GlobalPrice.java

package ac.ed.lurg.country;

import java.io.Serializable;

import ac.ed.lurg.ModelConfig;
import ac.ed.lurg.Timestep;
import ac.ed.lurg.types.Parameter;
import ac.ed.lurg.utils.LogWriter;

public class GlobalPrice implements Serializable {

	private static final long serialVersionUID = 2477952576838887039L;
	
	private int timestepId;
	private double exportPrice;
	private double importAmount;
	private double exportAmountBeforeLoss;
	private double transportLosses;
	private double stockLevel;

	private GlobalPrice(int timestepId, double exportPrice, double stockLevel, double importAmount, double exportAmountBeforeLoss, double transportLosses) {
		this.timestepId = timestepId;
		this.exportPrice = exportPrice;
		this.stockLevel = stockLevel;
		this.importAmount = importAmount;
		this.exportAmountBeforeLoss = exportAmountBeforeLoss;
		this.transportLosses = transportLosses;
	}
	
	public static GlobalPrice createInitial(double exportPrice, double intitalStock) {
		return new GlobalPrice(ModelConfig.START_TIMESTEP-1, exportPrice, intitalStock, Double.NaN, Double.NaN, Double.NaN);
	}
	
	public double getExportPrice(){
		return exportPrice;
	}

	public double getStockLevel(){
		return stockLevel;
	}
	
	public double getCountryImportPrice(double countryTradeBarrier, Timestep timestep) {

		int currentYear = timestep.getYear();
		double tradeBarrierMultiplier = (!ModelConfig.SHOCKS_POSSIBLE)? ModelConfig.TRADE_BARRIER_MULTIPLIER: ModelConfig.getParameter(Parameter.TRADE_BARRIER_MULTIPLIER, currentYear);
		double transportLossesRate =(!ModelConfig.SHOCKS_POSSIBLE) ? ModelConfig.TRANSPORT_LOSSES : ModelConfig.getParameter(Parameter.TRANSPORT_LOSSES, currentYear);
		double transportCosts = (!ModelConfig.SHOCKS_POSSIBLE) ? ModelConfig.TRANSPORT_COST : ModelConfig.getParameter(Parameter.TRANSPORT_COST, currentYear);
		
		double importPrice = exportPrice * (1 + transportCosts) * (1.0 + countryTradeBarrier*tradeBarrierMultiplier) / (1.0 - transportLossesRate);
		return importPrice;
	}

	public double getImportAmount() {
		return importAmount;
	}
	
	public double getExportsAfterTransportLosses() {
		return exportAmountBeforeLoss - transportLosses;
	}
	
	public double getExportsBeforeTransportLoss() {
		return exportAmountBeforeLoss ;
	}
	
	public double getTransportLosses() {
		return transportLosses;
	}

	public GlobalPrice createWithUpdatedMarketPrices(double newImports, double newExportAmountBeforeLoss, Timestep timestep, double production) {

		if (newImports > 0 || newExportAmountBeforeLoss > 0) {
			double oldDiff = timestep.getTimestep() != timestepId ? 0.0 : exportAmountBeforeLoss - transportLosses - importAmount; // if recomputing for same year need to back our previous adjustment
			double transportLossRate = (!ModelConfig.SHOCKS_POSSIBLE) ? ModelConfig.TRANSPORT_LOSSES : ModelConfig.getParameter(Parameter.TRANSPORT_LOSSES, timestep.getYear());
			double newTransportLosses = newExportAmountBeforeLoss * transportLossRate;
			double stockChange = newExportAmountBeforeLoss - newTransportLosses - newImports - oldDiff;
			
			double updatedStock;
			if (ModelConfig.IS_CALIBRATION_RUN  && timestep.getTimestep() <= ModelConfig.END_FIRST_STAGE_CALIBRATION)
				updatedStock = stockLevel;  // don't update stock in inital stage of calibration
			else
				updatedStock = stockLevel + stockChange;
				
			LogWriter.println(String.format("     imports %.2f, exports %.2f", newImports, newExportAmountBeforeLoss - newTransportLosses));
			LogWriter.println(String.format("     updatedStock %.2f, previous %.2f (last timestep %.2f), stockChange %.2f, oldDiff %.2f", updatedStock, stockLevel, stockLevel-oldDiff, stockChange, oldDiff));
			
			double adjustment;
			double financialSpeculationMultiplier = (!ModelConfig.SHOCKS_POSSIBLE)? 1.0 : ModelConfig.getParameter(Parameter.FINANCIAL_SPECULATION_MULTIPLIER,timestep.getYear());

			if (!ModelConfig.MARKET_ADJ_PRICE || (ModelConfig.IS_CALIBRATION_RUN && timestep.getTimestep() <= ModelConfig.END_FIRST_STAGE_CALIBRATION)) {
				adjustment = 1;
			}
			else if (ModelConfig.PRICE_UPDATE_BY_MARKET_IMBALANCE) {
				double ratio = stockChange/(production-stockChange);
				adjustment =  Math.exp(-ratio * ModelConfig.MARKET_LAMBA);
				LogWriter.println(String.format("     initally imbalance ratio= %.4f", ratio));
			}
			else {
				if (stockChange == 0 && production == 0)
					adjustment=1;
				else if (stockChange >= 0 && production != 0) // stock increasing, so decrease price.  stockChange is positive so adjustment < 1
					adjustment = 1 - ModelConfig.MARKET_LAMBA * stockChange/production;
				else // stock decreasing, so increase price.  stockChange is negative so adjustment > 1
					adjustment = 1 - ModelConfig.MARKET_LAMBA * stockChange/Math.max(0, stockLevel);
				
				LogWriter.print(String.format("     initally adjustment= %.4f", adjustment));
			}
			
			if (adjustment < ModelConfig.MAX_PRICE_DECREASE)
				adjustment = ModelConfig.MAX_PRICE_DECREASE;  // default to max down change

			if (adjustment > ModelConfig.MAX_PRICE_INCREASE)
				adjustment = ModelConfig.MAX_PRICE_INCREASE;  // default to max up change
			
			LogWriter.println(String.format(", after limit %.4f", adjustment));

			double newPrice = exportPrice * adjustment * financialSpeculationMultiplier;
			return new GlobalPrice(timestep.getTimestep(), newPrice, updatedStock, newImports, newExportAmountBeforeLoss, newTransportLosses);			
		}
		else {
			LogWriter.printlnError(String.format("Price for not updated (still %s), as no imports and no exports for it", exportPrice));
			return this;
		}
	}

	@Override
	public String toString() {
		return String.format("exportPrice=%.6f", exportPrice);
	}

	public double getStockChange() {
		return exportAmountBeforeLoss - transportLosses - importAmount;
	}

	public GlobalPrice createPriceAdjustedByFactor(double factor) {
		return new GlobalPrice(timestepId, exportPrice * factor, stockLevel, importAmount, exportAmountBeforeLoss, transportLosses);			
	}
}