/**
 * Copyright (C) 2017-2018, U.S. Government
 */
#include <Process.h>
#include <Logger.h>
#include <HirsRuntimeException.h>
#include <Utils.h>

#include <arpa/inet.h>
#include <dirent.h>

#include <cstdio>
#include <cerrno>
#include <cstring>

#include <sstream>
#include <iostream>
#include <string>
#include <utility>

using hirs::exception::HirsRuntimeException;
using hirs::log::Logger;
using hirs::utils::Process;
using hirs::file_utils::dirExists;
using hirs::file_utils::fileExists;
using hirs::file_utils::fileToString;
using hirs::file_utils::trimFilenameFromPath;
using hirs::string_utils::trimChar;
using std::cerr;
using std::endl;
using std::ostream;
using std::stringstream;
using std::string;
using std::to_string;

const Logger Process::LOGGER = Logger::getDefaultLogger();

const char* const Process::kPgrepCommand = "pgrep";
const int Process::kMaxStatFileProcessNameLength = 15;

/**
 * Constructor.
 * @param executable the executable to be run
 * @param arguments the arguments including options to be passed to the
 * executable (defaults to empty string)
 */
Process::Process(const string& executable, const string& arguments)
    : executable(executable), arguments(arguments) {
}

/**
 * Run the command and return the return value of the process.
 * @return the return value of the Linux process (between 0-255)
 */
int Process::run() {
    fflush(nullptr);  // Flush output streams of preexisting buffered output.
    stringstream commandStringStream;
    commandStringStream << executable;
    if (!arguments.empty()) {
        commandStringStream << " " << arguments;
    }

    string command = commandStringStream.str();
    LOGGER.info("Executing command: " + command);
    FILE* f = popen(command.c_str(), "re");
    if (f == nullptr) {
        stringstream errStream;
        errStream << "Unable to open output stream from command \""
                  << command << "\":" << strerror(errno) << endl;
        LOGGER.error(errStream.str());
        return -1;
    }
    int c;
    stringstream ss;
    while ((c = getc(f)) != EOF) {
        ss << static_cast<char>(c);
    }

    output = ss.str();

    // Linux return values are 0-255 even though pclose() returns a 32-bit int
    uint16_t retValAsBigEndian = static_cast<uint16_t>(pclose(f));
    return ntohs(retValAsBigEndian);
}

/**
 * Run the command and return the return value of the process.
 * @param osForErrorLogging ostream to collect error message on failure
 * @return the return value of the Linux process (between 0-255)
 */
int Process::run(ostream& osForErrorLogging) {
    int processReturnValue = run();
    if (processReturnValue != 0) {
        osForErrorLogging << "Call to " << executable
                          << " returned " << processReturnValue << endl;
    }

    if (processReturnValue == 127) {
        osForErrorLogging << "Is " << executable << " in your path?" << endl;
    }
    return processReturnValue;
}

/**
 * Return a string containing the standard output stream of the Linux process.
 * @return a string containing the standard output stream of the Linux process
 */
string Process::getOutputString() const {
    return output;
}

/**
 * Static function for calling a process that must succeed or throw
 * a HirsRuntimeException. This function is meant to be used with the
 * RUN_PROCESS_OR_THROW macro in order to capture the source file name
 * and source file line number for use in the exception message.
 *
 * @param executable the executable to be run
 * @param arguments the arguments including options to be passed to the
 * @param sourceFileName source file from which this method was called
 * @param sourceLineNumber line number of source file from which this method
 *                         was called
 * executable (defaults to empty string)
 */
string Process::run(const string& executable,
                    const string& arguments,
                    const string& sourceFileName,
                    int sourceLineNumber) {
    stringstream errorStream;
    Process p(executable, arguments);
    if (p.run(errorStream) != 0) {
        errorStream << "\n\n"
                    << "Process Output: "
                    << p.getOutputString();
        throw HirsRuntimeException(errorStream.str(),
                    sourceFileName + ": " + to_string(sourceLineNumber));
    }

    // Remove trailing newline if one exists
    string str = p.getOutputString();
    if (!str.empty() && str[str.length() - 1] == '\n') {
        str.erase(str.length() - 1);
    }
    return str;
}

/**
 * Static function to check if a specified process is currently running in the
 * local environment.
 *
 * @param executable the executable to check is running
 * @return true, if executable is found to be running / false, otherwise
 */
bool Process::isRunning(const string& executable) {
    // Check if executable includes path and trim to just process name if so
    string processName = trimFilenameFromPath(executable);
    // Log warning about including path to executable
    if (processName.length() < executable.length()) {
        stringstream warnStream;
        warnStream << "Including the path to an executable isn't recommended "
                   << "as this has no bearing on whether it's determined to "
                   << "be running in the local environment.";
        LOGGER.warn(warnStream.str());
    }

    // Sanitize any attempts to hijack the process
    processName = trimChar(processName, ';');

    // If the process name is longer than 15 characters log a warning
    if (processName.length() > kMaxStatFileProcessNameLength) {
        stringstream warnStream;
        warnStream << "A process name with length greater than "
                   << to_string(kMaxStatFileProcessNameLength)
                   << " may result in a false negative depending on the"
                   << " current runtime environment.";
        LOGGER.warn(warnStream.str());
    }
    return Process(kPgrepCommand, "-c " + processName).run() == 0;
}