This is a bit of a rubbish script that spiders thru json and decides whether something is a timestamp or not on some assy heuristics - basically if you have a bunch of numbers and you think some of them are dates then it will convert them

fixDates.rb

#!/usr/bin/env ruby
require 'json'
require 'pry'
require 'date'

# basically if the number results in a ts that is less than 10 years ago it's probably a timestamp :D 
YEARS_TO_BE_CONSIDERED_TIMESTAMP = 10

def fix_potential_timestamp potential_timestamp
#  binding.pry
  as_timestamp = DateTime.strptime(potential_timestamp.to_s, "%Q")
  if (DateTime.now.year - as_timestamp.year) > YEARS_TO_BE_CONSIDERED_TIMESTAMP
    potential_timestamp
  else
    as_timestamp.strftime("%FT%T.%3NZ")
  end
end

def fix_date data
  case data
    when String 
    data
    when Fixnum
    fix_potential_timestamp(data)
    when Array
    data.map {|x| fix_date(x)}
    when Hash
    data.inject({}) do |h, (k, v)|
      h[k] = fix_date(v)
      h
    end
  end
end


#ARGF.each do |line|
  #puts JSON.generate(fix_date(JSON.parse(line)))
#end

ARGF.each do |line|
  puts line
end