/*
 * 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"
#include "cacheentry.h"

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),
		_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),
		_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;
		_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				getCacheInterval()	const	{ return _cacheInterval; }
	unsigned 				getSubsampling()	const   { return _subsamplingFactor; }
	const CacheEntry* const	getCache() 			const	{ return _cache.get(); }
	const reading_t&		getLatestValue()	const	{ return _latestValue; }
	const bool				isInit()			const 	{ return _cache && _readingQueue; }

	// Exposing the reading queue is necessary for publishing sensor data from the collectagent
	boost::lockfree::spsc_queue<reading_t>* getReadingQueue() { return _readingQueue.get(); }

	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) {
		uint64_t cacheSize = _cacheInterval / interval + 1;
		if(!_cache) {
			//TODO: have all time-related configuration parameters use the same unit (e.g. milliseconds)
			_cache.reset(new CacheEntry( (uint64_t)_cacheInterval * 1000000, cacheSize));
		}
		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 method 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, bool storeGlobal=true) {
        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;

		storeReadingLocal(reading);
		if (storeGlobal) {
		    storeReadingGlobal(reading);
		}
	}

	/**
     * Store an unsigned reading, in order to get it pushed to the data base eventually.
     * Also this method 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.
     *
     * @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, bool storeGlobal=true) {
        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;

        storeReadingLocal(reading);
        if (storeGlobal) {
            storeReadingGlobal(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, unsigned leadingSpaces=16) {
	  std::string leading(leadingSpaces, ' ');
	  LOG_VAR(ll) << leading << "Sensor: " << _name;
	  LOG_VAR(ll) << leading << "    MQTT Topic:  " << _mqtt;
	  LOG_VAR(ll) << leading << "    Sink:        " << (getSinkPath() != "" ? getSinkPath() : "none");
      LOG_VAR(ll) << leading << "    SubSampling: " << getSubsampling();
      LOG_VAR(ll) << leading << (_skipConstVal ? "    Skipping constant values" : "    No skipping of constant values");
      LOG_VAR(ll) << leading << (_delta ? "    Storing delta readings" : "    Storing absolute readings");
	}

protected:

	/**
	 * Store reading within the sensor, but do not put it in the readingQueue
	 * so the reading does not get pushed but the caches are still updated.
	 */
	inline
	void storeReadingLocal(reading_t reading) {
	    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->store(reading);
        _latestValue = reading;
	}

	/**
	 * Store the reading in the readingQueue so it can get pushed.
	 */
	inline
	void storeReadingGlobal(reading_t reading) {
	    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;
        }
	}

	std::string _name;
	std::string _mqtt;
	std::string _sinkPath;
	bool _skipConstVal;
	unsigned int _cacheInterval;
	unsigned int _subsamplingFactor;
	unsigned int _subsamplingIndex;
	std::unique_ptr<CacheEntry> _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_ */