/*-
 * #%L
 * SciJava library for generic type reasoning.
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 * Copyright (C) 2016 - 2024 SciJava developers.
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 * modification, are permitted provided that the following conditions are met:
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 *    this list of conditions and the following disclaimer.
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 *    and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
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package org.scijava.types.extract;

import org.scijava.discovery.Discoverer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.*;

public class DefaultTypeReifier implements TypeReifier {

	private Map<Class<?>, TypeExtractor> extractors;
	private final Collection<Discoverer> discoverers;

	private final Logger log = LoggerFactory.getLogger(getClass());

	public DefaultTypeReifier(Discoverer... discoverers) {
		this(Arrays.asList(discoverers));
	}

	public DefaultTypeReifier(Collection<Discoverer> discoverers) {
		this.discoverers = discoverers;
	}

	@Override
	public Optional<TypeExtractor> getExtractor(final Class<?> c) {
		return Optional.ofNullable(extractors().getOrDefault(c, null));
	}

	// -- Helper methods --

	private Map<Class<?>, TypeExtractor> extractors() {
		if (extractors == null) initExtractors();
		return extractors;
	}

	private synchronized void initExtractors() {
		if (extractors != null) return;
		extractors = getInstances();
	}

	private Map<Class<?>, TypeExtractor> getInstances() {
		Map<Class<?>, TypeExtractor> instances = new HashMap<>();
		discoverers.stream() //
			.flatMap(d -> d.discover(TypeExtractor.class).stream()) //
			// Find the correct set for each extractor and add it.
			.sorted() //
			.forEach(e -> {
				var existing = instances.putIfAbsent(e.baseClass(), e);
				if (existing != null) {
					log.warn("TypeExtractor " + e + " ignored - " + existing //
						+ " has already declared responsibility for reifying Class " //
						+ e.baseClass());
				}
			});
		return instances;
	}
}
