88 lines
2.5 KiB
JavaScript
88 lines
2.5 KiB
JavaScript
import util from 'util';
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import * as api from './api.mjs';
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import { WATCH_BASE, PromiseQueue, escapeQuotes } from './util.mjs';
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import { retryable } from '../lib/retry.mjs';
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const GRAPH_NODE = ' "%s" [label="%s", URL="%s", fontcolor=blue]';
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const GRAPH_LINK = ' "%s" -> "%s"';
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const retryPlayerConfig = retryable(api.getPlayerConfig);
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/**
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* Explore the video graph starting from the given root.
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*
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* @async
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* @param string videoId Source video identifier.
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* @return Array.<Object, Object> Nodes and set of neighbors of each node.
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*/
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export const exploreVideos = async videoId =>
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{
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// Store metadata about each visited video
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const videosNodes = Object.create(null);
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videosNodes[videoId] = {};
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// List of videos linked from each video either through a card or an
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// endscreen item
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const nextVideos = Object.create(null);
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nextVideos[videoId] = new Set();
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// Pending video requests
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const queue = new PromiseQueue();
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queue.add(retryPlayerConfig(videoId));
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while (!queue.empty())
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{
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const config = await queue.next();
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const meta = api.getVideoMeta(config);
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videosNodes[meta.videoId] = meta;
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// Add links between this video and the linked ones
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api.getEndScreenVideos(config)
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.forEach(nextId => nextVideos[meta.videoId].add(nextId));
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api.getCardVideos(config)
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.forEach(nextId => nextVideos[meta.videoId].add(nextId));
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for (let nextId of nextVideos[meta.videoId])
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{
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if (!(nextId in videosNodes))
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{
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videosNodes[nextId] = {};
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nextVideos[nextId] = new Set();
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queue.add(retryPlayerConfig(nextId));
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}
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}
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}
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return [videosNodes, nextVideos];
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};
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/**
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* Convert a video graph to the GraphViz format.
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*
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* @param Object videosNodes Videos of the graph.
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* @param Object nextVideos For each video, list of next videos.
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* @return string GraphViz representation of the graph.
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*/
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export const toGraphviz = (videosNodes, nextVideos) =>
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{
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// Convert videosNodes
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const nodesStr = Object.entries(videosNodes).map(([id, {title}]) =>
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{
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const url = util.format(WATCH_BASE, id);
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return util.format(GRAPH_NODE, id, escapeQuotes(title), url);
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}).join('\n');
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// Convert edges
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const nextStr = Object.entries(nextVideos).map(([id, neighbors]) =>
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Array.from(neighbors)
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.map(neighbor => util.format(GRAPH_LINK, id, neighbor))
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.join('\n')
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).join('\n');
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return `digraph "" {
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${nodesStr}
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${nextStr}}`;
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};
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