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univocity's open source parsers for processing different text formats using a consistent API
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/*******************************************************************************
 * Copyright 2014 uniVocity Software Pty Ltd
 *
 * 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
 *
 * http://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 com.univocity.parsers.annotations.helpers;

import java.beans.*;
import java.lang.reflect.*;

import com.univocity.parsers.annotations.*;

/**
 * A helper class with information about the location of an field annotated with {@link Parsed} in a record.
 *
 * @author uniVocity Software Pty Ltd - [email protected]
 *
 */
public class FieldMapping {
	private final Field field;
	private int index;
	private String fieldName;
	private final Class beanClass;
	private final Method readMethod;
	private final Method writeMethod;
	private boolean accessible = false;

	/**
	 * Creates the mapping and identifies how it is mapped (by name or by index)
	 * @param beanClass the class that contains a the given field.
	 * @param field a {@link java.lang.reflect.Field} annotated with {@link Parsed}
	 * @param property the property descriptor of this field, if any. If this bean does not have getters/setters, it will be acessed directly.
	 */
	public FieldMapping(Class beanClass, Field field, PropertyDescriptor property) {
		this.beanClass = beanClass;
		this.field = field;
		this.readMethod = property != null ? property.getReadMethod() : null;
		this.writeMethod = property != null ? property.getWriteMethod() : null;

		determineFieldMapping();
	}

	private void determineFieldMapping() {
		Parsed parsed = field.getAnnotation(Parsed.class);
		index = parsed.index();

		if (index >= 0) {
			fieldName = null;
			return;
		}

		String name = parsed.field();
		if (name.isEmpty()) {
			name = field.getName();
		}
		fieldName = name;
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + ((fieldName == null) ? 0 : fieldName.hashCode());
		result = prime * result + index;
		return result;
	}

	@Override
	public boolean equals(Object obj) {
		if (obj == null) {
			return false;
		} else if (this == obj) {
			return true;
		}
		FieldMapping other = (FieldMapping) obj;
		if (fieldName == null) {
			if (other.fieldName != null) {
				return false;
			}
		} else if (!fieldName.equals(other.fieldName)) {
			return false;
		}
		return index == other.index;
	}

	public boolean isMappedToIndex() {
		return index >= 0;
	}

	public boolean isMappedToField() {
		return index < 0;
	}

	public int getIndex() {
		return index;
	}

	public String getFieldName() {
		return fieldName;
	}

	private void setAccessible(Method accessor) {
		if (accessor == null && !accessible) {
			this.field.setAccessible(true);
			accessible = true;
		}
	}

	public Object read(Object instance) {
		setAccessible(readMethod);
		try {
			if (readMethod != null) {
				return readMethod.invoke(instance);
			} else {
				return field.get(instance);
			}
		} catch (Throwable e) {
			throw new IllegalStateException("Unable to get value from field " + field.getName() + "' in " + this.beanClass.getName());
		}
	}

	public void write(Object instance, Object value) {
		setAccessible(writeMethod);
		try {
			if (writeMethod != null) {
				writeMethod.invoke(instance, value);
			} else {
				field.set(instance, value);
			}
		} catch (Throwable e) {
			throw new IllegalStateException("Unable to set value '" + value + "' for field " + field.getName() + "' in " + this.beanClass.getName());
		}

	}
}