class RuboCop::AST::NodePattern::Compiler::NodePatternSubcompiler

def access_element
  seq_head ? "#{access}.type" : access
end

def access_node
  return access if seq_head
  "#{compile_guard_clause} && #{access}"
end

def compile_args(arg_list, first: nil)
  args = arg_list&.map { |arg| compiler.compile_as_atom(arg) }
  args = [first, *args] if first
  "(#{args.join(', ')})" if args
end

def compile_guard_clause
  "#{access}.is_a?(::RuboCop::AST::Node)"
end

def compile_value_match(value)
  "#{value} === #{access_element}"
end

def initialize(compiler, var: nil, access: var, seq_head: false)
  super(compiler)
  @var = var
  @access = access
  @seq_head = seq_head
end

def multiple_access(kind)
  return yield @var if @var
  compiler.with_temp_variables(kind) do |var|
    memo = "#{var} = #{access}"
    @var = @access = var
    "(#{memo}; #{yield @var})"
  end
end

def visit_ascend
  compiler.with_temp_variables do |ascend|
    expr = compiler.compile_as_node_pattern(node.child, var: ascend)
    "(#{ascend} = #{access_node}) && (#{ascend} = #{ascend}.parent) && #{expr}"
  end
end

def visit_capture
  "(#{compiler.next_capture} = #{access_element}; #{compile(node.child)})"
end

def visit_descend
  compiler.with_temp_variables { |descendant| <<~RUBY.chomp }
    ::RuboCop::AST::NodePattern.descend(#{access}).any? do |#{descendant}|
      #{compiler.compile_as_node_pattern(node.child, var: descendant)}
    end
  RUBY
end

def visit_function_call
  "#{node.method_name}#{compile_args(node.arg_list, first: access_element)}"
end

def visit_intersection
  multiple_access(:intersection) do
    node.children.map { |child| compile(child) }
        .join(' && ')
  end
end

def visit_negation
  expr = compile(node.child)
  "!(#{expr})"
end

def visit_node_type
  "#{access_node}.#{node.child.to_s.tr('-', '_')}_type?"
end

def visit_other_type
  value = compiler.compile_as_atom(node)
  compile_value_match(value)
end

def visit_predicate
  "#{access_element}.#{node.method_name}#{compile_args(node.arg_list)}"
end

def visit_sequence
  multiple_access(:sequence) do |var|
    term = compiler.compile_sequence(node, var: var)
    "#{compile_guard_clause} && #{term}"
  end
end

def visit_unify
  name = compiler.bind(node.child) do |unify_name|
    # double assign to avoid "assigned but unused variable"
    return "(#{unify_name} = #{access_element}; #{unify_name} = #{unify_name}; true)"
  end
  compile_value_match(name)
end

def visit_union
  multiple_access(:union) do
    terms = compiler.each_union(node.children)
                    .map { |child| compile(child) }
    "(#{terms.join(' || ')})"
  end
end

def visit_wildcard
  'true'
end