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package net.dongliu.commons.collection;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.lang.reflect.Array;
import java.util.List;
import java.util.Map;
import java.util.Objects;

/**
 * Collection wrapper to handle raw list[String] / map[String, Object] collections
 *
 * @author Liu Dong
 */
public class RawValue {

    private static final RawValue nil = new RawValue(null);
    @Nullable
    private final Object value;

    private RawValue(@Nullable Object value) {
        this.value = value;
    }

    /**
     * Wrap collection value
     *
     * @param value a list, map, array or one plain value
     */
    @Nonnull
    public static RawValue of(Object value) {
        return new RawValue(Objects.requireNonNull(value));
    }

    /**
     * Get value at index, current value is array or list.
     *
     * @throws IndexOutOfBoundsException
     */
    @Nonnull
    public RawValue get(int index) {
        if (value == null) {
            return nil;
        }
        if (value instanceof List) {
            return new RawValue(((List) value).get(index));
        } else if (value.getClass().isArray()) {
            return new RawValue(Array.get(value, index));
        } else {
            throw new UnsupportedOperationException("Type " + value.getClass() + " cannot get by index");
        }
    }

    /**
     * Get value with key, current value map.
     *
     * @throws IndexOutOfBoundsException
     */
    @Nonnull
    public RawValue get(String key) {
        if (value == null) {
            return nil;
        }
        if (value instanceof Map) {
            return new RawValue(((Map) value).get(key));
        } else {
            throw new UnsupportedOperationException("Type " + value.getClass() + " cannot get by index");
        }
    }

    /**
     * Get current value as type T
     */
    @Nullable
    @SuppressWarnings("unchecked")
    public  T value() {
        return (T) value;
    }

    /**
     * Get current value as type T. if value is null, return default value
     */
    @Nonnull
    @SuppressWarnings("unchecked")
    public  T orElse(T defaultValue) {
        Objects.requireNonNull(defaultValue);
        if (value != null) {
            return (T) value;
        } else {
            return defaultValue;
        }
    }

    /**
     * If has value
     */
    public boolean present() {
        return value != null;
    }
}