ioquatix/lsync

# Copyright, 2016, by Samuel G. D. Williams. <http://www.codeotaku.com>
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

# This script takes a given path, and renames it with the given format. 
# It then ensures that there is a symlink called "latest" that points 
# to the renamed directory.

require 'samovar'

require 'periodical/filter'

# Required for strptime
require 'date'

module Synco
    module Command
        class Rotation
            include Comparable
            
            def initialize(path, time)
                @path = path
                @time = time
            end

            attr :time
            attr :path
            
            # Sort in reverse order by default
            def <=> other
                other.time <=> @time
            end
            
            def eql? other
                case other
                when Rotation
                    @path.eql?(other.path)
                else
                    @path.eql?(other.to_s)
                end
            end
            
            def hash
                @path.hash
            end
            
            def to_s
                @path
            end
        end
        
        class Prune < Samovar::Command
            self.description = "Prune old backups to reduce disk usage according to a given policy."
            
            options do
                option "--hourly <count>", "Set the number of hourly backups to keep.", default: 24, type: Integer
                option "--daily <count>", "Set the number of daily backups to keep.", default: 7*4, type: Integer
                option "--weekly <count>", "Set the number of weekly backups to keep.", default: 52, type: Integer
                option "--monthly <count>", "Set the number of monthly backups to keep.", default: 12*3, type: Integer
                option "--quarterly <count>", "Set the number of quaterly backups to keep.", default: 4*10, type: Integer
                option "--yearly <count>", "Set the number of yearly backups to keep.", default: 20, type: Integer
                
                option "--format <name>", "Set the name of the backup rotations, including strftime expansions.", default: BACKUP_NAME
                option "--latest <name>", "The name of the latest backup symlink.", default: LATEST_NAME
                
                option "--keep <new|old>", "Keep the younger or older backups within the same period division", default: 'old'
                
                option "--dry", "Print out what would be done rather than doing it."
            end
            
            def policy
                policy = Periodical::Filter::Policy.new
                
                policy << Periodical::Filter::Hourly.new(@options[:hourly])
                policy << Periodical::Filter::Daily.new(@options[:daily])
                policy << Periodical::Filter::Weekly.new(@options[:weekly])
                policy << Periodical::Filter::Monthly.new(@options[:monthly])
                policy << Periodical::Filter::Quarterly.new(@options[:quarterly])
                policy << Periodical::Filter::Yearly.new(@options[:yearly])
                
                return policy
            end
            
            def current_backups
                backups = []
                
                Dir['*'].each do |path|
                    next if path == @options[:latest]
                    date_string = File.basename(path)
                    
                    begin
                        backups << Rotation.new(path, DateTime.strptime(date_string, @options[:format]))
                    rescue ArgumentError
                        $stderr.puts "Skipping #{path}, error parsing #{date_string}: #{$!}"
                    end
                end
                
                return backups
            end
            
            def dry?
                @options[:dry]
            end
            
            def print_rotation(keep, erase)
                puts "*** Rotating backups (DRY!) ***"
                puts "\tKeeping:"
                keep.sort.each { |backup| puts "\t\t#{backup.path}" }
                puts "\tErasing:"
                erase.sort.each { |backup| puts "\t\t#{backup.path}" }
            end
            
            def perform_rotation(keep, erase)
                puts "*** Rotating backups ***"
                erase.sort.each do |backup|
                    puts "Erasing #{backup.path}..."
                    $stdout.flush

                    # Ensure that we can remove the backup
                    system("chmod", "-R", "ug+rwX", backup.path)
                    system("rm", "-rf", backup.path)
                end
            end
            
            def call
                backups = current_backups
                
                retain, erase = policy.filter(backups, keep: @options[:keep].to_sym, &:time)
                
                # We need to retain the latest backup regardless of policy
                if latest = @options[:latest] and File.exist?(latest)
                    latest_path = File.readlink(options[:latest])
                    latest_rotation = erase.find{|rotation| rotation.path == latest_path}
                    
                    if latest_rotation
                        puts "Retaining latest backup #{latest_rotation}"
                        erase.delete(latest_rotation)
                        retain << latest_rotation
                    end
                end

                if dry?
                    print_rotation(retain, erase)
                elsif erase.any?
                    perform_rotation(retain, erase)
                end
            end
        end
    end
end