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package net.dongliu.commons.collection;

import javax.annotation.Nullable;
import java.util.*;
import java.util.function.Function;

/**
 * Utils method for map
 *
 * @author Liu Dong
 */
public class Maps {

    /**
     * If map is null, return immutable empty map; else return self
     */
    public static  Map nullToEmpty(@Nullable Map map) {
        return map == null ? Maps.of() : map;
    }

    /**
     * Create immutable view of this Set.
     */
    public static  Map wrapImmutable(Map map) {
        return Collections.unmodifiableMap(map);
    }

    /**
     * Create a immutable map with content
     */
    public static  Map copyImmutable(Map map) {
        return Collections.unmodifiableMap(new HashMap<>(map));
    }

    /**
     * Convert map value, return new map
     */
    public static  Map convert(Map map, Function function) {
        Map newMap = Maps.create();
        map.forEach((k, v) -> newMap.put(k, function.apply(v)));
        return newMap;
    }

    /**
     * Create immutable empty map
     */
    public static  Map of() {
        return Collections.emptyMap();
    }

    /**
     * Create immutable map
     */
    public static  Map of(Map.Entry value) {
        return wrapImmutable(create(value));
    }

    /**
     * Create immutable map
     */
    public static  Map of(Map.Entry value1,
                                      Map.Entry value2) {
        return wrapImmutable(create(value1, value2));
    }

    /**
     * Create immutable map
     */
    public static  Map of(Map.Entry value1,
                                      Map.Entry value2,
                                      Map.Entry value3) {
        return wrapImmutable(create(value1, value2, value3));
    }

    /**
     * Create immutable map
     */
    public static  Map of(Map.Entry value1,
                                      Map.Entry value2,
                                      Map.Entry value3,
                                      Map.Entry value4) {
        return wrapImmutable(create(value1, value2, value3, value4));
    }

    /**
     * Create immutable map
     */
    public static  Map of(Map.Entry value1,
                                      Map.Entry value2,
                                      Map.Entry value3,
                                      Map.Entry value4,
                                      Map.Entry value5) {
        return wrapImmutable(create(value1, value2, value3, value4, value5));
    }

    @SafeVarargs
    public static  Map of(Map.Entry... values) {
        if (values.length == 0) {
            return of();
        }
        return wrapImmutable(create(values));
    }

    public static  Map of(Collection> values) {
        return wrapImmutable(create(values));
    }

    /**
     * Create mutable empty map
     */
    public static  Map create() {
        return new HashMap<>();
    }

    /**
     * Create mutable map
     */
    public static  Map create(Map.Entry value) {
        Map map = new HashMap<>();
        map.put(value.getKey(), value.getValue());
        return map;
    }

    /**
     * Create mutable map
     */
    public static  Map create(Map.Entry value1,
                                          Map.Entry value2) {
        Map map = new HashMap<>();
        map.put(value1.getKey(), value1.getValue());
        map.put(value2.getKey(), value2.getValue());
        return map;
    }

    /**
     * Create mutable map
     */
    public static  Map create(Map.Entry value1,
                                          Map.Entry value2,
                                          Map.Entry value3) {
        Map map = new HashMap<>();
        map.put(value1.getKey(), value1.getValue());
        map.put(value2.getKey(), value2.getValue());
        map.put(value3.getKey(), value3.getValue());
        return map;
    }

    /**
     * Create mutable map
     */
    public static  Map create(Map.Entry value1,
                                          Map.Entry value2,
                                          Map.Entry value3,
                                          Map.Entry value4) {
        Map map = new HashMap<>();
        map.put(value1.getKey(), value1.getValue());
        map.put(value2.getKey(), value2.getValue());
        map.put(value3.getKey(), value3.getValue());
        map.put(value4.getKey(), value4.getValue());
        return map;
    }

    /**
     * Create mutable map
     */
    public static  Map create(Map.Entry value1,
                                          Map.Entry value2,
                                          Map.Entry value3,
                                          Map.Entry value4,
                                          Map.Entry value5) {
        Map map = new HashMap<>();
        map.put(value1.getKey(), value1.getValue());
        map.put(value2.getKey(), value2.getValue());
        map.put(value3.getKey(), value3.getValue());
        map.put(value4.getKey(), value4.getValue());
        map.put(value5.getKey(), value5.getValue());
        return map;
    }

    @SafeVarargs
    public static  Map create(Map.Entry... values) {
        Map map = new HashMap<>();
        for (Map.Entry tuple : values) map.put(tuple.getKey(), tuple.getValue());
        return map;
    }

    public static  Map create(Collection> values) {
        Map map = new HashMap<>();
        for (Map.Entry tuple : values) map.put(tuple.getKey(), tuple.getValue());
        return map;
    }

    /**
     * Combine two list to map
     */
    public static  Map zip(List keys, List values) {
        if (keys.size() != values.size()) {
            throw new IllegalArgumentException("Key and value size not equals");
        }
        Map map = new HashMap<>();
        Iterator keyIter = keys.iterator();
        Iterator valueIter = values.iterator();
        while (keyIter.hasNext() && valueIter.hasNext()) {
            map.put(keyIter.next(), valueIter.next());
        }
        return map;
    }

}