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