#!/usr/bin/env ruby
#
# Copyright (C) 2013 Red Hat, GmbH
# 
# Simple XML metadata creation tool
#

require 'optparse'
require 'pathname'

#----------------------------------------------------------------

$prg = Pathname.new($0).basename

def init_units
  units = {}
  units[:bytes_per_sector] = 512
  units[:chars] = "bskKmMgGtTpPeEzZyY"
  units[:strings] = [ 'bytes', 'sectors',
                      'kilobytes', 'kibibytes', 'megabytes',  'mebibytes',
                      'gigabytes', 'gibibytes', 'terabytes',  'tebibytes',
                      'petabytes', 'pebibytes', 'exabytes',   'ebibytes',
                      'zetabytes', 'zebibytes', 'yottabytes', 'yobibytes' ]
  units[:factors] = [ 1, units[:bytes_per_sector] ]
  1.step(8) { |e| units[:factors] += [ 1024**e, 1000**e ] }
  units
end

def get_index(unit_char, units)
  unit_char ? units[:chars].index(unit_char) : 1
end

def to_sectors(size, units)
  a = size.split(/[#{units[:chars]}]/)
  s = size.to_i.to_s
  abort "#{$prg} - only one unit character allowed!" if a.length > 1 || size.length - s.length > 1
  abort "#{$prg} - invalid unit specifier!" if s != a[0]
  size.to_i * units[:factors][get_index(size[a[0].length], units)] / units[:bytes_per_sector]
end

def check_opts(opts)
  abort "#{$prg} - 3 arguments required!" if opts.length < 3
  abort "#{$prg} - block size must be > 0" if opts[:blocksize] <= 0
  abort "#{$prg} - thin size must be much greater/equal blocksize" if opts[:thinsize] < opts[:blocksize]
  abort "#{$prg} - number of thin provisioned devices or snapshots must be > 0" if opts[:thins].nil? || opts[:thins] == 0
  abort "#{$prg} - size variation too large!" if !opts[:variation].nil? && (opts[:variation] > 2 * (opts[:thinsize] - opts[:blocksize]))
end

def parse_command_line(argv, units)
  opts = {}

  os = OptionParser.new do |o|
    o.banner = "Thin Provisioning XML Test Metadata Generator.\nUsage: #{$prg} [opts]"
    o.on("-b", "--block-size BLOCKSIZE[#{units[:chars]}]", String,
         "Block size of thin provisioned devices.") do |bs|
      opts[:blocksize] = to_sectors(bs, units)
    end
    o.on("-s", "--thin-size SIZE[#{units[:chars]}]", String, "Average size of thin devices and snapshots.") do |sz|
      opts[:thinsize] = to_sectors(sz, units)
    end
    o.on("-r", "--range-mappings", "Create range mappings") do
      opts[:range] = true
    end
    o.on("-t", "--thins #THINS", Integer, "Sum of thin devices and snapshots.") do |mt|
      opts[:thins] = mt
    end
    o.on("-v", "--size-variation SIZE[#{units[:chars]}]", String, "Size variation of thin devices and snapshots.") do |sv|
      opts[:variation] = to_sectors(sv, units)
    end
    o.on("-h", "--help", "Output this help.") do
      puts o
      exit
    end
  end

  begin
    os.parse!(argv)
  rescue OptionParser::ParseError => e
    abort "#{$prg} #{e}\n#{$prg} #{os}"
  end

  check_opts(opts)
  opts
end

def begin_superblock(blocksize, nr_data_blocks)
  "<superblock uuid=\"\" time=\"0\" transaction=\"1\" data_block_size=\"#{blocksize}\" nr_data_blocks=\"#{nr_data_blocks}\">"
end

def end_superblock
  "</superblock>"
end

def begin_device(devid, size)
  "  <device dev_id=\"#{devid}\" mapped_blocks=\"#{size}\" transaction=\"0\" creation_time=\"0\" snap_time=\"0\">"
end

def end_device
  "  </device>"
end

def single_mapping(from, to)
  "    <single_mapping origin_block=\"#{from}\" data_block=\"#{to}\" time=\"1\"/>"
end

def range_mapping(from, to, length)
  "    <range_mapping origin_begin=\"#{from}\" data_begin=\"#{to}\" length=\"#{length}\" time=\"1\"/>"
end

def blocks(opts)
  opts[:thinsize] / opts[:blocksize]
end

def this_blocks(opts)
  opts[:variation].nil? ? blocks(opts) : (2 * opts[:thinsize] - rand(opts[:variation])) / 2 / opts[:blocksize]
end

def xml_metadata(opts, units)
  blks, dev_id, nr_data_blocks, to = [], 0, 0, 0

  0.step(opts[:thins] - 1) do
    blks << (b = this_blocks(opts))
    nr_data_blocks += b
  end

  puts begin_superblock(opts[:blocksize], nr_data_blocks)
  blks.each do |b|
    if opts[:range]
      puts begin_device(dev_id, b), range_mapping(0, to, b), end_device
    else
      puts begin_device(dev_id, b)
      0.step(b - 1) { |from| puts single_mapping(from, to + from) }
      puts end_device
    end
    dev_id += 1
    to += b
  end
  puts end_superblock
end


#----------------------------------------------------------------
# Main
#
xml_metadata(parse_command_line(ARGV, (units = init_units)), units)