Config.h

/*
 * A class for saving and retrieving parameters, with a scheme for command line
 * overrides.
 *
 * This uses nlohmann::json to parse json files.
 *
 * Author: Seb James
 */
#pragma once

#include <nlohmann/json.hpp>
#include <morph/tools.h>
#include <morph/vvec.h>
#include <morph/vec.h>
#include <list>
#include <fstream>
#include <sstream>
#include <string>
#include <iostream>
#include <stdexcept>
#ifndef __WIN__
# include <morph/Process.h>
#endif

namespace morph {
#ifndef __WIN__
    //! Callbacks class extends ProcessCallbacks
    class ConfigProcessCallbacks : public ProcessCallbacks
    {
    public:
        ConfigProcessCallbacks (ProcessData* p) { this->parent = p; }
        void startedSignal (std::string msg) { this->parent->setProcessStartedMsg (std::string("ConfigProcess started: ") + msg); }
        void errorSignal (int err) { this->parent->setErrorNum (err); }
        void processFinishedSignal (std::string msg) { this->parent->setProcessFinishedMsg (msg); }
        void readyReadStandardOutputSignal() { this->parent->setStdOutReady (true); }
        void readyReadStandardErrorSignal() { this->parent->setStdErrReady (true); }
    private:
        ProcessData* parent;
    };
#endif
    /*!
     * A configuration file class to help read simulation parameters from a JSON file.
     *
     * This reads a config file which should be arranged as a JSON file. The format is fairly
     * free-form; getters and setters are used to access the parameters stored in the config file.
     *
     * This class also provides code for updating the JSON config and writing out the updated config
     * into the log directory to make a record of the parameters used to generate a set of
     * simulation data.
     */
    class Config
    {
    public:
        //! Default constructor, when config should be a class member. Call init() before use.
        Config(){}

        //! Constructor which takes the path to the file that contains the JSON.
        Config (const std::string& configfile) { this->init (configfile); }

        //! Perform config file initialization.
        void init (const std::string& configfile)
        {
            this->thefile = configfile;
            std::stringstream ess;
            // Test for existence of the JSON file.
            std::ifstream jsonfile_test;
            jsonfile_test.open (configfile, std::ios::in);
            if (jsonfile_test.is_open()) {
                // File exists, should parse it
                jsonfile_test.close();
                // Parse the JSON
                std::ifstream jsonfile (configfile, std::ifstream::binary);
                jsonfile >> this->root;
                // JSON is open and parsed
                this->ready = true;
            } // else We are creating a new Config, with no pre-existing content
        }

#ifndef __WIN__
        /*!
         * Launch git sub-processes to determine info about the current
         * repository. Intended for use with code that will save a Json formatted log of
         * a simulation run.
         *
         * \a codedir The name of the directory in which significant code is located. If
         * git status detects changes in this directory, then information to this effect
         * will be inserted into this->root.
         */
        void insertGitInfo (const std::string& codedir)
        {
            ProcessData pD;
            ConfigProcessCallbacks cb(&pD);
            Process p;
            std::string command ("/usr/bin/git");

            std::list<std::string> args1;
            args1.push_back ("git");
            args1.push_back ("rev-parse");
            args1.push_back ("HEAD");

            try {
                p.setCallbacks (&cb);
                p.start (command, args1);
                p.probeProcess ();
                if (!p.waitForStarted()) {
                    throw std::runtime_error ("Process failed to start");
                }
                while (p.running() == true) {
                    p.probeProcess();
                }

                std::stringstream theOutput;
                theOutput << p.readAllStandardOutput();
                std::string line = "";
                int nlines = 0;
                while (getline (theOutput, line, '\n')) {
                    std::cout << "Current git HEAD: " << line << std::endl;
                    if (nlines++ > 0) {
                        break;
                    }
                    this->root["git_head"] = line; // Should be one line only
                }

            } catch (const std::exception& e) {
                std::cerr << "Exception: " << e.what() << std::endl;
                this->root["git_head"] = "unknown";
            }

            // Reset Process with arg true to keep callbacks
            p.reset (true);

            std::list<std::string> args2;
            args2.push_back ("git");
            args2.push_back ("status");

            try {
                p.start (command, args2);
                p.probeProcess ();
                if (!p.waitForStarted()) {
                    throw std::runtime_error ("Process failed to start");
                }
                while (p.running() == true) {
                    p.probeProcess();
                }

                std::stringstream theOutput;
                theOutput << p.readAllStandardOutput();
                std::string line = "";
                bool lm = false;
                bool ut = false;
                while (getline (theOutput, line, '\n')) {
                    if (line.find("modified:") != std::string::npos) {
                        if (line.find(codedir) != std::string::npos) {
                            if (!lm) {
                                this->root["git_modified_sim"] = true;
                                std::cout << "Repository has local modifications in " << codedir << " dir" << std::endl;
                            }
                            lm = true;
                        }
                    }
                    if (line.find("Untracked files:") != std::string::npos) {
                        if (line.find(codedir) != std::string::npos) {
                            if (!ut) {
                                this->root["git_untracked_sim"] = true;
                                std::cout << "Repository has untracked files present in " << codedir << " dir" << std::endl;
                            }
                            ut = true;
                        }
                    }
                }

            } catch (const std::exception& e) {
                std::stringstream ee;
                ee << "Exception: " << e.what();
                this->emsg = ee.str();
                this->root["git_status"] = "unknown";
            }

            // Reset for third call
            p.reset (true);

            // This gets the git branch name
            std::list<std::string> args3;
            args3.push_back ("git");
            args3.push_back ("rev-parse");
            args3.push_back ("--abbrev-ref");
            args3.push_back ("HEAD");

            try {
                p.start (command, args3);
                p.probeProcess ();
                if (!p.waitForStarted()) {
                    throw std::runtime_error ("Process failed to start");
                }
                while (p.running() == true) {
                    p.probeProcess();
                }

                std::stringstream theOutput;
                theOutput << p.readAllStandardOutput();
                std::string line = "";
                int nlines = 0;
                while (getline (theOutput, line, '\n')) {
                    std::cout << "Current git branch: " << line << std::endl;
                    if (nlines++ > 0) {
                        break;
                    }
                    this->root["git_branch"] = line; // Should be one line only
                }

            } catch (const std::exception& e) {
                std::stringstream ee;
                ee << "Exception: " << e.what();
                this->emsg = ee.str();
                this->root["git_branch"] = "unknown";
            }
        }
#endif // __WIN__

        void write() { this->write (this->thefile); }

        //! Write out the JSON to a different file.
        void write (const std::string& outfile)
        {
            std::ofstream configout;
            configout.open (outfile.c_str(), std::ios::out|std::ios::trunc);
            if (configout.is_open()) {
                // Make a copy of root
                nlohmann::json combined = this->root;
                // add config_overrides, if necessary
                if (!config_overrides.empty()) {
                    nlohmann::json co(this->config_overrides);
                    combined["config_overrides"] = co;
                }
                // Write out.
                configout << std::setw(4) << combined << std::endl;
                configout.close();
            } else {
                this->emsg = "Failed to open file '" + outfile + "' for writing";
            }
        }

        //! Output the config as a string of text
        std::string str() const
        {
            std::stringstream ss;
            if (!config_overrides.empty()) {
                nlohmann::json combined = this->root;
                nlohmann::json co(this->config_overrides);
                combined["config_overrides"] = co;
                ss << std::setw(4) << combined << std::endl;
            } else {
                ss << std::setw(4) << this->root << std::endl;
            }
            return ss.str();
        }

        //! map of configuation parameter overrides applied via command line
        std::map<std::string, std::string> config_overrides;

        /*!
         * Process command line args for 'Config overrides' and store as overrides for
         * the relevant params. Can be used multiple times.
         *
         * e.g. morph_program -co:varname=43 -co:"stringvar=something with spaces"
         *
         * Currently only works for single parameter overrides (ones that you can read
         * with Config::getFloat() and similar) and not arrays or complex objects.
         *
         */
        void process_args (int argc, char **argv)
        {
            for (int i = 0; i < argc; ++i) {
                std::string arg(argv[i]);
                std::string::size_type pos = std::string::npos;
                // co for 'Config override'
                if ((pos = arg.find ("-oc:")) == 0) {
                    std::cout << "NB: Use '-co:' rather than '-oc:'!!\n";
                }
                if ((pos = arg.find ("-co:")) == 0) {
                    std::string arg_ss = arg.substr (4);
                    // Split arg based on '='
                    std::vector<std::string> co = morph::tools::stringToVector (arg_ss, std::string("="));
                    if (co.size() >= 2) {
                        std::cout << "Override parameter '" << co[0] << "' with value '" << co[1] << "'\n";
                        //...so stick with using a map
                        this->config_overrides[co[0]] = co[1];
                    }
                }
            }
        }

        // Wrappers around gets
        template <typename T>
        T get (const std::string& thing, T defaultval) const
        {
            if (this->config_overrides.count(thing) > 0) {
                T rtn = defaultval;
                // There's an override to apply. Type will determine how the thing is processed
                if constexpr (std::is_same<std::decay_t<T>, bool>::value == true) {
                    std::string bval = this->config_overrides.at(thing);
                    if (bval == "true" || bval == "True") {
                        rtn = true;
                    } else if (bval == "false" || bval == "False") {
                        rtn = false;
                    } else {
                        rtn = std::stoi (bval) > 0 ? true : false;
                    }
                } else if constexpr (std::is_same<std::decay_t<T>, int>::value == true) {
                    rtn = std::stoi (this->config_overrides.at(thing));
                } else if constexpr (std::is_same<std::decay_t<T>, unsigned int>::value == true) {
                    rtn = std::stoul (this->config_overrides.at(thing));
                } else if constexpr (std::is_same<std::decay_t<T>, float>::value == true) {
                    rtn = std::stof (this->config_overrides.at(thing));
                } else if constexpr (std::is_same<std::decay_t<T>, double>::value == true) {
                    rtn = std::stod (this->config_overrides.at(thing));
                } else if constexpr (std::is_same<std::decay_t<T>, std::string>::value == true) {
                    rtn = this->config_overrides.at(thing);
                } else {
                    std::cout << "Type not handled by morph::Config::get, return default value: "
                              << defaultval << std::endl;
                }
                return rtn;

            } else {
                return this->root.contains(thing) ? this->root[thing].get<T>() : defaultval;
            }
        }
        // get as a json object
        nlohmann::json get (const std::string& thingname) const
        {
            nlohmann::json rtn;
            if (this->root.contains(thingname)) {
                rtn = this->root[thingname];
            }
            return rtn;
        }

        bool getBool (const std::string& thing, bool defaultval) const
        {
            return this->get<bool> (thing, defaultval);
        }
        int getInt (const std::string& thing, int defaultval) const
        {
            return this->get<int> (thing, defaultval);
        }
        unsigned int getUInt (const std::string& thing, unsigned int defaultval) const
        {
            return this->get<unsigned int> (thing, defaultval);
        }
        float getFloat (const std::string& thing, float defaultval) const
        {
            return this->get<float> (thing, defaultval);
        }
        double getDouble (const std::string& thing, double defaultval) const
        {
            return this->get<double> (thing, defaultval);
        }
        std::string getString (const std::string& thing, const std::string& defaultval) const
        {
            return this->get<std::string> (thing, defaultval);
        }
        // getArray is the same as get()
        nlohmann::json getArray (const std::string& arrayname) const
        {
            nlohmann::json rtn;
            if (this->root.contains(arrayname)) {
                rtn = this->root[arrayname];
            }
            return rtn;
        }
        // Get an array of numbers as a morph::vvec.
        template <typename T>
        morph::vvec<T> getvvec (const std::string& arrayname) const
        {
            nlohmann::json ar;
            if (this->root.contains(arrayname)) { ar = this->root[arrayname]; }
            morph::vvec<T> rtn (ar.size(), T{0});
            typename morph::vvec<T>::size_type i = 0U;
            for (auto el : ar) { rtn[i++] = static_cast<T>(el); }
            return rtn;
        }

        // Get an array of numbers as a morph::vec.
        template <typename T, std::size_t N>
        morph::vec<T, N> getvec (const std::string& arrayname) const
        {
            nlohmann::json ar;
            if (this->root.contains(arrayname)) { ar = this->root[arrayname]; }
            morph::vec<T, N> rtn = {T{0}};
            auto el = ar.begin();
            for (std::size_t i = 0; i < N && i < ar.size(); ++i) {
                rtn[i] = static_cast<T>(*el);
                el++;
            }
            return rtn;
        }

        // Setters
        template <typename T>
        void set (const std::string& thing, T value) { this->root[thing] = value; }
        template <typename T>
        void setArray (const std::string& thing, const std::vector<T>& values) { this->root[thing] = values; }

        //! Set true when json has been initialised (i.e. thefile has been read)
        bool ready = false;

        //! Any error message is here.
        std::string emsg = "";

        // The root object which is set up in the constructor
        nlohmann::json root;

        // The file that holds the JSON
        std::string thefile = "";
    };
} // namespace