cvsa/lib/net/bisectVideoStartFrom.ts

89 lines
2.1 KiB
TypeScript

import { getLatestVideos } from "lib/net/getLatestVideos.ts";
import { HOUR, SECOND } from "$std/datetime/constants.ts";
import { VideoListVideo } from "lib/net/bilibili.d.ts";
export async function getVideoPositionInNewList(timestamp: number): Promise<number | null | VideoListVideo[]> {
const virtualPageSize = 50;
let lowPage = 1;
let highPage = 1;
let foundUpper = false;
while (true) {
const ps = highPage < 2 ? 50 : 1
const pn = highPage < 2 ? 1 : highPage * virtualPageSize;
const videos = await getLatestVideos(pn, ps);
if (!videos || videos.length === 0) {
break;
}
const lastVideo = videos[videos.length - 1];
if (!lastVideo || !lastVideo.pubdate) {
break;
}
const lastTime = lastVideo.pubdate * SECOND + 8 * HOUR;
if (lastTime <= timestamp && highPage == 1) {
return videos;
}
else if (lastTime <= timestamp) {
foundUpper = true;
break;
} else {
lowPage = highPage;
highPage *= 2;
}
}
if (!foundUpper) {
return null;
}
let boundaryPage = highPage;
let lo = lowPage;
let hi = highPage;
while (lo <= hi) {
const mid = Math.floor((lo + hi) / 2);
const videos = await getLatestVideos(mid * virtualPageSize, 1);
if (!videos) {
return null;
}
if (videos.length === 0) {
hi = mid - 1;
continue;
}
const lastVideo = videos[videos.length - 1];
if (!lastVideo || !lastVideo.pubdate) {
hi = mid - 1;
continue;
}
const lastTime = lastVideo.pubdate * SECOND + 8 * HOUR;
if (lastTime > timestamp) {
lo = mid + 1;
} else {
boundaryPage = mid;
hi = mid - 1;
}
}
const boundaryVideos = await getLatestVideos(boundaryPage, virtualPageSize);
let indexInPage = 0;
if (boundaryVideos && boundaryVideos.length > 0) {
for (let i = 0; i < boundaryVideos.length; i++) {
const video = boundaryVideos[i];
if (!video.pubdate) {
continue;
}
const videoTime = video.pubdate * SECOND + 8 * HOUR;
if (videoTime > timestamp) {
indexInPage++;
} else {
break;
}
}
}
const count = (boundaryPage - 1) * virtualPageSize + indexInPage;
const safetyMargin = 5;
return count + safetyMargin;
}