/**
 *    Copyright (C) 2018-present MongoDB, Inc.
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the Server Side Public License, version 1,
 *    as published by MongoDB, Inc.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    Server Side Public License for more details.
 *
 *    You should have received a copy of the Server Side Public License
 *    along with this program. If not, see
 *    <http://www.mongodb.com/licensing/server-side-public-license>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the Server Side Public License in all respects for
 *    all of the code used other than as permitted herein. If you modify file(s)
 *    with this exception, you may extend this exception to your version of the
 *    file(s), but you are not obligated to do so. If you do not wish to do so,
 *    delete this exception statement from your version. If you delete this
 *    exception statement from all source files in the program, then also delete
 *    it in the license file.
 */

#include "mongo/platform/basic.h"

#include "mongo/util/errno_util.h"

#include <sstream>

#ifndef _WIN32
#include <cstring>  // For strerror_r
#include <errno.h>  // For errno
#endif

#include "mongo/util/scopeguard.h"
#include "mongo/util/text.h"

namespace mongo {

namespace {
const char kUnknownMsg[] = "Unknown error";
const int kBuflen = 256;  // strerror strings in non-English locales can be large.
}  // namespace

std::string errnoWithDescription(int errNumber) {
#if defined(_WIN32)
    if (errNumber == -1)
        errNumber = GetLastError();
#else
    if (errNumber < 0)
        errNumber = errno;
#endif

    char buf[kBuflen];
    char* msg{nullptr};

#if defined(__GNUC__) && defined(_GNU_SOURCE) && !(__ANDROID_API__ <= 22) && !defined(EMSCRIPTEN)
    msg = strerror_r(errNumber, buf, kBuflen);
#elif defined(_WIN32)

    LPWSTR errorText = nullptr;
    FormatMessageW(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_ALLOCATE_BUFFER |
                       FORMAT_MESSAGE_IGNORE_INSERTS,
                   nullptr,
                   errNumber,
                   0,
                   reinterpret_cast<LPWSTR>(&errorText),  // output
                   0,                                     // minimum size for output buffer
                   nullptr);

    if (errorText) {
        ON_BLOCK_EXIT([&errorText] { LocalFree(errorText); });
        std::string utf8ErrorText = toUtf8String(errorText);
        auto size = utf8ErrorText.find_first_of("\r\n");
        if (size == std::string::npos) {  // not found
            size = utf8ErrorText.length();
        }

        if (size >= kBuflen) {
            size = kBuflen - 1;
        }

        memcpy(buf, utf8ErrorText.c_str(), size);
        buf[size] = '\0';
        msg = buf;
    } else if (strerror_s(buf, kBuflen, errNumber) != 0) {
        msg = buf;
    }
#else /* XSI strerror_r */
    if (strerror_r(errNumber, buf, kBuflen) == 0) {
        msg = buf;
    }
#endif

    if (!msg) {
        return {kUnknownMsg};
    }

    return {msg};
}

std::pair<int, std::string> errnoAndDescription() {
#if defined(_WIN32)
    int errNumber = GetLastError();
#else
    int errNumber = errno;
#endif
    return {errNumber, errnoWithDescription(errNumber)};
}

std::string errnoWithPrefix(StringData prefix) {
    const auto suffix = errnoWithDescription();
    std::stringstream ss;
    if (!prefix.empty())
        ss << prefix << ": ";
    ss << suffix;
    return ss.str();
}

}  // namespace mongo