#!/usr/bin/env ruby

require 'optparse'
require 'yaml'
require 'tempfile'
require 'timeout'

def opt_parse(argv)
  options = {}
  @optparse = OptionParser.new do |opts|
    opts.banner = "Usage: #{__FILE__} --env <environment name> --database <database_name> --action <action> [options]"
    opts.separator ''
    opts.separator "Wrapper for eybackup used for listing, downloading and restoring database backups. The main purpose for this tool is to"
    opts.separator "simplify the process of accessing backups from one environment in a different environment (e.g. access Production backups"
    opts.separator "from Staging). This can also be used for restoring backups within the current environment."
    opts.separator ''
    opts.on('-h', '--help', 'Displays this Help message') { puts opts; exit}

    opts.separator ''
    opts.separator 'Common Options:'
    
    opts.on('-e', '--env environment_name', "Specifies the source environment name for the backups you will be working with.") { |env| options[:env] = env }
    opts.on('-d', '--database database_name', "Name of the source database to list backups for.") { |dbname| options[:databases] = [dbname] }
    actions=['list', 'restore', 'download']
    opts.on('-a', '--action action_name', "The action you want to perform using the backup #{actions}.") do |action|
      unless actions.include?(action)
        puts "Invalid action: '#{action}' must be one of #{actions}\n\n"
        puts opts
        exit 1
      end
      options[:action] = action
    end
    opts.on('-i', '--index BACKUP_INDEX', 'Download/Restore the backup specified by index','BACKUP_INDEX uses the format #{index_number}:#{db_name}',
        "The string 'last' will automatically reference the most recent available backup.") do |index|
      options[:index] = index
    end
    opts.on('-f', '--force', 'Force mode, skips all confirmation prompts for use with automated restores.') { options[:force] = true }
    
    opts.separator ''
    opts.separator 'Additional Options:'
    
    opts.on('-u', '--aws_secret_id key', 'AWS S3 Key') { |key| options[:aws_key_id] = key }
    opts.on('-p', '--aws_secret_key secret', 'AWS S3 Secret Key') { |secret| options[:aws_secret_key] = secret }
    opts.on('-b', '--backup_bucket bucket', 'AWS S3 bucket identifier') { |bucket| options[:backup_bucket] = bucket }
    opts.on('-v', '--verbose', "Enable debug info for this wrapper.") { $verbose = true }
    opts.on('-c', '--config', "Alternate config file for eyrestore (default ~/.eyrestore.confg.yml)") do |path| 
      unless File.exists?(path)
        puts "Invalid config file path '#{path}', no file at that location."
        exit 1
      end
      options[:def_config] = path
    end
    opts.separator ''
    opts.separator 'Examples:'
    opts.separator '* List backups from an environment named production for a database named todo'
    opts.separator "    sudo -i #{__FILE__} --env production --database todo --action list"
    opts.separator ''
    opts.separator '* Download the most recent backup from an environment named production for a database named todo'
    opts.separator "    sudo -i #{__FILE__} --env production --database todo --action download --index last"
    opts.separator ''
    opts.separator "* Download a backup from an environment named production for a database named todo, prompt with a list of available backups"
    opts.separator "    sudo -i #{__FILE__} --env production --database todo --action download"
    opts.separator ''
    opts.separator '* Restore the most recent backup from an environment named production for a database named todo'
    opts.separator "    sudo -i #{__FILE__} --env production --database todo --action restore --index last"
    opts.separator ''
  end
  @optparse.parse!
  options
end

def debug(msg)
  puts '[' + Time.now.strftime("%D %T") + ']: DEBUG: ' + msg if $verbose
end

def find_engine
  debug("Searching for database engine based on file '/etc/.*.backups.yml'")
  main_config = Dir['/etc/.*.backups.yml'].first
  abort "Failed to find eybackup config at '/etc/.*.backups.yml', this needs to run on a database instance." unless main_config
  debug("Found file '#{main_config}'")
  File.basename(main_config).split('.')[1]
end

def extra_validations(options)
  mandatory = [:databases, :env, :action]
  mandatory << :index if %w(download restore).include? options[:action]
  missing = mandatory.select{ |param| options[param].nil? }
  raise OptionParser::MissingArgument, missing.join(',') unless missing.empty?
end

def list_backups(engine, db, path)
  command = "eybackup -e #{engine} -l #{db} -c #{path}"
  debug("Listing backups with command: #{command}")
  res = %x{#{command}}
  last = res.chomp.split("\n").last
  if last.match(/0 backup\(s\) found/)
    abort "No Backups Found for that environment and database.\n Tips:\n  - double check the source environment name is correct\n  - you may have a legacy bucket (grep backup_bucket /etc/.*.backups.yml) in the source environment, pass to eyrestore with --backup_bucket"
  end
  res
end

def gets_timeout( prompt, secs )
  print prompt + "[timeout=#{secs}secs]: "
  Timeout::timeout( secs ) { gets.chomp }
rescue Timeout::Error
  puts "*timeout"
  ''  # return nil if timeout
end

def backup_idx(listing, index)
  if index == 'last'
    last_backup_idx(listing)
  else
    index
  end
end

def last_backup_idx(listing)
  last = listing.chomp.split("\n").last
  if last.split.first.match(/\d+:\w+/)
    index = last.split.first
  else
    index = last.split[3]
  end
end

options = opt_parse(ARGV)
options[:def_config] = '~/.eyrestore.config.yml' unless options[:def_config]

# auto-detect the type of database running in the given environment
engine = find_engine

# parse eybackup config file
config = YAML.load_file("/etc/.#{engine}.backups.yml")
this_env = config[:env]
# delete these just in case
config.delete(:env)
config.delete(:databases)

# override config from eyrestore config file
eyrestore = YAML.load_file(options[:def_config]) if File.exists?(options[:def_config])
config.merge!(eyrestore) unless eyrestore.nil?

# override config from command line options
config.merge!(options)
indexdb = config[:index].split(':')[1] if not config[:index].nil? and config[:index].include? ':'
config[:databases] = [indexdb] if config[:databases].nil? and not indexdb.nil? and indexdb.match(/^\w+$/)
begin
  extra_validations(config)
rescue OptionParser::MissingArgument => e
  puts e.message
  puts @optparse
  exit
end
debug("Config Options: '#{config}'")

# create a temporary configuration file from ~/.eyrestore.config.yml
temp_config = Tempfile.new("eyrestore")
temp_config.write(config.to_yaml)
temp_config.rewind
debug("Generated temporary config file: '#{temp_config.path}'")

db = config[:databases].first
temp = temp_config.path
if config[:action] == 'list' or ! config[:index]
  puts list_backups(engine, db, temp)
end

# confirm environment overwrite if restoring
if config[:action] == 'restore' and ! config[:force]
  response = gets_timeout("You are restoring the backup for '#{db}' from '#{config[:env]}' into '#{this_env}', THIS MAY BE DESTRUCTIVE; are you sure you want to proceed (Y/n) ? ", 30)
  exit unless response.downcase == 'y'
end


if ['download','restore'].include?(config[:action])  
  config[:index] = gets_timeout("Enter the backup index to use for #{config[:action]} (e.g. 9:#{db}) ", 30) unless config[:index]
  config[:index] = backup_idx(list_backups(engine, db, temp), config[:index])
  # config[:index] = last_backup_idx(list_backups(engine, db, temp)) if config[:index] == 'last'
  config[:index] = config[:index] + ":#{config[:databases].first}" if config[:index].match(/^\d+$/) and config[:databases] and config[:databases].size == 1
  abort "Invalid backup index '#{config[:index]}'; proper format is <number>:<dbname>." unless config[:index].match(/^\d+:\w+$/)
  
  action = config[:action] == 'restore' ? '-r' : '-d'
  debug("Set action flag for eybackup to '#{action}' based on action of '#{config[:action]}'")
  
  # test eybackup version for force option
  ey_cloud_server_version = Gem::Version.new(%x{/usr/local/ey_resin/ruby/bin/gem list ey_cloud_server}.split[1].gsub('(','').gsub(')','').gsub(',',''))
  force = ey_cloud_server_version >= Gem::Version.new('1.4.51') ? '--force' : ''
  debug("eybackup version '#{ey_cloud_server_version}' so force is set to '#{force}'")
  
  command="eybackup -e #{engine} -c #{temp} #{action} #{config[:index]} #{force}"
  
  puts "Running '#{config[:action]}' on index '#{config[:index]}'."
  debug("Running command: #{command}")
  
  res=%x{#{command}}
  puts res
  
  last_line = res.split("\n").last
  if last_line.nil?
    # No-op, eybackup messaging is adequate.
  elsif last_line.match(/^Filename/) and config[:action] == 'restore' and not last_line.match(/.gpz$/)
    puts "Restore complete!"
  else
    puts "Download complete!"
  end
end

# cleanup temporary config file
temp_config.close
temp_config.unlink