/*
 * Copyright 2002-2019 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.beans.factory.config;

import org.springframework.beans.BeanMetadataElement;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.ObjectUtils;

/**
 * Holder for a typed String value. Can be added to bean definitions
 * in order to explicitly specify a target type for a String value,
 * for example for collection elements.
 *
 * <p>This holder will just store the String value and the target type.
 * The actual conversion will be performed by the bean factory.
 *
 * @author Juergen Hoeller
 * @since 1.2
 * @see BeanDefinition#getPropertyValues
 * @see org.springframework.beans.MutablePropertyValues#addPropertyValue
 */
public class TypedStringValue implements BeanMetadataElement {

        @Nullable
        private String value;

        @Nullable
        private volatile Object targetType;

        @Nullable
        private Object source;

        @Nullable
        private String specifiedTypeName;

        private volatile boolean dynamic;


        /**
         * Create a new {@link TypedStringValue} for the given String value.
         * @param value the String value
         */
        public TypedStringValue(@Nullable String value) {
                setValue(value);
        }

        /**
         * Create a new {@link TypedStringValue} for the given String value
         * and target type.
         * @param value the String value
         * @param targetType the type to convert to
         */
        public TypedStringValue(@Nullable String value, Class<?> targetType) {
                setValue(value);
                setTargetType(targetType);
        }

        /**
         * Create a new {@link TypedStringValue} for the given String value
         * and target type.
         * @param value the String value
         * @param targetTypeName the type to convert to
         */
        public TypedStringValue(@Nullable String value, String targetTypeName) {
                setValue(value);
                setTargetTypeName(targetTypeName);
        }


        /**
         * Set the String value.
         * <p>Only necessary for manipulating a registered value,
         * for example in BeanFactoryPostProcessors.
         */
        public void setValue(@Nullable String value) {
                this.value = value;
        }

        /**
         * Return the String value.
         */
        @Nullable
        public String getValue() {
                return this.value;
        }

        /**
         * Set the type to convert to.
         * <p>Only necessary for manipulating a registered value,
         * for example in BeanFactoryPostProcessors.
         */
        public void setTargetType(Class<?> targetType) {
                Assert.notNull(targetType, "'targetType' must not be null");
                this.targetType = targetType;
        }

        /**
         * Return the type to convert to.
         */
        public Class<?> getTargetType() {
                Object targetTypeValue = this.targetType;
                if (!(targetTypeValue instanceof Class)) {
                        throw new IllegalStateException("Typed String value does not carry a resolved target type");
                }
                return (Class<?>) targetTypeValue;
        }

        /**
         * Specify the type to convert to.
         */
        public void setTargetTypeName(@Nullable String targetTypeName) {
                this.targetType = targetTypeName;
        }

        /**
         * Return the type to convert to.
         */
        @Nullable
        public String getTargetTypeName() {
                Object targetTypeValue = this.targetType;
                if (targetTypeValue instanceof Class) {
                        return ((Class<?>) targetTypeValue).getName();
                }
                else {
                        return (String) targetTypeValue;
                }
        }

        /**
         * Return whether this typed String value carries a target type .
         */
        public boolean hasTargetType() {
                return (this.targetType instanceof Class);
        }

        /**
         * Determine the type to convert to, resolving it from a specified class name
         * if necessary. Will also reload a specified Class from its name when called
         * with the target type already resolved.
         * @param classLoader the ClassLoader to use for resolving a (potential) class name
         * @return the resolved type to convert to
         * @throws ClassNotFoundException if the type cannot be resolved
         */
        @Nullable
        public Class<?> resolveTargetType(@Nullable ClassLoader classLoader) throws ClassNotFoundException {
                String typeName = getTargetTypeName();
                if (typeName == null) {
                        return null;
                }
                Class<?> resolvedClass = ClassUtils.forName(typeName, classLoader);
                this.targetType = resolvedClass;
                return resolvedClass;
        }


        /**
         * Set the configuration source {@code Object} for this metadata element.
         * <p>The exact type of the object will depend on the configuration mechanism used.
         */
        public void setSource(@Nullable Object source) {
                this.source = source;
        }

        @Override
        @Nullable
        public Object getSource() {
                return this.source;
        }

        /**
         * Set the type name as actually specified for this particular value, if any.
         */
        public void setSpecifiedTypeName(@Nullable String specifiedTypeName) {
                this.specifiedTypeName = specifiedTypeName;
        }

        /**
         * Return the type name as actually specified for this particular value, if any.
         */
        @Nullable
        public String getSpecifiedTypeName() {
                return this.specifiedTypeName;
        }

        /**
         * Mark this value as dynamic, i.e. as containing an expression
         * and hence not being subject to caching.
         */
        public void setDynamic() {
                this.dynamic = true;
        }

        /**
         * Return whether this value has been marked as dynamic.
         */
        public boolean isDynamic() {
                return this.dynamic;
        }


        @Override
        public boolean equals(@Nullable Object other) {
                if (this == other) {
                        return true;
                }
                if (!(other instanceof TypedStringValue)) {
                        return false;
                }
                TypedStringValue otherValue = (TypedStringValue) other;
                return (ObjectUtils.nullSafeEquals(this.value, otherValue.value) &&
                                ObjectUtils.nullSafeEquals(this.targetType, otherValue.targetType));
        }

        @Override
        public int hashCode() {
                return ObjectUtils.nullSafeHashCode(this.value) * 29 + ObjectUtils.nullSafeHashCode(this.targetType);
        }

        @Override
        public String toString() {
                return "TypedStringValue: value [" + this.value + "], target type [" + this.targetType + "]";
        }

}