/*
 * Copyright 2018 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.bean;

import com.opencsv.ICSVParser;
import com.opencsv.exceptions.CsvRequiredFieldEmptyException;
import org.apache.commons.collections4.MultiValuedMap;
import org.apache.commons.collections4.iterators.LazyIteratorChain;
import org.apache.commons.collections4.iterators.TransformIterator;

import java.lang.reflect.Field;
import java.util.*;
import java.util.stream.Collectors;

This class maintains a mapping from column position out of a CSV file to bean
fields.
Author:
Andrew Rucker Jones
Type parameters:
<T> – Type of the bean being converted
Since:
4.2/**
 * This class maintains a mapping from column position out of a CSV file to bean
 * fields.
 *
 * @param <T> Type of the bean being converted
 * @author Andrew Rucker Jones
 * @since 4.2
 */
public class FieldMapByPosition<T> extends AbstractFieldMap<String, Integer, PositionToBeanField<T>, T> implements Iterable<FieldMapByPositionEntry<T>> {
    
    private int maxIndex = Integer.MAX_VALUE;

    
Holds a Comparator to sort columns on writing. /** Holds a {@link java.util.Comparator} to sort columns on writing. */
    private Comparator<Integer> writeOrder = null;
    
    
Initializes this FieldMap. 
Params:
errorLocale – The locale to be used for error messages/**
     * Initializes this {@link FieldMap}.
     * 
     * @param errorLocale The locale to be used for error messages
     */
    public FieldMapByPosition(final Locale errorLocale) {
        super(errorLocale);
    }
    
    
This method generates a header that can be used for writing beans of the type provided back to a file. The ordering of the headers can be determined with the Comparator passed in to setColumnOrderOnWrite(Comparator). Otherwise, it is ascending according to position. /**
     * This method generates a header that can be used for writing beans of the
     * type provided back to a file.
     * The ordering of the headers can be determined with the
     * {@link java.util.Comparator} passed in to
     * {@link #setColumnOrderOnWrite(Comparator)}. Otherwise, it is ascending
     * according to position.
     */
    // The rest of the Javadoc is inherited.
    @Override
    public String[] generateHeader(final T bean) throws CsvRequiredFieldEmptyException {
        final List<Field> missingRequiredHeaders = new LinkedList<>();
        final SortedMap<Integer, String> headerMap = new TreeMap<>(writeOrder);
        for(Map.Entry<Integer, BeanField<T, Integer>> entry : simpleMap.entrySet()) {
            headerMap.put(entry.getKey(), entry.getValue().getField().getName());
        }
        for(ComplexFieldMapEntry<String, Integer, T> r : complexMapList) {
            @SuppressWarnings("unchecked")
            final MultiValuedMap<Integer,T> m = (MultiValuedMap<Integer, T>) r.getBeanField().getFieldValue(bean);
            boolean oneEntryMatched = false;
            if(m != null && !m.isEmpty()) {
                for(Map.Entry<Integer,T> entry : m.entries()) {
                    Integer key = entry.getKey();
                    if(r.contains(key)) {
                        headerMap.put(entry.getKey(), r.getBeanField().getField().getName());
                        oneEntryMatched = true;
                    }
                }
            }
            if(m == null || m.isEmpty() || !oneEntryMatched) {
                if(r.getBeanField().isRequired()) {
                    missingRequiredHeaders.add(r.getBeanField().getField());
                }
            }
        }
        
        // Convert to an array of header "names".
        // Since the user can pass in an arbitrary collation, we have to
        // re-sort to get the highest value.
        SortedSet<Integer> headerSet = new TreeSet<>(headerMap.keySet());
        int arraySize = headerSet.isEmpty() ? 0 : headerSet.last()+1;
        final String[] headers = new String[arraySize];
        int previousIndex = headerSet.isEmpty() ? 0 : headerSet.first();
        for(Integer i : headerSet) { // Fill in gaps
            for(int j = previousIndex+1; j < i ; j++) {
                headerMap.put(j, null);
            }
            previousIndex = i;
        }
        previousIndex = 0;
        for(String value : headerMap.values()) {
            headers[previousIndex++] = value;
        }
        
        // Report headers that should have been present
        if(!missingRequiredHeaders.isEmpty()) {
            String errorMessage = String.format(
                    ResourceBundle
                            .getBundle(ICSVParser.DEFAULT_BUNDLE_NAME, errorLocale)
                            .getString("header.required.field.absent"),
                    missingRequiredHeaders.stream()
                            .map(Field::getName)
                            .collect(Collectors.joining(" ")),
                    String.join(" ", headers));
            throw new CsvRequiredFieldEmptyException(bean.getClass(), missingRequiredHeaders, errorMessage);
        }
        
        return headers;
    }
    
    
Params:
rangeDefinition – A string describing the column positions to be
  matched.
See Also:
CsvBindAndJoinByPosition.position()/**
     * @param rangeDefinition A string describing the column positions to be
     *   matched.
     * @see CsvBindAndJoinByPosition#position() 
     */
    // The rest of the Javadoc is inherited
    @Override
    public void putComplex(final String rangeDefinition, final BeanField<T, Integer> field) {
        complexMapList.add(new PositionToBeanField<>(rangeDefinition, maxIndex, field, errorLocale));
    }
    
    
Sets the maximum index for all ranges specified in the entire field map. No ranges or mappings are ever removed so as to preserve information about required fields, but upper boundries are shortened as much as possible. If ranges or individual column positions were specified that lie wholly above maxIndex, these are preserved, though ranges are shortened to a single value (the lower boundry). 
Params:
maxIndex – The maximum index in the data being imported/**
     * Sets the maximum index for all ranges specified in the entire field map.
     * No ranges or mappings are ever removed so as to preserve information
     * about required fields, but upper boundries are shortened as much as
     * possible. If ranges or individual column positions were specified that
     * lie wholly above {@code maxIndex}, these are preserved, though ranges
     * are shortened to a single value (the lower boundry).
     * 
     * @param maxIndex The maximum index in the data being imported
     */
    public void setMaxIndex(int maxIndex) {
        this.maxIndex = maxIndex;
        
        // Attenuate all ranges that end past the last index down to the last index
        complexMapList.forEach(p -> p.attenuateRanges(maxIndex));
    }

    @Override
    public Iterator<FieldMapByPositionEntry<T>> iterator() {
        return new LazyIteratorChain<FieldMapByPositionEntry<T>>() {
            
            @Override
            protected Iterator<FieldMapByPositionEntry<T>> nextIterator(int count) {
                if(count <= complexMapList.size()) {
                    return complexMapList.get(count-1).iterator();
                }
                if(count == complexMapList.size()+1) {
                    return new TransformIterator<>(
                            simpleMap.entrySet().iterator(),
                            input -> new FieldMapByPositionEntry<T>(input.getKey(), input.getValue()));
                }
                return null;
            }
        };
    }

    
Sets the Comparator to be used to sort columns when writing beans to a CSV file. 
Params:
writeOrder – The Comparator to use. May be null, in which case the natural ordering is used.
Since:
4.3/**
     * Sets the {@link java.util.Comparator} to be used to sort columns when
     * writing beans to a CSV file.
     *
     * @param writeOrder The {@link java.util.Comparator} to use. May be
     *   {@code null}, in which case the natural ordering is used.
     * @since 4.3
     */
    public void setColumnOrderOnWrite(Comparator<Integer> writeOrder) {
        this.writeOrder = writeOrder;
    }
}