module Sashiko::Traced

# File lib/sashiko/traced.rb, line 84
def build_attributes(args, kwargs, options)
  extra = case options.attributes
          in Proc => fn then fn.arity.zero? ? fn.call : fn.call(*args, **kwargs)
          in Hash => h  then h
          else nil
          end

  # Fast path: nothing dynamic. Return the pre-baked frozen Hash
  # directly — OTel SDK copies it before storing on the Span.
  return options.static_attrs unless options.record_args || extra

  attrs = options.static_attrs.dup #: Hash[String, untyped]
  attrs["code.args.count"] = args.length + kwargs.length if options.record_args
  extra&.each { |k, v| attrs[k.to_s] = v }
  attrs
end

# File lib/sashiko/traced.rb, line 63
def install_overlay(klass)
  Module.new.tap do |m|
    klass.prepend(m)
    klass.instance_variable_set(:@__sashiko_overlay, m)
  end
end

# File lib/sashiko/traced.rb, line 61
  def overlay_for(klass) = klass.instance_variable_get(:@__sashiko_overlay) || Traced.install_overlay(klass)

  def install_overlay(klass)
    Module.new.tap do |m|
      klass.prepend(m)
      klass.instance_variable_set(:@__sashiko_overlay, m)
    end
  end

  def weave(overlay, options)
    overlay.define_method(options.method_name) do |*args, **kwargs, &block|
      attrs = Traced.build_attributes(args, kwargs, options)
      tracer = options.tracer || Sashiko.tracer
      tracer.in_span(options.span_name, attributes: attrs, kind: options.kind) do |span|
        super(*args, **kwargs, &block)
      rescue => e
        span.record_exception(e)
        span.status = OpenTelemetry::Trace::Status.error(e.message)
        ::Kernel.raise
      end
    end
  end

  def build_attributes(args, kwargs, options)
    extra = case options.attributes
            in Proc => fn then fn.arity.zero? ? fn.call : fn.call(*args, **kwargs)
            in Hash => h  then h
            else nil
            end

    # Fast path: nothing dynamic. Return the pre-baked frozen Hash
    # directly — OTel SDK copies it before storing on the Span.
    return options.static_attrs unless options.record_args || extra

    attrs = options.static_attrs.dup #: Hash[String, untyped]
    attrs["code.args.count"] = args.length + kwargs.length if options.record_args
    extra&.each { |k, v| attrs[k.to_s] = v }
    attrs
  end
end

# File lib/sashiko/traced.rb, line 70
def weave(overlay, options)
  overlay.define_method(options.method_name) do |*args, **kwargs, &block|
    attrs = Traced.build_attributes(args, kwargs, options)
    tracer = options.tracer || Sashiko.tracer
    tracer.in_span(options.span_name, attributes: attrs, kind: options.kind) do |span|
      super(*args, **kwargs, &block)
    rescue => e
      span.record_exception(e)
      span.status = OpenTelemetry::Trace::Status.error(e.message)
      ::Kernel.raise
    end
  end
end

# File lib/sashiko/traced.rb, line 25
def trace(method_name, name: nil, kind: :internal, attributes: nil, record_args: false, tracer: nil)
  method_sym = method_name.to_sym
  class_name = self.name
  static_attrs = { "code.function" => method_sym.to_s }
  static_attrs["code.namespace"] = class_name if class_name
  static_attrs.freeze

  options = Options.new(
    span_name: name || "#{class_name || "anon"}##{method_sym}",
    kind:,
    attributes:,
    record_args:,
    method_name: method_sym,
    class_name:,
    tracer:,
    static_attrs:,
  )
  Traced.weave(Traced.overlay_for(self), options)
end

# File lib/sashiko/traced.rb, line 49
def trace_all(matching:, kind: :internal, record_args: false, tracer: nil)
  overlay = Traced.overlay_for(self)
  already_overlaid = overlay.instance_methods(false)
  instance_methods(false)
    .select { |m| m.to_s.match?(matching) }
    .reject { |m| already_overlaid.include?(m) }
    .each   { |m| trace(m, kind:, record_args:, tracer:) }
end