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Standard set of models for geo coding, access control and elastic search abstraction
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package io.polyglotted.pgmodel.util;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.reflect.TypeParameter;
import com.google.common.reflect.TypeToken;
import com.google.gson.*;
import lombok.RequiredArgsConstructor;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.function.Function;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;

public abstract class ModelUtil {
    private static final Gson GSON = new GsonBuilder().disableHtmlEscaping()
       .registerTypeAdapter(ImmutableList.class, new ImmutableListDeserializer<>(ImmutableList::copyOf))
       .registerTypeAdapter(ImmutableMap.class, new ImmutableMapDeserializer())
       .registerTypeAdapter(Double.class, new DoubleSerializer())
       .create();

    public static String serialize(Object o) {
        return GSON.toJson(o);
    }

    @SuppressWarnings("unchecked")
    public static  T deserialize(String json, Class clazz) {
        return GSON.fromJson(json, clazz);
    }

    public static boolean jsonEquals(Object c, Object o) {
        return c == o || (!(o == null || c.getClass() != o.getClass()) && serialize(c).equals(serialize(o)));
    }

    public static int safeIndex(int num) { return num < 0 ? 0 : num; }

    public static boolean doubleEquals(double a, double b) {
        return a == b || Math.abs(a - b) < 0.0000001;
    }

    public static boolean equalsAll(Object... objects) {
        boolean result = true;
        checkArgument(checkNotNull(objects, "objects required").length % 2 == 0,
           "cannot compare unequal properties");
        for (int i = 0; i < objects.length; i += 2) {
            result = result && Objects.equals(objects[i], objects[i + 1]);
        }
        return result;
    }

    @RequiredArgsConstructor
    public static final class ImmutableListDeserializer implements JsonDeserializer {
        private final Function, E> function;

        @Override
        public E deserialize(final JsonElement json, final Type
           type, final JsonDeserializationContext context) throws JsonParseException {

            final Type[] typeArguments = ((ParameterizedType) type).getActualTypeArguments();
            final Type parameterizedType = listOf(typeArguments[0]).getType();

            return function.apply(context.deserialize(json, parameterizedType));
        }
    }

    @SuppressWarnings("unchecked")
    private static  TypeToken> listOf(final Type arg) {
        return new TypeToken>() {}
           .where(new TypeParameter() {}, (TypeToken) TypeToken.of(arg));
    }

    public static final class ImmutableMapDeserializer implements JsonDeserializer> {
        @Override
        public ImmutableMap deserialize(final JsonElement json, final Type
           type, final JsonDeserializationContext context) throws JsonParseException {
            return ImmutableMap.copyOf(context.deserialize(json, mapTypeOf(type)));
        }
    }

    @SuppressWarnings("unchecked")
    private static  Type mapTypeOf(final Type type) {
        final Type[] typeArguments = ((ParameterizedType) type).getActualTypeArguments();
        return new TypeToken>() {}
           .where(new TypeParameter() {}, (TypeToken) TypeToken.of(typeArguments[0]))
           .where(new TypeParameter() {}, (TypeToken) TypeToken.of(typeArguments[1]))
           .getType();
    }

    private static class DoubleSerializer implements JsonSerializer {
        @Override
        public JsonElement serialize(Double src, Type typeOfSrc, JsonSerializationContext context) {
            if (src == src.longValue())
                return new JsonPrimitive(src.longValue());
            return new JsonPrimitive(src);
        }
    }
}