Merge pull request #1163 from AudricV/yt-fix_comments_extraction

[YouTube] Support new comments data

Author: AudricV

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/YoutubeDescriptionHelper.java

@@ -0,0 +1,316 @@
+package org.schabi.newpipe.extractor.services.youtube;
+
+import static org.schabi.newpipe.extractor.services.youtube.YoutubeParsingHelper.getUrlFromNavigationEndpoint;
+import static org.schabi.newpipe.extractor.utils.Utils.isNullOrEmpty;
+
+import com.grack.nanojson.JsonObject;
+
+import org.jsoup.nodes.Entities;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Stack;
+import java.util.function.Function;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+public final class YoutubeDescriptionHelper {
+
+    private YoutubeDescriptionHelper() {
+    }
+
+    private static final String LINK_CLOSE = "</a>";
+    private static final String STRIKETHROUGH_OPEN = "<s>";
+    private static final String STRIKETHROUGH_CLOSE = "</s>";
+    private static final String BOLD_OPEN = "<b>";
+    private static final String BOLD_CLOSE = "</b>";
+    private static final String ITALIC_OPEN = "<i>";
+    private static final String ITALIC_CLOSE = "</i>";
+
+    // special link chips (e.g. for YT videos, YT channels or social media accounts):
+    // (u00a0) u00a0 u00a0 [/•] u00a0 <link content> u00a0 u00a0
+    private static final Pattern LINK_CONTENT_CLEANER_REGEX
+            = Pattern.compile("(?s)^ +[/•] +(.*?) +$");
+
+    /**
+     * Can be a command run, or a style run.
+     */
+    static final class Run {
+        @Nonnull final String open;
+        @Nonnull final String close;
+        final int pos;
+        @Nullable final Function<String, String> transformContent;
+        int openPosInOutput = -1;
+
+        Run(
+                @Nonnull final String open,
+                @Nonnull final String close,
+                final int pos
+        ) {
+            this(open, close, pos, null);
+        }
+
+        Run(
+                @Nonnull final String open,
+                @Nonnull final String close,
+                final int pos,
+                @Nullable final Function<String, String> transformContent
+        ) {
+            this.open = open;
+            this.close = close;
+            this.pos = pos;
+            this.transformContent = transformContent;
+        }
+
+        public boolean sameOpen(@Nonnull final Run other) {
+            return open.equals(other.open);
+        }
+    }
+
+    /**
+     * Parse a video description in the new "attributed" format, which contains the entire visible
+     * plaintext ({@code content}) and an array of {@code commandRuns} and {@code styleRuns}.
+     * Returns the formatted content in HTML format, and escapes the text to make sure there are no
+     * XSS attacks.
+     *
+     * <p>
+     * {@code commandRuns} include the links and their range in the text, while {@code styleRuns}
+     * include the styling to apply to various ranges in the text.
+     * </p>
+     *
+     * @param attributedDescription the JSON object of the attributed description
+     * @return the parsed description, in HTML format, as a string
+     */
+    @Nullable
+    public static String attributedDescriptionToHtml(
+            @Nullable final JsonObject attributedDescription
+    ) {
+        if (isNullOrEmpty(attributedDescription)) {
+            return null;
+        }
+
+        final String content = attributedDescription.getString("content");
+        if (content == null) {
+            return null;
+        }
+
+        // all run pairs must always of length at least 1, or they should be discarded,
+        // otherwise various assumptions made in runsToHtml may fail
+        final List<Run> openers = new ArrayList<>();
+        final List<Run> closers = new ArrayList<>();
+        addAllCommandRuns(attributedDescription, openers, closers);
+        addAllStyleRuns(attributedDescription, openers, closers);
+
+        // Note that sorting this way might put closers with the same close position in the wrong
+        // order with respect to their openers, causing unnecessary closes and reopens. E.g.
+        // <b>b<i>b&i</i></b> is instead generated as <b>b<i>b&i</b></i><b></b> if the </b> is
+        // encountered before the </i>. Solving this wouldn't be difficult, thanks to stable sort,
+        // but would require additional sorting steps which would just make this slower for the
+        // general case where it's unlikely there are coincident closes.
+        Collections.sort(openers, Comparator.comparingInt(run -> run.pos));
+        Collections.sort(closers, Comparator.comparingInt(run -> run.pos));
+
+        return runsToHtml(openers, closers, content);
+    }
+
+    /**
+     * Applies the formatting specified by the intervals stored in {@code openers} and {@code
+     * closers} to {@code content} in order to obtain valid HTML even when intervals overlap. For
+     * example &lt;b&gt;b&lt;i&gt;b&i&lt;/b&gt;i&lt;/i&gt; would not be valid HTML, so this function
+     * instead generates &lt;b&gt;b&lt;i&gt;b&i&lt;/i&gt;&lt;/b&gt;&lt;i&gt;i&lt;/i&gt;. Any HTML
+     * special characters in {@code rawContent} are escaped to make sure there are no XSS attacks.
+     *
+     * <p>
+     * Every opener in {@code openers} must have a corresponding closer in {@code closers}. Every
+     * corresponding (opener, closer) pair must have a length of at least one (i.e. empty intervals
+     * are not allowed).
+     * </p>
+     *
+     * @param openers    contains all of the places where a run begins, must have the same size of
+     *                   closers, must be ordered by {@link Run#pos}
+     * @param closers    contains all of the places where a run ends, must have the same size of
+     *                   openers, must be ordered by {@link Run#pos}
+     * @param rawContent the content to apply formatting to, and to escape to avoid XSS
+     * @return the formatted content in HTML
+     */
+    static String runsToHtml(
+            @Nonnull final List<Run> openers,
+            @Nonnull final List<Run> closers,
+            @Nonnull final String rawContent
+    ) {
+        final String content = rawContent.replace('\u00a0', ' ');
+        final Stack<Run> openRuns = new Stack<>();
+        final Stack<Run> tempStack = new Stack<>();
+        final StringBuilder textBuilder = new StringBuilder();
+        int currentTextPos = 0;
+        int openersIndex = 0;
+        int closersIndex = 0;
+
+        // openers and closers have the same length, but we will surely finish openers earlier than
+        // closers, since every opened interval needs to be closed at some point and there can't be
+        // empty intervals, hence check only closersIndex < closers.size()
+        while (closersIndex < closers.size()) {
+            final int minPos = openersIndex < openers.size()
+                    ? Math.min(closers.get(closersIndex).pos, openers.get(openersIndex).pos)
+                    : closers.get(closersIndex).pos;
+
+            // append piece of text until current index
+            textBuilder.append(Entities.escape(content.substring(currentTextPos, minPos)));
+            currentTextPos = minPos;
+
+            if (closers.get(closersIndex).pos == minPos) {
+                // even in case of position tie, first process closers
+                final Run closer = closers.get(closersIndex);
+                ++closersIndex;
+
+                // because of the assumptions, this while wouldn't need the !openRuns.empty()
+                // condition, because no run will close before being opened, but let's be sure
+                while (!openRuns.empty()) {
+                    final Run popped = openRuns.pop();
+                    if (popped.sameOpen(closer)) {
+                        // before closing the current run, if the run has a transformContent
+                        // function, use it to transform the content of the current run, based on
+                        // the openPosInOutput set when the current run was opened
+                        if (popped.transformContent != null && popped.openPosInOutput >= 0) {
+                            textBuilder.replace(popped.openPosInOutput, textBuilder.length(),
+                                    popped.transformContent.apply(
+                                            textBuilder.substring(popped.openPosInOutput)));
+                        }
+                        // close the run that we really need to close
+                        textBuilder.append(popped.close);
+                        break;
+                    }
+                    // we keep popping from openRuns, closing all of the runs we find,
+                    // until we find the run that we really need to close ...
+                    textBuilder.append(popped.close);
+                    tempStack.push(popped);
+                }
+                while (!tempStack.empty()) {
+                    // ... and then we reopen all of the runs that we didn't need to close
+                    // e.g. in <b>b<i>b&i</b>i</i>, when </b> is encountered, </i></b><i> is printed
+                    // instead, to make sure the HTML is valid, obtaining <b>b<i>b&i</i></b><i>i</i>
+                    final Run popped = tempStack.pop();
+                    textBuilder.append(popped.open);
+                    openRuns.push(popped);
+                }
+
+            } else {
+                // this will never be reached if openersIndex >= openers.size() because of the
+                // way minPos is calculated
+                final Run opener = openers.get(openersIndex);
+                textBuilder.append(opener.open);
+                opener.openPosInOutput = textBuilder.length(); // save for transforming later
+                openRuns.push(opener);
+                ++openersIndex;
+            }
+        }
+
+        // append last piece of text
+        textBuilder.append(Entities.escape(content.substring(currentTextPos)));
+
+        return textBuilder.toString()
+                .replace("\n", "<br>")
+                .replace("  ", " &nbsp;");
+    }
+
+    private static void addAllCommandRuns(
+            @Nonnull final JsonObject attributedDescription,
+            @Nonnull final List<Run> openers,
+            @Nonnull final List<Run> closers
+    ) {
+        attributedDescription.getArray("commandRuns")
+                .stream()
+                .filter(JsonObject.class::isInstance)
+                .map(JsonObject.class::cast)
+                .forEach(run -> {
+                    final JsonObject navigationEndpoint = run.getObject("onTap")
+                            .getObject("innertubeCommand");
+
+                    final int startIndex = run.getInt("startIndex", -1);
+                    final int length = run.getInt("length", 0);
+                    if (startIndex < 0 || length < 1 || navigationEndpoint == null) {
+                        return;
+                    }
+
+                    final String url = getUrlFromNavigationEndpoint(navigationEndpoint);
+                    if (url == null) {
+                        return;
+                    }
+
+                    final String open = "<a href=\"" + Entities.escape(url) + "\">";
+                    final Function<String, String> transformContent = getTransformContentFun(run);
+
+                    openers.add(new Run(open, LINK_CLOSE, startIndex, transformContent));
+                    closers.add(new Run(open, LINK_CLOSE, startIndex + length, transformContent));
+                });
+    }
+
+    private static Function<String, String> getTransformContentFun(final JsonObject run) {
+        final String accessibilityLabel = run.getObject("onTapOptions")
+                .getObject("accessibilityInfo")
+                .getString("accessibilityLabel", "")
+                // accessibility labels are e.g. "Instagram Channel Link: instagram_profile_name"
+                .replaceFirst(" Channel Link", "");
+
+        final Function<String, String> transformContent;
+        if (accessibilityLabel.isEmpty() || accessibilityLabel.startsWith("YouTube: ")) {
+            // if there is no accessibility label, or the link points to YouTube, cleanup the link
+            // text, see LINK_CONTENT_CLEANER_REGEX's documentation for more details
+            transformContent = (content) -> {
+                final Matcher m = LINK_CONTENT_CLEANER_REGEX.matcher(content);
+                if (m.find()) {
+                    return m.group(1);
+                }
+                return content;
+            };
+        } else {
+            // if there is an accessibility label, replace the link text with it, because on the
+            // YouTube website an ambiguous link text is next to an icon explaining which service it
+            // belongs to, but since we can't add icons, we instead use the accessibility label
+            // which contains information about the service
+            transformContent = (content) -> accessibilityLabel;
+        }
+
+        return transformContent;
+    }
+
+    private static void addAllStyleRuns(
+            @Nonnull final JsonObject attributedDescription,
+            @Nonnull final List<Run> openers,
+            @Nonnull final List<Run> closers
+    ) {
+        attributedDescription.getArray("styleRuns")
+                .stream()
+                .filter(JsonObject.class::isInstance)
+                .map(JsonObject.class::cast)
+                .forEach(run -> {
+                    final int start = run.getInt("startIndex", -1);
+                    final int length = run.getInt("length", 0);
+                    if (start < 0 || length < 1) {
+                        return;
+                    }
+                    final int end = start + length;
+
+                    if (run.has("strikethrough")) {
+                        openers.add(new Run(STRIKETHROUGH_OPEN, STRIKETHROUGH_CLOSE, start));
+                        closers.add(new Run(STRIKETHROUGH_OPEN, STRIKETHROUGH_CLOSE, end));
+                    }
+
+                    if (run.getBoolean("italic", false)) {
+                        openers.add(new Run(ITALIC_OPEN, ITALIC_CLOSE, start));
+                        closers.add(new Run(ITALIC_OPEN, ITALIC_CLOSE, end));
+                    }
+
+                    if (run.has("weightLabel")
+                            && !"FONT_WEIGHT_NORMAL".equals(run.getString("weightLabel"))) {
+                        openers.add(new Run(BOLD_OPEN, BOLD_CLOSE, start));
+                        closers.add(new Run(BOLD_OPEN, BOLD_CLOSE, end));
+                    }
+                });
+    }
+}