one line in cmdline.txt expected"  unless 1 == lines.length
				opts = {}
				lines[0].split( ' ').each do |line|
					/^([^=]*)(?:=(.*))?/ =~ line
					opts[$1.to_sym] = $2
				end
				opts[:root] = @vgpath+'root'
				opts[:rootfstype] = :xfs
				opts.delete :init
				opts.map {|k,v| v ? "#{k}=#{v}" : "#{k}" }.join(' ')
			end

			dest.root.join( 'etc').chdir do
				XPathname.glob( 'rc*.d/*resize2fs_once').each do |fn|
					fn.unlink
				end
			end

			set_hostname
		end

		preload, preload_x = dest.root+'etc/ld.so.preload', dest.root+'etc/ld.so.preload.tp'
		task "Prepare to chroot to raspbian" do
			@qemu_bin.copy @qemu_bin_src, preserve: true
			after { @qemu_bin.unlink }

			if preload.exist?
				preload.rename preload_x
				after { preload_x.rename preload }
			end
		end

		task "update, upgrade and install" do
			ish = sh.chroot( dest.root).chdir( '/')
			ish.apt :update
			ish.apt :upgrade, -:y
			ish.apt :update

			install_packages_from_dir(
				XPathname.new( $0).expand_path.dirname + 'raspbian-files',
				XPathname.new( 'files')
			)

			# We mount /run/udev for lvm-scanning - vgs / vgcfgbackup need it to connect to udev.
			addmp[:run_udev].mkdir
			mount '/run/udev', addmp[:run_udev], --:bind

			# prevent installing exim by installing nullmailer
			#ish.apt *%w[install -y lvm2 xfsprogs nullmailer dracut]
			#dest.root.join( 'etc/dracut.conf.d/10-denkn.conf').open 'w' do |f|
			#	f.puts 'add_modules+="lvm"'
			#	f.puts 'add_drivers+="dm-mod xfs"'
			#	f.puts 'compress="xz"'
			#end

			ish.apt *%w[install -y lvm2 xfsprogs initramfs-tools]
			dest.root.join( 'etc/initramfs-tools/initramfs.conf').replace_i do |f|
				replace = { compress: 'COMPRESS=xz', }
				f.each_line.flat_map do |l|
					case l.chomp!
					when /^COMPRESS=/    then replace.delete :compress
					when /^# *COMPRESS=/ then [l, replace.delete( :compress)]
					else l
					end
				end + replace.values
			end

			# strange error while generating initramfs;
			# it want to delete this directory, but it does not exist.
			#overlays = dest.root + 'usr/share/rpikernelhack/overlays'
			#overlays.mkpath
			#overlays.join( '.keep').write ''

			# generates implicite initramfs
			ish.system *%w[dpkg-reconfigure raspberrypi-kernel]
		end
	end
end