/**
 * Copyright (C) 2012 - present by OpenGamma Inc. and the OpenGamma group of companies
 *
 * Please see distribution for license.
 */
package com.opengamma.financial.analytics;

import java.util.Collections;
import java.util.Set;

import com.google.common.collect.Iterables;
import com.opengamma.OpenGammaRuntimeException;
import com.opengamma.engine.ComputationTarget;
import com.opengamma.engine.ComputationTargetSpecification;
import com.opengamma.engine.function.AbstractFunction;
import com.opengamma.engine.function.FunctionCompilationContext;
import com.opengamma.engine.function.FunctionExecutionContext;
import com.opengamma.engine.function.FunctionInputs;
import com.opengamma.engine.target.ComputationTargetType;
import com.opengamma.engine.value.ComputedValue;
import com.opengamma.engine.value.ValueRequirement;
import com.opengamma.engine.value.ValueRequirementNames;
import com.opengamma.engine.value.ValueSpecification;
import com.opengamma.financial.OpenGammaExecutionContext;
import com.opengamma.financial.currency.CurrencyPairs;
import com.opengamma.financial.currency.CurrencyPairsSource;
import com.opengamma.util.async.AsynchronousExecution;

/**
 *
 */
public class CurrencyPairsFunction extends AbstractFunction.NonCompiledInvoker {

  /** Name of the currency pairs name property */
  public static final String CURRENCY_PAIRS_NAME = "CurrencyPairsName";

  @Override
  public Set<ComputedValue> execute(final FunctionExecutionContext executionContext, final FunctionInputs inputs, final ComputationTarget target,
      final Set<ValueRequirement> desiredValues) throws AsynchronousExecution {
    final ValueRequirement desiredValue = Iterables.getOnlyElement(desiredValues);
    final String name = desiredValue.getConstraint(CURRENCY_PAIRS_NAME);
    @SuppressWarnings("deprecation")
    final CurrencyPairsSource ccyPairsSource = OpenGammaExecutionContext.getCurrencyPairsSource(executionContext);
    final CurrencyPairs currencyPairs = ccyPairsSource.getCurrencyPairs(name);
    if (currencyPairs == null) {
      throw new OpenGammaRuntimeException("Could not get CurrencyPairs called " + CurrencyPairs.DEFAULT_CURRENCY_PAIRS);
    }
    return Collections.singleton(new ComputedValue(new ValueSpecification(ValueRequirementNames.CURRENCY_PAIRS, ComputationTargetSpecification.NULL,
        createValueProperties().with(CURRENCY_PAIRS_NAME, name).get()), currencyPairs));
  }

  @Override
  public ComputationTargetType getTargetType() {
    return ComputationTargetType.NULL;
  }

  @Override
  public Set<ValueSpecification> getResults(final FunctionCompilationContext myContext, final ComputationTarget target) {
    return Collections.singleton(new ValueSpecification(ValueRequirementNames.CURRENCY_PAIRS, target.toSpecification(),
        createValueProperties().withAny(CURRENCY_PAIRS_NAME).get()));
  }

  @Override
  public Set<ValueRequirement> getRequirements(final FunctionCompilationContext myContext, final ComputationTarget target, final ValueRequirement desiredValue) {
    final Set<String> names = desiredValue.getConstraints().getValues(CURRENCY_PAIRS_NAME);
    if (names == null || names.size() != 1) {
      return null;
    }
    return Collections.emptySet();
  }

}