70 lines
1.4 KiB
TypeScript
70 lines
1.4 KiB
TypeScript
// Copyright 2021 Signal Messenger, LLC
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// SPDX-License-Identifier: AGPL-3.0-only
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import LinkifyIt from 'linkify-it';
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export function graphemeAndLinkAwareSlice(
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str: string,
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length: number,
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buffer = 100
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): {
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hasReadMore: boolean;
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text: string;
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} {
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if (str.length <= length + buffer) {
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return { text: str, hasReadMore: false };
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}
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let text: string | undefined;
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for (const { index } of new Intl.Segmenter().segment(str)) {
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if (!text && index >= length) {
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text = str.slice(0, index);
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}
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if (text && index > length) {
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text = expandToIncludeEntireLink(str, text);
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return {
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text,
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hasReadMore: text.length < str.length,
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};
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}
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}
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return {
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text: str,
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hasReadMore: false,
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};
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}
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const expandToIncludeEntireLink = (
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original: string,
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truncated: string
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): string => {
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const linksInText = new LinkifyIt().match(original);
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if (!linksInText) {
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return truncated;
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}
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const invalidTruncationRanges: Array<LinkRange> = linksInText.map(
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({ index: startIndex, lastIndex }) => ({ startIndex, lastIndex })
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);
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const truncatedLink: Array<LinkRange> = invalidTruncationRanges.filter(
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({ startIndex, lastIndex }) =>
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startIndex < truncated.length && lastIndex > truncated.length
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);
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if (truncatedLink.length === 0) {
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return truncated;
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}
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return original.slice(0, truncatedLink[0].lastIndex);
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};
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type LinkRange = {
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startIndex: number;
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lastIndex: number;
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};
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