#ifndef BAIDU_PADDLE_SERVING_PREDICTOR_UTILS_H
#define BAIDU_PADDLE_SERVING_PREDICTOR_UTILS_H

#include "common/macros.h"
#include "common/inner_common.h"

namespace baidu {
namespace paddle_serving {
namespace predictor {

class TimerFlow {
public:
    static const int MAX_SIZE = 1024;

    TimerFlow() {
        init();
    }

    void init() {
        _csize = 0;
        _name = NULL;
        _started = false;
        _auto = false;
    }

    TimerFlow(const char* name) : _csize(0), _name(name) {
        _last = _start = base::cpuwide_time_us();
        _auto = true;
        _started = true;
    }

    void set_name(const char* name) {
        _name = name;
    }

    void start() {
        _last = _start = base::cpuwide_time_us();
        _started = true;
    }

    bool check(const char* tag) {
        if (!_started) {
            LOG(WARNING) << "Timer not started yet!";
            return false;
        }
        uint64_t now = base::cpuwide_time_us();
        if (!appendf("%s:%lu|", tag, now - _last)) {
            LOG(WARNING) 
                << "Failed check timer: " << _name 
                << ", value = [" << tag << ":" 
                << (now - _last) << "]!" << noflush;
            return false;
        }

        _last = now;
        return true;
    }

    std::string info() {
        return std::string(_buf);
    }

    void end() {
        uint64_t now = base::cpuwide_time_us();
        if (!appendf("total:%lu", now - _start)) {
            LOG(WARNING) << "Failed dump time_info[" << _name << "]";
        }
        _started = false;
    }

    ~TimerFlow() {
        if (!_auto) {
            return;
        }
        uint64_t now = base::cpuwide_time_us();
        if (appendf("total:%lu,%s", now - _start, _name)) {
            LOG(INFO) 
                << " " << _name << "_tc=[" << _buf << "]";
        } else {
            LOG(WARNING) << "Failed dump time_info[" << _name << "]";
        }
    }

private:
    bool appendf(const char* fmt, ...) {
        va_list ap;
        va_start(ap, fmt);
        try {
            int bytes = vsnprintf(_buf + _csize, MAX_SIZE - _csize, fmt, ap);
            if (bytes >= MAX_SIZE - _csize || bytes < 0) {
                LOG(WARNING) << "Overflow when appendf!" << noflush;
                return false;
            }
            _csize += bytes;
        } CATCH_ANY_AND_RET(false);

        va_end(ap);
        return true;
    }

private:
    char _buf[1024];
    int _csize;
    uint64_t _start;
    uint64_t _last;
    const char* _name;
    bool _started;
    bool _auto;
};

template<bool flag>
struct derived_from_message {};

template<typename T, typename TBase>
class TIsDerivedFromB {
private:
    static uint8_t check(TBase*) {
        return 1;
    }

    static uint32_t check(void*) {
        return 0;
    }

public:
    enum {
        // function call cannot apprear in a constant-expression
        RESULT = (sizeof(uint8_t) == sizeof(check((T*)(NULL)))),
    };
};

template<typename TBase>
class IsDerivedFrom {
private:
    static bool check(TBase*) {
        return true;
    }

    static bool check(void*) {
        return false;
    }

public:
    template<typename T>
    static bool yes(T* x) {
        return check(x);
    }
};

} // predictor
} // paddle_serving
} // baidu

#endif