// Include qpdf-config.h first so off_t is guaranteed to have the right size.
#include <qpdf/qpdf-config.h>

#include <qpdf/QUtil.hh>
#include <qpdf/PointerHolder.hh>
#ifdef USE_INSECURE_RANDOM
# include <qpdf/InsecureRandomDataProvider.hh>
#endif
#include <qpdf/SecureRandomDataProvider.hh>

#include <cmath>
#include <iomanip>
#include <sstream>
#include <fstream>
#include <stdexcept>
#include <stdio.h>
#include <errno.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#ifdef _WIN32
#include <windows.h>
#include <direct.h>
#include <io.h>
#else
#include <unistd.h>
#include <sys/stat.h>
#endif

std::string
QUtil::int_to_string(long long num, int length)
{
    return int_to_string_base(num, 10, length);
}

std::string
QUtil::int_to_string_base(long long num, int base, int length)
{
    // Backward compatibility -- int_to_string, which calls this
    // function, used to use sprintf with %0*d, so we interpret length
    // such that a negative value appends spaces and a positive value
    // prepends zeroes.
    if (! ((base == 8) || (base == 10) || (base == 16)))
    {
        throw std::logic_error(
            "int_to_string_base called with unsupported base");
    }
    std::ostringstream buf;
    buf << std::setbase(base) << std::nouppercase << num;
    std::string result;
    if ((length > 0) &&
        (buf.str().length() < static_cast<size_t>(length)))
    {
	result.append(length - buf.str().length(), '0');
    }
    result += buf.str();
    if ((length < 0) && (buf.str().length() < static_cast<size_t>(-length)))
    {
	result.append(-length - buf.str().length(), ' ');
    }
    return result;
}

std::string
QUtil::double_to_string(double num, int decimal_places)
{
    // Backward compatibility -- this code used to use sprintf and
    // treated decimal_places <= 0 to mean to use the default, which
    // was six decimal places.  Also sprintf with %*.f interprets the
    // length as fixed point rather than significant figures.
    if (decimal_places <= 0)
    {
        decimal_places = 6;
    }
    std::ostringstream buf;
    buf << std::setprecision(decimal_places) << std::fixed << num;
    return buf.str();
}

long long
QUtil::string_to_ll(char const* str)
{
    errno = 0;
#ifdef _MSC_VER
    long long result = _strtoi64(str, 0, 10);
#else
    long long result = strtoll(str, 0, 10);
#endif
    if (errno == ERANGE)
    {
        throw std::runtime_error(
            std::string("overflow/underflow converting ") + str
            + " to 64-bit integer");
    }
    return result;
}

int
QUtil::string_to_int(char const* str)
{
    errno = 0;
    long long_val = strtol(str, 0, 10);
    if (errno == ERANGE)
    {
        throw std::runtime_error(
            std::string("overflow/underflow converting ") + str
            + " to long integer");
    }
    int result = static_cast<int>(long_val);
    if (static_cast<long>(result) != long_val)
    {
        throw std::runtime_error(
            std::string("overflow/underflow converting ") + str
            + " to integer");
    }
    return result;
}

unsigned char*
QUtil::unsigned_char_pointer(std::string const& str)
{
    return reinterpret_cast<unsigned char*>(const_cast<char*>(str.c_str()));
}

unsigned char*
QUtil::unsigned_char_pointer(char const* str)
{
    return reinterpret_cast<unsigned char*>(const_cast<char*>(str));
}

void
QUtil::throw_system_error(std::string const& description)
{
#ifdef _MSC_VER
    // "94" is mentioned in the MSVC docs, but it's still safe if the
    // message is longer.  strerror_s is a templated function that
    // knows the size of buf and truncates.
    char buf[94];
    if (strerror_s(buf, errno) != 0)
    {
        throw std::runtime_error(description + ": failed with an unknown error");
    }
    else
    {
        throw std::runtime_error(description + ": " + buf);
    }
#else
    throw std::runtime_error(description + ": " + strerror(errno));
#endif
}

int
QUtil::os_wrapper(std::string const& description, int status)
{
    if (status == -1)
    {
	throw_system_error(description);
    }
    return status;
}

FILE*
QUtil::safe_fopen(char const* filename, char const* mode)
{
    FILE* f = 0;
#ifdef _MSC_VER
    errno_t err = fopen_s(&f, filename, mode);
    if (err != 0)
    {
        errno = err;
        throw_system_error(std::string("open ") + filename);
    }
#else
    f = fopen_wrapper(std::string("open ") + filename, fopen(filename, mode));
#endif
    return f;
}

FILE*
QUtil::fopen_wrapper(std::string const& description, FILE* f)
{
    if (f == 0)
    {
	throw_system_error(description);
    }
    return f;
}

int
QUtil::seek(FILE* stream, qpdf_offset_t offset, int whence)
{
#if HAVE_FSEEKO
    return fseeko(stream, static_cast<off_t>(offset), whence);
#elif HAVE_FSEEKO64
    return fseeko64(stream, offset, whence);
#else
# if defined _MSC_VER || defined __BORLANDC__
    return _fseeki64(stream, offset, whence);
# else
    return fseek(stream, static_cast<long>(offset), whence);
# endif
#endif
}

qpdf_offset_t
QUtil::tell(FILE* stream)
{
#if HAVE_FSEEKO
    return static_cast<qpdf_offset_t>(ftello(stream));
#elif HAVE_FSEEKO64
    return static_cast<qpdf_offset_t>(ftello64(stream));
#else
# if defined _MSC_VER || defined __BORLANDC__
    return _ftelli64(stream);
# else
    return static_cast<qpdf_offset_t>(ftell(stream));
# endif
#endif
}

bool
QUtil::same_file(char const* name1, char const* name2)
{
    if ((name1 == 0) || (strlen(name1) == 0) ||
        (name2 == 0) || (strlen(name2) == 0))
    {
        return false;
    }
#ifdef _WIN32
    HANDLE fh1 = CreateFile(name1, GENERIC_READ, FILE_SHARE_READ,
                            NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
    HANDLE fh2 = CreateFile(name2, GENERIC_READ, FILE_SHARE_READ,
                            NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
    BY_HANDLE_FILE_INFORMATION fi1;
    BY_HANDLE_FILE_INFORMATION fi2;
    bool same = false;
    if ((fh1 != INVALID_HANDLE_VALUE) &&
        (fh2 != INVALID_HANDLE_VALUE) &&
        GetFileInformationByHandle(fh1, &fi1) &&
        GetFileInformationByHandle(fh2, &fi2) &&
        (fi1.dwVolumeSerialNumber == fi2.dwVolumeSerialNumber) &&
        (fi1.nFileIndexLow == fi2.nFileIndexLow) &&
        (fi1.nFileIndexHigh == fi2.nFileIndexHigh))
    {
        same = true;
    }
    if (fh1 != INVALID_HANDLE_VALUE)
    {
        CloseHandle(fh1);
    }
    if (fh2 != INVALID_HANDLE_VALUE)
    {
        CloseHandle(fh2);
    }
    return same;
#else
    struct stat st1;
    struct stat st2;
    if ((stat(name1, &st1) == 0) &&
        (stat(name2, &st2) == 0) &&
        (st1.st_ino == st2.st_ino) &&
        (st1.st_dev == st2.st_dev))
    {
        return true;
    }
#endif
    return false;
}

char*
QUtil::copy_string(std::string const& str)
{
    char* result = new char[str.length() + 1];
    // Use memcpy in case string contains nulls
    result[str.length()] = '\0';
    memcpy(result, str.c_str(), str.length());
    return result;
}

std::string
QUtil::hex_encode(std::string const& input)
{
    std::string result;
    for (unsigned int i = 0; i < input.length(); ++i)
    {
        result += QUtil::int_to_string_base(
            static_cast<int>(static_cast<unsigned char>(input.at(i))), 16, 2);
    }
    return result;
}

std::string
QUtil::hex_decode(std::string const& input)
{
    std::string result;
    size_t pos = 0;
    for (std::string::const_iterator p = input.begin(); p != input.end(); ++p)
    {
        char ch = *p;
        bool skip = false;
        if ((*p >= 'A') && (*p <= 'F'))
        {
            ch -= 'A';
            ch += 10;
        }
        else if ((*p >= 'a') && (*p <= 'f'))
        {
            ch -= 'a';
            ch += 10;
        }
        else if ((*p >= '0') && (*p <= '9'))
        {
            ch -= '0';
        }
        else
        {
            skip = true;
        }
        if (! skip)
        {
            if (pos == 0)
            {
                result.push_back(ch << 4);
                pos = 1;
            }
            else
            {
                result[result.length()-1] += ch;
                pos = 0;
            }
        }
    }
    return result;
}

void
QUtil::binary_stdout()
{
#ifdef _WIN32
    _setmode(_fileno(stdout), _O_BINARY);
#endif
}

void
QUtil::binary_stdin()
{
#ifdef _WIN32
    _setmode(_fileno(stdin), _O_BINARY);
#endif
}

void
QUtil::setLineBuf(FILE* f)
{
#ifndef _WIN32
    setvbuf(f, reinterpret_cast<char *>(NULL), _IOLBF, 0);
#endif
}

char*
QUtil::getWhoami(char* argv0)
{
    char* whoami = 0;
    if (((whoami = strrchr(argv0, '/')) == NULL) &&
        ((whoami = strrchr(argv0, '\\')) == NULL))
    {
	whoami = argv0;
    }
    else
    {
	++whoami;
    }

    if ((strlen(whoami) > 4) &&
	(strcmp(whoami + strlen(whoami) - 4, ".exe") == 0))
    {
	whoami[strlen(whoami) - 4] = '\0';
    }

    return whoami;
}

bool
QUtil::get_env(std::string const& var, std::string* value)
{
    // This was basically ripped out of wxWindows.
#ifdef _WIN32
# ifdef NO_GET_ENVIRONMENT
    return false;
# else
    // first get the size of the buffer
    DWORD len = ::GetEnvironmentVariable(var.c_str(), NULL, 0);
    if (len == 0)
    {
        // this means that there is no such variable
        return false;
    }

    if (value)
    {
	char* t = new char[len + 1];
        ::GetEnvironmentVariable(var.c_str(), t, len);
	*value = t;
	delete [] t;
    }

    return true;
# endif
#else
    char* p = getenv(var.c_str());
    if (p == 0)
    {
        return false;
    }
    if (value)
    {
        *value = p;
    }

    return true;
#endif
}

time_t
QUtil::get_current_time()
{
#ifdef _WIN32
    // The procedure to get local time at this resolution comes from
    // the Microsoft documentation.  It says to convert a SYSTEMTIME
    // to a FILETIME, and to copy the FILETIME to a ULARGE_INTEGER.
    // The resulting number is the number of 100-nanosecond intervals
    // between January 1, 1601 and now.  POSIX threads wants a time
    // based on January 1, 1970, so we adjust by subtracting the
    // number of seconds in that time period from the result we get
    // here.
    SYSTEMTIME sysnow;
    GetSystemTime(&sysnow);
    FILETIME filenow;
    SystemTimeToFileTime(&sysnow, &filenow);
    ULARGE_INTEGER uinow;
    uinow.LowPart = filenow.dwLowDateTime;
    uinow.HighPart = filenow.dwHighDateTime;
    ULONGLONG now = uinow.QuadPart;
    return ((now / 10000000LL) - 11644473600LL);
#else
    return time(0);
#endif
}

std::string
QUtil::toUTF8(unsigned long uval)
{
    std::string result;

    // A UTF-8 encoding of a Unicode value is a single byte for
    // Unicode values <= 127.  For larger values, the first byte of
    // the UTF-8 encoding has '1' as each of its n highest bits and
    // '0' for its (n+1)th highest bit where n is the total number of
    // bytes required.  Subsequent bytes start with '10' and have the
    // remaining 6 bits free for encoding.  For example, an 11-bit
    // Unicode value can be stored in two bytes where the first is
    // 110zzzzz, the second is 10zzzzzz, and the z's represent the
    // remaining bits.

    if (uval > 0x7fffffff)
    {
	throw std::runtime_error("bounds error in QUtil::toUTF8");
    }
    else if (uval < 128)
    {
	result += static_cast<char>(uval);
    }
    else
    {
	unsigned char bytes[7];
	bytes[6] = '\0';
	unsigned char* cur_byte = &bytes[5];

	// maximum value that will fit in the current number of bytes
	unsigned char maxval = 0x3f; // six bits

	while (uval > maxval)
	{
	    // Assign low six bits plus 10000000 to lowest unused
	    // byte position, then shift
	    *cur_byte = static_cast<unsigned char>(0x80 + (uval & 0x3f));
	    uval >>= 6;
	    // Maximum that will fit in high byte now shrinks by one bit
	    maxval >>= 1;
	    // Slide to the left one byte
	    if (cur_byte <= bytes)
	    {
		throw std::logic_error("QUtil::toUTF8: overflow error");
	    }
	    --cur_byte;
	}
	// If maxval is k bits long, the high (7 - k) bits of the
	// resulting byte must be high.
	*cur_byte = static_cast<unsigned char>(
            (0xff - (1 + (maxval << 1))) + uval);

	result += reinterpret_cast<char*>(cur_byte);
    }

    return result;
}

// Random data support

long
QUtil::random()
{
    long result = 0L;
    initializeWithRandomBytes(
        reinterpret_cast<unsigned char*>(&result),
        sizeof(result));
    return result;
}

static RandomDataProvider* random_data_provider = 0;

#ifdef USE_INSECURE_RANDOM
static RandomDataProvider* insecure_random_data_provider =
    InsecureRandomDataProvider::getInstance();
#else
static RandomDataProvider* insecure_random_data_provider = 0;
#endif
static RandomDataProvider* secure_random_data_provider =
    SecureRandomDataProvider::getInstance();

static void
initialize_random_data_provider()
{
    if (random_data_provider == 0)
    {
        if (secure_random_data_provider)
        {
            random_data_provider = secure_random_data_provider;
        }
        else if (insecure_random_data_provider)
        {
            random_data_provider = insecure_random_data_provider;
        }
    }
    // QUtil.hh has comments indicating that getRandomDataProvider(),
    // which calls this method, never returns null.
    if (random_data_provider == 0)
    {
        throw std::logic_error("QPDF has no random data provider");
    }
}

void
QUtil::setRandomDataProvider(RandomDataProvider* p)
{
    random_data_provider = p;
}

RandomDataProvider*
QUtil::getRandomDataProvider()
{
    initialize_random_data_provider();
    return random_data_provider;
}

void
QUtil::initializeWithRandomBytes(unsigned char* data, size_t len)
{
    initialize_random_data_provider();
    random_data_provider->provideRandomData(data, len);
}

void
QUtil::srandom(unsigned int seed)
{
#ifdef HAVE_RANDOM
    ::srandom(seed);
#else
    srand(seed);
#endif
}

bool
QUtil::is_hex_digit(char ch)
{
    return (ch && (strchr("0123456789abcdefABCDEF", ch) != 0));
}

bool
QUtil::is_space(char ch)
{
    return (ch && (strchr(" \f\n\r\t\v", ch) != 0));
}

bool
QUtil::is_digit(char ch)
{
    return ((ch >= '0') && (ch <= '9'));
}

bool
QUtil::is_number(char const* p)
{
    // ^[\+\-]?(\.\d*|\d+(\.\d*)?)$
    if (! *p)
    {
        return false;
    }
    if ((*p == '-') || (*p == '+'))
    {
        ++p;
    }
    bool found_dot = false;
    bool found_digit = false;
    for (; *p; ++p)
    {
        if (*p == '.')
        {
            if (found_dot)
            {
                // only one dot
                return false;
            }
            found_dot = true;
        }
        else if (QUtil::is_digit(*p))
        {
            found_digit = true;
        }
        else
        {
            return false;
        }
    }
    return found_digit;
}

std::list<std::string>
QUtil::read_lines_from_file(char const* filename)
{
    std::ifstream in(filename, std::ios_base::binary);
    if (! in.is_open())
    {
        throw_system_error(std::string("open ") + filename);
    }
    std::list<std::string> lines = read_lines_from_file(in);
    in.close();
    return lines;
}

std::list<std::string>
QUtil::read_lines_from_file(std::istream& in)
{
    std::list<std::string> result;
    std::string* buf = 0;

    char c;
    while (in.get(c))
    {
	if (buf == 0)
	{
	    result.push_back("");
	    buf = &(result.back());
	    buf->reserve(80);
	}

	if (buf->capacity() == buf->size())
	{
	    buf->reserve(buf->capacity() * 2);
	}
	if (c == '\n')
	{
            // Remove any carriage return that preceded the
            // newline and discard the newline
            if ((! buf->empty()) && ((*(buf->rbegin())) == '\r'))
            {
                buf->erase(buf->length() - 1);
            }
	    buf = 0;
	}
	else
	{
	    buf->append(1, c);
	}
    }

    return result;
}

int
QUtil::strcasecmp(char const *s1, char const *s2)
{
#ifdef _WIN32
    return _stricmp(s1, s2);
#else
    return ::strcasecmp(s1, s2);
#endif
}