/*
* Copyright 2025 Google. This software is provided as-is, without warranty or representation for any use or purpose.
* Your use of it is subject to your agreement with Google.
*/

package com.example.util;

import com.google.protobuf.ListValue;
import com.google.protobuf.NullValue;
import com.google.protobuf.Struct;
import com.google.protobuf.Value;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

public class ProtobufUtil {

    private static final Logger logger = LoggerFactory.getLogger(ProtobufUtil.class);

    /**
     * Converts a Java Object to a Protobuf Value.
     * Supports primitive types, String, Map, and List.
     * Maps will be converted to Protobuf Structs.
     * Lists will be converted to Protobuf ListValues.
     */
    @SuppressWarnings("rawtypes")
    public static Value convertJavaObjectToProtobufValue(Object obj) {
        if (obj == null) {
            return Value.newBuilder().setNullValue(NullValue.NULL_VALUE).build();
        } else if (obj instanceof Boolean) {
            return Value.newBuilder().setBoolValue((Boolean) obj).build();
        } else if (obj instanceof Integer) {
            return Value.newBuilder().setNumberValue(((Integer) obj).doubleValue()).build();
        } else if (obj instanceof Long) {
            return Value.newBuilder().setNumberValue(((Long) obj).doubleValue()).build();
        } else if (obj instanceof Double) {
            return Value.newBuilder().setNumberValue((Double) obj).build();
        } else if (obj instanceof String) {
            return Value.newBuilder().setStringValue((String) obj).build();
        } else if (obj instanceof Enum) {
            return Value.newBuilder().setStringValue(((Enum) obj).name()).build();
        } else if (obj instanceof Map) {
            Struct.Builder structBuilder = Struct.newBuilder();
            ((Map<?, ?>) obj).forEach((key, val) ->
                    structBuilder.putFields(String.valueOf(key), convertJavaObjectToProtobufValue(val))
            );
            return Value.newBuilder().setStructValue(structBuilder.build()).build();
        } else if (obj instanceof List) {
            ListValue.Builder listValueBuilder = ListValue.newBuilder();
            ((List<?>) obj).forEach(item ->
                    listValueBuilder.addValues(convertJavaObjectToProtobufValue(item))
            );
            return Value.newBuilder().setListValue(listValueBuilder.build()).build();
        }
        logger.warn("Unsupported type for Protobuf conversion: {}. Converting to String.", obj.getClass().getName());
        return Value.newBuilder().setStringValue(obj.toString()).build();
    }

    /**
     * Converts a Protobuf Value to a Java Object.
     * Supports Null, Boolean, Number, String, Struct (to Map), and ListValue (to List).
     */
    public static Object convertProtobufValueToJavaObject(Value protobufValue) {
        return switch (protobufValue.getKindCase()) {
            case NULL_VALUE -> null;
            case BOOL_VALUE -> protobufValue.getBoolValue();
            case NUMBER_VALUE -> protobufValue.getNumberValue();
            case STRING_VALUE -> protobufValue.getStringValue();
            case STRUCT_VALUE -> protobufValue.getStructValue().getFieldsMap().entrySet().stream()
                    .collect(Collectors.toMap(
                            Map.Entry::getKey,
                            entry -> convertProtobufValueToJavaObject(entry.getValue()),
                            (oldValue, newValue) -> oldValue,
                            LinkedHashMap::new
                    ));
            case LIST_VALUE -> protobufValue.getListValue().getValuesList().stream()
                    .map(ProtobufUtil::convertProtobufValueToJavaObject) // Use static method reference
                    .collect(Collectors.toList());
            default -> {
                logger.warn("Unsupported Protobuf Value type: {}. Returning null.", protobufValue.getKindCase());
                yield null;
            }
        };
    }
}