class Spoom::Deadcode::Remover::NodeContext

def attached_comments(node)
  comments = [] #: Array[Prism::Comment]
  start_line = node.location.start_line - 1
  start_line.downto(1) do |line|
    comment = @comments[line]
    break unless comment
    comments << comment
  end
  comments.reverse
end

def attached_sig
  previous_nodes.reverse_each do |node|
    if node.is_a?(Prism::Comment)
      next
    elsif sorbet_signature?(node)
      return T.cast(node, Prism::CallNode)
    else
      break
    end
  end
  nil
end

def attached_sigs
  nodes = [] #: Array[Prism::Node]
  previous_nodes.reverse_each do |prev_node|
    break unless sorbet_signature?(prev_node)
    nodes << prev_node
  end
  nodes.reverse
end

def comments_between_lines(start_line, end_line)
  comments = [] #: Array[Prism::Comment]
  (start_line + 1).upto(end_line - 1) do |line|
    comment = @comments[line]
    comments << comment if comment
  end
  comments
end

def initialize(source, comments, node, nesting)
  @source = source
  @comments = comments
  @node = node
  @nesting = nesting
end

def next_node
  next_nodes.first
end

def next_nodes
  parent = parent_node
  child_nodes = parent.child_nodes.compact
  index = child_nodes.index(node)
  raise Error, "Node #{@node} not found in nesting node #{parent}" unless index
  T.must(child_nodes.compact[(index + 1)..-1])
end

def parent_context
  nesting = @nesting.dup
  parent = nesting.pop
  raise Error, "No parent context for node #{@node}" unless parent
  NodeContext.new(@source, @comments, parent, nesting)
end

def parent_node
  parent = @nesting.last
  raise Error, "No parent for node #{node}" unless parent
  parent
end

def previous_node
  previous_nodes.last
end

def previous_nodes
  parent = parent_node
  child_nodes = parent.child_nodes.compact
  index = child_nodes.index(@node)
  raise Error, "Node #{@node} not found in parent #{parent}" unless index
  T.must(child_nodes[0...index])
end

def sclass_context
  sclass = nil #: Prism::SingletonClassNode?
  nesting = @nesting.dup
  until nesting.empty? || sclass
    node = nesting.pop
    next unless node.is_a?(Prism::SingletonClassNode)
    sclass = node
  end
  return unless sclass.is_a?(Prism::SingletonClassNode)
  body = sclass.body
  return NodeContext.new(@source, @comments, sclass, nesting) unless body.is_a?(Prism::StatementsNode)
  nodes = body.child_nodes.reject do |node|
    sorbet_signature?(node) || sorbet_extend_sig?(node)
  end
  if nodes.size <= 1
    return NodeContext.new(@source, @comments, sclass, nesting)
  end
  nil
end

def sorbet_extend_sig?(node)
  return false unless node.is_a?(Prism::CallNode)
  return false unless node.name == :extend
  args = node.arguments
  return false unless args
  return false unless args.arguments.size == 1
  args.arguments.first&.slice == "T::Sig"
end

def sorbet_signature?(node)
  node.is_a?(Prism::CallNode) && node.name == :sig
end