// Copyright 2002 and onwards Google Inc.

#include "gutil/stringprintf.h"

#include <stdarg.h> // For va_list and related operations

#include <stdio.h>  // MSVC requires this for _vsnprintf

#include <vector>

#include <ostream>

using std::vector;

#include "common/logging.h"

// IWYU pragma: no_include <butil/macros.h>

#include "gutil/macros.h" // IWYU pragma: keep

#ifdef _MSC_VER

enum { IS__MSC_VER = 1 };

#else

enum { IS__MSC_VER = 0 };

#endif

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

    // First try with a small fixed size buffer

    static const int kSpaceLength = 1024;

    char space[kSpaceLength];

    // 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, kSpaceLength, format, backup_ap);

    va_end(backup_ap);

    if (result < kSpaceLength) {

        if (result >= 0) {

            // Normal case -- everything fit.

            dst->append(space, result);

            return;

        }

        if (IS__MSC_VER) {

            // Error or MSVC running out of space.  MSVC 8.0 and higher

            // can be asked about space needed with the special idiom below:

            va_copy(backup_ap, ap);

            result = vsnprintf(nullptr, 0, format, backup_ap);

            va_end(backup_ap);

        }

        if (result < 0) {

            // Just an error.

            return;

        }

    }

    // Increase the buffer size to the size requested by vsnprintf,

    // plus one for the closing \0.

    int length = result + 1;

    auto 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;

}

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

    va_list ap;

    va_start(ap, format);

    string result;

    StringAppendV(&result, format, ap);

    va_end(ap);

    return result;

}

const string& SStringPrintf(string* dst, const char* format, ...) {

    va_list ap;

    va_start(ap, format);

    dst->clear();

    StringAppendV(dst, format, ap);

    va_end(ap);

    return *dst;

}

void StringAppendF(string* dst, const char* format, ...) {

    va_list ap;

    va_start(ap, format);

    StringAppendV(dst, format, ap);

    va_end(ap);

}

// Max arguments supported by StringPrintVector

const int kStringPrintfVectorMaxArgs = 32;

// An empty block of zero for filler arguments.  This is const so that if

// printf tries to write to it (via %n) then the program gets a SIGSEGV

// and we can fix the problem or protect against an attack.

static const char string_printf_empty_block[256] = {'\0'};

string StringPrintfVector(const char* format, const vector<string>& v) {

    CHECK_LE(v.size(), kStringPrintfVectorMaxArgs)

            << "StringPrintfVector currently only supports up to " << kStringPrintfVectorMaxArgs

            << " arguments. "

            << "Feel free to add support for more if you need it.";

    // Add filler arguments so that bogus format+args have a harder time

    // crashing the program, corrupting the program (%n),

    // or displaying random chunks of memory to users.

    const char* cstr[kStringPrintfVectorMaxArgs];

    for (int i = 0; i < v.size(); ++i) {

        cstr[i] = v[i].c_str();

    }

    for (int i = v.size(); i < arraysize(cstr); ++i) {

        cstr[i] = &string_printf_empty_block[0];

    }

    // I do not know any way to pass kStringPrintfVectorMaxArgs arguments,

    // or any way to build a va_list by hand, or any API for printf

    // that accepts an array of arguments.  The best I can do is stick

    // this COMPILE_ASSERT right next to the actual statement.

    COMPILE_ASSERT(kStringPrintfVectorMaxArgs == 32, arg_count_mismatch);

    return StringPrintf(format, cstr[0], cstr[1], cstr[2], cstr[3], cstr[4], cstr[5], cstr[6],

                        cstr[7], cstr[8], cstr[9], cstr[10], cstr[11], cstr[12], cstr[13], cstr[14],

                        cstr[15], cstr[16], cstr[17], cstr[18], cstr[19], cstr[20], cstr[21],

                        cstr[22], cstr[23], cstr[24], cstr[25], cstr[26], cstr[27], cstr[28],

                        cstr[29], cstr[30], cstr[31]);

}