require 'minitest_helper'

class TestHaskell < MiniTest::Unit::TestCase
  def setup
    @string  = 'str'
    @numeric = 1
    @symbol  = :test
    @array   = [1, 2, 3]
    @hash    = { test: :hash }
  end

  def test_type_list
    assert_equal_to_s "Numeric -> Numeric", Numeric >= Numeric
    assert_equal_to_s "Numeric -> Numeric -> Array", Numeric >= Numeric >= Array
    assert_equal_to_s "Hash -> Symbol -> Numeric -> Array -> String", Hash >= Symbol >= Numeric >= Array >= String
  end

  def test_correct_type
    assert_correct_type Numeric >= Numeric, [@numeric], @numeric
    assert_correct_type Numeric >= Array,   [@numeric], @array
    assert_correct_type Numeric >= String,  [@numeric], @string
    assert_correct_type Numeric >= Hash,    [@numeric], @hash
    assert_correct_type Numeric >= Symbol,  [@numeric], @symbol
    assert_correct_type Numeric >= Boolean, [@numeric], true
    assert_correct_type Numeric >= Boolean, [@numeric], false

    assert_correct_type Boolean >= Numeric >= Numeric, [true, @numeric], @numeric
    assert_correct_type Boolean >= Array   >= Array,   [true, @array  ], @array
    assert_correct_type Boolean >= String  >= String,  [true, @string ], @string
    assert_correct_type Boolean >= Hash    >= Hash,    [true, @hash   ], @hash
    assert_correct_type Boolean >= Symbol  >= Symbol,  [true, @symbol ], @symbol
  end

  def test_wrong_return_type
    assert_wrong_rtn Numeric >= Numeric, [@numeric], @array
    assert_wrong_rtn Numeric >= Numeric, [@numeric], @string
    assert_wrong_rtn Numeric >= Numeric, [@numeric], @hash
    assert_wrong_rtn Numeric >= Numeric, [@numeric], @symbol

    assert_wrong_rtn Numeric >= Numeric >= Numeric, [@numeric, @numeric], @array
    assert_wrong_rtn Numeric >= Numeric >= Numeric, [@numeric, @numeric], @string
    assert_wrong_rtn Numeric >= Numeric >= Numeric, [@numeric, @numeric], @hash
    assert_wrong_rtn Numeric >= Numeric >= Numeric, [@numeric, @numeric], @symbol
  end

  def test_wrong_args_type
    assert_wrong_arg Numeric >= Numeric, [@array ], @numeric
    assert_wrong_arg Numeric >= Numeric, [@string], @numeric
    assert_wrong_arg Numeric >= Numeric, [@hash  ], @numeric
    assert_wrong_arg Numeric >= Numeric, [@symbol], @numeric

    assert_wrong_arg Numeric >= Numeric >= Numeric, [@numeric, @array ], @numeric
    assert_wrong_arg Numeric >= Numeric >= Numeric, [@numeric, @string], @numeric
    assert_wrong_arg Numeric >= Numeric >= Numeric, [@numeric, @hash  ], @numeric
    assert_wrong_arg Numeric >= Numeric >= Numeric, [@numeric, @symbol], @numeric
  end

  def test_any
    assert_correct_type Any >= Any, [@array ], @numeric
    assert_correct_type Any >= Any, [@string], @numeric
    assert_correct_type Any >= Any, [@hash  ], @numeric
    assert_correct_type Any >= Any, [@symbol], @numeric

    assert_correct_type Any >= Any >= Any, [@numeric, @array ], @numeric
    assert_correct_type Any >= Any >= Any, [@numeric, @string], @numeric
    assert_correct_type Any >= Any >= Any, [@numeric, @hash  ], @numeric
    assert_correct_type Any >= Any >= Any, [@numeric, @symbol], @numeric
  end

  private
    def assert_equal_to_s(str, val)
      assert_equal str, val.to_s
    end

    def assert_correct_type(type_list, args, val)
      assert_equal val, define_test_method(type_list, args, val).call(*args)
    end

    def assert_wrong_arg(type_list, args, val)
      assert_raises(ArgumentError) { define_test_method(type_list, args, val).call(*args) }
    end

    def assert_wrong_rtn(type_list, args, val)
      assert_raises(TypeError) { define_test_method(type_list, args, val).call(*args) }
    end

    def define_test_method(type_list, args, val)
      klass = Class.new.class_eval <<-RUBY_CODE
        def call(#{arg_literal(args.count)})
          #{obj_literal(val)}
        end
        type #{obj_literal(type_list)}, :call
      RUBY_CODE

      klass.new
    end

    def obj_literal(obj)
      "ObjectSpace._id2ref(#{obj.__id__})"
    end

    def arg_literal(count)
      ('a'..'z').to_a[0..count-1].join(',')
    end
end