require 'erb'

class GenerateStructs

  @@field_ignore_list = ['StrucId', 'Version', 'StrucLength']

  # Store path to WebSphere MQ Structures
  def initialize(wmq_includepath, templates_path = '.')
    @path           = wmq_includepath
    @templates_path = templates_path
  end

  def extract_struct (filename, struct_name)
    properties_list = []
    line_number     = 0
    found           = false
    File.open(filename) do |file|
      file.each do |line|
        line_number += 1
        line.rstrip!
        # Skip empty and comment lines
        if line.length > 0 && line !~ /^\s*\/\*/
          if !found
            found = true if line =~ /^\s*struct\s*tag#{struct_name}/
          else
            return(properties_list) if line =~ /^\s*\};/
            match = /\s*(MQ\w+)\s+(\w+);/.match(line)
            if match
              type    = match[1]
              element = match[2]
              properties_list.push([type, element])
            end
          end
        end
      end
    end
    properties_list
  end

  def rubyize_name(name)
    name.gsub(/::/, '/').
      gsub(/([A-Z]+)([A-Z][a-z])/, '\1_\2').
      gsub(/([a-z\d])([A-Z])/, '\1_\2').
      tr("-", "_").
      downcase
  end

  def self.test_rubyize_name
    test = self.new
    [
      ['a', 'a'],
      ['A', 'a'],
      ['Aa', 'aa'],
      ['AA', 'aa'],
      ['AaA', 'aa_a'],
      ['MyFieldName', 'my_field_name'],
      ['MMyFieldNName', 'm_my_field_n_name'],
      ['ABCdefGHIjKlMnOPQrSTuvwxYz', 'ab_cdef_gh_ij_kl_mn_op_qr_s_tuvwx_yz']
    ].each do |item|
      str = test.rubyize_name(item[0])
      raise("rubyize_name('#{item[0]}') == #{str} != '#{item[1]})") if str != item[1]
    end
  end

  def generate_structs(erb)
    erb.result(binding)
  end

  def generate(target_filename = 'wmq_structs.c')
    erb = nil
    File.open(@templates_path+'/wmq_structs.erb') { |file| erb = ERB.new(file.read) }
    File.open(target_filename, 'w') { |file| file.write(generate_structs(erb)) }
    puts "Generated #{target_filename}"
  end
end

# TODO Auto Daisy-Chain Headers: Format, CodedCharSetId, Encoding
# TODO During Deblock validate that data size left at least matches struct size
if $0 == __FILE__
  path = ARGV[0] || raise("Mandatory parameter: 'WebSphere MQ Include path' is missing")
  path = path + '/'
  GenerateStructs.new(path, 'generate').generate
end