/**
 * Copyright (C) the original author or authors.
 *
 * 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 ninja.template;

import java.io.IOException;
import java.io.OutputStream;

import ninja.Context;
import ninja.Result;
import ninja.utils.ResponseStreams;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.inject.Inject;
import com.google.inject.Singleton;

@Singleton
public class TemplateEngineJson implements TemplateEngine {

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

    private final ObjectMapper objectMapper;

    @Inject
    public TemplateEngineJson(ObjectMapper objectMapper) {
        
        this.objectMapper = objectMapper;
        
    }

    @Override
    public void invoke(Context context, Result result) {

        ResponseStreams responseStreams = context.finalizeHeaders(result);
        
        try (OutputStream outputStream  = responseStreams.getOutputStream()) {

            Class<?> jsonView = result.getJsonView();
            if (jsonView != null) {
                objectMapper.writerWithView(jsonView).writeValue(outputStream, result.getRenderable());
            } else {
                objectMapper.writeValue(outputStream, result.getRenderable());
            }

            
        } catch (IOException e) {

            logger.error("Error while rendering json", e);
        }
        

    }

    @Override
    public String getContentType() {
        return Result.APPLICATION_JSON;
    }

    @Override
    public String getSuffixOfTemplatingEngine() {
        // intentionally returns null...
        return null;
    }
}
