module EacRubyUtils::LocalTimeZone

def auto
  %w[tz_env debian_config offset].lazy.map { |s| send("by_#{s}") }.find(&:present?)
end

def auto_set
  ::Time.zone = auto
end

def by_debian_config
  path = ::Pathname.new(DEBIAN_CONFIG_PATH)
  path.exist? ? path.read.strip.if_present { |v| ::ActiveSupport::TimeZone[v] } : nil
end

def by_offset
  ::ActiveSupport::TimeZone[::Time.now.getlocal.gmt_offset]
end

def by_timedatectl
  executable = ::EacRubyUtils::Envs.local.executable('timedatectl', '--version')
  return nil unless executable.exist?
  TIMEDATECTL_TIMEZONE_LINE_PATTERN.if_match(executable.command.execute!) { |m| m[1] }
    .if_present { |v| ::ActiveSupport::TimeZone[v] }
end

def by_tz_env
  ENV['TZ'].presence
end