// Copyright 2018 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "shill/dns_server_tester.h"

#include <string>

#include <base/bind.h>
#include <base/strings/string_number_conversions.h>
#include <base/strings/string_util.h>

#include "shill/connection.h"
#include "shill/dns_client.h"
#include "shill/dns_client_factory.h"
#include "shill/error.h"
#include "shill/event_dispatcher.h"

using base::Bind;
using base::Callback;
using std::string;
using std::vector;

namespace shill {

namespace {

constexpr char kDnsTestHostname[] = "www.gstatic.com";
constexpr int kDnsTestRetryIntervalMilliseconds = 60000;

}  // namespace

DnsServerTester::DnsServerTester(ConnectionRefPtr connection,
                                 EventDispatcher* dispatcher,
                                 const vector<string>& dns_servers,
                                 const bool retry_until_success,
                                 const Callback<void(const Status)>& callback)
    : connection_(connection),
      dispatcher_(dispatcher),
      retry_until_success_(retry_until_success),
      weak_ptr_factory_(this),
      dns_result_callback_(callback),
      dns_test_client_(DnsClientFactory::GetInstance()->CreateDnsClient(
          IPAddress::kFamilyIPv4,
          connection_->interface_name(),
          dns_servers,
          DnsClient::kDnsTimeoutMilliseconds,
          dispatcher_,
          Bind(&DnsServerTester::DnsClientCallback,
               weak_ptr_factory_.GetWeakPtr()))) {}

DnsServerTester::~DnsServerTester() {
  Stop();
}

void DnsServerTester::Start() {
  // Stop existing attempt.
  Stop();
  // Schedule the test to start immediately.
  StartAttempt(0);
}

void DnsServerTester::StartAttempt(int delay_ms) {
  start_attempt_.Reset(
      Bind(&DnsServerTester::StartAttemptTask, weak_ptr_factory_.GetWeakPtr()));
  dispatcher_->PostDelayedTask(FROM_HERE, start_attempt_.callback(), delay_ms);
}

void DnsServerTester::StartAttemptTask() {
  Error error;
  if (!dns_test_client_->Start(kDnsTestHostname, &error)) {
    LOG(ERROR) << __func__ << ": Failed to start DNS client "
               << error.message();
    CompleteAttempt(kStatusFailure);
  }
}

void DnsServerTester::Stop() {
  start_attempt_.Cancel();
  StopAttempt();
}

void DnsServerTester::StopAttempt() {
  if (dns_test_client_) {
    dns_test_client_->Stop();
  }
}

void DnsServerTester::CompleteAttempt(Status status) {
  if (status == kStatusFailure && retry_until_success_) {
    // Schedule the test to restart after retry timeout interval.
    StartAttempt(kDnsTestRetryIntervalMilliseconds);
    return;
  }

  dns_result_callback_.Run(status);
}

void DnsServerTester::DnsClientCallback(const Error& error,
                                        const IPAddress& ip) {
  Status status = kStatusSuccess;
  if (!error.IsSuccess()) {
    status = kStatusFailure;
  }

  CompleteAttempt(status);
}

}  // namespace shill