#!/usr/bin/env ruby
#
# William Stearns <wstearns@cloudpassage.com>

# Copyright (c) 2013, William Stearns <wstearns@cloudpassage.com>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without modification,
# are permitted provided that the following conditions are met:
#   * Redistributions of source code must retain the above copyright
#     notice, this list of conditions and the following disclaimer.
#   * Redistributions in binary form must reproduce the above copyright
#     notice, this list of conditions and the following disclaimer in the
#     documentation and/or other materials provided with the distribution.
#   * Neither the name of the CloudPassage, Inc. nor the
#     names of its contributors may be used to endorse or promote products
#     derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL CLOUDPASSAGE, INC. BE LIABLE FOR ANY DIRECT,
# INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED ANDON ANY THEORY OF
# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
# OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
# ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

# you may need to install the optparse, and json gems with:
# sudo gem install optparse json

#Version 0.5

#======== User-modifiable values
#======== End of user-modifiable values


#======== Functions
#======== End of functions


#======== Loadable modules
require 'rubygems'
require 'optparse'
require 'json'
#======== End of loadable modules


#======== Initialization
array_name = ""
filters = [ ]
connector_is_and = true
#======== End of initialization



optparse = OptionParser.new do |opts|
  opts.banner = "Print only certain elements of the top level array in a json block.  Usage: jsonfilter.rb [options]"

  opts.on("-a array_name", "Array name") do |array_name_input|
    array_name = array_name_input
  end

  opts.on("-f filter", "Filter") do |filter_input|
    filters << filter_input.split(" ",3) unless filters.include?(filter_input.split(" ",3))
  end

  opts.on("-o", "--or", "Change boolean connector to \"or\"") do
    connector_is_and = false
  end

  opts.on_tail("-h", "--help", "Show help text") do
    $stderr.puts opts
    exit
  end
end
optparse.parse!


raw_stdin_string = $stdin.read.gsub(/\n/," ")
insplit = raw_stdin_string.match(/^([^\{]*)(\{.*\})([^\}]*)/)
prefix = insplit[1]
raw_stdin = JSON insplit[2]
postfix = insplit[3]


json_to_print = "{ \"#{array_name}\": ["
displayed = 0


raw_stdin[array_name].each do |one_block|
  #Start with "true" if the tests are connected by "and", start with "false" if connected by "or"
  display = connector_is_and
  filters.each do |one_filter|
    case one_filter[1]
    when "==", "="
      #Must reverse logic to remove entries if the connector is "and"
      display = (not connector_is_and) if connector_is_and ^ (one_block[one_filter[0]] == one_filter[2])
    when "!="
      display = (not connector_is_and) if connector_is_and ^ (one_block[one_filter[0]] != one_filter[2])
    when ">"
#FIXME - can we remove .to_i to allow string comparisons as well?
      display = (not connector_is_and) if connector_is_and ^ (one_block[one_filter[0]].to_i > one_filter[2].to_i)
    when "<"
      display = (not connector_is_and) if connector_is_and ^ (one_block[one_filter[0]].to_i < one_filter[2].to_i)
    when "<="
      display = (not connector_is_and) if connector_is_and ^ (one_block[one_filter[0]].to_i <= one_filter[2].to_i)
    when ">="
      display = (not connector_is_and) if connector_is_and ^ (one_block[one_filter[0]].to_i >= one_filter[2].to_i)
    else
      $stderr.puts "Operator #{one_filter[1]} is not yet implemented, exiting."
      exit 1
    end
  end
  if display
    #$stderr.print '+'
    if displayed > 0
      json_to_print += ","
    end
    displayed += 1
    json_to_print += one_block.to_json.to_s
  #else
  #  $stderr.print '.'
  end
end
$stderr.flush
json_to_print += "\n]"

#Delete the array we've been working with; if there's anything left, we'll send it out unmodified
raw_stdin.delete(array_name)
if raw_stdin.length > 0
  json_to_print += ","
  #Print the remaining hash, minus the first ("{") and last ("}") characters
  json_to_print += raw_stdin.to_json[1,raw_stdin.to_json.length-2]
end

json_to_print += " }"

puts prefix
puts JSON.pretty_generate(JSON json_to_print)
puts postfix

#$stderr.puts " Complete."