package com.commafeed.backend.feed;
import java.io.StringReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Arrays;
import java.util.Collections;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
import java.util.regex.Pattern;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.codec.binary.Base64;
import org.apache.commons.lang3.ArrayUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.time.DateUtils;
import org.apache.commons.math3.stat.descriptive.SummaryStatistics;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Document.OutputSettings;
import org.jsoup.nodes.Element;
import org.jsoup.nodes.Entities.EscapeMode;
import org.jsoup.safety.Cleaner;
import org.jsoup.safety.Whitelist;
import org.jsoup.select.Elements;
import org.mozilla.universalchardet.UniversalDetector;
import org.w3c.css.sac.InputSource;
import org.w3c.dom.css.CSSStyleDeclaration;
import com.commafeed.backend.feed.FeedEntryKeyword.Mode;
import com.commafeed.backend.model.FeedEntry;
import com.commafeed.backend.model.FeedSubscription;
import com.commafeed.frontend.model.Entry;
import com.google.common.collect.Lists;
import com.steadystate.css.parser.CSSOMParser;
import edu.uci.ics.crawler4j.url.URLCanonicalizer;
/**
* Utility methods related to feed handling
*
*/
@Slf4j
public class FeedUtils {
private static final String ESCAPED_QUESTION_MARK = Pattern.quote("?");
private static final List<String> ALLOWED_IFRAME_CSS_RULES = Arrays.asList("height", "width", "border");
private static final List<String> ALLOWED_IMG_CSS_RULES = Arrays.asList("display", "width", "height");
private static final char[] FORBIDDEN_CSS_RULE_CHARACTERS = new char[] { '(', ')' };
private static final Whitelist WHITELIST = buildWhiteList();
public static String truncate(String string, int length) {
if (string != null) {
string = string.substring(0, Math.min(length, string.length()));
}
return string;
}
private static synchronized Whitelist buildWhiteList() {
Whitelist whitelist = new Whitelist();
whitelist.addTags("a", "b", "blockquote", "br", "caption", "cite", "code", "col", "colgroup", "dd", "div", "dl", "dt", "em", "h1",
"h2", "h3", "h4", "h5", "h6", "i", "iframe", "img", "li", "ol", "p", "pre", "q", "small", "strike", "strong", "sub", "sup",
"table", "tbody", "td", "tfoot", "th", "thead", "tr", "u", "ul");
whitelist.addAttributes("div", "dir");
whitelist.addAttributes("pre", "dir");
whitelist.addAttributes("code", "dir");
whitelist.addAttributes("table", "dir");
whitelist.addAttributes("p", "dir");
whitelist.addAttributes("a", "href", "title");
whitelist.addAttributes("blockquote", "cite");
whitelist.addAttributes("col", "span", "width");
whitelist.addAttributes("colgroup", "span", "width");
whitelist.addAttributes("iframe", "src", "height", "width", "allowfullscreen", "frameborder", "style");
whitelist.addAttributes("img", "align", "alt", "height", "src", "title", "width", "style");
whitelist.addAttributes("ol", "start", "type");
whitelist.addAttributes("q", "cite");
whitelist.addAttributes("table", "border", "bordercolor", "summary", "width");
whitelist.addAttributes("td", "border", "bordercolor", "abbr", "axis", "colspan", "rowspan", "width");
whitelist.addAttributes("th", "border", "bordercolor", "abbr", "axis", "colspan", "rowspan", "scope", "width");
whitelist.addAttributes("ul", "type");
whitelist.addProtocols("a", "href", "ftp", "http", "https", "mailto");
whitelist.addProtocols("blockquote", "cite", "http", "https");
whitelist.addProtocols("img", "src", "http", "https");
whitelist.addProtocols("q", "cite", "http", "https");
whitelist.addEnforcedAttribute("a", "target", "_blank");
return whitelist;
}
/**
* Detect feed encoding by using the declared encoding in the xml processing instruction and by detecting the characters used in the
* feed
*
*/
public static String guessEncoding(byte[] bytes) {
String extracted = extractDeclaredEncoding(bytes);
if (StringUtils.startsWithIgnoreCase(extracted, "iso-8859-")) {
if (StringUtils.endsWith(extracted, "1") == false) {
return extracted;
}
} else if (StringUtils.startsWithIgnoreCase(extracted, "windows-")) {
return extracted;
}
return detectEncoding(bytes);
}
/**
* Detect encoding by analyzing characters in the array
*/
public static String detectEncoding(byte[] bytes) {
String DEFAULT_ENCODING = "UTF-8";
UniversalDetector detector = new UniversalDetector(null);
detector.handleData(bytes, 0, bytes.length);
detector.dataEnd();
String encoding = detector.getDetectedCharset();
detector.reset();
if (encoding == null) {
encoding = DEFAULT_ENCODING;
} else if (encoding.equalsIgnoreCase("ISO-8859-1")) {
encoding = "windows-1252";
}
return encoding;
}
public static String replaceHtmlEntitiesWithNumericEntities(String source) {
String result = source;
for (String entity : HtmlEntities.NUMERIC_MAPPING.keySet()) {
result = StringUtils.replace(result, entity, HtmlEntities.NUMERIC_MAPPING.get(entity));
}
return result;
}
/**
* Normalize the url. The resulting url is not meant to be fetched but rather used as a mean to identify a feed and avoid duplicates
*/
public static String normalizeURL(String url) {
if (url == null) {
return null;
}
String normalized = URLCanonicalizer.getCanonicalURL(url);
if (normalized == null) {
normalized = url;
}
// convert to lower case, the url probably won't work in some cases
// after that but we don't care we just want to compare urls to avoid
// duplicates
normalized = normalized.toLowerCase();
// store all urls as http
if (normalized.startsWith("https")) {
normalized = "http" + normalized.substring(5);
}
// remove the www. part
normalized = normalized.replace("//www.", "//");
// feedproxy redirects to feedburner
normalized = normalized.replace("feedproxy.google.com", "feeds.feedburner.com");
// feedburner feeds have a special treatment
if (normalized.split(ESCAPED_QUESTION_MARK)[0].contains("feedburner.com")) {
normalized = normalized.replace("feeds2.feedburner.com", "feeds.feedburner.com");
normalized = normalized.split(ESCAPED_QUESTION_MARK)[0];
normalized = StringUtils.removeEnd(normalized, "/");
}
return normalized;
}
/**
* Extract the declared encoding from the xml
*/
public static String extractDeclaredEncoding(byte[] bytes) {
int index = ArrayUtils.indexOf(bytes, (byte) '>');
if (index == -1) {
return null;
}
String pi = new String(ArrayUtils.subarray(bytes, 0, index + 1));
index = StringUtils.indexOf(pi, "encoding=\"");
if (index == -1) {
return null;
}
String encoding = pi.substring(index + 10, pi.length());
encoding = encoding.substring(0, encoding.indexOf('"'));
return encoding;
}
public static String handleContent(String content, String baseUri, boolean keepTextOnly) {
if (StringUtils.isNotBlank(content)) {
baseUri = StringUtils.trimToEmpty(baseUri);
Document dirty = Jsoup.parseBodyFragment(content, baseUri);
Cleaner cleaner = new Cleaner(WHITELIST);
Document clean = cleaner.clean(dirty);
for (Element e : clean.select("iframe[style]")) {
String style = e.attr("style");
String escaped = escapeIFrameCss(style);
e.attr("style", escaped);
}
for (Element e : clean.select("img[style]")) {
String style = e.attr("style");
String escaped = escapeImgCss(style);
e.attr("style", escaped);
}
clean.outputSettings(new OutputSettings().escapeMode(EscapeMode.base).prettyPrint(false));
Element body = clean.body();
if (keepTextOnly) {
content = body.text();
} else {
content = body.html();
}
}
return content;
}
public static String escapeIFrameCss(String orig) {
String rule = "";
CSSOMParser parser = new CSSOMParser();
try {
List<String> rules = Lists.newArrayList();
CSSStyleDeclaration decl = parser.parseStyleDeclaration(new InputSource(new StringReader(orig)));
for (int i = 0; i < decl.getLength(); i++) {
String property = decl.item(i);
String value = decl.getPropertyValue(property);
if (StringUtils.isBlank(property) || StringUtils.isBlank(value)) {
continue;
}
if (ALLOWED_IFRAME_CSS_RULES.contains(property) && StringUtils.containsNone(value, FORBIDDEN_CSS_RULE_CHARACTERS)) {
rules.add(property + ":" + decl.getPropertyValue(property) + ";");
}
}
rule = StringUtils.join(rules, "");
} catch (Exception e) {
log.error(e.getMessage(), e);
}
return rule;
}
public static String escapeImgCss(String orig) {
String rule = "";
CSSOMParser parser = new CSSOMParser();
try {
List<String> rules = Lists.newArrayList();
CSSStyleDeclaration decl = parser.parseStyleDeclaration(new InputSource(new StringReader(orig)));
for (int i = 0; i < decl.getLength(); i++) {
String property = decl.item(i);
String value = decl.getPropertyValue(property);
if (StringUtils.isBlank(property) || StringUtils.isBlank(value)) {
continue;
}
if (ALLOWED_IMG_CSS_RULES.contains(property) && StringUtils.containsNone(value, FORBIDDEN_CSS_RULE_CHARACTERS)) {
rules.add(property + ":" + decl.getPropertyValue(property) + ";");
}
}
rule = StringUtils.join(rules, "");
} catch (Exception e) {
log.error(e.getMessage(), e);
}
return rule;
}
public static boolean isRTL(FeedEntry entry) {
String text = entry.getContent().getContent();
if (StringUtils.isBlank(text)) {
text = entry.getContent().getTitle();
}
if (StringUtils.isBlank(text)) {
return false;
}
text = Jsoup.parse(text).text();
if (StringUtils.isBlank(text)) {
return false;
}
return EstimateDirection.isRTL(text);
}
public static String trimInvalidXmlCharacters(String xml) {
if (StringUtils.isBlank(xml)) {
return null;
}
StringBuilder sb = new StringBuilder();
boolean firstTagFound = false;
for (int i = 0; i < xml.length(); i++) {
char c = xml.charAt(i);
if (!firstTagFound) {
if (c == '<') {
firstTagFound = true;
} else {
continue;
}
}
if (c >= 32 || c == 9 || c == 10 || c == 13) {
if (!Character.isHighSurrogate(c) && !Character.isLowSurrogate(c)) {
sb.append(c);
}
}
}
return sb.toString();
}
/**
* When there was an error fetching the feed
*
*/
public static Date buildDisabledUntil(int errorCount) {
Date now = new Date();
int retriesBeforeDisable = 3;
if (errorCount >= retriesBeforeDisable) {
int disabledHours = errorCount - retriesBeforeDisable + 1;
disabledHours = Math.min(24 * 7, disabledHours);
return DateUtils.addHours(now, disabledHours);
}
return now;
}
/**
* When the feed was refreshed successfully
*/
public static Date buildDisabledUntil(Date publishedDate, Long averageEntryInterval, Date defaultRefreshInterval) {
Date now = new Date();
if (publishedDate == null) {
// feed with no entries, recheck in 24 hours
return DateUtils.addHours(now, 24);
} else if (publishedDate.before(DateUtils.addMonths(now, -1))) {
// older than a month, recheck in 24 hours
return DateUtils.addHours(now, 24);
} else if (publishedDate.before(DateUtils.addDays(now, -14))) {
// older than two weeks, recheck in 12 hours
return DateUtils.addHours(now, 12);
} else if (publishedDate.before(DateUtils.addDays(now, -7))) {
// older than a week, recheck in 6 hours
return DateUtils.addHours(now, 6);
} else if (averageEntryInterval != null) {
// use average time between entries to decide when to refresh next, divided by factor
int factor = 2;
// not more than 6 hours
long date = Math.min(DateUtils.addHours(now, 6).getTime(), now.getTime() + averageEntryInterval / factor);
// not less than default refresh interval
date = Math.max(defaultRefreshInterval.getTime(), date);
return new Date(date);
} else {
// unknown case, recheck in 24 hours
return DateUtils.addHours(now, 24);
}
}
public static Long averageTimeBetweenEntries(List<FeedEntry> entries) {
if (entries.isEmpty() || entries.size() == 1) {
return null;
}
List<Long> timestamps = getSortedTimestamps(entries);
SummaryStatistics stats = new SummaryStatistics();
for (int i = 0; i < timestamps.size() - 1; i++) {
long diff = Math.abs(timestamps.get(i) - timestamps.get(i + 1));
stats.addValue(diff);
}
return (long) stats.getMean();
}
public static List<Long> getSortedTimestamps(List<FeedEntry> entries) {
List<Long> timestamps = Lists.newArrayList();
for (FeedEntry entry : entries) {
timestamps.add(entry.getUpdated().getTime());
}
Collections.sort(timestamps);
Collections.reverse(timestamps);
return timestamps;
}
public static String removeTrailingSlash(String url) {
if (url.endsWith("/")) {
url = url.substring(0, url.length() - 1);
}
return url;
}
/**
*
* @param url
* the url of the entry
* @param feedLink
* the url of the feed as described in the feed
* @param feedUrl
* the url of the feed that we used to fetch the feed
* @return an absolute url pointing to the entry
*/
public static String toAbsoluteUrl(String url, String feedLink, String feedUrl) {
url = StringUtils.trimToNull(StringUtils.normalizeSpace(url));
if (url == null || url.startsWith("http")) {
return url;
}
String baseUrl = (feedLink == null || isRelative(feedLink)) ? feedUrl : feedLink;
if (baseUrl == null) {
return url;
}
String result = null;
try {
result = new URL(new URL(baseUrl), url).toString();
} catch (MalformedURLException e) {
log.debug("could not parse url : " + e.getMessage(), e);
result = url;
}
return result;
}
public static boolean isRelative(final String url) {
// the regex means "doesn't start with 'scheme://'"
if ((url != null) && (url.startsWith("/") == false) && (!url.matches("^\\w+\\:\\/\\/.*")) && !(url.startsWith("#"))) {
return true;
} else {
return false;
}
}
public static String getFaviconUrl(FeedSubscription subscription, String publicUrl) {
return removeTrailingSlash(publicUrl) + "/rest/feed/favicon/" + subscription.getId();
}
public static String proxyImages(String content, String publicUrl, boolean proxyImages) {
if (!proxyImages) {
return content;
}
if (StringUtils.isBlank(content)) {
return content;
}
Document doc = Jsoup.parse(content);
Elements elements = doc.select("img");
for (Element element : elements) {
String href = element.attr("src");
if (href != null) {
String proxy = removeTrailingSlash(publicUrl) + "/rest/server/proxy?u=" + imageProxyEncoder(href);
element.attr("src", proxy);
}
}
return doc.body().html();
}
public static String rot13(String msg) {
StringBuilder message = new StringBuilder();
for (char c : msg.toCharArray()) {
if (c >= 'a' && c <= 'm')
c += 13;
else if (c >= 'n' && c <= 'z')
c -= 13;
else if (c >= 'A' && c <= 'M')
c += 13;
else if (c >= 'N' && c <= 'Z')
c -= 13;
message.append(c);
}
return message.toString();
}
public static String imageProxyEncoder(String url) {
return Base64.encodeBase64String(rot13(url).getBytes());
}
public static String imageProxyDecoder(String code) {
return rot13(new String(Base64.decodeBase64(code)));
}
public static void removeUnwantedFromSearch(List<Entry> entries, List<FeedEntryKeyword> keywords) {
Iterator<Entry> it = entries.iterator();
while (it.hasNext()) {
Entry entry = it.next();
boolean keep = true;
for (FeedEntryKeyword keyword : keywords) {
String title = Jsoup.parse(entry.getTitle()).text();
String content = Jsoup.parse(entry.getContent()).text();
boolean condition = !StringUtils.containsIgnoreCase(content, keyword.getKeyword())
&& !StringUtils.containsIgnoreCase(title, keyword.getKeyword());
if (keyword.getMode() == Mode.EXCLUDE) {
condition = !condition;
}
if (condition) {
keep = false;
break;
}
}
if (!keep) {
it.remove();
}
}
}
}