/*-
 * #%L
 * Java implementation of the SciJava Ops matching engine.
 * %%
 * 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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 *    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.ops.engine.struct;

import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.scijava.ops.engine.exceptions.impl.OpDependencyPositionException;
import org.scijava.ops.spi.OpDependency;
import org.scijava.struct.MemberParser;

/**
 * Looks for {@link OpDependency} annotations on
 * {@link java.lang.reflect.Parameter}s. For each such parameter with an
 * {@link OpDependency} annotation, this class creates a
 * {@link MethodParameterOpDependencyMember}.
 *
 * @author Gabriel Selzer
 */
public class MethodOpDependencyMemberParser implements
	MemberParser<Method, MethodParameterOpDependencyMember<?>>
{

	/**
	 * Parses out the {@link MethodParameterOpDependencyMember}s from {@code
	 * source}
	 *
	 * @param source the {@link Object} to parse
	 * @param structType TODO
	 * @return a {@link List} of all {@link MethodParameterOpDependencyMember}s
	 *         described via the {@link OpDependency} annotation in {@code source}
	 */
	@Override
	public List<MethodParameterOpDependencyMember<?>> parse(Method source,
		Type structType)
	{
		if (source == null) return null;

		source.setAccessible(true);

		final var items =
			new ArrayList<MethodParameterOpDependencyMember<?>>();

		// Parse method level @OpDependency annotations.
		parseMethodOpDependencies(items, source);

		return items;
	}

	private static void parseMethodOpDependencies(
		final List<MethodParameterOpDependencyMember<?>> items,
		final Method annotatedMethod)
	{
        var isDependency = Arrays.stream(annotatedMethod.getParameters()) //
			.map(param -> param.isAnnotationPresent(OpDependency.class)).toArray(
				Boolean[]::new);
		for (var i = 0; i < isDependency.length - 1; i++) {
			if (!isDependency[i] && isDependency[i + 1]) {
				// OpDependencies must come first so that they can be curried within
				// LambdaMetafactory
				throw new OpDependencyPositionException(annotatedMethod);
			}
		}

		final var methodParams = annotatedMethod
			.getParameters();

		for (var methodParam : methodParams) {
			final var dependency = methodParam.getAnnotation(
				OpDependency.class);
			if (dependency == null) continue;

			final var name = methodParam.getName();
			final var methodParamType = methodParam.getParameterizedType();
			items.add(new MethodParameterOpDependencyMember<>( //
				name, //
				"", //
				methodParamType, //
				dependency //
			));
		}
	}

}
