/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.sling.cms.core.insights.impl.providers;

import java.io.StringReader;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.HashSet;
import java.util.Set;

import javax.json.Json;
import javax.json.JsonArray;
import javax.json.JsonObject;
import javax.json.JsonReader;

import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ByteArrayEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
import org.apache.sling.cms.core.insights.impl.BaseInsightProvider;
import org.apache.sling.cms.core.insights.impl.providers.HTMLValdiatorInsightProvider.Config;
import org.apache.sling.cms.i18n.I18NDictionary;
import org.apache.sling.cms.i18n.I18NProvider;
import org.apache.sling.cms.insights.Insight;
import org.apache.sling.cms.insights.InsightProvider;
import org.apache.sling.cms.insights.InsightRequest;
import org.apache.sling.cms.insights.Message;
import org.apache.sling.cms.insights.PageInsightRequest;
import org.osgi.service.component.annotations.Activate;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.Reference;
import org.osgi.service.metatype.annotations.AttributeDefinition;
import org.osgi.service.metatype.annotations.Designate;
import org.osgi.service.metatype.annotations.ObjectClassDefinition;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Component(service = InsightProvider.class, immediate = true)
@Designate(ocd = Config.class)
public class HTMLValdiatorInsightProvider extends BaseInsightProvider {

    public static final String I18N_KEY_HTMLVALIDATOR_DANGER = "There were {0} validation errors and {1} warnings";
    public static final String I18N_KEY_HTMLVALIDATOR_WARN = "There were {0} validation warnings";
    public static final String I18N_KEY_HTMLVALIDATOR_SUCCESS = "HTML Validation successful!";

    @ObjectClassDefinition(name = "%htmlvalidator.config.name", description = "%htmlvalidator.config.description", localization = "OSGI-INF/l10n/bundle")
    public @interface Config {
        @AttributeDefinition(name = "%htmlvalidator.param.enabled.name", description = "%htmlvalidator.param.enabled.description")
        boolean enabled() default true;
    }

    @Reference
    private I18NProvider i18nProvider;

    private static final Logger log = LoggerFactory.getLogger(HTMLValdiatorInsightProvider.class);

    private Config config;

    @Activate
    public void activate(Config config) {
        this.config = config;
    }

    @Override
    protected Insight doEvaluateRequest(InsightRequest request) throws Exception {
        Insight insight = new Insight(this, request);
        insight.setScored(true);
        PageInsightRequest pageRequest = (PageInsightRequest) request;

        String html = pageRequest.getPageHtml();

        HttpPost httpPost = new HttpPost("http://validator.w3.org/nu/?out=json&showsource=no&level=all");
        httpPost.addHeader("Content-type", "text/html; charset=utf-8");
        HttpEntity htmlEntity = new ByteArrayEntity(html.getBytes(StandardCharsets.UTF_8));
        httpPost.setEntity(htmlEntity);

        I18NDictionary dictionary = i18nProvider.getDictionary(request.getResource().getResourceResolver());

        CloseableHttpResponse response = null;
        JsonReader reader = null;
        try (CloseableHttpClient client = HttpClients.createDefault()) {
            response = client.execute(httpPost);
            HttpEntity entity = response.getEntity();
            reader = Json.createReader(new StringReader(EntityUtils.toString(entity)));
            JsonObject json = reader.readObject();
            log.debug("Loaded response: {}", json);
            JsonArray messages = json.getJsonArray("messages");
            int errors = 0;
            int warnings = 0;
            Set<String> msgSet = new HashSet<>();
            for (int i = 0; i < messages.size(); i++) {
                JsonObject message = messages.getJsonObject(i);
                if ("error".equals(message.getString("type"))) {
                    errors++;
                    String messageStr = message.getString("message");
                    if (!msgSet.contains(messageStr)) {
                        insight.addMessage(Message.danger(messageStr));
                        msgSet.add(messageStr);
                    }
                } else if ("info".equals(message.getString("type")) && message.containsKey("subtype")
                        && "warning".equals(message.getString("subtype"))) {
                    warnings++;
                    String messageStr = message.getString("message");
                    if (!msgSet.contains(messageStr)) {
                        insight.addMessage(Message.warn(messageStr));
                        msgSet.add(messageStr);
                    }
                }
            }
            updateInsight(insight, pageRequest, dictionary, errors, warnings);
        } finally {
            if (reader != null) {
                reader.close();
            }
        }

        return insight;
    }

    private void updateInsight(Insight insight, PageInsightRequest pageRequest, I18NDictionary dictionary, int errors,
            int warnings) throws UnsupportedEncodingException {
        double score;
        if (errors > 5) {
            insight.setPrimaryMessage(Message
                    .danger(dictionary.get(I18N_KEY_HTMLVALIDATOR_DANGER, new Object[] { errors, warnings })));
            score = 0.2;
        } else if (errors > 0) {
            insight.setPrimaryMessage(Message
                    .danger(dictionary.get(I18N_KEY_HTMLVALIDATOR_DANGER, new Object[] { errors, warnings })));
            score = 0.4;
        } else if (warnings > 5) {
            insight.setPrimaryMessage(
                    Message.warn(dictionary.get(I18N_KEY_HTMLVALIDATOR_WARN, new Object[] { warnings })));
            score = 0.6;
        } else if (warnings > 0) {
            insight.setPrimaryMessage(
                    Message.warn(dictionary.get(I18N_KEY_HTMLVALIDATOR_WARN, new Object[] { warnings })));
            score = 0.8;
        } else {
            insight.setPrimaryMessage(Message.success(dictionary.get(I18N_KEY_HTMLVALIDATOR_SUCCESS)));
            score = 1.0;
        }
        insight.setScore(score);
        insight.setMoreDetailsLink("https://validator.w3.org/nu/?doc="
                + URLEncoder.encode(pageRequest.getPage().getPublishedUrl(), StandardCharsets.UTF_8.toString()));
    }

    @Override
    public String getId() {
        return "htmlvalidator";
    }

    @Override
    public String getTitle() {
        return "HTML Validator";
    }

    @Override
    public boolean isEnabled(InsightRequest request) {
        if (!config.enabled()) {
            log.debug("HTML Validator is not enabled");
            return false;
        }
        if (request.getType() != InsightRequest.TYPE.PAGE) {
            log.debug("Request {} is not a page", request);
            return false;
        }
        return true;
    }

}