/*
 * Copyright 2016 Andrew Rucker Jones.
 *
 * 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.opencsv.exceptions;

import java.lang.reflect.Field;
import java.util.Collections;
import java.util.List;
import org.apache.commons.collections4.CollectionUtils;
import org.apache.commons.collections4.list.UnmodifiableList;

This exception should be thrown when a field marked as required is empty in
the CSV file.
Author:
Andrew Rucker Jones
Since:
3.8/**
 * This exception should be thrown when a field marked as required is empty in
 * the CSV file.
 *
 * @author Andrew Rucker Jones
 * @since 3.8
 */
public class CsvRequiredFieldEmptyException extends CsvException {
    private static final long serialVersionUID = 1L;

    private final Class<?> beanClass;
    private transient final List<Field> destinationFields;

    
Default constructor, in case no further information is necessary.
/**
     * Default constructor, in case no further information is necessary.
     */
    public CsvRequiredFieldEmptyException() {
        beanClass = null;
        destinationFields = Collections.emptyList();
    }

    
Constructor with a simple text.
Params:
message – Human-readable error text/**
     * Constructor with a simple text.
     *
     * @param message Human-readable error text
     */
    public CsvRequiredFieldEmptyException(String message) {
        super(message);
        beanClass = null;
        destinationFields = Collections.emptyList();
    }

    
Constructor for setting the intended class and field of the target bean.
These may not be known in every context.
This constructor is provided for backward compatibility and for
convenience if you only have one missing destination field.
Params:
beanClass –        Class of the destination bean
destinationField – Field of the destination field in the destination bean/**
     * Constructor for setting the intended class and field of the target bean.
     * <p>These may not be known in every context.</p>
     * <p>This constructor is provided for backward compatibility and for
     * convenience if you only have one missing destination field.</p>
     *
     * @param beanClass        Class of the destination bean
     * @param destinationField Field of the destination field in the destination bean
     */
    public CsvRequiredFieldEmptyException(Class<?> beanClass, Field destinationField) {
        this.beanClass = beanClass;
        this.destinationFields = Collections.singletonList(destinationField);
    }
    
    
Constructor for setting the intended class and fields of the target bean.
These may not be known in every context.
Params:
beanClass –        Class of the destination bean
destinationFields – Fields of the destination fields in the destination bean
Since:
4.2/**
     * Constructor for setting the intended class and fields of the target bean.
     * These may not be known in every context.
     *
     * @param beanClass        Class of the destination bean
     * @param destinationFields Fields of the destination fields in the destination bean
     * @since 4.2
     */
    public CsvRequiredFieldEmptyException(Class<?> beanClass, List<Field> destinationFields) {
        this.beanClass = beanClass;
        this.destinationFields = new UnmodifiableList<>(destinationFields);
    }
    
    
Constructor for setting the intended class of the target bean and a
human-readable error message.
These may not be known in every context.
Params:
beanClass – Class of the destination bean
message – Human-readable error text
Since:
3.10/**
     * Constructor for setting the intended class of the target bean and a
     * human-readable error message.
     * These may not be known in every context.
     *
     * @param beanClass Class of the destination bean
     * @param message Human-readable error text
     * @since 3.10
     */
    public CsvRequiredFieldEmptyException(Class<?> beanClass, String message) {
        super(message);
        this.beanClass = beanClass;
        this.destinationFields = Collections.emptyList();
    }

    
Constructor for setting the intended class and field of the target bean
along with an error message.
The class and field may not be known in every context.
This constructor is provided for backward compatibility and for
convenience if you only have one missing destination field.
Params:
beanClass –        Class of the destination bean
destinationField – Field of the destination field in the destination bean
message –          Human-readable error text/**
     * Constructor for setting the intended class and field of the target bean
     * along with an error message.
     * <p>The class and field may not be known in every context.</p>
     * <p>This constructor is provided for backward compatibility and for
     * convenience if you only have one missing destination field.</p>
     *
     * @param beanClass        Class of the destination bean
     * @param destinationField Field of the destination field in the destination bean
     * @param message          Human-readable error text
     */
    public CsvRequiredFieldEmptyException(Class<?> beanClass, Field destinationField, String message) {
        super(message);
        this.beanClass = beanClass;
        this.destinationFields = Collections.singletonList(destinationField);
    }

    
Constructor for setting the intended class and fields of the target bean
along with an error message.
The class and field may not be known in every context.
Params:
beanClass –        Class of the destination bean
destinationFields – Field of the destination field in the destination bean
message –          Human-readable error text
Since:
4.2/**
     * Constructor for setting the intended class and fields of the target bean
     * along with an error message.
     * The class and field may not be known in every context.
     *
     * @param beanClass        Class of the destination bean
     * @param destinationFields Field of the destination field in the destination bean
     * @param message          Human-readable error text
     * @since 4.2
     */
    public CsvRequiredFieldEmptyException(Class<?> beanClass, List<Field> destinationFields, String message) {
        super(message);
        this.beanClass = beanClass;
        this.destinationFields = new UnmodifiableList<>(destinationFields);
    }

    
Gets the class of the bean to which the value was to be assigned.
Returns:
The class of the bean to which the destination field belongs/**
     * Gets the class of the bean to which the value was to be assigned.
     *
     * @return The class of the bean to which the destination field belongs
     */
    public Class<?> getBeanClass() {
        return beanClass;
    }

    
Gets the field from the Reflection API that was to be assigned.
This method is provided as a convenience for when you know there can
be only one field, or you really only care about the first field.
destinationFields is marked transient, because Field is not Serializable. If for any reason this exception is serialized and deserialized, this method will subsequently return null.
Returns:
The first destination field that was to receive the empty value/**
     * Gets the field from the Reflection API that was to be assigned.
     * <p>This method is provided as a convenience for when you know there can
     * be only one field, or you really only care about the first field.</p>
     * <p>{@code destinationFields} is marked {@code transient}, because
     * {@link java.lang.reflect.Field} is not {@link java.io.Serializable}. If
     * for any reason this exception is serialized and deserialized, this method
     * will subsequently return {@code null}.</p>
     *
     * @return The first destination field that was to receive the empty value
     */
    public Field getDestinationField() {
        return CollectionUtils.isEmpty(destinationFields)?null:destinationFields.get(0);
    }
    
    
Returns the complete list of all fields that were to be empty. destinationFields is marked transient, because Field is not Serializable. If for any reason this exception is serialized and deserialized, this method will subsequently return null. 
Returns:
All destination fields that were to receive the empty value
Since:
4.2/**
     * Returns the complete list of all fields that were to be empty.
     * {@code destinationFields} is marked {@code transient}, because
     * {@link java.lang.reflect.Field} is not {@link java.io.Serializable}. If
     * for any reason this exception is serialized and deserialized, this method
     * will subsequently return {@code null}.
     *
     * @return All destination fields that were to receive the empty value
     * @since 4.2
     */
    public List<Field> getDestinationFields() {
        return destinationFields;
    }
}