/* Copyright (C) 2013 BMW Group
 * Author: Manfred Bathelt (manfred.bathelt@bmw.de)
 * Author: Juergen Gehring (juergen.gehring@bmw.de)
 * 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/. */
#ifndef COMMONAPI_UTILS_H_
#define COMMONAPI_UTILS_H_

#include <unistd.h>
#include <dirent.h>
#include <dlfcn.h>
#include <sys/stat.h>

#include <cstring>
#include <string>
#include <sstream>
#include <vector>
#include <algorithm>
#include <iostream>


namespace CommonAPI {


#if  __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1)
#  define COMMONAPI_DEPRECATED __attribute__ ((__deprecated__))
#elif defined(_MSC_VER) && (_MSC_VER >= 1300)
#  define COMMONAPI_DEPRECATED __declspec(deprecated)
#else
#  define COMMONAPI_DEPRECATED
#endif


/**
 * \brief Returns the fully qualified name of the binary.
 *
 * @return The name of the currently executing binary.
 */
inline std::string getCurrentBinaryFileFQN() {
    char fqnOfBinary[FILENAME_MAX];
    char pathToProcessImage[FILENAME_MAX];

    sprintf(pathToProcessImage, "/proc/%d/exe", getpid());
    const ssize_t lengthOfFqn = readlink(pathToProcessImage, fqnOfBinary, sizeof(fqnOfBinary) - 1);

    if (lengthOfFqn != -1) {
        fqnOfBinary[lengthOfFqn] = '\0';
        return std::string(std::move(fqnOfBinary));
    } else {
        return std::string("");
    }
}

/**
 * \brief Splits a std::string according to the given delim-char.
 *
 * The string will be splitted at each position the delim char is encountered. The delim itself
 * will be removed from the result.
 *
 * @param s: The string that is to be splitted
 * @param delim: The character that separates the resulting string tokens in the original string
 * @param elems: Reference to the vector that shall be filled with the splitted string elements.
 *
 * @return A reference to the vector you passed in (elems)
 */
inline std::vector<std::string>& split(const std::string& s, char delim, std::vector<std::string>& elems) {
    std::istringstream ss(s);
    std::string item;
    while (std::getline(ss, item, delim)) {
        elems.push_back(item);
    }
    return elems;
}

/**
 * \brief Splits a std::string according to the given delim-char.
 *
 * The string will be splitted at each position the delim char is encountered. The delim itself
 * will be removed from the result.
 *
 * @param s: The string that is to be splitted
 * @param delim: The character that separates the resulting string tokens in the original string
 *
 * @return A vector containing the splitted string elements.
 */
inline std::vector<std::string> split(const std::string& s, char delim) {
    std::vector<std::string> elems;
    return split(s, delim, elems);
}

/**
 * \brief Trims whitespaces from beginning and end of a std::string.
 *
 * @param toTrim: The string that is to be trimmed.
 */
inline void trim(std::string& toTrim) {
    toTrim.erase(
                    toTrim.begin(),
                    std::find_if(toTrim.begin(),
                                 toTrim.end(),
                                 std::not1(std::ptr_fun<int, int>(std::isspace)))
    );
    toTrim.erase(
                    std::find_if(toTrim.rbegin(),
                                 toTrim.rend(),
                                 std::not1(std::ptr_fun<int, int>(std::isspace))).base(),
                    toTrim.end()
    );
}

/**
 * \brief Checks whether the given string contains nothing but digits.
 *
 * @param toCheck: The string that is to be checked on the presence of anything but digits.
 *
 * @return true if toCheck contains nothing but digits, false otherwise.
 */
inline bool containsOnlyDigits(const std::string& toCheck) {
    auto firstNonDigitIt = std::find_if(
                    toCheck.begin(),
                    toCheck.end(),
                    [](char c) {
                        return !std::isdigit(c);
                    });

    return firstNonDigitIt == toCheck.end();
}

/**
 * \brief Checks whether the given string contains nothing but alphanumeric characters.
 *
 * @param toCheck: The string that is to be checked on the presence of anything but alphanumeric characters.
 *
 * @return true if toCheck contains nothing but alphanumeric characters, false otherwise.
 */
inline bool containsOnlyAlphanumericCharacters(const std::string& toCheck) {
    auto firstNonAlphanumericCharacterIt = std::find_if(
                    toCheck.begin(),
                    toCheck.end(),
                    [](char c) {
                        return !std::isalnum(c);
                    });

    return firstNonAlphanumericCharacterIt == toCheck.end();
}

/**
 * \brief Checks whether the given std::string is a valid CommonAPI domain name.
 *
 * @param domainName: The std::string that is to be checked.
 *
 * @return true if domainName is a valid CommonAPI domainName, false otherwise.
 */
inline bool isValidDomainName(const std::string& domainName) {
    return containsOnlyAlphanumericCharacters(domainName);
}

/**
 * \brief Checks whether the given std::string is a valid CommonAPI service name.
 *
 * @param serviceName: The std::string that is to be checked.
 *
 * @return true if serviceName is a valid CommonAPI serviceName, false otherwise.
 */
inline bool isValidServiceName(const std::string& serviceName) {
    bool isValid = serviceName[0] != '.' && serviceName[serviceName.size() - 1] != '.';

    if (isValid) {
        std::vector<std::string> splittedServiceName = split(serviceName, '.');

        for (auto serviceNameElementIt = splittedServiceName.begin();
                        serviceNameElementIt != splittedServiceName.end() && isValid;
                        ++serviceNameElementIt) {
            isValid &= containsOnlyAlphanumericCharacters(*serviceNameElementIt);
        }
    }

    return isValid;
}

/**
 * \brief Checks whether the given std::string is a valid CommonAPI instance ID.
 *
 * @param instanceId: The std::string that is to be checked.
 *
 * @return true if instanceId is a valid CommonAPI instance ID, false otherwise.
 */
inline bool isValidInstanceId(const std::string& instanceId) {
    //Validation rules for ServiceName and InstanceID are equivalent
    return isValidServiceName(instanceId);
}

/**
 * \brief Checks whether the given std::string is a valid CommonAPI address.
 *
 * @param commonApiAddressName: The std::string that is to be checked.
 *
 * @return true if commonApiAddress is a valid CommonAPI address, false otherwise.
 */
inline bool isValidCommonApiAddress(const std::string& commonApiAddress) {
    std::vector<std::string> splittedAddress = split(commonApiAddress, ':');
    if (splittedAddress.size() != 3) {
        return false;
    }
    return isValidDomainName(splittedAddress[0]) && isValidServiceName(splittedAddress[1]) && isValidInstanceId(splittedAddress[2]);
}


/**
 * \brief Loads a specific generic library at runtime.
 *
 * The library will be loaded using dlopen(3) with the flags (RTLD_NOW | RTLD_GLOBAL), if all pre-checks are
 * successful. Pre-checks include the verification that the given parameters actually point to a library and
 * optionally if the library matches the standard name pattern for CommonAPI generic libraries. The standard
 * name pattern is "lib<wellKnownMiddlewareName>Gen-<arbitraryName>.so[.major[.minor.revision]]".
 *
 * @param wellKnownMiddlewareName: The name of the middleware that requests the loading of the library.
 * @param libraryName: The name of the library that shall be loaded.
 * @param path: The path at which the library is to be found. path + library name together make up the fully
 *              qualified name of the library.
 * @param checkStandardNamePattern: If set to true, it will be ensured the library matches the CommonAPI
 *                                  standard name pattern for generic libraries. This is meant as a safety measure
 *                                  to prevent the loading of unnecessary or the wrong libraries. Set to false if
 *                                  you are sure about what you are doing.
 * @return true if the library could be loaded successfully, false otherwise.
 *
 * @note The well known middleware name is included as a parameter because the additional libraries normally are needed
 *       only by specific middlewares. This name however will only be taken into consideration during name checking
 *       if the checkStandardNamePattern flag is set to true.
 */
inline bool loadGenericLibrary(const std::string& wellKnownMiddlewareName, const std::string& libraryName, const std::string& path, bool checkStandardNamePattern = true) {
    std::string fqnOfLibrary = path + libraryName;
    struct stat filestat;
    if (stat(fqnOfLibrary.c_str(), &filestat)) {
        return false;
    }
    if (S_ISDIR(filestat.st_mode)) {
        return false;
    }

    if (checkStandardNamePattern) {
        const std::string generatedLibPrefix = "lib" + wellKnownMiddlewareName + "Gen-";
        if (strncmp(generatedLibPrefix.c_str(), libraryName.c_str(), generatedLibPrefix.length()) != 0) {
            return false;
        }

        const char* fileNamePtr = libraryName.c_str();
        while ((fileNamePtr = strchr(fileNamePtr + 1, '.'))) {
            if (strncmp(".so\0", fileNamePtr, 4) == 0 || strncmp(".so.", fileNamePtr, 4) == 0) {
                break;
            }
        }

        if (!fileNamePtr) {
            return false;
        }
    }

    dlopen(fqnOfLibrary.c_str(), RTLD_NOW | RTLD_GLOBAL);
    return true;
}

/**
 * \brief Loads a specific generic library at runtime.
 *
 * The library will be loaded using dlopen(3) with the flags (RTLD_NOW | RTLD_GLOBAL), if all pre-checks are
 * successful. Pre-checks include the verification that the given parameters actually point to a library and
 * optionally if the library matches the standard name pattern for CommonAPI generic libraries. The standard
 * name pattern is "lib<wellKnownMiddlewareName>Gen-<arbitraryName>.so[.major[.minor.revision]]".
 *
 * @param wellKnownMiddlewareName: The name of the middleware that requests the loading of the library.
 * @param fqnOfLibrary: The fully qualified name of the library.
 * @param checkStandardNamePattern: If set to true, it will be ensured the library matches the CommonAPI
 *                                  standard name pattern for generic libraries. This is meant as a safety measure
 *                                  to prevent the loading of unnecessary or the wrong libraries. Set to false if
 *                                  you are sure about what you are doing.
 * @return true if the library could be loaded successfully, false otherwise.
 *
 * @note The well known middleware name is included as a parameter because the additional libraries normally are needed
 *       only by specific middlewares. This name however will only be taken into consideration during name checking
 *       if the checkStandardNamePattern flag is set to true.
 */
inline bool loadGenericLibrary(const std::string& wellKnownMiddlewareName,
                               const std::string& fqnOfLibrary,
                               bool checkStandardNamePattern = true) {
    uint32_t position = fqnOfLibrary.find_last_of("/\\");
    std::string path = fqnOfLibrary.substr(0, position + 1);
    std::string file = fqnOfLibrary.substr(position + 1);
    return loadGenericLibrary(wellKnownMiddlewareName, file, path, checkStandardNamePattern);
}


/**
 * \brief Searches the given path for additional generic CommonAPI libraries and loads them.
 *
 * All libraries for which the pre-checks are successful will be loaded using dlopen(3) with the flags
 * (RTLD_NOW | RTLD_GLOBAL). Pre-checks include the verification that the given parameters actually point
 * to a library and if the library matches the standard name pattern for CommonAPI generic libraries.
 * The standard name pattern is "lib<wellKnownMiddlewareName>Gen-<arbitraryName>.so[.major[.minor.revision]]".
 *
 * @param wellKnownMiddlewareName: The name of the middleware that requests the loading of the library. Will
 *                                 be used to perform the name check.
 * @param singleSearchPath: The directory that is to be searched for libraries.
 */
inline void findAndLoadGenericLibraries(const std::string& requestedMiddlewareName, const std::string& singleSearchPath) {
    DIR *directory = opendir(singleSearchPath.c_str());

    if (directory != NULL) {
        struct dirent* entry;

        while ((entry = readdir(directory))) {
            loadGenericLibrary(requestedMiddlewareName, entry->d_name, singleSearchPath, true);
        }
    }
}

/**
 * \brief Searches the given paths for additional generic CommonAPI libraries and loads them.
 *
 * All libraries for which the pre-checks are successful will be loaded using dlopen(3) with the flags
 * (RTLD_NOW | RTLD_GLOBAL). Pre-checks include the verification that the given parameters actually point
 * to a library and if the library matches the standard name pattern for CommonAPI generic libraries.
 * The standard name pattern is "lib<wellKnownMiddlewareName>Gen-<arbitraryName>.so[.major[.minor.revision]]".
 *
 * @param wellKnownMiddlewareName: The name of the middleware that requests the loading of the library. Will
 *                                 be used to perform the name check.
 * @param searchPaths: The directories that are to be searched for libraries.
 */
inline void findAndLoadGenericLibraries(const std::string& requestedMiddlewareName, const std::vector<std::string>& searchPaths) {
    for (const std::string& singleSearchPath : searchPaths) {
        findAndLoadGenericLibraries(requestedMiddlewareName, singleSearchPath.c_str());
    }
}


} //namespace CommonAPI


#endif /* COMMONAPI_UTILS_H_ */