Base Implementation: Parse the upload date of StreamInfoItems

In the format '2 days ago' (in English) on a YouTube channel page.
(Parser extensible to other pages.)

extractor/src/main/java/org/schabi/newpipe/extractor/StreamingService.java

@@ -17,6 +17,7 @@ import org.schabi.newpipe.extractor.linkhandler.SearchQueryHandlerFactory;
 import org.schabi.newpipe.extractor.playlist.PlaylistExtractor;
 import org.schabi.newpipe.extractor.search.SearchExtractor;
 import org.schabi.newpipe.extractor.stream.StreamExtractor;
+import org.schabi.newpipe.extractor.stream.TimeAgoParser;
 import org.schabi.newpipe.extractor.subscription.SubscriptionExtractor;
 import org.schabi.newpipe.extractor.utils.Localization;
 
@@ -222,7 +223,7 @@ public abstract class StreamingService {
     public ChannelExtractor getChannelExtractor(ListLinkHandler linkHandler) throws ExtractionException {
         return getChannelExtractor(linkHandler, NewPipe.getPreferredLocalization());
     }
-    
+
     public PlaylistExtractor getPlaylistExtractor(ListLinkHandler linkHandler) throws ExtractionException {
         return getPlaylistExtractor(linkHandler, NewPipe.getPreferredLocalization());
     }
@@ -230,7 +231,7 @@ public abstract class StreamingService {
     public StreamExtractor getStreamExtractor(LinkHandler linkHandler) throws ExtractionException {
         return getStreamExtractor(linkHandler, NewPipe.getPreferredLocalization());
     }
-    
+
     public CommentsExtractor getCommentsExtractor(ListLinkHandler urlIdHandler) throws ExtractionException {
         return getCommentsExtractor(urlIdHandler, NewPipe.getPreferredLocalization());
     }
@@ -287,7 +288,7 @@ public abstract class StreamingService {
     public StreamExtractor getStreamExtractor(String url) throws ExtractionException {
         return getStreamExtractor(getStreamLHFactory().fromUrl(url), NewPipe.getPreferredLocalization());
     }
-    
+
     public CommentsExtractor getCommentsExtractor(String url) throws ExtractionException {
         ListLinkHandlerFactory llhf = getCommentsLHFactory();
         if(null == llhf) {
@@ -296,6 +297,9 @@ public abstract class StreamingService {
         return getCommentsExtractor(llhf.fromUrl(url), NewPipe.getPreferredLocalization());
     }
 
+    public TimeAgoParser getTimeAgoParser() {
+        return new TimeAgoParser(TimeAgoParser.DEFAULT_AGO_PHRASES);
+    }
 
     /**
      * Figures out where the link is pointing to (a channel, a video, a playlist, etc.)

extractor/src/main/java/org/schabi/newpipe/extractor/services/soundcloud/SoundcloudParsingHelper.java

@@ -79,23 +79,22 @@ public class SoundcloudParsingHelper {
         return dl.head(apiUrl).getResponseCode() == 200;
     }
 
-    public static String toDateString(String time) throws ParsingException {
+    static Date parseDate(String time) throws ParsingException {
         try {
-            Date date;
+            return new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'").parse(time);
-            // Have two date formats, one for the 'api.soundc...' and the other 'api-v2.soundc...'.
+        } catch (ParseException e1) {
             try {
-                date = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'").parse(time);
+                return new SimpleDateFormat("yyyy/MM/dd HH:mm:ss +0000").parse(time);
-            } catch (Exception e) {
+            } catch (ParseException e2) {
-                date = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss +0000").parse(time);
+                throw new ParsingException(e1.getMessage(), e2);
             }
-
-            SimpleDateFormat newDateFormat = new SimpleDateFormat("yyyy-MM-dd");
-            return newDateFormat.format(date);
-        } catch (ParseException e) {
-            throw new ParsingException(e.getMessage(), e);
         }
     }
 
+    static String toTextualDate(String time) throws ParsingException {
+        return new SimpleDateFormat("yyyy-MM-dd").format(parseDate(time));
+    }
+
     /**
      * Call the endpoint "/resolve" of the api.<p>
      * 

extractor/src/main/java/org/schabi/newpipe/extractor/services/soundcloud/SoundcloudStreamExtractor.java

@@ -51,7 +51,7 @@ public class SoundcloudStreamExtractor extends StreamExtractor {
     @Nonnull
     @Override
     public String getUploadDate() throws ParsingException {
-        return SoundcloudParsingHelper.toDateString(track.getString("created_at"));
+        return SoundcloudParsingHelper.toTextualDate(track.getString("created_at"));
     }
 
     @Nonnull

extractor/src/main/java/org/schabi/newpipe/extractor/services/soundcloud/SoundcloudStreamInfoItemExtractor.java

@@ -5,6 +5,8 @@ import org.schabi.newpipe.extractor.exceptions.ParsingException;
 import org.schabi.newpipe.extractor.stream.StreamInfoItemExtractor;
 import org.schabi.newpipe.extractor.stream.StreamType;
 
+import java.util.Calendar;
+
 import static org.schabi.newpipe.extractor.utils.Utils.replaceHttpWithHttps;
 
 public class SoundcloudStreamInfoItemExtractor implements StreamInfoItemExtractor {
@@ -41,8 +43,19 @@ public class SoundcloudStreamInfoItemExtractor implements StreamInfoItemExtracto
     }
 
     @Override
-    public String getUploadDate() throws ParsingException {
+    public String getTextualUploadDate() throws ParsingException {
-        return SoundcloudParsingHelper.toDateString(itemObject.getString("created_at"));
+        return SoundcloudParsingHelper.toTextualDate(getCreatedAt());
+    }
+
+    @Override
+    public Calendar getUploadDate() throws ParsingException {
+        Calendar uploadTime = Calendar.getInstance();
+        uploadTime.setTime(SoundcloudParsingHelper.parseDate(getCreatedAt()));
+        return uploadTime;
+    }
+
+    private String getCreatedAt() {
+        return itemObject.getString("created_at");
     }
 
     @Override

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeChannelExtractor.java

@@ -18,6 +18,7 @@ import org.schabi.newpipe.extractor.linkhandler.ListLinkHandler;
 import org.schabi.newpipe.extractor.services.youtube.linkHandler.YoutubeParsingHelper;
 import org.schabi.newpipe.extractor.stream.StreamInfoItem;
 import org.schabi.newpipe.extractor.stream.StreamInfoItemsCollector;
+import org.schabi.newpipe.extractor.stream.TimeAgoParser;
 import org.schabi.newpipe.extractor.utils.DonationLinkHelper;
 import org.schabi.newpipe.extractor.utils.Localization;
 import org.schabi.newpipe.extractor.utils.Parser;
@@ -53,6 +54,8 @@ public class YoutubeChannelExtractor extends ChannelExtractor {
     private static final String CHANNEL_FEED_BASE = "https://www.youtube.com/feeds/videos.xml?channel_id=";
     private static final String CHANNEL_URL_PARAMETERS = "/videos?view=0&flow=list&sort=dd&live_view=10000&gl=US&hl=en";
 
+    private final TimeAgoParser timeAgoParser = getService().getTimeAgoParser();
+
     private Document doc;
 
     public YoutubeChannelExtractor(StreamingService service, ListLinkHandler linkHandler, Localization localization) {
@@ -230,7 +233,7 @@ public class YoutubeChannelExtractor extends ChannelExtractor {
         final String uploaderUrl = getUrl();
         for (final Element li : element.children()) {
             if (li.select("div[class=\"feed-item-dismissable\"]").first() != null) {
-                collector.commit(new YoutubeStreamInfoItemExtractor(li) {
+                collector.commit(new YoutubeStreamInfoItemExtractor(li, timeAgoParser) {
                     @Override
                     public String getUrl() throws ParsingException {
                         try {

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubePlaylistExtractor.java

@@ -18,6 +18,7 @@ import org.schabi.newpipe.extractor.services.youtube.linkHandler.YoutubeParsingH
 import org.schabi.newpipe.extractor.stream.StreamInfoItem;
 import org.schabi.newpipe.extractor.stream.StreamInfoItemsCollector;
 import org.schabi.newpipe.extractor.stream.StreamType;
+import org.schabi.newpipe.extractor.stream.TimeAgoParser;
 import org.schabi.newpipe.extractor.utils.Localization;
 import org.schabi.newpipe.extractor.utils.Utils;
 
@@ -28,6 +29,8 @@ import java.io.IOException;
 @SuppressWarnings("WeakerAccess")
 public class YoutubePlaylistExtractor extends PlaylistExtractor {
 
+    private final TimeAgoParser timeAgoParser = getService().getTimeAgoParser();
+
     private Document doc;
 
     public YoutubePlaylistExtractor(StreamingService service, ListLinkHandler linkHandler, Localization localization) {
@@ -192,7 +195,7 @@ public class YoutubePlaylistExtractor extends PlaylistExtractor {
                 continue;
             }
 
-            collector.commit(new YoutubeStreamInfoItemExtractor(li) {
+            collector.commit(new YoutubeStreamInfoItemExtractor(li, timeAgoParser) {
                 public Element uploaderLink;
 
                 @Override
@@ -258,7 +261,7 @@ public class YoutubePlaylistExtractor extends PlaylistExtractor {
                 }
 
                 @Override
-                public String getUploadDate() throws ParsingException {
+                public String getTextualUploadDate() throws ParsingException {
                     return "";
                 }
 

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeSearchExtractor.java

@@ -9,6 +9,7 @@ import org.schabi.newpipe.extractor.InfoItem;
 import org.schabi.newpipe.extractor.StreamingService;
 import org.schabi.newpipe.extractor.exceptions.ExtractionException;
 import org.schabi.newpipe.extractor.exceptions.ParsingException;
+import org.schabi.newpipe.extractor.linkhandler.SearchQueryHandler;
 import org.schabi.newpipe.extractor.search.InfoItemsSearchCollector;
 import org.schabi.newpipe.extractor.search.SearchExtractor;
 import org.schabi.newpipe.extractor.linkhandler.SearchQueryHandler;
@@ -129,7 +130,7 @@ public class YoutubeSearchExtractor extends SearchExtractor {
 
                 // video item type
             } else if ((el = item.select("div[class*=\"yt-lockup-video\"]").first()) != null) {
-                collector.commit(new YoutubeStreamInfoItemExtractor(el));
+                collector.commit(new YoutubeStreamInfoItemExtractor(el, getService().getTimeAgoParser()));
             } else if ((el = item.select("div[class*=\"yt-lockup-channel\"]").first()) != null) {
                 collector.commit(new YoutubeChannelInfoItemExtractor(el));
             } else if ((el = item.select("div[class*=\"yt-lockup-playlist\"]").first()) != null &&

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeStreamExtractor.java

@@ -75,6 +75,8 @@ public class YoutubeStreamExtractor extends StreamExtractor {
 
     /*//////////////////////////////////////////////////////////////////////////*/
 
+    private final TimeAgoParser timeAgoParser = getService().getTimeAgoParser();
+
     private Document doc;
     @Nullable
     private JsonObject playerArgs;
@@ -932,7 +934,7 @@ public class YoutubeStreamExtractor extends StreamExtractor {
      * This is encapsulated in a StreamInfoItem object, which is a subset of the fields in a full StreamInfo.
      */
     private StreamInfoItemExtractor extractVideoPreviewInfo(final Element li) {
-        return new YoutubeStreamInfoItemExtractor(li) {
+        return new YoutubeStreamInfoItemExtractor(li, timeAgoParser) {
 
             @Override
             public String getUrl() throws ParsingException {
@@ -959,7 +961,7 @@ public class YoutubeStreamExtractor extends StreamExtractor {
             }
 
             @Override
-            public String getUploadDate() throws ParsingException {
+            public String getTextualUploadDate() throws ParsingException {
                 return "";
             }
 

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeStreamInfoItemExtractor.java

@@ -1,12 +1,17 @@
 package org.schabi.newpipe.extractor.services.youtube.extractors;
 
 import org.jsoup.nodes.Element;
+import org.jsoup.select.Elements;
 import org.schabi.newpipe.extractor.exceptions.ParsingException;
 import org.schabi.newpipe.extractor.services.youtube.linkHandler.YoutubeParsingHelper;
 import org.schabi.newpipe.extractor.stream.StreamInfoItemExtractor;
 import org.schabi.newpipe.extractor.stream.StreamType;
+import org.schabi.newpipe.extractor.stream.TimeAgoParser;
 import org.schabi.newpipe.extractor.utils.Utils;
 
+import javax.annotation.Nullable;
+import java.util.Calendar;
+
 /*
  * Copyright (C) Christian Schabesberger 2016 <chris.schabesberger@mailbox.org>
  * YoutubeStreamInfoItemExtractor.java is part of NewPipe.
@@ -28,9 +33,18 @@ import org.schabi.newpipe.extractor.utils.Utils;
 public class YoutubeStreamInfoItemExtractor implements StreamInfoItemExtractor {
 
     private final Element item;
+    private final TimeAgoParser timeAgoParser;
 
-    public YoutubeStreamInfoItemExtractor(Element item) {
+    private String cachedUploadDate;
+
+    /**
+     * Creates an extractor of StreamInfoItems from a YouTube page.
+     * @param item          The page element
+     * @param timeAgoParser A parser of the textual dates or {@code null}.
+     */
+    public YoutubeStreamInfoItemExtractor(Element item, @Nullable TimeAgoParser timeAgoParser) {
         this.item = item;
+        this.timeAgoParser = timeAgoParser;
     }
 
     @Override
@@ -126,20 +140,35 @@ public class YoutubeStreamInfoItemExtractor implements StreamInfoItemExtractor {
     }
 
     @Override
-    public String getUploadDate() throws ParsingException {
+    public String getTextualUploadDate() throws ParsingException {
+        if (cachedUploadDate != null) {
+            return cachedUploadDate;
+        }
+
         try {
             Element meta = item.select("div[class=\"yt-lockup-meta\"]").first();
             if (meta == null) return "";
 
-            Element li = meta.select("li").first();
+            final Elements li = meta.select("li");
-            if(li == null) return "";
+            if (li.isEmpty()) return "";
 
-            return meta.select("li").first().text();
+            return cachedUploadDate = li.first().text();
         } catch (Exception e) {
             throw new ParsingException("Could not get upload date", e);
         }
     }
 
+    @Override
+    public Calendar getUploadDate() throws ParsingException {
+        String textualUploadDate = getTextualUploadDate();
+        if (timeAgoParser != null
+                && textualUploadDate != null && !"".equals(textualUploadDate)) {
+            return timeAgoParser.parse(textualUploadDate);
+        } else {
+            return null;
+        }
+    }
+
     @Override
     public long getViewCount() throws ParsingException {
         String input;

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeTrendingExtractor.java

@@ -35,12 +35,15 @@ import org.schabi.newpipe.extractor.services.youtube.linkHandler.YoutubeParsingH
 import org.schabi.newpipe.extractor.stream.StreamInfoItem;
 import org.schabi.newpipe.extractor.stream.StreamInfoItemsCollector;
 import org.schabi.newpipe.extractor.utils.Localization;
+import org.schabi.newpipe.extractor.stream.TimeAgoParser;
 
 import javax.annotation.Nonnull;
 import java.io.IOException;
 
 public class YoutubeTrendingExtractor extends KioskExtractor<StreamInfoItem> {
 
+    private final TimeAgoParser timeAgoParser = getService().getTimeAgoParser();
+
     private Document doc;
 
     public YoutubeTrendingExtractor(StreamingService service,
@@ -93,7 +96,7 @@ public class YoutubeTrendingExtractor extends KioskExtractor<StreamInfoItem> {
         for(Element ul : uls) {
             for(final Element li : ul.children()) {
                 final Element el = li.select("div[class*=\"yt-lockup-dismissable\"]").first();
-                collector.commit(new YoutubeStreamInfoItemExtractor(li) {
+                collector.commit(new YoutubeStreamInfoItemExtractor(li, timeAgoParser) {
                     @Override
                     public String getUrl() throws ParsingException {
                         try {

extractor/src/main/java/org/schabi/newpipe/extractor/stream/StreamInfoItem.java

@@ -22,6 +22,8 @@ package org.schabi.newpipe.extractor.stream;
 
 import org.schabi.newpipe.extractor.InfoItem;
 
+import java.util.Calendar;
+
 /**
  * Info object for previews of unopened videos, eg search results, related videos
  */
@@ -29,7 +31,8 @@ public class StreamInfoItem extends InfoItem {
     private final StreamType streamType;
 
     private String uploaderName;
-    private String uploadDate;
+    private String textualUploadDate;
+    private Calendar uploadDate;
     private long viewCount = -1;
     private long duration = -1;
 
@@ -52,14 +55,6 @@ public class StreamInfoItem extends InfoItem {
         this.uploaderName = uploader_name;
     }
 
-    public String getUploadDate() {
-        return uploadDate;
-    }
-
-    public void setUploadDate(String upload_date) {
-        this.uploadDate = upload_date;
-    }
-
     public long getViewCount() {
         return viewCount;
     }
@@ -84,12 +79,36 @@ public class StreamInfoItem extends InfoItem {
         this.uploaderUrl = uploaderUrl;
     }
 
+    /**
+     * @return The original textual upload date as returned by the streaming service.
+     * @see #getUploadDate()
+     */
+    public String getTextualUploadDate() {
+        return textualUploadDate;
+    }
+
+    public void setTextualUploadDate(String upload_date) {
+        this.textualUploadDate = upload_date;
+    }
+
+    /**
+     * @return The (approximated) date and time this item was uploaded or {@code null}.
+     * @see #getTextualUploadDate()
+     */
+    public Calendar getUploadDate() {
+        return uploadDate;
+    }
+
+    public void setUploadDate(Calendar uploadDate) {
+        this.uploadDate = uploadDate;
+    }
+
     @Override
     public String toString() {
         return "StreamInfoItem{" +
                 "streamType=" + streamType +
                 ", uploaderName='" + uploaderName + '\'' +
-                ", uploadDate='" + uploadDate + '\'' +
+                ", textualUploadDate='" + textualUploadDate + '\'' +
                 ", viewCount=" + viewCount +
                 ", duration=" + duration +
                 ", uploaderUrl='" + uploaderUrl + '\'' +

extractor/src/main/java/org/schabi/newpipe/extractor/stream/StreamInfoItemExtractor.java

@@ -3,6 +3,8 @@ package org.schabi.newpipe.extractor.stream;
 import org.schabi.newpipe.extractor.InfoItemExtractor;
 import org.schabi.newpipe.extractor.exceptions.ParsingException;
 
+import java.util.Calendar;
+
 /*
  * Created by Christian Schabesberger on 28.02.16.
  *
@@ -64,10 +66,30 @@ public interface StreamInfoItemExtractor extends InfoItemExtractor {
     String getUploaderUrl() throws ParsingException;
 
     /**
-     * Extract the uploader name
+     * Extract the textual upload date of this item.
-     * @return the uploader name
+     * The original textual date provided by the service may be used if it is short;
-     * @throws ParsingException thrown if there is an error in the extraction
+     * otherwise the format "yyyy-MM-dd" or an locale specific version is preferred.
+     *
+     * @return The original textual upload date.
+     * @throws ParsingException if there is an error in the extraction
+     * @see #getUploadDate()
      */
-    String getUploadDate() throws ParsingException;
+    String getTextualUploadDate() throws ParsingException;
+
+    /**
+     * Extracts the upload date and time of this item and parses it.
+     * <p>
+     *     If the service doesn't provide an exact time, an approximation can be returned.
+     *     The approximation should be marked by setting seconds and milliseconds to zero.
+     *     <br>
+     *     If the service doesn't provide any date at all, then {@code null} should be returned.
+     * </p>
+     *
+     * @return The (approximated) date and time this item was uploaded or {@code null}.
+     * @throws ParsingException if there is an error in the extraction
+     *                          or the extracted date couldn't be parsed.
+     * @see #getTextualUploadDate()
+     */
+    Calendar getUploadDate() throws ParsingException;
 
 }

extractor/src/main/java/org/schabi/newpipe/extractor/stream/StreamInfoItemsCollector.java

@@ -61,10 +61,15 @@ public class StreamInfoItemsCollector extends InfoItemsCollector<StreamInfoItem,
             addError(e);
         }
         try {
-            resultItem.setUploadDate(extractor.getUploadDate());
+            resultItem.setTextualUploadDate(extractor.getTextualUploadDate());
         } catch (Exception e) {
             addError(e);
         }
+        try {
+            resultItem.setUploadDate(extractor.getUploadDate());
+        } catch (ParsingException e) {
+            addError(e);
+        }
         try {
             resultItem.setViewCount(extractor.getViewCount());
         } catch (Exception e) {

extractor/src/main/java/org/schabi/newpipe/extractor/stream/TimeAgoParser.java

@@ -0,0 +1,158 @@
+package org.schabi.newpipe.extractor.stream;
+
+/*
+ * Created by wojcik.online on 2018-01-25.
+ */
+
+import org.schabi.newpipe.extractor.exceptions.ParsingException;
+
+import java.util.Calendar;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.EnumMap;
+import java.util.Map;
+
+/**
+ * A helper class that is meant to be used by services that need to parse upload dates in the
+ * format '2 days ago' or similar.
+ */
+public class TimeAgoParser {
+
+    /**
+     * A set of english phrases that are contained in the time units.
+     * (e.g. '7 minutes ago' contains 'min')
+     */
+    public static Map<TimeAgoUnit, Collection<String>> DEFAULT_AGO_PHRASES =
+            new EnumMap<>(TimeAgoUnit.class);
+
+    private final Map<TimeAgoUnit, Collection<String>> agoPhrases;
+
+    private final Calendar consistentNow;
+
+    /**
+     * Creates a helper to parse upload dates in the format '2 days ago'.
+     * <p>
+     *     Instantiate a new {@link TimeAgoParser} every time you extract a new batch of items.
+     * </p>
+     * @param agoPhrases A set of phrases how to recognize the time units in a given language.
+     */
+    public TimeAgoParser(Map<TimeAgoUnit, Collection<String>> agoPhrases) {
+        this.agoPhrases = agoPhrases;
+        consistentNow = Calendar.getInstance();
+    }
+
+    /**
+     * Parses a textual date in the format '2 days ago' into a Calendar representation.
+     * Beginning with days ago, marks the date as approximated by setting minutes, seconds
+     * and milliseconds to 0.
+     * @param textualDate The original date as provided by the streaming service
+     * @return The parsed (approximated) time
+     * @throws ParsingException if the time unit could not be recognized
+     */
+    public Calendar parse(String textualDate) throws ParsingException {
+        int timeAgoAmount;
+        try {
+            timeAgoAmount = parseTimeAgoAmount(textualDate);
+        } catch (NumberFormatException e) {
+            // If there is no valid number in the textual date,
+            // assume it is 1 (as in 'a second ago').
+            timeAgoAmount = 1;
+        }
+
+        TimeAgoUnit timeAgoUnit = parseTimeAgoUnit(textualDate);
+        return getCalendar(timeAgoAmount, timeAgoUnit);
+    }
+
+    private int parseTimeAgoAmount(String textualDate) throws NumberFormatException {
+        String timeValueStr = textualDate.replaceAll("\\D+", "");
+        return Integer.parseInt(timeValueStr);
+    }
+
+    private TimeAgoUnit parseTimeAgoUnit(String textualDate) throws ParsingException {
+        for (TimeAgoUnit timeAgoUnit : agoPhrases.keySet()) {
+            for (String agoPhrase : agoPhrases.get(timeAgoUnit)) {
+                if (textualDate.toLowerCase().contains(agoPhrase.toLowerCase())){
+                    return timeAgoUnit;
+                }
+            }
+        }
+
+        throw new ParsingException("Unable to parse the date: " + textualDate);
+    }
+
+    private Calendar getCalendar(int timeAgoAmount, TimeAgoUnit timeAgoUnit) {
+        Calendar calendarTime = getNow();
+
+        switch (timeAgoUnit) {
+            case SECONDS:
+                calendarTime.add(Calendar.SECOND, -timeAgoAmount);
+                break;
+
+            case MINUTES:
+                calendarTime.add(Calendar.MINUTE, -timeAgoAmount);
+                break;
+
+            case HOURS:
+                calendarTime.add(Calendar.HOUR_OF_DAY, -timeAgoAmount);
+                break;
+
+            case DAYS:
+                calendarTime.add(Calendar.DAY_OF_MONTH, -timeAgoAmount);
+                markApproximatedTime(calendarTime);
+                break;
+
+            case WEEKS:
+                calendarTime.add(Calendar.WEEK_OF_YEAR, -timeAgoAmount);
+                markApproximatedTime(calendarTime);
+                break;
+
+            case MONTHS:
+                calendarTime.add(Calendar.MONTH, -timeAgoAmount);
+                markApproximatedTime(calendarTime);
+                break;
+
+            case YEARS:
+                calendarTime.add(Calendar.YEAR, -timeAgoAmount);
+                // Prevent `PrettyTime` from showing '12 months ago'.
+                calendarTime.add(Calendar.DAY_OF_MONTH, -1);
+                markApproximatedTime(calendarTime);
+                break;
+        }
+
+        return calendarTime;
+    }
+
+    private Calendar getNow() {
+        return (Calendar) consistentNow.clone();
+    }
+
+    /**
+     * Marks the time as approximated by setting minutes, seconds and milliseconds to 0.
+     * @param calendarTime Time to be marked as approximated
+     */
+    private void markApproximatedTime(Calendar calendarTime) {
+        calendarTime.set(Calendar.MINUTE, 0);
+        calendarTime.set(Calendar.SECOND, 0);
+        calendarTime.set(Calendar.MILLISECOND, 0);
+    }
+
+    static {
+        DEFAULT_AGO_PHRASES.put(TimeAgoUnit.SECONDS, Collections.singleton("sec"));
+        DEFAULT_AGO_PHRASES.put(TimeAgoUnit.MINUTES, Collections.singleton("min"));
+        DEFAULT_AGO_PHRASES.put(TimeAgoUnit.HOURS, Collections.singleton("hour"));
+        DEFAULT_AGO_PHRASES.put(TimeAgoUnit.DAYS, Collections.singleton("day"));
+        DEFAULT_AGO_PHRASES.put(TimeAgoUnit.WEEKS, Collections.singleton("week"));
+        DEFAULT_AGO_PHRASES.put(TimeAgoUnit.MONTHS, Collections.singleton("month"));
+        DEFAULT_AGO_PHRASES.put(TimeAgoUnit.YEARS, Collections.singleton("year"));
+    }
+
+    public enum TimeAgoUnit {
+        SECONDS,
+        MINUTES,
+        HOURS,
+        DAYS,
+        WEEKS,
+        MONTHS,
+        YEARS,
+    }
+}

extractor/src/test/java/org/schabi/newpipe/Downloader.java

@@ -41,6 +41,7 @@ import static java.util.Collections.singletonList;
 public class Downloader implements org.schabi.newpipe.extractor.Downloader {
 
     private static final String USER_AGENT = "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:43.0) Gecko/20100101 Firefox/43.0";
+    private static final String DEFAULT_HTTP_ACCEPT_LANGUAGE = "en";
     private static String mCookies = "";
 
     private static Downloader instance = null;
@@ -171,6 +172,7 @@ public class Downloader implements org.schabi.newpipe.extractor.Downloader {
         URL url = new URL(siteUrl);
         HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
         // HttpsURLConnection con = NetCipher.getHttpsURLConnection(url);
+        con.setRequestProperty("Accept-Language", DEFAULT_HTTP_ACCEPT_LANGUAGE);
         return dl(con);
     }
 

extractor/src/test/java/org/schabi/newpipe/extractor/services/DefaultTests.java

@@ -4,6 +4,7 @@ import org.schabi.newpipe.extractor.InfoItem;
 import org.schabi.newpipe.extractor.ListExtractor;
 import org.schabi.newpipe.extractor.stream.StreamInfoItem;
 
+import java.util.Calendar;
 import java.util.List;
 
 import static org.junit.Assert.*;
@@ -27,6 +28,14 @@ public final class DefaultTests {
                 StreamInfoItem streamInfoItem = (StreamInfoItem) item;
                 assertNotEmpty("Uploader name not set: " + item, streamInfoItem.getUploaderName());
                 assertNotEmpty("Uploader url not set: " + item, streamInfoItem.getUploaderUrl());
+
+                final String textualUploadDate = streamInfoItem.getTextualUploadDate();
+                if (textualUploadDate != null && !textualUploadDate.isEmpty()) {
+                    final Calendar uploadDate = streamInfoItem.getUploadDate();
+                    assertNotNull("No parsed upload date", uploadDate);
+                    assertTrue("Upload date not in the past", uploadDate.before(Calendar.getInstance()));
+                }
+
             }
         }
     }