NBEngine/engine/NBCore/Logger.hpp

#pragma once
#ifndef _NB_LOGGER
#define _NB_LOGGER

#include <atomic>
#include <chrono>
#include <ostream>
#include <thread>
#include <type_traits>
#include <unordered_map>
#include <vector>

#include "DataSink.hpp"
#include "Processes.hpp"
#include "ThreadSafeQueue.hpp"


namespace nb {

typedef std::chrono::time_point<
    std::chrono::system_clock,
    std::chrono::nanoseconds
> LoggerTimePoint;

struct LogEvent{
    const LoggerTimePoint time;
    const unsigned char lvl;
    const std::string msg;
    const std::thread::id tid;
    const uint64_t pid;
};

typedef std::string (*LogProcessFunction)(const LoggerTimePoint&, const std::string&);
typedef std::unordered_map<uint8_t, LogProcessFunction> LogProcessFunctionMap;

template<typename LogType, typename Logger, typename ST=std::ostream*>
class LoggerBase
: public MultithreadedDataProcessor<LogType, Logger>{
    using StreamType = ST;
    using LoggerType = Logger;
    using Base = MultithreadedDataProcessor<LogType, LoggerType>;
public:
    bool run() {
        if (!type_ptr->isRunning()) {
            this->_running = true;
            this->_runningThread = std::make_shared<std::thread>([&]{
                while(type_ptr->isRunning()) {
                    type_ptr->flush();
                }
                type_ptr->flush();
            });
        }
        return type_ptr->isRunning();
    }
protected:
    LoggerBase() = default;

    StreamType _ostream;

private:
    LoggerType* type_ptr = static_cast<LoggerType*>(this);
};

template <typename T, typename... Pack>
struct PackIsType;

template <typename T, typename PackType>
struct PackIsType<T, PackType> {
    const bool value = std::is_base_of<T, PackType>::value;
};

template <typename T, typename FirstPack, typename... Pack>
struct PackIsType<T, FirstPack, Pack...> {
    const bool value = std::is_base_of<T, FirstPack>::value && PackIsType<T, Pack...>::value;
};

template <typename T, typename Pack1, typename... Pack>
struct StreamRefToPtrVec {
    StreamRefToPtrVec(std::vector<T*> _vec, Pack1& p1, Pack&... packs)
    : vec(_vec) {
        static_assert(std::is_base_of<T, Pack1>::value);
        vec.push_back(&p1);
        vec = StreamRefToPtrVec<T, Pack...>(vec, packs...).vec;
    }

    StreamRefToPtrVec(Pack1& p1, Pack&... packs)
    : StreamRefToPtrVec({}, p1, packs...) {}

    std::vector<T*> vec;
};

template <typename T, typename Pack>
struct StreamRefToPtrVec<T, Pack> {
    StreamRefToPtrVec(std::vector<T*> _vec, Pack& p1)
    : vec(_vec) {
        static_assert(std::is_base_of<T, Pack>::value);
        vec.push_back(&p1);
    }

    StreamRefToPtrVec(Pack& p1)
    : StreamRefToPtrVec({}, p1) {}

    std::vector<T*> vec;
};

template <typename LT>
class DebugLogger : public LoggerBase<LogEvent, LT, std::vector<std::ostream*>>{
    using StreamType = std::vector<std::ostream*>;
    using LoggerType = LT;
    using Base = LoggerBase<LogEvent, LoggerType, StreamType>;
public:

    template<typename... ST>
    DebugLogger(ST&... streams) : _ostream(StreamRefToPtrVec<std::ostream, ST...>(streams...).vec) {}

    ~DebugLogger() { type_ptr->stop(); }

    void log(const std::string& msg, const uint8_t& lvl=0xFF) {
        type_ptr->push(LogEvent{
            std::chrono::system_clock::now(),
            lvl,
            msg,
            std::this_thread::get_id(),
            GetPID(),
        });
    }

    template <size_t N>
    void log(char const(&msg) [N], const uint8_t& lvl=0xFF) {
        type_ptr->log(std::string(msg), lvl);
    }

    void log(const std::exception& err, const uint8_t& lvl=0xFF) {
        type_ptr->log(err.what(), lvl);
    }

    template<typename U>
    void warn(const U& val, const uint8_t& lvl=0x01) { type_ptr->log(val, lvl); }

    template<typename U>
    void error(const U& val) { type_ptr->log(val, 0xFF); }

protected:
    std::vector<std::ostream*> _ostream;

private:
    LoggerType* type_ptr = static_cast<LoggerType*>(this);

};

class DefaultDebugLogger : public DebugLogger<DefaultDebugLogger> {
    using LoggerType = DefaultDebugLogger;
    using Base = DebugLogger<DefaultDebugLogger>;
public:
    using Base::Base;

    ~DefaultDebugLogger() { stop(); }

    friend class BufferedDataProcessor<LogEvent, ThreadsafeQueue<LogEvent>, DefaultDebugLogger>;

protected:
    using Base::_ostream;

    bool process(const LogEvent& msg) {
        for (const auto os : this->_ostream) {
            (*os) << msg.pid << " - " << msg.tid << " : " << msg.msg << "\n";
        }
        return true;
    }

};

/* class BasicLogger : public LoggerBase<BasicLogger> {
public:
    using Base = LoggerBase<BasicLogger>;
    BasicLogger(std::ostream& stream) : Base(stream) {}

    virtual void process(const LogEvent& event) {
        *_ostreams[0] << event.msg << "\n";
    }
}; */

} // namespace nb
#endif // _NB_LOGGER