/*
 * Copyright 2002-2023 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.aot.hint;

import java.util.Objects;

import org.springframework.lang.Nullable;

/**
 * Base {@link TypeReference} implementation that ensures consistent behaviour
 * for {@code equals()}, {@code hashCode()}, and {@code toString()} based on
 * the {@linkplain #getCanonicalName() canonical name}.
 *
 * @author Stephane Nicoll
 * @since 6.0
 */
public abstract class AbstractTypeReference implements TypeReference {

	private final String packageName;

	private final String simpleName;

	@Nullable
	private final TypeReference enclosingType;

	protected AbstractTypeReference(String packageName, String simpleName, @Nullable TypeReference enclosingType) {
		this.packageName = packageName;
		this.simpleName = simpleName;
		this.enclosingType = enclosingType;
	}

	@Override
	public String getName() {
		TypeReference enclosingType = getEnclosingType();
		String simpleName = getSimpleName();
		return (enclosingType != null ? (enclosingType.getName() + '$' + simpleName) :
				addPackageIfNecessary(simpleName));
	}

	@Override
	public String getPackageName() {
		return this.packageName;
	}

	@Override
	public String getSimpleName() {
		return this.simpleName;
	}

	@Nullable
	@Override
	public TypeReference getEnclosingType() {
		return this.enclosingType;
	}

	protected abstract boolean isPrimitive();

	protected String addPackageIfNecessary(String part) {
		if (this.packageName.isEmpty() ||
				this.packageName.equals("java.lang") && isPrimitive()) {
			return part;
		}
		return this.packageName + '.' + part;
	}

	@Override
	public int hashCode() {
		return Objects.hash(getCanonicalName());
	}

	@Override
	public boolean equals(@Nullable Object other) {
		if (this == other) {
			return true;
		}
		if (!(other instanceof TypeReference otherReference)) {
			return false;
		}
		return getCanonicalName().equals(otherReference.getCanonicalName());
	}

	@Override
	public String toString() {
		return getCanonicalName();
	}

}
