/*
 * Copyright (c) 2005-2010 KOM – Multimedia Communications Lab
 *
 * This file is part of PeerfactSim.KOM.
 *
 * PeerfactSim.KOM is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * any later version.
 *
 * PeerfactSim.KOM is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with PeerfactSim.KOM.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package de.tud.kom.p2psim.impl.vehicular.caching.decision;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import de.tudarmstadt.maki.simonstrator.api.Time;
import de.tudarmstadt.maki.simonstrator.api.component.sensor.environment.data.TemporalDependencyMatrix;
import de.tudarmstadt.maki.simonstrator.api.component.sensor.environment.data.VectoralProperty;
import de.tudarmstadt.maki.simonstrator.api.component.sensor.environment.data.measurement.MeasurementDistributionTypeContainer;
import de.tudarmstadt.maki.simonstrator.api.component.vehicular.caching.decision.CacheDecisionStrategy;
import de.tudarmstadt.maki.simonstrator.api.component.vehicular.information.AvailableInformationAttributes;
import de.tudarmstadt.maki.simonstrator.api.component.vehicular.information.PointInformation;
import de.tudarmstadt.maki.simonstrator.api.component.vehicular.information.RoadInformation;
import de.tudarmstadt.maki.simonstrator.api.component.vehicular.roadnetwork.RoadNetworkEdge;

public class TTLbasedVectoralCacheDecisionStrategy implements CacheDecisionStrategy {
	private static final long SCALING = Time.SECOND;

	private static final double ACCURACY_FACTOR = 100000;

	private static final double MIN_STEP = 0.00001;

	private double accuracy = 1;

	private double costWrongKeep = 1;
	private double costWrongChange = 1;

	private Object _lastDecision = null;

	public TTLbasedVectoralCacheDecisionStrategy(Map<String, String> pParams) {
		for (Entry<String, String> param : pParams.entrySet()) {
			switch (param.getKey()) {
			case "ACCURACY":
				accuracy = Double.valueOf(param.getValue());
				break;
			case "COST_RATIO":
				double ratio = Double.valueOf(param.getValue());
				costWrongChange = 2 / (ratio + 1);
				costWrongKeep = 2 - costWrongChange;
				break;
			default:
				break;
			}
		}
	}

	public double getCostWrongChange() {
		return costWrongChange;
	}

	public double getCostWrongKeep() {
		return costWrongKeep;
	}

	@Override
	public <T extends PointInformation> T decideOnCorrectInformation(
			List<T> pSimilarPointInformation) {
		if (pSimilarPointInformation.size() == 1) {
			T decision = pSimilarPointInformation.get(0);
			_lastDecision = decision.getValue();
			return decision;
		} else if (pSimilarPointInformation.size() == 0) {
			return null;
		}
		
		Collections.sort(pSimilarPointInformation, new Comparator<T>() {

			@Override
			public int compare(T pArg0, T pArg1) {
				return Long.compare(pArg0.getDetectionDate(), pArg1.getDetectionDate());
			}
			
		});

		long minTimestamp = Long.MAX_VALUE;
		long maxTimestamp = 0;
		Object value = pSimilarPointInformation.get(0).getValue();
		if (value instanceof VectoralProperty) {
			value = ((VectoralProperty) value).getMostProbableIndex();
		}
		boolean differentValue = false;
		
		List<Integer> possibleValues = new ArrayList<>();
		
		for (T t : pSimilarPointInformation) {
			if (!t.hasAttribute(AvailableInformationAttributes.TTL)) {
				throw new AssertionError("Unable to perform TTL-based majority voting witout TTL");
			}
			long timestamp = t.getDetectionDate();

			if (timestamp < minTimestamp) {
				minTimestamp = timestamp;
			}
			if (timestamp > maxTimestamp) {
				maxTimestamp = timestamp;
			}

			Object currentValue = t.getValue();
			if (currentValue instanceof VectoralProperty) {
				VectoralProperty currentProperty = (VectoralProperty) currentValue;
				currentValue = currentProperty.getMostProbableIndex();
				
				if (!value.equals(currentValue)) {
					differentValue = true;
				}
				
				for (int i = 0; i < currentProperty.getValueProbabilities().length; i++) {
					if (!possibleValues.contains(i)) {
						possibleValues.add(i);
					}
				}
			}
		}
		
		if (differentValue) {
			long difference = maxTimestamp - minTimestamp;

			if (difference == 0) {
				return pSimilarPointInformation.get(pSimilarPointInformation.size() - 1);
			}

			double rate = difference / ((double) (pSimilarPointInformation.size() - 1) * SCALING);

			long ttl = getTTL(pSimilarPointInformation.get(0));
			double numberOfMessages = ttl / rate + 1;

			VectoralProperty currentProperty = null;

			List<Double> bValues = new ArrayList<>();
			double b;
			for (Integer possibleValue : possibleValues) {
				double temp = determineB((VectoralProperty) pSimilarPointInformation.get(0).getValue(), ((RoadInformation)pSimilarPointInformation.get(0)).getEdge(), possibleValue, getChangeRate(pSimilarPointInformation.get(0), rate), rate, 1 - accuracy, numberOfMessages, costWrongKeep, costWrongChange);
				
				if (!Double.isNaN(temp)) {
					bValues.add(temp);
				}
			}
			
			Collections.sort(bValues);
			
			if (bValues.size() > 0) {
				if (bValues.size() % 2 == 0) {
					b = (bValues.get(bValues.size() / 2) + bValues.get(bValues.size() / 2 - 1)) / 2.0;
				} else {
					b = bValues.get(bValues.size() / 2);
				}
			} else {
				b = Double.NEGATIVE_INFINITY;
			}
			
			int count = 0;
			for (T t : pSimilarPointInformation) {
				RoadInformation roadInformation = ((RoadInformation) t);
				VectoralProperty property = (VectoralProperty) roadInformation.getValue();
				
				double impact = calculateImpact(1 - accuracy, numberOfMessages, (((t.getDetectionDate() - maxTimestamp) / SCALING  + ttl) / (double)ttl) * numberOfMessages, b) / (accuracy);

				TemporalDependencyMatrix dependencyMatrix = property.getDependencyMatrix();
				dependencyMatrix = modifyDependencyMatrix(dependencyMatrix.age((maxTimestamp - property.getDetectionDate()) / SCALING), impact);
				
 				VectoralProperty agedProperty = property.age(1, dependencyMatrix);
				if (currentProperty != null) {
					currentProperty = currentProperty.combine(agedProperty);
				} else {
					currentProperty = agedProperty;
				}
			}
			
			if (Double.isNaN(currentProperty.getValueProbabilities()[0])) {
				return pSimilarPointInformation.get(pSimilarPointInformation.size() - 1);
			}
			
			RoadInformation roadInformation = new RoadInformation(currentProperty);
			
			copyAttributes((RoadInformation) pSimilarPointInformation.get(0), roadInformation);
			
			_lastDecision = roadInformation.getValue();
			
			return (T) roadInformation;
		} else {
			maxTimestamp = -1;
			T maxFitting = null;
			for (T t : pSimilarPointInformation) {
				long timestamp = (long) t.getAttribute(AvailableInformationAttributes.TTL);

				if (timestamp > maxTimestamp) {
					maxTimestamp = timestamp;
					maxFitting = t;
				}
			}

			_lastDecision = maxFitting.getValue();

			return maxFitting;
		}
	}

	/**
	 * @param pT
	 * @return
	 */
	private <T extends PointInformation> double getAccuracy(T pT) {
//		if (pT instanceof RoadInformation) {
//			RoadInformation roadInformation = ((RoadInformation) pT);
//			VectoralProperty property = (VectoralProperty) roadInformation.getValue();
//			double accuracy = property.getProbabilityForIndex(property.getMostProbableIndex());
//			return accuracy;
//		}
		return this.accuracy;
	}

	private <T extends PointInformation> double getChangeRate(T pT, double pRate) {
//		if (pT instanceof RoadInformation) {
//			RoadInformation roadInformation = ((RoadInformation) pT);
//			VectoralProperty property = (VectoralProperty) roadInformation.getValue();
//			
//			TemporalDependencyMatrix dependencyMatrix = property.getDependencyMatrix();
//			return 1 - Math.pow(1 - dependencyMatrix.getChangeProbability(0), pRate * (SCALING / Time.SECOND));
//		}
		return getChangeProbability((long) (getTTL(pT) / pRate));
	}

	public <T extends PointInformation> long getTTL(
			T pT) {
		return (long)pT.getAttribute(AvailableInformationAttributes.TTL) / SCALING;
	}

	/**
	 * @param pT
	 * @param pRoadInformation
	 */
	private void copyAttributes(RoadInformation pSrc, RoadInformation pDest) {
		for (AvailableInformationAttributes attribute : pSrc.getAvailableAttributes()) {
			pDest.setAttribute(attribute, pSrc.getAttribute(attribute));
		}
	}

	private TemporalDependencyMatrix modifyDependencyMatrix(
			TemporalDependencyMatrix pDependencyMatrix, double pImpact) {
		TemporalDependencyMatrix result = pDependencyMatrix.clone();
		
		double[][] dependencies = result.getDependencies();
		for (int i = 0; i < dependencies.length; i++) {
			double finalPercentages = 1.0 / dependencies[i].length;
			
			for (int j = 0; j < dependencies[i].length; j++) {
				dependencies[i][j] = finalPercentages + (pDependencyMatrix.getDependencies()[i][j] - finalPercentages) * pImpact;
			}
		}
		
		return result;
	}

	public double calculateImpact(double errorProbability, double pNumberOfMessages, double pMessageNumber, double b) {
		double age = pNumberOfMessages - pMessageNumber;
		if (errorProbability == 0) {
			if (pMessageNumber == pNumberOfMessages) {
				return 1;
			} else {
				return 0;
			}
		} else if (errorProbability == 1) {
			return 1;
		} else if (errorProbability == 0.5 || b == 0) {
			return (1 - errorProbability) / pNumberOfMessages * age + errorProbability;
		} else if (b == Double.NEGATIVE_INFINITY) {
			if (pMessageNumber == pNumberOfMessages) {
				return 1;
			} else {
				return 0;
			}
		}

		return (1 - errorProbability) * (Math.exp(b * age) - Math.exp(b * pNumberOfMessages)) / (1 - Math.exp(b * pNumberOfMessages));
	}

	public double getChangeProbability(long ttl) {
		return 1 - Math.pow(0.5, 1 / (double) ttl);
	}

	public int getOptimalMessageAmountForSwitch(double changeProbability, double errorProbability, double costSlow, double costFast) {
		return (int) Math.round(Math.log(-changeProbability / Math.log(errorProbability) * costSlow / costFast) / Math.log(errorProbability));
	}

	public double determineB(VectoralProperty pTemplate, RoadNetworkEdge pRoadNetworkEdge, int pPossibleValue, double change, double rate, double errorProbability, double pNumberOfMessages, double costSlow, double costFast) {
		if (errorProbability == 0 || errorProbability == 1 || errorProbability == 0.5) {
			return Double.NaN;
		}
		
		if (_lastDecision != null) {
			if (pPossibleValue == ((VectoralProperty)_lastDecision).getMostProbableIndex()) {
				return Double.NaN;
			}
		} else {
			if (pPossibleValue == pTemplate.getDefaultIndex()) {
				return Double.NaN;
			}
		}
		
		double b;
		double p_c = change;
		
		int optimalAmount = getOptimalMessageAmountForSwitch(p_c, errorProbability, costSlow, costFast);
		
		if ((int)pNumberOfMessages <= optimalAmount) {
			return Double.POSITIVE_INFINITY;
		}
		
		if (optimalAmount == 1) {
			return Double.NEGATIVE_INFINITY;
		}
		
		boolean first = true;
		
		double step = 10;
		
		if (errorProbability < 0.5) {
			b = -1 * step;
		} else {
			b = 1 * step;
		}
		
		do {
			VectoralProperty valueAfterN = calculateMostProbable(pTemplate, pRoadNetworkEdge, pPossibleValue, optimalAmount, rate, errorProbability, pNumberOfMessages, b);
			double probableValueAfterN = Double.NaN;
			if (valueAfterN != null) {
				probableValueAfterN = valueAfterN.getMostProbableIndex();
			}
			VectoralProperty valueBeforeN = calculateMostProbable(pTemplate, pRoadNetworkEdge, pPossibleValue, optimalAmount - 1, rate, errorProbability, pNumberOfMessages, b);
			double probableValueBeforeN = Double.NaN;
			if (valueBeforeN != null) {
				probableValueBeforeN = valueBeforeN.getMostProbableIndex();
			}
			
			if (probableValueAfterN == pPossibleValue && probableValueAfterN != probableValueBeforeN) {
				return b;
			}
			
			if (!Double.isNaN(probableValueBeforeN) && !Double.isNaN(probableValueBeforeN) && step >= MIN_STEP) {
				if (probableValueAfterN != pPossibleValue) {
					if (b < 0) {
						b -= step;
						if (!first) {
							step *= 0.5;
						}
					} else {
						b -= step;
						step *= 0.5;
						first = false;
					}
				} else if (probableValueAfterN == pPossibleValue && probableValueAfterN == probableValueBeforeN) {
					if (b > 0) {
						b += step;
						if (!first) {
							step *= 0.5;
						}
					} else {
						b += step;
						step *= 0.5;
						first = false;
					}
				} else {
					return Double.NaN;
				}
			} else {
				return Double.NaN;
			}
		} while (true);
	}

	public VectoralProperty calculateMostProbable(VectoralProperty pTemplate, RoadNetworkEdge pRoadNetworkEdge, int pNewValue, int optimalMessageAmount, double rate, double errorProbability, double pNumberOfMessages, double b) {
		VectoralProperty currentProperty = null;
		
		for (int a = optimalMessageAmount + 1; a <= pNumberOfMessages; a++) {
			VectoralProperty jamProperty = pTemplate.clone();
			
			if (_lastDecision != null) {
				jamProperty.set(((VectoralProperty)_lastDecision).getMostProbableIndex(), accuracy, MeasurementDistributionTypeContainer.getDistribution(pTemplate.getClass()));
			} else {
				jamProperty.set(pTemplate.getDefaultIndex(), accuracy, MeasurementDistributionTypeContainer.getDistribution(pTemplate.getClass()));
			}
			TemporalDependencyMatrix temporalDependencyMatrix = jamProperty.getDependencyMatrix();
			temporalDependencyMatrix = temporalDependencyMatrix.age((long) (a * rate));
			double impact = calculateImpact(errorProbability, pNumberOfMessages, pNumberOfMessages - a, b);
			
			if (Double.isNaN(impact)) {
				return null;
			}
			
			temporalDependencyMatrix = modifyDependencyMatrix(temporalDependencyMatrix, impact);
			jamProperty = (VectoralProperty) jamProperty.age(1, temporalDependencyMatrix);

			if (currentProperty != null) {
				currentProperty = (VectoralProperty) currentProperty.combine(jamProperty);
			} else {
				currentProperty = jamProperty;
			}
		}
		
		for (int a = 0; a <= optimalMessageAmount; a++) {
			VectoralProperty jamProperty = pTemplate.clone();
			jamProperty.setGaussianWithAccuracy(pNewValue, accuracy);

			TemporalDependencyMatrix temporalDependencyMatrix = jamProperty.getDependencyMatrix();
			temporalDependencyMatrix = temporalDependencyMatrix.age((long) (a * rate));
			double impact = calculateImpact(errorProbability, pNumberOfMessages, pNumberOfMessages - a, b);

			if (Double.isNaN(impact)) {
				return null;
			}

			temporalDependencyMatrix = modifyDependencyMatrix(temporalDependencyMatrix, impact);
			jamProperty = (VectoralProperty) jamProperty.age(1, temporalDependencyMatrix);

			if (currentProperty != null) {
				currentProperty = (VectoralProperty) currentProperty.combine(jamProperty);
			} else {
				currentProperty = jamProperty;
			}
		}

		return currentProperty;
	}
}