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package me.aifaq.commons.lang;

import com.google.common.base.Preconditions;
import me.aifaq.commons.lang.base.Function;
import me.aifaq.commons.lang.base.MappableFunction;
import me.aifaq.commons.lang.base.OperableFunction;
import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.lang3.StringUtils;

import java.math.BigDecimal;
import java.util.*;

/**
 * @author Wang Wei [[email protected]]
 * @since 10:10 2017/5/17
 */
public class CollectionUtil {
	/**
	 * 如果对象为null，返回0
	 *
	 * @param object
	 * @return
	 */
	public static int size(Object object) {
		if (object == null) {
			return 0;
		}
		return CollectionUtils.size(object);
	}

	/**
	 * 自定义函数转换得到List
	 *
	 * @param sources  源数据集合
	 * @param function 转换函数
	 * @param       源数据类型
	 * @param       目标数据类型
	 * @return
	 */
	public static  List transformList(Collection sources, Function function) {
		Preconditions.checkNotNull(function);

		if (CollectionUtils.isEmpty(sources)) {
			return new ArrayList<>(0);
		}
		final List targets = new ArrayList<>(sources.size());
		for (S source : sources) {
			if (source == null && function.skipIfNull()) {
				continue;
			}
			final T target = function.apply(source);
			if (target == null && function.skipIfApplyNull()) {
				continue;
			}
			targets.add(target);
		}
		return targets;
	}

	/**
	 * 自定义函数转换得到Set
	 *
	 * @param sources  源数据集合
	 * @param function 转换函数
	 * @param       源数据类型
	 * @param       目标数据类型
	 * @return
	 */
	public static  Set transformSet(Collection sources, Function function) {
		Preconditions.checkNotNull(function);

		if (CollectionUtils.isEmpty(sources)) {
			return new HashSet<>();
		}
		final Set targets = new HashSet<>();
		for (S source : sources) {
			if (source == null && function.skipIfNull()) {
				continue;
			}
			final T target = function.apply(source);
			if (target == null && function.skipIfApplyNull()) {
				continue;
			}
			targets.add(target);
		}
		return targets;
	}

	/**
	 * 自定义函数转换得到Map
	 *
	 * @param sources  源数据集合
	 * @param function 转换函数
	 * @param       源数据类型
	 * @param       目标数据类型
	 * @return
	 */
	public static  Map transformMap(Collection sources, MappableFunction function) {
		Preconditions.checkNotNull(function);

		if (CollectionUtils.isEmpty(sources)) {
			return new HashMap<>();
		}
		final Map targets = new HashMap<>();
		for (S source : sources) {
			if (source == null && function.skipIfNull()) {
				continue;
			}
			final Map.Entry entry = function.apply(source);
			if (entry == null && function.skipIfApplyNull()) {
				continue;
			}
			targets.put(entry.getKey(), entry.getValue());
		}
		return targets;
	}

	/**
	 * 求和
	 *
	 * @param sources  源数据集合
	 * @param function 转换函数
	 * @param       源数据类型
	 * @return
	 */
	public static  BigDecimal sum(Collection sources, OperableFunction function) {
		Preconditions.checkNotNull(function);

		if (CollectionUtils.isEmpty(sources)) {
			return BigDecimal.ZERO;
		}
		BigDecimal result = BigDecimal.ZERO;
		for (S source : sources) {
			if (source == null && function.skipIfNull()) {
				continue;
			}
			final BigDecimal target = function.apply(source);
			if (target == null && function.skipIfApplyNull()) {
				continue;
			}
			result = result.add(target);
		}
		return result;
	}

	/**
	 * 是否存在null值
	 *
	 * @param collection
	 * @return
	 */
	public static boolean hasNull(Collection collection) {
		if (collection == null) {
			return true;
		}
		for (Object object : collection) {
			if (object == null) {
				return true;
			}
		}
		return false;
	}

	/**
	 * 拼接字符串
	 *
	 * @param collection 目标集合
	 * @param separator  拼接字符
	 * @param ignoreNull 是否忽略null值
	 * @return
	 */
	public static String join(Collection collection, Object separator, boolean ignoreNull) {
		if (CollectionUtils.isEmpty(collection)) {
			return StringUtils.EMPTY;
		}
		final StringBuilder result = new StringBuilder();
		int mark = 0;
		for (Object object : collection) {
			if (object == null && ignoreNull) {
				continue;
			}
			if (mark++ > 0) {
				result.append(separator);
			}
			result.append(object);
		}
		return result.toString();
	}

	/**
	 * @see #join(Collection, Object, boolean)
	 */
	public static String join(Collection collection, Object seperator) {
		return join(collection, seperator, true);
	}

	/**
	 * @see #join(Collection, Object, boolean)
	 */
	public static String join(Collection collection) {
		return join(collection, StringUtil.COMMA, true);
	}

	/**
	 * 拼接字符串
	 *
	 * @param collection   目标集合
	 * @param separator    拼接字符
	 * @param nullReplaced null被替换的值
	 * @return
	 */
	public static String join(Collection collection, Object separator, Object nullReplaced) {
		if (CollectionUtils.isEmpty(collection)) {
			return StringUtils.EMPTY;
		}
		final StringBuilder result = new StringBuilder();
		int mark = 0;
		for (Object object : collection) {
			if (mark++ > 0) {
				result.append(separator);
			}
			result.append(object == null ? nullReplaced : object);
		}
		return result.toString();
	}

	/**
	 * 添加元素至集合中
	 *
	 * @param target
	 * @param source
	 * @param 
	 * @return
	 */
	public static  Collection addAll(Collection target, Iterable source) {
		Preconditions.checkNotNull(target);

		if (source == null) {
			return target;
		}
		final Iterator iterator = source.iterator();
		while (iterator.hasNext()) {
			target.add(iterator.next());
		}
		return target;
	}

	/**
	 * 获取集合的首个元素
	 *
	 * @param collection
	 * @param 
	 * @return
	 */
	public static  T first(Collection collection) {
		if (CollectionUtils.isEmpty(collection)) {
			return null;
		}
		final Iterator iterator = collection.iterator();

		return iterator.hasNext() ? iterator.next() : null;
	}
}