argraph

#!/usr/bin/env ruby
# ActiveRecord belongs_to graph generator (for rails apps)
# by tlehman
#
# If no args are given, all models are mapped out.
# Otherwise, the graph is restricted to the models given
#   Example:
#       $ argraph Author Post Comment
#       digraph {
#         Post -> Author
#         Comment -> Post
#       }

class Model < Struct.new(:filename, :modelname, :parents); end

def parents_of(filename)
  lines = File.open(filename).readlines
  parents = []
  lines.grep(/belongs_to/).each do |line|
    if /:class_name => .(?<other_model>([A-Z][a-z]*)+)./ =~ line
      parents << other_model
    else
      /^\s*belongs_to :(?<other_model>[a-z_]+)/ =~ line
      next unless other_model
      parents << camel_case(other_model)
    end
  end
  parents.uniq
end

def all_models
  models = []
  Dir["app/models/**/*.rb"].each do |filename|
    file = File.open(filename)
    contents = file.read
    file.close

    /class (?<modelname>([A-Z][a-z]*)+) < ActiveRecord::Base/ =~ contents
    next unless modelname

    models << Model.new(filename, modelname, parents_of(filename))
  end

  models
end

def camel_case(snake_case)
  snake_case.split("_").map(&:capitalize).join
end

def print_as_digraph(models)
  puts "digraph {"

  models.each do |model|
    model.parents.each do |parent|
      puts " #{model.modelname} -> #{parent}"
    end
  end

  puts "}"
end

def model_list_given?
  return false if ARGV.empty?

  ARGV.all? { |arg| arg.match(/([A-Z][a-z]+)/) }
end

def models_from_args
  models = []
  ARGV.each do |arg|
    filename = `grep -r 'class #{arg} *<' app/models | awk -F: '{print $1}'`.strip
    if filename == ""
      STDERR.puts "Error: #{arg} is not a model" 
      next
    end
    models << Model.new(filename, arg, parents_of(filename) & ARGV)
  end
  models
end

def main
  models = model_list_given? ? models_from_args : all_models

  print_as_digraph(models)
end

main