/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "mozilla/Components.h"
#include "mozilla/HelperMacros.h"
#include "mozilla/Maybe.h"
#include "mozilla/PageloadEvent.h"
#include "mozilla/Preferences.h"
#include "mozilla/RandomNum.h"
#include "mozilla/ScopeExit.h"
#include "mozilla/glean/DomMetrics.h"
#include "mozilla/glean/GleanPings.h"

#include "nsIChannel.h"
#include "nsIEffectiveTLDService.h"
#include "nsITransportSecurityInfo.h"
#include "nsIURI.h"
#include "nsIX509Cert.h"
#include "nsThreadUtils.h"

#include "ScopedNSSTypes.h"
#include "cert.h"
#include "portreg.h"

#include <string_view>

namespace mozilla::performance::pageload_event {

/* static */
uint32_t PageloadEventData::sPageLoadEventCounter = 0;

// We don't want to record an event for every page load, so instead we
// randomly sample the events based on the channel.
//
// For nightly and beta, 100% of page loads will be sent using the default
// page_load ping, and 10% will be sent as page_load_domain pings.
//
// For release, 10% of page loads will be sent using the default ping,
// and 0.1% will be sent as page_load_domain pings.

// Normal sampling
#ifdef EARLY_BETA_OR_EARLIER
static constexpr uint64_t kNormalSamplingInterval = 1;  // Every pageload.
#else
static constexpr uint64_t kNormalSamplingInterval = 3;  // Every 3 pageloads.
#endif

// Domain sampling
#ifdef NIGHTLY_BUILD
static constexpr uint64_t kDomainSamplingInterval = 10;  // Every 10 pageloads.
#else
static constexpr uint64_t kDomainSamplingInterval =
    1000;  // Every 1000 pageloads.
#endif

PageloadEventType GetPageloadEventType() {
  static_assert(kDomainSamplingInterval >= kNormalSamplingInterval,
                "kDomainSamplingInterval should always be higher than "
                "kNormalSamplingInterval");

  Maybe<uint64_t> rand = mozilla::RandomUint64();
  if (rand.isSome()) {
    uint64_t result =
        static_cast<uint64_t>(rand.value() % kDomainSamplingInterval);
    if (result == 0) {
      return PageloadEventType::kDomain;
    }
    result = static_cast<uint64_t>(rand.value() % kNormalSamplingInterval);
    if (result == 0) {
      return PageloadEventType::kNormal;
    }
  }
  return PageloadEventType::kNone;
}

void PageloadEventData::SetDocumentFeature(DocumentFeature aFeature) {
  uint32_t value = 0;
  if (documentFeatures.isSome()) {
    value = documentFeatures.value();
  }
  value |= aFeature;
  documentFeatures = mozilla::Some(value);
}

void PageloadEventData::SetUserFeature(UserFeature aFeature) {
  uint32_t value = 0;
  if (userFeatures.isSome()) {
    value = userFeatures.value();
  }
  value |= aFeature;
  userFeatures = mozilla::Some(value);
}

// Check for a wildcard in the given cn and return the wildcard
// basename if the hn matches this wildcard.
//
// Using the rules outlined in RFC 2818 and 9525, wildcard names
// must start with "*." in the left-most label.
//
// e.g. `cn = *..example.com` would match `hn = foo.example.com`
//      and we would just return example.com in this case.
static bool DomainMatchesWildcard(char* cn, const char* hn,
                                  nsCString& newDomainOut) {
  if (!cn) {
    return false;
  }

  // Check if cn contains a wildcard. Must start with "*.".
  const bool wildcard = PORT_Strncmp(cn, "*.", 2) == 0;

  if (!wildcard) {
    return false;
  }

  // Get suffix after wildcard label.
  const char* cn_suffix = cn + 2;

  // Check for dot in hn
  const char* hn_suffix = PORT_Strchr(hn, '.');
  if (!hn_suffix) {
    return false;
  }

  // Skip the dot
  hn_suffix++;

  // Need three labels to match a wildcard
  if (!PORT_Strchr(hn_suffix, '.')) {
    return false;
  }

  // Check if the wildcard suffix matches the hn suffix.
  // If true, return the wildcard suffix.
  if (PORT_Strcasecmp(cn_suffix, hn_suffix) == 0) {
    newDomainOut.Assign(cn_suffix);
    return true;
  }

  return false;
}

// There are several conditions before we can assign an etld+1 domain:
// 1.  The server's IP address must be a public IP.
// 2.  The suffix must be on the PSL (Public Suffix List).
// 3.  The certificate chain root must be in the built in root list to
// ensure the trust anchor is public.
// 4.  If the domain matches a wildcard name, then replace it with the
// basename of the wildcard instead.
bool PageloadEventData::MaybeSetPublicRegistrableDomain(nsCOMPtr<nsIURI> aURI,
                                                        nsIChannel* aChannel) {
  MOZ_ASSERT(aChannel, "Expecting a valid channel.");

  nsCOMPtr<nsIEffectiveTLDService> tldService =
      mozilla::components::EffectiveTLD::Service();
  if (!tldService) {
    return false;
  }

  // Make sure the IP address range of the host is public.
  nsCOMPtr<nsILoadInfo> loadInfo = aChannel->LoadInfo();
  if (loadInfo->GetIpAddressSpace() != nsILoadInfo::IPAddressSpace::Public) {
    return false;
  }

  nsCOMPtr<nsITransportSecurityInfo> tsi;
  nsresult rv = aChannel->GetSecurityInfo(getter_AddRefs(tsi));
  if (NS_FAILED(rv) || !tsi) {
    return false;
  }

  // Make sure the cert root is in the builtin list.
  bool rootIsBuiltIn = false;
  rv = tsi->GetIsBuiltCertChainRootBuiltInRoot(&rootIsBuiltIn);
  if (NS_FAILED(rv) || !rootIsBuiltIn) {
    return false;
  }

  // Make sure the suffix is on the PSL.
  bool hasKnownPublicSuffix = false;
  rv = tldService->HasKnownPublicSuffix(aURI, &hasKnownPublicSuffix);
  if (NS_FAILED(rv) || !hasKnownPublicSuffix) {
    return false;
  }

  // Get cert for wildcard matching.
  nsCOMPtr<nsIX509Cert> cert;
  rv = tsi->GetServerCert(getter_AddRefs(cert));
  if (NS_FAILED(rv) || !cert) {
    return false;
  }

  UniqueCERTCertificate nssCert(cert->GetCert());
  if (!nssCert) {
    return false;
  }

  // Get ETLD+1 from url, or return on failure.
  nsAutoCString currentBaseDomain;
  rv = tldService->GetBaseDomain(aURI, 0, currentBaseDomain);
  if (NS_FAILED(rv) || currentBaseDomain.IsEmpty()) {
    return false;
  }

  SECStatus secrv = SECFailure;

  // cn and cnbuf is used by CERT_RFC1485_EscapeAndQuote as an output
  // buffer and will add a null terminator.
  const size_t cnBufLen = 255;
  char cnBuf[cnBufLen];

  UniquePLArenaPool arena(PORT_NewArena(DER_DEFAULT_CHUNKSIZE));
  if (!arena) {
    return false;
  }

  // Get subject alternate namelist.
  SECItem subAltName = {siBuffer, nullptr, 0};
  auto onScopeExit = mozilla::MakeScopeExit(
      [&]() { SECITEM_FreeItem(&subAltName, PR_FALSE); });

  secrv = CERT_FindCertExtension(nssCert.get(), SEC_OID_X509_SUBJECT_ALT_NAME,
                                 &subAltName);
  if (secrv != SECSuccess) {
    return false;
  }

  CERTGeneralName* nameList =
      CERT_DecodeAltNameExtension(arena.get(), &subAltName);
  if (!nameList) {
    return false;
  }

  // Loop through the subject alternate namelist and check if any of
  // them are wildcards and match the domain we were given. If a match
  // was found, replace the domain with the wildcard basename.
  CERTGeneralName* current = nameList;
  const char* hn = currentBaseDomain.get();
  do {
    if (current->type == certDNSName) {
      // EscapeAndQuote will copy and add a null terminator.
      secrv = CERT_RFC1485_EscapeAndQuote(cnBuf, cnBufLen,
                                          (char*)current->name.other.data,
                                          current->name.other.len);
      if (secrv != SECSuccess) {
        return false;
      }

      nsCString newDomain;
      if (DomainMatchesWildcard(cnBuf, hn, newDomain)) {
        mDomain = mozilla::Some(newDomain);
        return true;
      }
    }
    current = CERT_GetNextGeneralName(current);
  } while (current && current != nameList);

  // If a matching wildcard wasn't found, use the original etld+1.
  mDomain = mozilla::Some(currentBaseDomain);
  return true;
}

void PageloadEventData::SendAsPageLoadEvent() {
  mozilla::glean::perf::PageLoadExtra extra;

#define COPY_METRIC(name, type) extra.name = this->name;
  FOR_EACH_PAGELOAD_METRIC(COPY_METRIC)
#undef COPY_METRIC

  mozilla::glean::perf::page_load.Record(mozilla::Some(extra));

  // Send the PageLoadPing after every 10 page loads, or on startup.
  if (++sPageLoadEventCounter >= 10) {
    NS_SUCCEEDED(NS_DispatchToMainThreadQueue(
        NS_NewRunnableFunction(
            "PageLoadPingIdleTask",
            [] { mozilla::glean_pings::Pageload.Submit("threshold"_ns); }),
        EventQueuePriority::Idle));
    sPageLoadEventCounter = 0;
  }
}

static mozilla::Maybe<uint32_t> AddMultiplicativeNoise(
    const mozilla::Maybe<uint32_t>& input, double relativeRange = 0.10) {
  mozilla::Maybe<uint64_t> rand = mozilla::RandomUint64();
  if (!input || !rand) {
    return mozilla::Nothing{};
  }

  // Generate a range based on the relative range.
  double normalizedRand =
      static_cast<double>(rand.value()) /
      (static_cast<double>(std::numeric_limits<uint64_t>::max()) + 1.0);

  double multiplier = 1.0 + (normalizedRand * 2.0 - 1.0) * relativeRange;
  uint32_t output =
      static_cast<uint32_t>(std::round(input.value() * multiplier));
  ;
  return mozilla::Some(output);
}

void PageloadEventData::SendAsPageLoadDomainEvent() {
  MOZ_ASSERT(HasDomain());

  mozilla::glean::perf::PageLoadDomainExtra extra;
  extra.domain = this->mDomain;
  extra.httpVer = this->httpVer;
  extra.sameOriginNav = this->sameOriginNav;
  extra.documentFeatures = this->documentFeatures;
  extra.loadType = this->loadType;

  // Add some noise to any numerical metrics.
  extra.lcpTime = AddMultiplicativeNoise(this->lcpTime);

#ifdef NIGHTLY_BUILD
  extra.channel = mozilla::Some("nightly"_ns);
#else
  extra.channel = mozilla::Some("release"_ns);
#endif

  // Get the major version number.
  nsCString version(MOZ_STRINGIFY(MOZ_APP_VERSION_DISPLAY));
  int32_t dotIndex = version.FindChar('.');
  if (dotIndex != kNotFound) {
    version.SetLength(dotIndex);
  }
  nsresult rv;
  int32_t majorVersion = version.ToInteger(&rv);
  if (NS_SUCCEEDED(rv)) {
    extra.appVersionMajor = mozilla::Some(static_cast<uint32_t>(majorVersion));
  }

  if constexpr (std::string_view(MOZ_STRINGIFY(MOZ_UPDATE_CHANNEL)) ==
                "release") {
    nsAutoCString country;
    if (NS_SUCCEEDED(mozilla::Preferences::GetCString("browser.search.region",
                                                      country)) &&
        !country.IsEmpty()) {
      static constexpr std::string_view kAllowedCountries[] = {
          "US", "DE", "FR", "GB", "CA", "PL", "JP",
          "IN", "BR", "ID", "MX", "IT", "ES", "NL",
      };
      for (const auto& allowed : kAllowedCountries) {
        if (country.EqualsASCII(allowed.data(), allowed.size())) {
          extra.country = mozilla::Some(country);
          break;
        }
      }
    }
  }

  // If the event is a page_load_domain event, then immediately send it.
  mozilla::glean::perf::page_load_domain.Record(mozilla::Some(extra));

  // The etld events must be sent by themselves for privacy preserving
  // reasons.
  NS_SUCCEEDED(NS_DispatchToMainThreadQueue(
      NS_NewRunnableFunction("PageloadBaseDomainPingIdleTask",
                             [] {
                               mozilla::glean_pings::PageloadBaseDomain.Submit(
                                   "pageload"_ns);
                             }),
      EventQueuePriority::Idle));
}

}  // namespace mozilla::performance::pageload_event