class ElasticAPM::Middleware

def call(env)
  begin
    if running? && !path_ignored?(env)
      transaction = start_transaction(env)
    end
    resp = @app.call env
  rescue InternalError
    raise # Don't report ElasticAPM errors
  rescue ::Exception => e
    context = ElasticAPM.build_context(rack_env: env, for_type: :error)
    ElasticAPM.report(e, context: context, handled: false)
    raise
  ensure
    if resp && transaction
      status, headers, _body = resp
      transaction.add_response(status, headers: headers.dup)
    end
    ElasticAPM.end_transaction http_result(status)
  end
  resp
end

def config
  @config ||= ElasticAPM.agent.config
end

def http_result(status)
  status && "HTTP #{status.to_s[0]}xx"
end

def initialize(app)
  @app = app
end

def path_ignored?(env)
  config.ignore_url_patterns.any? do |r|
    env['PATH_INFO'].match r
  end
end

def running?
  ElasticAPM.running?
end

def start_transaction(env)
  context = ElasticAPM.build_context(rack_env: env, for_type: :transaction)
  ElasticAPM.start_transaction 'Rack', 'request',
    context: context,
    trace_context: trace_context(env)
end

def trace_context(env)
  return unless (header = env['HTTP_ELASTIC_APM_TRACEPARENT'])
  TraceContext.parse(header)
rescue TraceContext::InvalidTraceparentHeader
  warn "Couldn't parse invalid traceparent header: #{header.inspect}"
  nil
end