/* vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
 * 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 "Helpers.h"
#include "mozIStorageError.h"
#include "prio.h"
#include "nsString.h"
#include "nsNavHistory.h"
#include "mozilla/Base64.h"
#include "mozilla/HashFunctions.h"
#include <algorithm>
#include "mozilla/Services.h"

// The length of guids that are used by history and bookmarks.
#define GUID_LENGTH 12

// Maximum number of chars to use for calculating hashes. This value has been
// picked to ensure low hash collisions on a real world common places.sqlite.
// While collisions are not a big deal for functionality, a low ratio allows
// for slightly more efficient SELECTs.
#define MAX_CHARS_TO_HASH 1500U

namespace mozilla {
namespace places {

////////////////////////////////////////////////////////////////////////////////
//// AsyncStatementCallback

NS_IMPL_ISUPPORTS(
  AsyncStatementCallback
, mozIStorageStatementCallback
)

NS_IMETHODIMP
WeakAsyncStatementCallback::HandleResult(mozIStorageResultSet *aResultSet)
{
  MOZ_ASSERT(false, "Was not expecting a resultset, but got it.");
  return NS_OK;
}

NS_IMETHODIMP
WeakAsyncStatementCallback::HandleCompletion(uint16_t aReason)
{
  return NS_OK;
}

NS_IMETHODIMP
WeakAsyncStatementCallback::HandleError(mozIStorageError *aError)
{
#ifdef DEBUG
  int32_t result;
  nsresult rv = aError->GetResult(&result);
  NS_ENSURE_SUCCESS(rv, rv);
  nsAutoCString message;
  rv = aError->GetMessage(message);
  NS_ENSURE_SUCCESS(rv, rv);

  nsAutoCString warnMsg;
  warnMsg.AppendLiteral("An error occurred while executing an async statement: ");
  warnMsg.AppendInt(result);
  warnMsg.Append(' ');
  warnMsg.Append(message);
  NS_WARNING(warnMsg.get());
#endif

  return NS_OK;
}

#define URI_TO_URLCSTRING(uri, spec) \
  nsAutoCString spec; \
  if (NS_FAILED(aURI->GetSpec(spec))) { \
    return NS_ERROR_UNEXPECTED; \
  }

// Bind URI to statement by index.
nsresult // static
URIBinder::Bind(mozIStorageStatement* aStatement,
                int32_t aIndex,
                nsIURI* aURI)
{
  NS_ASSERTION(aStatement, "Must have non-null statement");
  NS_ASSERTION(aURI, "Must have non-null uri");

  URI_TO_URLCSTRING(aURI, spec);
  return URIBinder::Bind(aStatement, aIndex, spec);
}

// Statement URLCString to statement by index.
nsresult // static
URIBinder::Bind(mozIStorageStatement* aStatement,
                int32_t index,
                const nsACString& aURLString)
{
  NS_ASSERTION(aStatement, "Must have non-null statement");
  return aStatement->BindUTF8StringByIndex(
    index, StringHead(aURLString, URI_LENGTH_MAX)
  );
}

// Bind URI to statement by name.
nsresult // static
URIBinder::Bind(mozIStorageStatement* aStatement,
                const nsACString& aName,
                nsIURI* aURI)
{
  NS_ASSERTION(aStatement, "Must have non-null statement");
  NS_ASSERTION(aURI, "Must have non-null uri");

  URI_TO_URLCSTRING(aURI, spec);
  return URIBinder::Bind(aStatement, aName, spec);
}

// Bind URLCString to statement by name.
nsresult // static
URIBinder::Bind(mozIStorageStatement* aStatement,
                const nsACString& aName,
                const nsACString& aURLString)
{
  NS_ASSERTION(aStatement, "Must have non-null statement");
  return aStatement->BindUTF8StringByName(
    aName, StringHead(aURLString, URI_LENGTH_MAX)
  );
}

// Bind URI to params by index.
nsresult // static
URIBinder::Bind(mozIStorageBindingParams* aParams,
                int32_t aIndex,
                nsIURI* aURI)
{
  NS_ASSERTION(aParams, "Must have non-null statement");
  NS_ASSERTION(aURI, "Must have non-null uri");

  URI_TO_URLCSTRING(aURI, spec);
  return URIBinder::Bind(aParams, aIndex, spec);
}

// Bind URLCString to params by index.
nsresult // static
URIBinder::Bind(mozIStorageBindingParams* aParams,
                int32_t index,
                const nsACString& aURLString)
{
  NS_ASSERTION(aParams, "Must have non-null statement");
  return aParams->BindUTF8StringByIndex(
    index, StringHead(aURLString, URI_LENGTH_MAX)
  );
}

// Bind URI to params by name.
nsresult // static
URIBinder::Bind(mozIStorageBindingParams* aParams,
                const nsACString& aName,
                nsIURI* aURI)
{
  NS_ASSERTION(aParams, "Must have non-null params array");
  NS_ASSERTION(aURI, "Must have non-null uri");

  URI_TO_URLCSTRING(aURI, spec);
  return URIBinder::Bind(aParams, aName, spec);
}

// Bind URLCString to params by name.
nsresult // static
URIBinder::Bind(mozIStorageBindingParams* aParams,
                const nsACString& aName,
                const nsACString& aURLString)
{
  NS_ASSERTION(aParams, "Must have non-null params array");

  nsresult rv = aParams->BindUTF8StringByName(
    aName, StringHead(aURLString, URI_LENGTH_MAX)
  );
  NS_ENSURE_SUCCESS(rv, rv);
  return NS_OK;
}

#undef URI_TO_URLCSTRING

nsresult
GetReversedHostname(nsIURI* aURI, nsString& aRevHost)
{
  nsAutoCString forward8;
  nsresult rv = aURI->GetHost(forward8);
  // Not all URIs have a host.
  if (NS_FAILED(rv))
    return rv;

  // can't do reversing in UTF8, better use 16-bit chars
  GetReversedHostname(NS_ConvertUTF8toUTF16(forward8), aRevHost);
  return NS_OK;
}

void
GetReversedHostname(const nsString& aForward, nsString& aRevHost)
{
  ReverseString(aForward, aRevHost);
  aRevHost.Append(char16_t('.'));
}

void
ReverseString(const nsString& aInput, nsString& aReversed)
{
  aReversed.Truncate(0);
  for (int32_t i = aInput.Length() - 1; i >= 0; i--) {
    aReversed.Append(aInput[i]);
  }
}

static
nsresult
GenerateRandomBytes(uint32_t aSize,
                    uint8_t* _buffer)
{
  // On Windows, we'll use its built-in cryptographic API.
#if defined(XP_WIN)
  const nsNavHistory* history = nsNavHistory::GetConstHistoryService();
  HCRYPTPROV cryptoProvider;
  nsresult rv = history->GetCryptoProvider(cryptoProvider);
  NS_ENSURE_SUCCESS(rv, rv);
  BOOL rc = CryptGenRandom(cryptoProvider, aSize, _buffer);
  return rc ? NS_OK : NS_ERROR_FAILURE;

  // On Unix, we'll just read in from /dev/urandom.
#elif defined(XP_UNIX)
  NS_ENSURE_ARG_MAX(aSize, INT32_MAX);
  PRFileDesc* urandom = PR_Open("/dev/urandom", PR_RDONLY, 0);
  nsresult rv = NS_ERROR_FAILURE;
  if (urandom) {
    int32_t bytesRead = PR_Read(urandom, _buffer, aSize);
    if (bytesRead == static_cast<int32_t>(aSize)) {
      rv = NS_OK;
    }
    (void)PR_Close(urandom);
  }
  return rv;
#endif
}

nsresult
GenerateGUID(nsACString& _guid)
{
  _guid.Truncate();

  // Request raw random bytes and base64url encode them.  For each set of three
  // bytes, we get one character.
  const uint32_t kRequiredBytesLength =
    static_cast<uint32_t>(GUID_LENGTH / 4 * 3);

  uint8_t buffer[kRequiredBytesLength];
  nsresult rv = GenerateRandomBytes(kRequiredBytesLength, buffer);
  NS_ENSURE_SUCCESS(rv, rv);

  rv = Base64URLEncode(kRequiredBytesLength, buffer,
                       Base64URLEncodePaddingPolicy::Omit, _guid);
  NS_ENSURE_SUCCESS(rv, rv);

  NS_ASSERTION(_guid.Length() == GUID_LENGTH, "GUID is not the right size!");
  return NS_OK;
}

bool
IsValidGUID(const nsACString& aGUID)
{
  nsCString::size_type len = aGUID.Length();
  if (len != GUID_LENGTH) {
    return false;
  }

  for (nsCString::size_type i = 0; i < len; i++ ) {
    char c = aGUID[i];
    if ((c >= 'a' && c <= 'z') || // a-z
        (c >= 'A' && c <= 'Z') || // A-Z
        (c >= '0' && c <= '9') || // 0-9
        c == '-' || c == '_') { // - or _
      continue;
    }
    return false;
  }
  return true;
}

void
TruncateTitle(const nsACString& aTitle, nsACString& aTrimmed)
{
  if (aTitle.IsVoid()) {
    return;
  }
  aTrimmed = aTitle;
  if (aTitle.Length() > TITLE_LENGTH_MAX) {
    aTrimmed = StringHead(aTitle, TITLE_LENGTH_MAX);
  }
}

PRTime
RoundToMilliseconds(PRTime aTime) {
  return aTime - (aTime % PR_USEC_PER_MSEC);
}

PRTime
RoundedPRNow() {
  return RoundToMilliseconds(PR_Now());
}

nsresult
HashURL(const nsACString& aSpec, const nsACString& aMode, uint64_t *_hash)
{
  NS_ENSURE_ARG_POINTER(_hash);

  // HashString doesn't stop at the string boundaries if a length is passed to
  // it, so ensure to pass a proper value.
  const uint32_t maxLenToHash = std::min(static_cast<uint32_t>(aSpec.Length()),
                                         MAX_CHARS_TO_HASH);

  if (aMode.IsEmpty()) {
    // URI-like strings (having a prefix before a colon), are handled specially,
    // as a 48 bit hash, where first 16 bits are the prefix hash, while the
    // other 32 are the string hash.
    // The 16 bits have been decided based on the fact hashing all of the IANA
    // known schemes, plus "places", does not generate collisions.
    // Since we only care about schemes, we just search in the first 50 chars.
    // The longest known IANA scheme, at this time, is 30 chars.
    const nsDependentCSubstring& strHead = StringHead(aSpec, 50);
    nsACString::const_iterator start, tip, end;
    strHead.BeginReading(tip);
    start = tip;
    strHead.EndReading(end);
    uint32_t strHash = HashString(aSpec.BeginReading(), maxLenToHash);
    if (FindCharInReadable(':', tip, end)) {
      const nsDependentCSubstring& prefix = Substring(start, tip);
      uint64_t prefixHash = static_cast<uint64_t>(HashString(prefix) & 0x0000FFFF);
      // The second half of the url is more likely to be unique, so we add it.
      *_hash = (prefixHash << 32) + strHash;
    } else {
      *_hash = strHash;
    }
  } else if (aMode.EqualsLiteral("prefix_lo")) {
    // Keep only 16 bits.
    *_hash = static_cast<uint64_t>(HashString(aSpec.BeginReading(), maxLenToHash) & 0x0000FFFF) << 32;
  } else if (aMode.EqualsLiteral("prefix_hi")) {
    // Keep only 16 bits.
    *_hash = static_cast<uint64_t>(HashString(aSpec.BeginReading(), maxLenToHash) & 0x0000FFFF) << 32;
    // Make this a prefix upper bound by filling the lowest 32 bits.
    *_hash +=  0xFFFFFFFF;
  } else {
    return NS_ERROR_FAILURE;
  }

  return NS_OK;
}

bool
GetHiddenState(bool aIsRedirect,
               uint32_t aTransitionType)
{
  return aTransitionType == nsINavHistoryService::TRANSITION_FRAMED_LINK ||
         aTransitionType == nsINavHistoryService::TRANSITION_EMBED ||
         aIsRedirect;
}

////////////////////////////////////////////////////////////////////////////////
//// AsyncStatementCallbackNotifier

NS_IMETHODIMP
AsyncStatementCallbackNotifier::HandleCompletion(uint16_t aReason)
{
  if (aReason != mozIStorageStatementCallback::REASON_FINISHED)
    return NS_ERROR_UNEXPECTED;

  nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
  if (obs) {
    (void)obs->NotifyObservers(nullptr, mTopic, nullptr);
  }

  return NS_OK;
}

////////////////////////////////////////////////////////////////////////////////
//// AsyncStatementCallbackNotifier

NS_IMETHODIMP
AsyncStatementTelemetryTimer::HandleCompletion(uint16_t aReason)
{
  if (aReason == mozIStorageStatementCallback::REASON_FINISHED) {
    Telemetry::AccumulateTimeDelta(mHistogramId, mStart);
  }
  return NS_OK;
}

} // namespace places
} // namespace mozilla