class RuboCop::Cop::Style::HashEachMethods

def check_argument(variable)
  return unless variable.block_argument?
  (@block_args ||= []).push(variable)
end

def check_unused_block_args(node, key, value)
  return if node.body.nil?
  value_unused = unused_block_arg_exist?(node, value)
  key_unused = unused_block_arg_exist?(node, key)
  return if value_unused && key_unused
  if value_unused
    message = message('each_key', node.method_name, value.source)
    unused_range = key.source_range.end.join(value.source_range.end)
    register_each_args_offense(node, message, 'each_key', unused_range)
  elsif key_unused
    message = message('each_value', node.method_name, key.source)
    unused_range = key.source_range.begin.join(value.source_range.begin)
    register_each_args_offense(node, message, 'each_value', unused_range)
  end
end

def correct_args(node, corrector)
  args = node.parent.arguments
  name, = *args.children.find { |arg| used?(arg) }
  corrector.replace(args, "|#{name}|")
end

def correct_implicit(node, corrector, method_name)
  corrector.replace(node, method_name)
  correct_args(node, corrector)
end

def correct_key_value_each(node, corrector)
  receiver = node.receiver.receiver
  name = "each_#{node.receiver.method_name.to_s.chop}"
  return correct_implicit(node, corrector, name) unless receiver
  new_source = receiver.source + "#{node.loc.dot.source}#{name}"
  corrector.replace(node, new_source)
end

def format_message(method_name, current)
  format(MSG, prefer: "each_#{method_name[0..-2]}", current: current)
end

def handleable?(node)
  return false if use_array_converter_method_as_preceding?(node)
  return false unless (root_receiver = root_receiver(node))
  return false if hash_mutated?(node, root_receiver)
  !root_receiver.literal? || root_receiver.hash_type?
end

def kv_range(outer_node)
  outer_node.receiver.loc.selector.join(outer_node.loc.selector)
end

def message(prefer, method_name, unused_code)
  format(
    UNUSED_BLOCK_ARG_MSG, prefer: prefer, current: method_name, unused_code: unused_code
  )
end

def on_block(node)
  return unless handleable?(node)
  kv_each(node) do |target, method|
    register_kv_offense(target, method) and return
  end
  return unless (key, value = each_arguments(node))
  check_unused_block_args(node, key, value)
end

def on_block_pass(node)
  kv_each_with_block_pass(node.parent) do |target, method|
    register_kv_with_block_pass_offense(node, target, method)
  end
end

def register_each_args_offense(node, message, prefer, unused_range)
  add_offense(node, message: message) do |corrector|
    corrector.replace(node.send_node.loc.selector, prefer)
    corrector.remove(unused_range)
  end
end

def register_kv_offense(target, method)
  return unless (parent_receiver = target.receiver.receiver)
  return if allowed_receiver?(parent_receiver)
  current = target.receiver.loc.selector.join(target.source_range.end).source
  add_offense(kv_range(target), message: format_message(method, current)) do |corrector|
    correct_key_value_each(target, corrector)
  end
end

def register_kv_with_block_pass_offense(node, target, method)
  return unless (parent_receiver = node.parent.receiver.receiver)
  return if allowed_receiver?(parent_receiver)
  range = target.loc.selector.join(node.parent.loc.selector.end)
  add_offense(range, message: format_message(method, range.source)) do |corrector|
    corrector.replace(range, "each_#{method[0..-2]}")
  end
end

def root_receiver(node)
  receiver = node.receiver
  if receiver&.receiver
    root_receiver(receiver)
  else
    receiver
  end
end

def unused_block_arg_exist?(node, block_arg)
  lvar_sources = node.body.each_descendant(:lvar).map(&:source)
  if block_arg.mlhs_type?
    block_arg.each_descendant(:arg, :restarg).all? do |descendant|
      lvar_sources.none?(descendant.source.delete_prefix('*'))
    end
  else
    lvar_sources.none?(block_arg.source.delete_prefix('*'))
  end
end

def use_array_converter_method_as_preceding?(node)
  return false unless (preceding_method = node.children.first.children.first)
  return false unless preceding_method.type?(:call, :any_block)
  ARRAY_CONVERTER_METHODS.include?(preceding_method.method_name)
end

def used?(arg)
  @block_args.find { |var| var.declaration_node.loc == arg.loc }.used?
end