117 lines
3.2 KiB
JavaScript
117 lines
3.2 KiB
JavaScript
import debug from 'debug';
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import util from 'util';
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import fetch from 'node-fetch';
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import { WATCH_BASE } from './util.mjs';
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import { retryable, exclusive } from './retry.mjs';
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import { TemporaryError } from './retry.mjs';
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const log = debug('youtube-maze:api');
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const METADATA_REGEXES = [
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/window\["ytInitialPlayerResponse"\] = (\{.*?\});/,
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/var ytInitialPlayerResponse = (\{.*?\});/,
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];
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/**
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* Fetch metadata about a YouTube video.
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*
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* @async
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* @param String videoId Identifier of the video to fetch.
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* @return Object The video metadata object.
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*/
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const bareGetMetadata = async (videoId) =>
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{
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const url = util.format(WATCH_BASE, encodeURIComponent(videoId));
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log(`Fetching ${videoId} (${url})`);
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const res = await fetch(url);
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if (res.status === 429)
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{
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throw new TemporaryError('Too many requests');
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}
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else if (res.status !== 200)
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{
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throw new Error(`Invalid YouTube HTTP status: ${res.status}`);
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}
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const body = await res.text();
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const searchResults = METADATA_REGEXES.map(regex => body.match(regex));
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const searchResult = searchResults.find(item => item !== null);
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if (searchResult === null)
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{
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throw new TemporaryError(`Incomplete YouTube response for video ${videoId}`);
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}
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const metadata = JSON.parse(searchResult[1]);
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if (metadata.playabilityStatus.status !== 'OK')
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{
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throw new Error(`Video ${videoId} is not available; \
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status: ${metadata.playabilityStatus.status}; \
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reason: "${metadata.playabilityStatus.reason}"`);
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}
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const actualId = metadata.videoDetails.videoId;
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if (videoId !== actualId)
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{
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throw new Error(`Video ${videoId} has actual id ${actualId}`);
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}
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log(`Done fetching ${videoId}`);
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return metadata;
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};
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export const getMetadata = exclusive(retryable(bareGetMetadata));
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/**
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* Get video ID and title.
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*
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* @param Object metadata The video metadata object from `getMetadata`.
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* @return Object Containing the video ID and title.
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*/
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export const getVideoInfo = metadata => ({
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videoId: metadata.videoDetails.videoId,
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title: metadata.videoDetails.title,
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});
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/**
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* Find videos linked from the endscreen of a YouTube video.
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*
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* @param Object metadata The video metadata object from `getMetadata`.
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* @return List of identifiers of linked videos.
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*/
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export const getEndScreenVideos = metadata =>
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{
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if (!('endscreen' in metadata))
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{
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return [];
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}
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return metadata.endscreen.endscreenRenderer.elements
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.map(elt => elt.endscreenElementRenderer)
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.filter(rdr => 'watchEndpoint' in rdr.endpoint)
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.map(rdr => rdr.endpoint.watchEndpoint.videoId);
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};
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/**
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* Find videos linked from as cards from a YouTube video.
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*
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* @param Object metadata The video metadata object from `getMetadata`.
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* @return List of identifiers of linked videos.
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*/
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export const getCardVideos = metadata =>
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{
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if (!('cards' in metadata))
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{
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return [];
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}
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return metadata.cards.cardCollectionRenderer.cards
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.map(card => card.cardRenderer.content)
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.filter(content => 'videoInfoCardContentRenderer' in content)
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.map(content => content.videoInfoCardContentRenderer)
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.map(rdr => rdr.action.watchEndpoint.videoId);
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};
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