/*
 * SensorBase.h
 *
 *  Created on: 09.08.2018
 *      Author: Micha Mueller
 */

#ifndef SRC_SENSORBASE_H_
#define SRC_SENSORBASE_H_

#include <fstream>
#include <memory>
#include <string>
#include <limits.h>
#include <boost/lockfree/spsc_queue.hpp>
#include "logging.h"

typedef struct {
	int64_t  value;
	uint64_t timestamp;
} reading_t;

typedef struct {
  uint64_t value;
  uint64_t timestamp;
} ureading_t;

class SensorBase {
public:
	static const size_t QUEUE_MAXLIMIT=1024;

	SensorBase(const std::string& name) :
		_name(name),
		_mqtt(""),
		_sinkPath(""),
		_skipConstVal(false),
		_cacheInterval(900000),
		_subsamplingFactor(1),
		_subsamplingIndex(0),
		_cacheSize(1),
		_cacheIndex(0),
		_cache(nullptr),
		_delta(false),
		_firstReading(true),
		_readingQueue(nullptr),
		_sinkFile(nullptr) {

        _lastRawUValue.timestamp = 0;
        _lastRawUValue.value     = 0;
        _lastRawValue.timestamp = 0;
        _lastRawValue.value     = 0;
        _latestValue.timestamp	= 0;
        _latestValue.value		= 0;
        _lastSentValue.timestamp= 0;
        _lastSentValue.value	= 0;
        _accumulator.timestamp  = 0;
        _accumulator.value		= 0;
	}

	SensorBase(const SensorBase& other) :
		_name(other._name),
		_mqtt(other._mqtt),
		_skipConstVal(other._skipConstVal),
		_cacheInterval(other._cacheInterval),
		_subsamplingFactor(other._subsamplingFactor),
		_subsamplingIndex(0),
		_cacheSize(other._cacheSize),
		_cacheIndex(0),
		_cache(nullptr),
		_delta(other._delta),
		_firstReading(true),
		_lastRawUValue(other._lastRawUValue),
		_lastRawValue(other._lastRawValue),
		_latestValue(other._latestValue),
        _lastSentValue(other._lastSentValue),
        _accumulator(other._accumulator),
		_readingQueue(nullptr),
		_sinkFile(nullptr) {}

	virtual ~SensorBase() {}

	SensorBase& operator=(const SensorBase& other) {
		_name = other._name;
		_mqtt = other._mqtt;
		_skipConstVal = other._skipConstVal;
		_cacheInterval = other._cacheInterval;
		_subsamplingFactor = other._subsamplingFactor;
		_subsamplingIndex = 0;
		_cacheSize = other._cacheSize;
		_cacheIndex = 0;
		_cache.reset(nullptr);
		_delta = other._delta;
		_firstReading = true;
		_lastRawUValue.timestamp = other._lastRawUValue.timestamp;
        _lastRawUValue.value     = other._lastRawUValue.value;
		_lastRawValue.timestamp = other._lastRawValue.timestamp;
        _lastRawValue.value     = other._lastRawValue.value;
		_latestValue.timestamp	= other._latestValue.timestamp;
		_latestValue.value		= other._latestValue.value;
        _lastSentValue.timestamp= other._lastSentValue.timestamp;
        _lastSentValue.value	= other._lastSentValue.value;
        _accumulator.timestamp  = other._accumulator.timestamp;
        _accumulator.value      = other._accumulator.value;
		_readingQueue.reset(nullptr);
		_sinkFile.reset(nullptr);

		return *this;
	}

	const bool 				isDelta()			const 	{ return _delta;}
	const std::string& 		getName() 			const	{ return _name; }
	const std::string&		getMqtt() 			const	{ return _mqtt; }
	const std::string&		getSinkPath() 		const	{ return _sinkPath; }
	bool					getSkipConstVal()	const	{ return _skipConstVal; }
	unsigned				getCacheSize()		const	{ return _cacheSize; }
	unsigned				getCacheInterval()	const	{ return _cacheInterval; }
	unsigned 				getSubsampling()	const   { return _subsamplingFactor; }
	const reading_t * const	getCache() 			const	{ return _cache.get(); }
	const reading_t&		getLatestValue()	const	{ return _latestValue; }
	const bool				isInit()			const 	{ return _cache && _readingQueue; }

	void	setSkipConstVal(bool skipConstVal)				{ _skipConstVal = skipConstVal;	}
	void	setDelta(const bool delta) 						{ _delta = delta; }
	void	setName(const std::string& name, int cpuID=-1)	{ _name = formatName(name, cpuID); }
	void	setMqtt(const std::string& mqtt)				{ _mqtt = mqtt; }
	void 	setSinkPath(const std::string& path)			{ _sinkPath = path; }
	void 	setCacheInterval(unsigned cacheInterval)		{ _cacheInterval = cacheInterval; }
	void	setSubsampling(unsigned factor)					{ _subsamplingFactor = factor; }
	void    setLastRaw(int64_t raw)                         { _lastRawValue.value = raw; }
	void    setLastURaw(uint64_t raw)                       { _lastRawUValue.value = raw; }

	const std::size_t	getSizeOfReadingQueue() const { return _readingQueue->read_available(); }
	std::size_t 		popReadingQueue(reading_t *reads, std::size_t max) const	{ return _readingQueue->pop(reads, max); }
	void 				clearReadingQueue() const	{ reading_t buf; while(_readingQueue->pop(buf)) {} }
	void				pushReadingQueue(reading_t *reads, std::size_t count) const	{ _readingQueue->push(reads, count); }

	void initSensor(unsigned interval) {
		_cacheSize = _cacheInterval / interval + 1;
		if(!_cache) {
			_cache.reset(new reading_t[_cacheSize]);
			for(unsigned i = 0; i < _cacheSize; i++) {
				_cache[i] = _latestValue;	//_latestValue should equal (0,0) at this point
			}
		}
		if(!_readingQueue) {
			_readingQueue.reset(new boost::lockfree::spsc_queue<reading_t>(QUEUE_MAXLIMIT));
		}
		if(!_sinkFile && _sinkPath != "") {
			_sinkFile.reset(new std::ofstream(_sinkPath));
			if(!_sinkFile->is_open())
				_sinkFile.reset(nullptr);
		}
	}

	/**
	 * Store a reading, in order to get it pushed to the data base eventually.
	 * Also this methods takes care of other optional reading post-processing,
	 * e.g. delta computation, subsampling, caching, scaling, etc.
	 *
	 * This is the primary storeReading() and should be used whenever possible.
	 *
	 * @param rawReading  Reading struct with value and timestamp to be stored.
	 * @param factor      Scaling factor, which is applied to the reading value (optional)
	 * @param maxValue    Maximum possible value of the reading; required for the
	 *                    delta computation to detect an overflow.
	 */
	void storeReading(reading_t rawReading, double factor=1.0, long long maxValue=LLONG_MAX) {
		reading_t reading = rawReading;
		if( _delta ) {
		    if (!_firstReading) {
              if (rawReading.value < _lastRawValue.value)
                  reading.value = (rawReading.value + (maxValue - _lastRawValue.value)) * factor;
              else
                  reading.value = (rawReading.value - _lastRawValue.value) * factor;
		    } else {
		      _firstReading = false;
		      _lastRawValue = rawReading;
		      return;
		    }
			_lastRawValue = rawReading;
		}
		else
			reading.value = rawReading.value * factor;

		if( _delta )
			// If in delta mode, _accumulator acts as a buffer, summing all deltas for the subsampling period
		    _accumulator.value += reading.value;
		else
		    _accumulator.value = reading.value;

		if (_subsamplingIndex++ % _subsamplingFactor == 0) {
            _accumulator.timestamp = reading.timestamp;
            //TODO: if sensor starts with values of 0, these won't be pushed. This should be fixed
            if( !(_skipConstVal && (_accumulator.value == _lastSentValue.value)) ) {
                _readingQueue->push(_accumulator);
                _lastSentValue = _accumulator;
            }
            // We reset the accumulator's value for the correct accumulation of deltas
			_accumulator.value = 0;
		}
		if (_sinkFile) {
		    try {
                _sinkFile->seekp(0, std::ios::beg);
                *_sinkFile << reading.value << std::endl;
            } catch(const std::exception &e) { _sinkFile->close(); _sinkFile.reset(nullptr); }
		}

		_cache[_cacheIndex] = reading;
		_cacheIndex = (_cacheIndex + 1) % _cacheSize;
		_latestValue = reading;
	}

	int64_t getCacheOffset(int64_t t) {
		if( t < 0)
			return -1;
		// Converting from milliseconds to nanoseconds
		int64_t offset = ( ( (int64_t)_cacheSize * t ) / ( (int64_t)_cacheInterval * 1000000 ) ) + 1;
		if(offset > _cacheSize)
			return -1;
		return ( _cacheSize + _cacheIndex - offset ) % _cacheSize;
	}

	/**
     * Store an unsigned reading, in order to get it pushed to the data base eventually.
     * Also this methods takes care of other optional reading post-processing,
     * e.g. delta computation, subsampling, caching, scaling, etc.
     *
     * This is a variant of the primary storeReading() for monotonically increasing
     * sensors reading unsigned 64bit values which may require more than the 63bit
     * offered by a signed reading_t. The readings are still stored as signed int64
     * in the database, therefore all such sensors should enable storage of deltas!
     *
     * This variant only adapts the delta computation for ureading_t actually.
     * FIXME: Avoid code duplication
     *
     * @param rawReading  Reading struct with (usigned) value and timestamp to be stored.
     * @param factor      Scaling factor, which is applied to the reading value (optional)
     * @param maxValue    Maximum possible value of the reading; required for the
     *                    delta computation to detect an overflow.
     */
	void storeReading(ureading_t rawReading, double factor=1.0, unsigned long long maxValue=ULLONG_MAX) {
        reading_t reading;
        reading.timestamp = rawReading.timestamp;
        if( _delta ) {
            if (!_firstReading) {
              if (rawReading.value < _lastRawUValue.value)
                  reading.value = (rawReading.value + (maxValue - _lastRawUValue.value)) * factor;
              else
                  reading.value = (rawReading.value - _lastRawUValue.value) * factor;
            } else {
              _firstReading = false;
              _lastRawUValue = rawReading;
              return;
            }
            _lastRawUValue = rawReading;
        }
        else
            reading.value = rawReading.value * factor;

        if( _delta )
            // If in delta mode, _accumulator acts as a buffer, summing all deltas for the subsampling period
            _accumulator.value += reading.value;
        else
            _accumulator.value = reading.value;

        if (_subsamplingIndex++ % _subsamplingFactor == 0) {
            _accumulator.timestamp = reading.timestamp;
            //TODO: if sensor starts with values of 0, these won't be pushed. This should be fixed
            if( !(_skipConstVal && (_accumulator.value == _lastSentValue.value)) ) {
                _readingQueue->push(_accumulator);
                _lastSentValue = _accumulator;
            }
            // We reset the accumulator's value for the correct accumulation of deltas
            _accumulator.value = 0;
        }
        if (_sinkFile) {
            try {
                _sinkFile->seekp(0, std::ios::beg);
                *_sinkFile << reading.value << std::endl;
            } catch(const std::exception &e) { _sinkFile->close(); _sinkFile.reset(nullptr); }
        }

        _cache[_cacheIndex] = reading;
        _cacheIndex = (_cacheIndex + 1) % _cacheSize;
        _latestValue = reading;
    }

	static std::string formatName(const std::string& name, int cpuID=-1) {return cpuID<0 ? name : "cpu" + std::to_string(cpuID) + "." + name;}

	virtual void printConfig(LOG_LEVEL ll, LOGGER& lg) {
	  LOG_VAR(ll) << "    Sensor: " << _name;
	  LOG_VAR(ll) << "     MQTT Topic:  " << _mqtt;
	  LOG_VAR(ll) << "     sink:        " << getSinkPath();
      LOG_VAR(ll) << "     subSampling: " << getSubsampling();
      if(_skipConstVal) {
        LOG_VAR(ll) << "     Skipping constant values";
      } else {
        LOG_VAR(ll) << "     No skipping of constant values";
      }

      if(_delta) {
        LOG_VAR(ll) << "     Storing delta readings";
      } else {
        LOG_VAR(ll) << "     Storing absolute readings";
      }
	}

protected:

	std::string _name;
	std::string _mqtt;
	std::string _sinkPath;
	bool _skipConstVal;
	unsigned int _cacheInterval;
	unsigned int _subsamplingFactor;
	unsigned int _subsamplingIndex;
	unsigned int _cacheSize;
	unsigned int _cacheIndex;
	std::unique_ptr<reading_t[]> _cache;
	bool _delta;
	bool _firstReading;
	ureading_t _lastRawUValue;
	reading_t _lastRawValue;
	reading_t _latestValue;
	reading_t _lastSentValue;
	reading_t _accumulator;
	std::unique_ptr<boost::lockfree::spsc_queue<reading_t>> _readingQueue;
	std::unique_ptr<std::ofstream> _sinkFile;
};

//for better readability
using SBasePtr = std::shared_ptr<SensorBase>;

#endif /* SRC_SENSORBASE_H_ */