class OpenTelemetry::Metrics::Meter

def create_counter(name, unit: nil, description: nil)
  create_instrument(:counter, name, unit, description, nil) { COUNTER }
end

def create_histogram(name, unit: nil, description: nil)
  create_instrument(:histogram, name, unit, description, nil) { HISTOGRAM }
end

def create_instrument(kind, name, unit, description, callback)
  @mutex.synchronize do
    OpenTelemetry.logger.warn("duplicate instrument registration occurred for instrument #{name}") if @instrument_registry.include? name
    @instrument_registry[name] = yield
  end
end

def create_observable_counter(name, callback:, unit: nil, description: nil)
  create_instrument(:observable_counter, name, unit, description, callback) { OBSERVABLE_COUNTER }
end

def create_observable_gauge(name, callback:, unit: nil, description: nil)
  create_instrument(:observable_gauge, name, unit, description, callback) { OBSERVABLE_GAUGE }
end

def create_observable_up_down_counter(name, callback:, unit: nil, description: nil)
  create_instrument(:observable_up_down_counter, name, unit, description, callback) { OBSERVABLE_UP_DOWN_COUNTER }
end

def create_up_down_counter(name, unit: nil, description: nil)
  create_instrument(:up_down_counter, name, unit, description, nil) { UP_DOWN_COUNTER }
end

def initialize
  @mutex = Mutex.new
  @instrument_registry = {}
end