/*
 * Copyright 2008-2020 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.data.util;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.util.List;

import org.springframework.lang.Nullable;

Interface to access property types and resolving generics on the way. Starting with a ClassTypeInformation you can traverse properties using getProperty(String) to access type information. 
Author:
Oliver Gierke, Mark Paluch/**
 * Interface to access property types and resolving generics on the way. Starting with a {@link ClassTypeInformation}
 * you can traverse properties using {@link #getProperty(String)} to access type information.
 *
 * @author Oliver Gierke
 * @author Mark Paluch
 */
public interface TypeInformation<S> {

	
Returns the TypeInformations for the parameters of the given Constructor. 
Params:
constructor – must not be null.
Returns:
/**
	 * Returns the {@link TypeInformation}s for the parameters of the given {@link Constructor}.
	 *
	 * @param constructor must not be {@literal null}.
	 * @return
	 */
	List<TypeInformation<?>> getParameterTypes(Constructor<?> constructor);

	
Returns the property information for the property with the given name. Supports property traversal through dot
notation.
Params:
property – 
Returns:
/**
	 * Returns the property information for the property with the given name. Supports property traversal through dot
	 * notation.
	 *
	 * @param property
	 * @return
	 */
	@Nullable
	TypeInformation<?> getProperty(String property);

	
Returns the property information for the property with the given name or throw IllegalArgumentException if the type information cannot be resolved. Supports property traversal through dot notation. 
Params:
property – 
Throws:
IllegalArgumentException – if the type information cannot be resolved.
Returns:
Since:
2.0/**
	 * Returns the property information for the property with the given name or throw {@link IllegalArgumentException} if
	 * the type information cannot be resolved. Supports property traversal through dot notation.
	 *
	 * @param property
	 * @return
	 * @throws IllegalArgumentException if the type information cannot be resolved.
	 * @since 2.0
	 */
	default TypeInformation<?> getRequiredProperty(String property) {

		TypeInformation<?> typeInformation = getProperty(property);

		if (typeInformation != null) {
			return typeInformation;
		}

		throw new IllegalArgumentException(
				String.format("Could not find required property %s on %s!", property, getType()));
	}

	
Returns whether the type can be considered a collection, which means it's a container of elements, e.g. a Collection and Array or anything implementing Iterable. If this returns true you can expect getComponentType() to return a non-null value. 
Returns:
/**
	 * Returns whether the type can be considered a collection, which means it's a container of elements, e.g. a
	 * {@link java.util.Collection} and {@link java.lang.reflect.Array} or anything implementing {@link Iterable}. If this
	 * returns {@literal true} you can expect {@link #getComponentType()} to return a non-{@literal null} value.
	 *
	 * @return
	 */
	boolean isCollectionLike();

	
Returns the component type for Collections or the key type for Maps. 
Returns:
/**
	 * Returns the component type for {@link java.util.Collection}s or the key type for {@link java.util.Map}s.
	 *
	 * @return
	 */
	@Nullable
	TypeInformation<?> getComponentType();

	
Returns the component type for Collections, the key type for Maps or the single generic type if available. Throws IllegalStateException if the component value type cannot be resolved. 
Throws:
IllegalStateException – if the component type cannot be resolved, e.g. if a raw type is used or the type is
          not generic in the first place.
Returns:
Since:
2.0/**
	 * Returns the component type for {@link java.util.Collection}s, the key type for {@link java.util.Map}s or the single
	 * generic type if available. Throws {@link IllegalStateException} if the component value type cannot be resolved.
	 *
	 * @return
	 * @throws IllegalStateException if the component type cannot be resolved, e.g. if a raw type is used or the type is
	 *           not generic in the first place.
	 * @since 2.0
	 */
	default TypeInformation<?> getRequiredComponentType() {

		TypeInformation<?> componentType = getComponentType();

		if (componentType != null) {
			return componentType;
		}

		throw new IllegalStateException(String.format("Can't resolve required component type for %s!", getType()));
	}

	
Returns whether the property is a Map. If this returns true you can expect getComponentType() as well as getMapValueType() to return something not null. 
Returns:
/**
	 * Returns whether the property is a {@link java.util.Map}. If this returns {@literal true} you can expect
	 * {@link #getComponentType()} as well as {@link #getMapValueType()} to return something not {@literal null}.
	 *
	 * @return
	 */
	boolean isMap();

	
Will return the type of the value in case the underlying type is a Map. 
Returns:
/**
	 * Will return the type of the value in case the underlying type is a {@link java.util.Map}.
	 *
	 * @return
	 */
	@Nullable
	TypeInformation<?> getMapValueType();

	
Will return the type of the value in case the underlying type is a Map or throw IllegalStateException if the map value type cannot be resolved. 
Throws:
IllegalStateException – if the map value type cannot be resolved, usually due to the current Map type being a raw one.
Returns:
Since:
2.0/**
	 * Will return the type of the value in case the underlying type is a {@link java.util.Map} or throw
	 * {@link IllegalStateException} if the map value type cannot be resolved.
	 *
	 * @return
	 * @throws IllegalStateException if the map value type cannot be resolved, usually due to the current
	 *           {@link java.util.Map} type being a raw one.
	 * @since 2.0
	 */
	default TypeInformation<?> getRequiredMapValueType() {

		TypeInformation<?> mapValueType = getMapValueType();

		if (mapValueType != null) {
			return mapValueType;
		}

		throw new IllegalStateException(String.format("Can't resolve required map value type for %s!", getType()));
	}

	
Returns the type of the property. Will resolve generics and the generic context of
Returns:
/**
	 * Returns the type of the property. Will resolve generics and the generic context of
	 *
	 * @return
	 */
	Class<S> getType();

	
Returns a ClassTypeInformation to represent the TypeInformation of the raw type of the current instance. 
Returns:
/**
	 * Returns a {@link ClassTypeInformation} to represent the {@link TypeInformation} of the raw type of the current
	 * instance.
	 *
	 * @return
	 */
	ClassTypeInformation<?> getRawTypeInformation();

	
Transparently returns the Map value type if the type is a Map, returns the component type if the type isCollectionLike() or the simple type if none of this applies. 
Returns:
the map value, collection component type or the current type, null it the current type is a raw Map or Collection./**
	 * Transparently returns the {@link java.util.Map} value type if the type is a {@link java.util.Map}, returns the
	 * component type if the type {@link #isCollectionLike()} or the simple type if none of this applies.
	 *
	 * @return the map value, collection component type or the current type, {@literal null} it the current type is a raw
	 *         {@link java.util.Map} or {@link java.util.Collection}.
	 */
	@Nullable
	TypeInformation<?> getActualType();

	
Transparently returns the Map value type if the type is a Map, returns the component type if the type isCollectionLike() or the simple type if none of this applies. 
Throws:
IllegalArgumentException – if the current type is a raw Map or Collection and no value or component type is available.
Returns:
Since:
2.0/**
	 * Transparently returns the {@link java.util.Map} value type if the type is a {@link java.util.Map}, returns the
	 * component type if the type {@link #isCollectionLike()} or the simple type if none of this applies.
	 *
	 * @return
	 * @throws IllegalArgumentException if the current type is a raw {@link java.util.Map} or {@link java.util.Collection}
	 *           and no value or component type is available.
	 * @since 2.0
	 */
	default TypeInformation<?> getRequiredActualType() {

		TypeInformation<?> result = getActualType();

		if (result == null) {
			throw new IllegalStateException(
					"Expected to be able to resolve a type but got null! This usually stems from types implementing raw Map or Collection interfaces!");
		}

		return result;
	}

	
Returns a TypeInformation for the return type of the given Method. Will potentially resolve generics information against the current types type parameter bindings. 
Params:
method – must not be null.
Returns:
/**
	 * Returns a {@link TypeInformation} for the return type of the given {@link Method}. Will potentially resolve
	 * generics information against the current types type parameter bindings.
	 *
	 * @param method must not be {@literal null}.
	 * @return
	 */
	TypeInformation<?> getReturnType(Method method);

	
Returns the TypeInformations for the parameters of the given Method. 
Params:
method – must not be null.
Returns:
/**
	 * Returns the {@link TypeInformation}s for the parameters of the given {@link Method}.
	 *
	 * @param method must not be {@literal null}.
	 * @return
	 */
	List<TypeInformation<?>> getParameterTypes(Method method);

	
Returns the TypeInformation for the given raw super type. 
Params:
superType – must not be null.
Returns:
the TypeInformation for the given raw super type or null in case the current TypeInformation does not implement the given type./**
	 * Returns the {@link TypeInformation} for the given raw super type.
	 *
	 * @param superType must not be {@literal null}.
	 * @return the {@link TypeInformation} for the given raw super type or {@literal null} in case the current
	 *         {@link TypeInformation} does not implement the given type.
	 */
	@Nullable
	TypeInformation<?> getSuperTypeInformation(Class<?> superType);

	
Returns the TypeInformation for the given raw super type. 
Params:
superType – must not be null.
Throws:
IllegalArgumentException – in case the current TypeInformation does not implement the given type.
Returns:
the TypeInformation for the given raw super type.
Since:
2.0/**
	 * Returns the {@link TypeInformation} for the given raw super type.
	 *
	 * @param superType must not be {@literal null}.
	 * @return the {@link TypeInformation} for the given raw super type.
	 * @throws IllegalArgumentException in case the current {@link TypeInformation} does not implement the given type.
	 * @since 2.0
	 */
	default TypeInformation<?> getRequiredSuperTypeInformation(Class<?> superType) {

		TypeInformation<?> result = getSuperTypeInformation(superType);

		if (result == null) {
			throw new IllegalArgumentException(String.format(
					"Can't retrieve super type information for %s! Does current type really implement the given one?",
					superType));
		}

		return result;
	}

	
Returns if the current TypeInformation can be safely assigned to the given one. Mimics semantics of Class.isAssignableFrom(Class) but takes generics into account. Thus it will allow to detect that a List<Long> is assignable to List<? extends Number>. 
Params:
target – 
Returns:
/**
	 * Returns if the current {@link TypeInformation} can be safely assigned to the given one. Mimics semantics of
	 * {@link Class#isAssignableFrom(Class)} but takes generics into account. Thus it will allow to detect that a
	 * {@code List<Long>} is assignable to {@code List<? extends Number>}.
	 *
	 * @param target
	 * @return
	 */
	boolean isAssignableFrom(TypeInformation<?> target);

	
Returns the TypeInformation for the type arguments of the current TypeInformation. 
Returns:
/**
	 * Returns the {@link TypeInformation} for the type arguments of the current {@link TypeInformation}.
	 *
	 * @return
	 */
	List<TypeInformation<?>> getTypeArguments();

	
Specializes the given (raw) ClassTypeInformation using the context of the current potentially parameterized type, basically turning the given raw type into a parameterized one. Will return the given type as is if no generics are involved. 
Params:
type – must not be null.
Returns:
will never be null./**
	 * Specializes the given (raw) {@link ClassTypeInformation} using the context of the current potentially parameterized
	 * type, basically turning the given raw type into a parameterized one. Will return the given type as is if no
	 * generics are involved.
	 *
	 * @param type must not be {@literal null}.
	 * @return will never be {@literal null}.
	 */
	TypeInformation<? extends S> specialize(ClassTypeInformation<?> type);

	
Returns whether the current type is a sub type of the given one, i.e. whether it's assignable but not the same one.
Params:
type – must not be null.
Returns:
Since:
2.2/**
	 * Returns whether the current type is a sub type of the given one, i.e. whether it's assignable but not the same one.
	 * 
	 * @param type must not be {@literal null}.
	 * @return
	 * @since 2.2
	 */
	default boolean isSubTypeOf(Class<?> type) {
		return !type.equals(getType()) && type.isAssignableFrom(getType());
	}
}