package emu.grasscutter.utils;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonElement;
import com.google.gson.JsonSyntaxException;
import com.google.gson.TypeAdapter;
import com.google.gson.reflect.TypeToken;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;

import emu.grasscutter.data.common.DynamicFloat;
import lombok.val;

public final class JsonUtils {
    // Adapters
    static class DynamicFloatAdapter extends TypeAdapter<DynamicFloat> {
        @Override
        public DynamicFloat read(JsonReader reader) throws IOException {
            switch (reader.peek()) {
                case STRING:
                    return new DynamicFloat(reader.nextString());
                case NUMBER:
                    return new DynamicFloat((float) reader.nextDouble());
                case BEGIN_ARRAY:
                    reader.beginArray();
                    val opStack = new ArrayList<DynamicFloat.StackOp>();
                    while (reader.hasNext()) {
                        opStack.add(switch (reader.peek()) {
                            case STRING -> new DynamicFloat.StackOp(reader.nextString());
                            case NUMBER -> new DynamicFloat.StackOp((float) reader.nextDouble());
                            default -> throw new IOException("Invalid DynamicFloat definition - " + reader.peek().name());
                        });
                    }
                    reader.endArray();
                    return new DynamicFloat(opStack);
                default:
                    throw new IOException("Invalid DynamicFloat definition - " + reader.peek().name());
            }
        }

        @Override
        public void write(JsonWriter writer, DynamicFloat f) {};
    }

    static final Gson gson = new GsonBuilder()
        .setPrettyPrinting()
        .registerTypeAdapter(DynamicFloat.class, new DynamicFloatAdapter())
        .create();

    /*
     * Encode an object to a JSON string
     */
    public static String encode(Object object) {
        return gson.toJson(object);
    }

    public static <T> T decode(JsonElement jsonElement, Class<T> classType) throws JsonSyntaxException {
        return gson.fromJson(jsonElement, classType);
    }

    public static <T> T loadToClass(Reader fileReader, Class<T> classType) throws IOException {
        return gson.fromJson(fileReader, classType);
    }

    @Deprecated(forRemoval = true)
    public static <T> T loadToClass(String filename, Class<T> classType) throws IOException {
        try (InputStreamReader fileReader = new InputStreamReader(new FileInputStream(Utils.toFilePath(filename)), StandardCharsets.UTF_8)) {
            return loadToClass(fileReader, classType);
        }
    }

    public static <T> T loadToClass(Path filename, Class<T> classType) throws IOException {
        try (var fileReader = Files.newBufferedReader(filename, StandardCharsets.UTF_8)) {
            return loadToClass(fileReader, classType);
        }
    }

    public static <T> List<T> loadToList(Reader fileReader, Class<T> classType) throws IOException {
        return gson.fromJson(fileReader, TypeToken.getParameterized(List.class, classType).getType());
    }

    @Deprecated(forRemoval = true)
    public static <T> List<T> loadToList(String filename, Class<T> classType) throws IOException {
        try (InputStreamReader fileReader = new InputStreamReader(new FileInputStream(Utils.toFilePath(filename)), StandardCharsets.UTF_8)) {
            return loadToList(fileReader, classType);
        }
    }

    public static <T> List<T> loadToList(Path filename, Class<T> classType) throws IOException {
        try (var fileReader = Files.newBufferedReader(filename, StandardCharsets.UTF_8)) {
            return loadToList(fileReader, classType);
        }
    }

    public static <T1,T2> Map<T1,T2> loadToMap(Reader fileReader, Class<T1> keyType, Class<T2> valueType) throws IOException {
        return gson.fromJson(fileReader, TypeToken.getParameterized(Map.class, keyType, valueType).getType());
    }

    @Deprecated(forRemoval = true)
    public static <T1,T2> Map<T1,T2> loadToMap(String filename, Class<T1> keyType, Class<T2> valueType) throws IOException {
        try (InputStreamReader fileReader = new InputStreamReader(new FileInputStream(Utils.toFilePath(filename)), StandardCharsets.UTF_8)) {
            return loadToMap(fileReader, keyType, valueType);
        }
    }

    public static <T1,T2> Map<T1,T2> loadToMap(Path filename, Class<T1> keyType, Class<T2> valueType) throws IOException {
        try (var fileReader = Files.newBufferedReader(filename, StandardCharsets.UTF_8)) {
            return loadToMap(fileReader, keyType, valueType);
        }
    }

    /**
     * Safely JSON decodes a given string.
     * @param jsonData The JSON-encoded data.
     * @return JSON decoded data, or null if an exception occurred.
     */
    public static <T> T decode(String jsonData, Class<T> classType) {
        try {
            return gson.fromJson(jsonData, classType);
        } catch (Exception ignored) {
            return null;
        }
    }
}