Select configuration via flag -c

The configuration names used to be positional arguments at the end of
the invocation of mpbackup. Now, they are specified with the flag c and
can occur at any position.

This commit also adds the --version flag that prints the version number.

mpbackup

@@ -4,22 +4,43 @@ require 'optparse'
 require 'pathname'
 require 'yaml'
 
-ENV.delete('RESTIC_REPOSITORY')
-ENV.delete('RESTIC_PASSWORD')
-
 DEFAULT_CONFIG_FILE = Pathname.new('/etc/mpbackup/config.yaml')
+NAME = 'mpbackup'
+VERSION = '0.1.0'
+
+def set_restic_vars(repo, password)
+  ENV['RESTIC_REPOSITORY'] = repo
+  ENV['RESTIC_PASSWORD'] = password
+end
+
+def unset_restic_vars
+  ENV.delete('RESTIC_REPOSITORY')
+  ENV.delete('RESTIC_PASSWORD')
+end
+
+unset_restic_vars
 
 options = {}
+options[:config_names] = []
 
 OptionParser.new do |parser|
-  parser.on("-f CONFIG_FILE", "--config-file CONFIG_FILE", "Path to config file") do |v|
+  parser.on("-c NAME", "--configuration-name NAME", "Name of the configuration to use") do |v|
+    options[:config_names] << v
+  end
+
+  parser.on("-f CONFIG_FILE", "--config-file CONFIG_FILE", "Path to the configuration file") do |v|
     options[:config_file] = v
   end
 
-  parser.on("-h", "--help", "Prints this help") do
+  parser.on("-h", "--help", "Print this help") do
       puts parser
       exit
   end
+
+  parser.on('--version', "Print version number") do
+    puts "#{NAME}, #{VERSION}"
+    exit
+  end
 end.parse!
 
 if options[:config_file]
@@ -35,14 +56,15 @@ end
 
 def do_backup(config)
   puts "Applying configuration ‘#{config['name']}’ …"
-  ENV['RESTIC_REPOSITORY'] = config['repository']
+  repo = config['repository']
-  puts "Repository: #{ENV['RESTIC_REPOSITORY']}"
+  puts "Repository: #{repo}"
   if config['password-file']
     puts "Reading password from file #{config['password-file']} …"
-    ENV['RESTIC_PASSWORD'] = File.open(config['password-file'], &:gets).chomp
+    password = File.open(config['password-file'], &:gets).chomp
   else
-    ENV['RESTIC_PASSWORD'] = STDIN.getpass('Please put in your restic password: ')
+    password = STDIN.getpass('Please put in your restic password: ')
   end
+  set_restic_vars(repo, password)
 
   puts "Backing up with restic …"
   # https://restic.readthedocs.io/en/latest/040_backup.html#including-and-excluding-files
@@ -80,18 +102,18 @@ def do_backup(config)
     end
   end
 
-  ENV.delete('RESTIC_REPOSITORY')
+  unset_restic_vars
-  ENV.delete('RESTIC_PASSWORD')
 end
 
 puts "Using config file #{config_file} …"
 configs = YAML.load_stream(File.open(config_file))
-if ARGV.empty?
+config_names = options[:config_names]
+if config_names.empty?
   puts "No configuration name has been given. Will use the first "\
     "configuration from the file (‘#{configs.dig(0, 'name')}’)."
   do_backup(configs[0])
 else
-  ARGV.each do |config_name|
+  config_names.each do |config_name|
     configs.each do |config|
       if config_name == config['name']
         do_backup(config)