/*
 * This file is a part of the SteamWar software.
 *
 * Copyright (C) 2023  SteamWar.de-Serverteam
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

package de.steamwar.command;

import java.lang.annotation.*;
import java.lang.reflect.Method;
import java.lang.reflect.Parameter;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.Optional;
import java.util.function.Function;

public interface Handler {

    default Optional<Class<?>> getGenericTypeOfReturn(Method method) {
        Type type;
        try {
            type = method.getGenericReturnType();
        } catch (Exception e) {
            return Optional.empty();
        }
        if (!(type instanceof ParameterizedType)) {
            return Optional.empty();
        }
        ParameterizedType parameterizedType = (ParameterizedType) type;
        Type[] generics = parameterizedType.getActualTypeArguments();
        if (generics.length != 1 && generics.length != 2) {
            return Optional.empty();
        }
        Type genericType = generics[generics.length - 1];
        try {
            return Optional.of(Class.forName(genericType.getTypeName()));
        } catch (Exception e) {
            return Optional.empty();
        }
    }

    @Retention(RetentionPolicy.RUNTIME)
    @Target(ElementType.ANNOTATION_TYPE)
    @interface Implementation {
        Class<? extends Handler> value();
    }

    interface DataCheckable {
        boolean hasExecutorMapper(Class<?> clazz);
        boolean hasMapper(String key);
        boolean hasValidator(String key);
        boolean hasSupplier(String key);
    }

    interface DataReadable {
        Function<?, ?> getExecutorMapper(Class<?> clazz);
        <A, B> AbstractTypeMapper<A, B> getMapper(String key);
        <A, B> AbstractTypeValidator<A, B> getValidator(String key);
        <A, B> AbstractTypeSupplier<A, B> getSupplier(String key);
    }

    interface DataWritable {
        Function<?, ?> getExecutorMapper(Class<?> clazz);

        <A, B> void addMapper(String key, boolean local, AbstractTypeMapper<A, B> mapper);
        <A, B> void addValidator(String key, boolean local, AbstractTypeValidator<A, B> validator);
        <A, B> void addSupplier(String key, boolean local, AbstractTypeSupplier<A, B> supplier);
        /**
         * Invoking the same method twice will result in the exact same result.
         */
        <T> T invoke(Method method);
        void addCommand(Method method, String[] subCommand, String[] description, boolean noTabComplete);
    }

    interface HandlerMethod<T extends Annotation> extends Handler {
        void check(T annotation, Method method, DataCheckable dataCheckable) throws Exception;

        int getRunPriority();

        void run(T annotation, Method method, DataWritable dataWritable);
    }

    interface HandlerParameter<T extends Annotation, A, B> extends Handler {
        void check(T annotation, Parameter parameter, int index, DataCheckable dataCheckable) throws Exception;

        default boolean needsParentTypeMapper() {
            return false;
        }

        /**
         * Null values are allowed to be returned.
         */
        default AbstractTypeMapper<A, B> getTypeMapper(T annotation, Parameter parameter, int index, DataReadable dataReadable, AbstractTypeMapper<A, B> parentTypeMapper) {
            return null;
        }

        default int getValidatorPriority() {
            return 0;
        }

        /**
         * Null values are allowed to be returned.
         */
        default AbstractTypeValidator<A, B> getValidator(T annotation, Parameter parameter, int index, DataReadable dataReadable) {
            return null;
        }
    }
}