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package com.github.leeonky.util;

import java.lang.reflect.Array;
import java.util.*;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;

import static com.github.leeonky.util.BeanClass.create;

public class CollectionHelper {

    @SuppressWarnings("unchecked")
    public static  Stream toStream(Object collection) {
        if (collection != null) {
            Class collectionType = collection.getClass();
            if (collectionType.isArray())
                return IntStream.range(0, Array.getLength(collection)).mapToObj(i -> (E) Array.get(collection, i));
            else if (collection instanceof Iterable)
                return StreamSupport.stream(((Iterable) collection).spliterator(), false);
            else if (collection instanceof Stream)
                return (Stream) collection;
        }
        throw new CannotToStreamException(collection);
    }

    public static  T convert(Object collection, BeanClass toType) {
        return convert(collection, toType, Converter.getInstance());
    }

    @SuppressWarnings("unchecked")
    public static  T convert(Object collection, BeanClass toType, Converter elementConverter) {
        if (collection != null) {
            Class elementType = toType.getElementType().getType();
            return (T) toType.createCollection((toStream(collection).map(o ->
                    elementConverter.convert(elementType, o))).collect(Collectors.toList()));
        }
        return null;
    }

    public static Object createCollection(Collection elements, BeanClass type) {
        if (type.getType().isArray())
            return createArray(elements, type);
        if (type.getType().isInterface())
            return createInterfaceCollection(elements, type);
        if (Collection.class.isAssignableFrom(type.getType()))
            return createClassCollection(elements, type);
        throw new IllegalStateException(String.format("Cannot create instance of collection type %s", type.getName()));
    }

    @SuppressWarnings("unchecked")
    private static Collection