muzak

defmodule Test do
  def modify(num) do
    if num in [2, 5, 9, 10, 12, 31] do
      num
    else
      num + 1
    end
  end

  def add_to_num(num) do
    if num > 10 do
      num + 10
    else
      num + 1
    end
  end
end

#defmodule MutationTestingExperiment do
  #def mutate() do
    #{_mod, mod_binary, _filename} = :code.get_object_code(Test)

    #{:ok, {_, [{:abstract_code, {:raw_abstract_v1, [file, _module | rest] = abstract}}]}} =
      #:beam_lib.chunks(mod_binary, [:abstract_code])

    #Agent.start(fn -> abstract end, name: TestAgent)
    #renamed_forms = [file, {:attribute, 1, :module, TestSavedVersion} | rest]
    #altered_forms = Enum.map(abstract, &mutate/1)

    #compile_and_load(renamed_forms)
    #compile_and_load(altered_forms)
  #end

  #def unmutate() do
    #abstract = Agent.get(TestAgent, & &1)

    #:code.purge(Test)
    #:code.delete(Test)

    #compile_and_load(abstract)

    #:code.purge(Test.Saved.Version)
    #:code.delete(Test.Saved.Version)
  #end

  #defp compile_and_load(abstract) do
    #case :compile.forms(abstract, [:return_errors]) do
      #{:ok, module_name, binary} -> :code.load_binary(module_name, '', binary)
      #{:ok, module_name, binary, _} -> :code.load_binary(module_name, '', binary)
      #_ -> :error
    #end
  #end

  #defp mutate({:attribute, _, _, _} = form) do
    #form
  #end

  #defp mutate({:function, 2, :pure_fun, 1, body}) do
    #[{:clause, 2, [{:var, 2, :_num@1}], [], clause}] = body
    #new_clause = Enum.map(clause, &mutate/1)
    #{:function, 2, :pure_fun, 1, [{:clause, 2, [{:var, 2, :_num@1}], [], new_clause}]}
  #end

  #defp mutate({:case, 3, condition, clauses}) do
    #{:op, 3, :>, {:var, 3, :_num@1}, {:integer, 0, 10}} = condition

    #new_condition_1 = {:op, 3, :<, {:var, 3, :_num@1}, {:integer, 0, 10}}
    #new_condition_2 = {:op, 3, :>, {:var, 3, :_num@1}, {:integer, 0, 0}}

    #[clause1, clause2] = clauses

    #{:clause, [generated: true, location: 3], [{:atom, 0, false}], [],
     #[{:op, 6, :+, {:var, 6, :_num@1}, {:integer, 0, 1}}]} = clause1

    #new_clause1_1 =
      #{:clause, [generated: true, location: 3], [{:atom, 0, false}], [],
       #[{:op, 6, :-, {:var, 6, :_num@1}, {:integer, 0, 1}}]}

    #new_clause1_2 =
      #{:clause, [generated: true, location: 3], [{:atom, 0, false}], [],
       #[{:op, 6, :+, {:var, 6, :_num@1}, {:integer, 0, 0}}]}

    #new_clause1_3 =
      #{:clause, [generated: true, location: 3], [{:atom, 0, true}], [],
       #[{:op, 6, :+, {:var, 6, :_num@1}, {:integer, 0, 1}}]}

    #{:clause, [generated: true, location: 3], [{:atom, 0, true}], [],
     #[{:op, 4, :+, {:var, 4, :_num@1}, {:integer, 0, 10}}]} = clause2

    #new_clause2_1 =
      #{:clause, [generated: true, location: 3], [{:atom, 0, true}], [],
       #[{:op, 4, :-, {:var, 4, :_num@1}, {:integer, 0, 10}}]}

    #new_clause2_2 =
      #{:clause, [generated: true, location: 3], [{:atom, 0, true}], [],
       #[{:op, 4, :+, {:var, 4, :_num@1}, {:integer, 0, 0}}]}

    #new_clause2_3 =
      #{:clause, [generated: true, location: 3], [{:atom, 0, false}], [],
       #[{:op, 4, :+, {:var, 4, :_num@1}, {:integer, 0, 10}}]}

    #case Enum.random(0..7) do
      #0 -> {:case, 3, new_condition_1, [clause1, clause2]}
      #1 -> {:case, 3, new_condition_2, [clause1, clause2]}
      #2 -> {:case, 3, condition, [new_clause1_1, clause2]}
      #3 -> {:case, 3, condition, [new_clause1_2, clause2]}
      #4 -> {:case, 3, condition, [new_clause1_3, clause2]}
      #5 -> {:case, 3, condition, [clause1, new_clause2_1]}
      #6 -> {:case, 3, condition, [clause1, new_clause2_2]}
      #_ -> {:case, 3, condition, [clause1, new_clause2_3]}
    #end
  #end

  #defp mutate(form) do
    #form
  #end
#end