/*
 * #%L
 * SciJava Common shared library for SciJava software.
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 * Wisconsin-Madison, Broad Institute of MIT and Harvard, Max Planck
 * Institute of Molecular Cell Biology and Genetics, University of
 * Konstanz, and KNIME GmbH.
 * %%
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 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
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package org.scijava.convert;

import java.lang.reflect.Type;
import java.util.Collection;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.Set;

import org.scijava.plugin.AbstractHandlerService;
import org.scijava.util.ConversionUtils;

/**
 * Abstract superclass for {@link ConvertService} implementations. Sets this
 * service as the active delegate service in {@link ConversionUtils}.
 *
 * @author Mark Hiner
 */
public abstract class AbstractConvertService extends AbstractHandlerService<ConversionRequest, Converter<?, ?>>
		implements ConvertService {

	// -- ConversionService methods --
	@SuppressWarnings({ "unchecked", "rawtypes" })
	@Override
	public Class<Converter<?, ?>> getPluginType() {
		return (Class) Converter.class;
	}

	@Override
	public Class<ConversionRequest> getType() {
		return ConversionRequest.class;
	}

	@Override
	public Converter<?, ?> getHandler(final Object src, final Class<?> dest) {
		return getHandler(new ConversionRequest(src, dest));
	}

	@Override
	public Converter<?, ?> getHandler(final Class<?> src, final Class<?> dest) {
		return getHandler(new ConversionRequest(src, dest));
	}

	@Override
	public Converter<?, ?> getHandler(final Object src, final Type dest) {
		return getHandler(new ConversionRequest(src, dest));
	}

	@Override
	public Converter<?, ?> getHandler(final Class<?> src, final Type dest) {
		return getHandler(new ConversionRequest(src, dest));
	}

	@Override
	public boolean supports(final Object src, final Class<?> dest) {
		return supports(new ConversionRequest(src, dest));
	}

	@Override
	public boolean supports(final Class<?> src, final Class<?> dest) {
		return supports(new ConversionRequest(src, dest));
	}

	@Override
	public boolean supports(final Object src, final Type dest) {
		return supports(new ConversionRequest(src, dest));
	}

	@Override
	public boolean supports(final Class<?> src, final Type dest) {
		return supports(new ConversionRequest(src, dest));
	}

	@Override
	public Collection<Object> getCompatibleInputs(final Class<?> dest) {
		final Set<Object> objects = new LinkedHashSet<>();

		for (final Converter<?, ?> c : getInstances()) {
			if (dest.isAssignableFrom(c.getOutputType())) {
				c.populateInputCandidates(objects);
			}
		}

		return objects;
	}

	@Override
	public Object convert(final Object src, final Type dest) {
		return convert(new ConversionRequest(src, dest));
	}

	@Override
	public <T> T convert(final Object src, final Class<T> dest) {
		// NB: repeated code with convert(ConversionRequest), because the
		// handler's convert method respects the T provided
		final Converter<?, ?> handler = getHandler(src, dest);
		return handler == null ? null : handler.convert(src, dest);
	}

	@Override
	public Object convert(final ConversionRequest request) {
		final Converter<?, ?> handler = getHandler(request);
		return handler == null ? null : handler.convert(request);
	}

	@Override
	public Collection<Class<?>> getCompatibleInputClasses(final Class<?> dest) {
		final Set<Class<?>> compatibleClasses = new HashSet<>();

		for (final Converter<?, ?> converter : getInstances()) {
			addIfMatches(dest, converter.getOutputType(), converter.getInputType(), compatibleClasses);
		}

		return compatibleClasses;
	}

	@Override
	public Collection<Class<?>> getCompatibleOutputClasses(final Class<?> source) {
		final Set<Class<?>> compatibleClasses = new HashSet<>();

		for (final Converter<?, ?> converter : getInstances()) {
			addIfMatches(source, converter.getInputType(), converter.getOutputType(), compatibleClasses);
		}

		return compatibleClasses;
	}

	// -- Service methods --

	@Override
	public void initialize() {
		ConversionUtils.setDelegateService(this, getPriority());
	}

	// -- Helper methods --

	/**
	 * Test two classes; if they match, a third class is added to the provided
	 * set of classes.
	 */
	private void addIfMatches(final Class<?> c1, final Class<?> c2, final Class<?> toAdd, final Set<Class<?>> classes) {
		if (c1 == c2)
			classes.add(toAdd);
	}
}
