/*
 * Copyright (c) 2019, 2020 Oracle and/or its affiliates. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.fnproject.fn.runtime.testfns.coercions;

import com.fnproject.fn.api.*;
import org.apache.commons.io.IOUtils;

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.Optional;

public class StringReversalCoercion implements InputCoercion<String>, OutputCoercion {
    @Override
    public Optional<String> tryCoerceParam(InvocationContext currentContext, int arg, InputEvent input, MethodWrapper methodWrapper) {
        return Optional.of(
                input.consumeBody(is -> {
                    try {
                        return new StringBuffer(IOUtils.toString(is, StandardCharsets.UTF_8)).reverse().toString();
                    } catch (IOException e) {
                        return null; // Tests will fail if we end up here
                    }
                })
        );
    }

    @Override
    public Optional<OutputEvent> wrapFunctionResult(InvocationContext ctx, MethodWrapper method, Object value) {
        if (ctx.getRuntimeContext().getMethod().getTargetMethod().getReturnType().equals(String.class)) {
            try {
                String reversedOutput = new StringBuffer((String) value).reverse().toString();
                return Optional.of(OutputEvent.fromBytes(reversedOutput.getBytes(), OutputEvent.Status.Success, "text/plain"));
            } catch (ClassCastException e) {
                return Optional.empty();
            }
        } else {
            return Optional.empty();
        }
    }
}
