class RubyLsp::Listeners::SignatureHelp

# File lib/ruby_lsp/listeners/signature_help.rb, line 19
def initialize(response_builder, global_state, nesting, dispatcher, typechecker_enabled)
  @typechecker_enabled = typechecker_enabled
  @response_builder = response_builder
  @global_state = global_state
  @index = T.let(global_state.index, RubyIndexer::Index)
  @nesting = nesting
  dispatcher.register(self, :on_call_node_enter)
end

# File lib/ruby_lsp/listeners/signature_help.rb, line 29
def on_call_node_enter(node)
  return if @typechecker_enabled
  return unless self_receiver?(node)

  message = node.message
  return unless message

  methods = @index.resolve_method(message, @nesting.join("::"))
  return unless methods

  target_method = methods.first
  return unless target_method

  parameters = target_method.parameters
  name = target_method.name

  # If the method doesn't have any parameters, there's no need to show signature help
  return if parameters.empty?

  label = "#{name}(#{parameters.map(&:decorated_name).join(", ")})"

  arguments_node = node.arguments
  arguments = arguments_node&.arguments || []
  active_parameter = (arguments.length - 1).clamp(0, parameters.length - 1)

  # If there are arguments, then we need to check if there's a trailing comma after the end of the last argument
  # to advance the active parameter to the next one
  if arguments_node &&
      node.slice.byteslice(arguments_node.location.end_offset - node.location.start_offset) == ","
    active_parameter += 1
  end

  signature_help = Interface::SignatureHelp.new(
    signatures: [
      Interface::SignatureInformation.new(
        label: label,
        parameters: parameters.map { |param| Interface::ParameterInformation.new(label: param.name) },
        documentation: Interface::MarkupContent.new(
          kind: "markdown",
          value: markdown_from_index_entries("", methods),
        ),
      ),
    ],
    active_parameter: active_parameter,
  )
  @response_builder.replace(signature_help)
end