#!/usr/bin/env ruby
require 'json'
require 'pathname'
require 'fileutils'
require 'open3'

LXC_PATH = Pathname.new("/data/containers")
BACKUP_LOCATIONS = %w{home srv etc usr/local}
CONFIG_PATH = "/etc/lxc/container.json"
BACKUP_PATH = "/mnt/backup/attic"
ATTIC_PATH = Pathname.new("/data/attic")
PASSWORD_FILE = ATTIC_PATH.join("passwordfile").to_s
KEEP_DAILY = 7
KEEP_WEEKLY = 4
KEEP_MONTHLY = 0

def load_config
  return JSON.load(File.open(CONFIG_PATH))
rescue SystemCallError => e
  abort "failed to open configuration '#{CONFIG_PATH}', #{e}"
rescue JSON::ParserError => e
  abort "failed to parse configuration '#{CONFIG_PATH}', #{e}"
end

def sh(cmd, env={}, *args)
  pretty_args = args.map {|arg| "'#{arg}'"}
  puts ([cmd] + pretty_args).join(" ")
  system(env, cmd, *args)
end

class Container
  def initialize(name, backup_paths, backup_scripts)
    @name = name
    @backup_paths = backup_paths
    @backup_scripts = backup_scripts
    @path = LXC_PATH.join(name, "rootfs")
  end
  def backup_paths
    paths = BACKUP_LOCATIONS
    if @backup_paths.is_a?(Array)
      paths += @backup_paths
    end
    paths.map do |relative_path|
      @path.join(relative_path)
    end
  end
  def run_backup_scripts
    if @backup_scripts.is_a?(Array)
      @backup_scripts.map do |script|
        backup_script(script)
      end
    else
      []
    end
  end

  private
  def backup_script(script)
    unless script.is_a?(Hash)
      abort("backup-scripts: Expected an Object, got #{script.class}")
    end
    command = script["command"]
    if command.nil?
      abort("command not set for backup-scripts for container '#{@name}'")
    end
    backupname = script["backupname"]
    if backupname.nil?
      abort("backupname not set for backup-scripts for container '#{@name}'")
    end
    backupname = ATTIC_PATH.join(backupname.gsub("/", ""))
    FileUtils.mkdir_p(backupname)
    puts "cd #{backupname}"
    Dir.chdir(backupname) do
      sh(command)
    end
    backupname
  end

  def empty_directory?(path)
    return false unless Dir.exists?(path)
    return Dir.entries(path).size <= 2 # - [".", ".."]
  end
end

config = load_config
backup_paths = BACKUP_LOCATIONS.map do |location|
  "/#{location}"
end
config["network"].each do |container, data|
  next if data["lxc"] == false
  container = Container.new(container, data["backup-paths"], data["backup-scripts"])
  backup_paths += container.backup_paths
  backup_paths += container.run_backup_scripts
end

env = { "ATTIC_PASSPHRASE" => File.read(PASSWORD_FILE).chomp }
now = Time.now.strftime("%Y-%m-%d-%H:%M:%S")
paths = backup_paths.map {|path| path.to_s }
sh("attic", env, "create", "--stats", "#{BACKUP_PATH}::eve-#{now}",
	'--exclude', '*/srv/repo',
	'--exclude', '*/home/joerg/git',
	'--exclude', '*/home/joerg/login/git',
	*paths)
sh("attic", env, "prune", "-v", BACKUP_PATH,
		"--keep-daily", KEEP_DAILY.to_s,
		"--keep-weekly", KEEP_WEEKLY.to_s,
		"--keep-monthly", KEEP_MONTHLY.to_s)