class RBS::Test::TypeCheck

def args(method_name, method_type, fun, call, errors, type_error:, argument_error:)
  test = zip_args(call.arguments, fun) do |val, param|
    unless self.value(val, param.type)
      errors << type_error.new(klass: self_class,
                               method_name: method_name,
                               method_type: method_type,
                               param: param,
                               value: val)
    end
  end
  unless test
    errors << argument_error.new(klass: self_class,
                                 method_name: method_name,
                                 method_type: method_type)
  end
end

def each_sample(array, &block)
  if block
    if sample_size && array.size > sample_size
      if sample_size > 0
        size = array.size
        sample_size.times do
          yield array[rand(size)]
        end
      end
    else
      array.each(&block)
    end
  else
    enum_for :each_sample, array
  end
end

def get_class(type_name)
  const_cache[type_name] ||= Object.const_get(type_name.to_s)
end

def initialize(self_class:, builder:, sample_size:, unchecked_classes:)
  @self_class = self_class
  @builder = builder
  @sample_size = sample_size
  @unchecked_classes = unchecked_classes.uniq
  @const_cache = {}
end

def is_double?(value)
  unchecked_classes.any? { |unchecked_class| Test.call(value, IS_AP, Object.const_get(unchecked_class))}
end

def keyword?(value)
  value.is_a?(Hash) && value.keys.all? {|key| key.is_a?(Symbol) }
end

def method_call(method_name, method_type, call, errors:)
  args(method_name, method_type, method_type.type, call.method_call, errors, type_error: Errors::ArgumentTypeError, argument_error: Errors::ArgumentError)
  self.return(method_name, method_type, method_type.type, call.method_call, errors, return_error: Errors::ReturnTypeError)
  if method_type.block
    case
    when !call.block_calls.empty?
      call.block_calls.each do |block_call|
        args(method_name, method_type, method_type.block.type, block_call, errors, type_error: Errors::BlockArgumentTypeError, argument_error: Errors::BlockArgumentError)
        self.return(method_name, method_type, method_type.block.type, block_call, errors, return_error: Errors::BlockReturnTypeError)
      end
    when !call.block_given
      # Block is not given
      if method_type.block.required
        errors << Errors::MissingBlockError.new(klass: self_class, method_name: method_name, method_type: method_type)
      end
    else
      # Block is given, but not yielded
    end
  else
    if call.block_given
      errors << Errors::UnexpectedBlockError.new(klass: self_class, method_name: method_name, method_type: method_type)
    end
  end
  errors
end

def overloaded_call(method, method_name, call, errors:)
  es = method.method_types.map do |method_type|
    es = method_call(method_name, method_type, call, errors: [])
    if es.empty?
      return errors
    else
      es
    end
  end
  if es.size == 1
    errors.push(*es[0])
  else
    errors << Errors::UnresolvedOverloadingError.new(
      klass: self_class,
      method_name: method_name,
      method_types: method.method_types
    )
  end
  errors
end

def return(method_name, method_type, fun, call, errors, return_error:)
  if call.return?
    unless value(call.return_value, fun.return_type)
      errors << return_error.new(klass: self_class,
                                 method_name: method_name,
                                 method_type: method_type,
                                 type: fun.return_type,
                                 value: call.return_value)
    end
  end
end

def value(val, type)
  if is_double?(val)
    RBS.logger.info("A double (#{val.inspect}) is detected!")
    return true 
  end
  case type
  when Types::Bases::Any
    true
  when Types::Bases::Bool
    true
  when Types::Bases::Top
    true
  when Types::Bases::Bottom
    false
  when Types::Bases::Void
    true
  when Types::Bases::Self
    Test.call(val, IS_AP, self_class)
  when Types::Bases::Nil
    Test.call(val, IS_AP, ::NilClass)
  when Types::Bases::Class
    Test.call(val, IS_AP, Class)
  when Types::Bases::Instance
    Test.call(val, IS_AP, self_class)
  when Types::ClassInstance
    klass = get_class(type.name)
    case
    when klass == ::Array
      Test.call(val, IS_AP, klass) && each_sample(val).all? {|v| value(v, type.args[0]) }
    when klass == ::Hash
      Test.call(val, IS_AP, klass) && each_sample(val.keys).all? do |key|
        value(key, type.args[0]) && value(val[key], type.args[1])
      end
    when klass == ::Range
      Test.call(val, IS_AP, klass) && value(val.begin, type.args[0]) && value(val.end, type.args[0])
    when klass == ::Enumerator
      if Test.call(val, IS_AP, klass)
        case val.size
        when Float::INFINITY
          values = []
          ret = self
          val.lazy.take(10).each do |*args|
            values << args
            nil
          end
        else
          values = []
          ret = val.each do |*args|
            values << args
            nil
          end
        end
        each_sample(values).all? do |v|
          if v.size == 1
            # Only one block argument.
            value(v[0], type.args[0]) || value(v, type.args[0])
          else
            value(v, type.args[0])
          end
        end &&
          if ret.equal?(self)
            type.args[1].is_a?(Types::Bases::Bottom)
          else
            value(ret, type.args[1])
          end
      end
    else
      Test.call(val, IS_AP, klass)
    end
  when Types::ClassSingleton
    klass = get_class(type.name)
    val == klass
  when Types::Interface
    methods = Set.new(Test.call(val, METHODS))
    if (definition = builder.build_interface(type.name))
      definition.methods.each_key.all? do |method_name|
        methods.member?(method_name)
      end
    end
  when Types::Variable
    true
  when Types::Literal
    val == type.literal
  when Types::Union
    type.types.any? {|type| value(val, type) }
  when Types::Intersection
    type.types.all? {|type| value(val, type) }
  when Types::Optional
    Test.call(val, IS_AP, ::NilClass) || value(val, type.type)
  when Types::Alias
    value(val, builder.expand_alias(type.name))
  when Types::Tuple
    Test.call(val, IS_AP, ::Array) &&
      type.types.map.with_index {|ty, index| value(val[index], ty) }.all?
  when Types::Record
    Test::call(val, IS_AP, ::Hash) && 
      type.fields.map {|key, type| value(val[key], type) }.all?
  when Types::Proc
    Test::call(val, IS_AP, ::Proc)
  else
    false
  end
end

def zip_args(args, fun, &block)
  case
  when args.empty?
    if fun.required_positionals.empty? && fun.trailing_positionals.empty? && fun.required_keywords.empty?
      true
    else
      false
    end
  when !fun.required_positionals.empty?
    yield_self do
      param, fun_ = fun.drop_head
      yield(args.first, param)
      zip_args(args.drop(1), fun_, &block)
    end
  when fun.has_keyword?
    yield_self do
      hash = args.last
      if keyword?(hash)
        zip_keyword_args(hash, fun, &block) &&
          zip_args(args.take(args.size - 1),
                   fun.update(required_keywords: {}, optional_keywords: {}, rest_keywords: nil),
                   &block)
      else
        fun.required_keywords.empty? &&
          zip_args(args,
                   fun.update(required_keywords: {}, optional_keywords: {}, rest_keywords: nil),
                   &block)
      end
    end
  when !fun.trailing_positionals.empty?
    yield_self do
      param, fun_ = fun.drop_tail
      yield(args.last, param)
      zip_args(args.take(args.size - 1), fun_, &block)
    end
  when !fun.optional_positionals.empty?
    yield_self do
      param, fun_ = fun.drop_head
      yield(args.first, param)
      zip_args(args.drop(1), fun_, &block)
    end
  when fun.rest_positionals
    yield_self do
      yield(args.first, fun.rest_positionals)
      zip_args(args.drop(1), fun, &block)
    end
  else
    false
  end
end

def zip_keyword_args(hash, fun)
  fun.required_keywords.each do |name, param|
    if hash.key?(name)
      yield(hash[name], param)
    else
      return false
    end
  end
  fun.optional_keywords.each do |name, param|
    if hash.key?(name)
      yield(hash[name], param)
    end
  end
  hash.each do |name, value|
    next if fun.required_keywords.key?(name)
    next if fun.optional_keywords.key?(name)
    if fun.rest_keywords
      yield value, fun.rest_keywords
    else
      return false
    end
  end
  true
end