// Copyright 1999-2005 The RE2 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 <stdarg.h>

#include <stdio.h>

#include "util/strutil.h"

#ifdef _WIN32

#define snprintf _snprintf

#define vsnprintf _vsnprintf

#endif

namespace re2 {

// ----------------------------------------------------------------------

// CEscapeString()

//    Copies 'src' to 'dest', escaping dangerous characters using

//    C-style escape sequences.  'src' and 'dest' should not overlap.

//    Returns the number of bytes written to 'dest' (not including the \0)

//    or (size_t)-1 if there was insufficient space.

// ----------------------------------------------------------------------

static size_t CEscapeString(const char* src, size_t src_len,

                            char* dest, size_t dest_len) {

  const char* src_end = src + src_len;

  size_t used = 0;

  for (; src < src_end; src++) {

    if (dest_len - used < 2)   // space for two-character escape

      return (size_t)-1;

    unsigned char c = *src;

    switch (c) {

      case '\n': dest[used++] = '\\'; dest[used++] = 'n';  break;

      case '\r': dest[used++] = '\\'; dest[used++] = 'r';  break;

      case '\t': dest[used++] = '\\'; dest[used++] = 't';  break;

      case '\"': dest[used++] = '\\'; dest[used++] = '\"'; break;

      case '\'': dest[used++] = '\\'; dest[used++] = '\''; break;

      case '\\': dest[used++] = '\\'; dest[used++] = '\\'; break;

      default:

        // Note that if we emit \xNN and the src character after that is a hex

        // digit then that digit must be escaped too to prevent it being

        // interpreted as part of the character code by C.

        if (c < ' ' || c > '~') {

          if (dest_len - used < 5)   // space for four-character escape + \0

            return (size_t)-1;

          snprintf(dest + used, 5, "\\%03o", c);

          used += 4;

        } else {

          dest[used++] = c; break;

        }

    }

  }

  if (dest_len - used < 1)   // make sure that there is room for \0

    return (size_t)-1;

  dest[used] = '\0';   // doesn't count towards return value though

  return used;

}

// ----------------------------------------------------------------------

// CEscape()

//    Copies 'src' to result, escaping dangerous characters using

//    C-style escape sequences.  'src' and 'dest' should not overlap.

// ----------------------------------------------------------------------

std::string CEscape(const StringPiece& src) {

  const size_t dest_len = src.size() * 4 + 1; // Maximum possible expansion

  char* dest = new char[dest_len];

  const size_t used = CEscapeString(src.data(), src.size(),

                                    dest, dest_len);

  std::string s = std::string(dest, used);

  delete[] dest;

  return s;

}

void PrefixSuccessor(std::string* prefix) {

  // We can increment the last character in the string and be done

  // unless that character is 255, in which case we have to erase the

  // last character and increment the previous character, unless that

  // is 255, etc. If the string is empty or consists entirely of

  // 255's, we just return the empty string.

  while (!prefix->empty()) {

    char& c = prefix->back();

    if (c == '\xff') {  // char literal avoids signed/unsigned.

      prefix->pop_back();

    } else {

      ++c;

      break;

    }

  }

}

static void StringAppendV(std::string* dst, const char* format, va_list ap) {

  // First try with a small fixed size buffer

  char space[1024];

  // It's possible for methods that use a va_list to invalidate

  // the data in it upon use.  The fix is to make a copy

  // of the structure before using it and use that copy instead.

  va_list backup_ap;

  va_copy(backup_ap, ap);

  int result = vsnprintf(space, sizeof(space), format, backup_ap);

  va_end(backup_ap);

  if ((result >= 0) && (static_cast<size_t>(result) < sizeof(space))) {

    // It fit

    dst->append(space, result);

    return;

  }

  // Repeatedly increase buffer size until it fits

  int length = sizeof(space);

  while (true) {

    if (result < 0) {

      // Older behavior: just try doubling the buffer size

      length *= 2;

    } else {

      // We need exactly "result+1" characters

      length = result+1;

    }

    char* buf = new char[length];

    // Restore the va_list before we use it again

    va_copy(backup_ap, ap);

    result = vsnprintf(buf, length, format, backup_ap);

    va_end(backup_ap);

    if ((result >= 0) && (result < length)) {

      // It fit

      dst->append(buf, result);

      delete[] buf;

      return;

    }

    delete[] buf;

  }

}

std::string StringPrintf(const char* format, ...) {

  va_list ap;

  va_start(ap, format);

  std::string result;

  StringAppendV(&result, format, ap);

  va_end(ap);

  return result;

}

}  // namespace re2