package com.temp.shared.utils;

import java.util.*;

/**
 * Utility methods around Collections / Arrays to reduce the code in other
 * places (e.g. the Activities).
 *
 * @author georgs
 */
public class CollectionsUtils {
    public static <T> List<T> deNull( List<T> list ) {
        if ( list != null ) { // can not "in line" as compiler gets confused!
            return list;
        }
        return Collections.emptyList();
    }

    public static <T> List<T> noEmpty( List<T> list ) {
        return isEmpty( list ) ? null : list;
    }

    public static boolean isEmpty( Collection<?> collection ) {
        return (collection == null) || collection.isEmpty();
    }

    public static boolean isEmpty( Map<?, ?> collection ) {
        return (collection == null) || collection.isEmpty();
    }

    public static boolean isEmpty( Object[] array ) {
        return (array == null) || (array.length == 0);
    }

    /**
     * Use type inference to create a map - from Guava
     */
    public static <V> List<V> newArrayList() {
        return new ArrayList<V>();
    }

    /**
     * Use type inference to create a map - from Guava
     */
    public static <K, V> Map<K, V> newHashMap() {
        return new HashMap<K, V>();
    }

    public static Map<String, String> newMap( String... keyValuePairs ) {
        Map<String, String> map = newHashMap();
        if ( !isEmpty( keyValuePairs ) ) {
            if ( (keyValuePairs.length & 1) == 1 ) { // Odd == Not Paired!
                throw new IllegalArgumentException( "To construct a String String Map, must provide Strings in pairs (key, value)" );
            }
            for ( int i = 0; i < keyValuePairs.length; ) {
                String key = keyValuePairs[i++];
                String value = keyValuePairs[i++];
                addNonEmptiesTo( map, key, value );
            }
        }
        return map;
    }

    public static Map<String, String> addNonEmptiesTo( Map<String, String> map, String key, String value ) {
        map.put( Assert.notNullOrEmpty( "key", key ), Assert.notNullOrEmpty( "value", value ) );
        return map;
    }

    public static <K, V> Map<K, V> addNonNullsTo( Map<K, V> map, K key, V value ) {
        Assert.notNull( "key", key );
        Assert.notNull( "value", value );
        map.put( key, value );
        return map;
    }
}