aswi20220x00-gitlab/webapp/utils/selectionUtils.ts @ baf6fc22

import { AnnotationInfo } from '../api';
import { DOCUMENT_TAG_ID_ATTRIBUTE_NAME } from '../constants';

export interface SelectionInfo {
    startElementId: number;
    endElementId: number;
    startPositionOriginalDocument: number;
    endPositionOriginalDocument: number;
    selectionLengthOriginalDocument: number;

    selectedText: string;
}

export function GetSelectionInfo(annotation: AnnotationInfo): SelectionInfo | null {
    const selection = window.getSelection();
    if (!selection) {
        return null;
    }
    if (selection.type.toLowerCase() != 'range') {
        return null; // nothing is selected
    }

    if (!annotation?.tagStartPositions || !annotation.tagLengths) {
        // invalid data provided from API
        console.log('start or lengths not found');
        return null;
    }

    let startTag = selection.anchorNode; // anchor node = node where selection started
    let endTag = selection.focusNode; // focus node = node where selection ended

    if (!startTag || !endTag) {
        console.log('Selection not found');
        return null;
    }

    if (startTag.nodeName.includes('#')) {
        // it is not an element (usually #text)
        startTag = startTag.parentNode;
    }
    if (endTag.nodeName.includes('#')) {
        // it is not an element (usually #text)
        endTag = endTag.parentNode;
    }

    if (!startTag || !endTag) {
        console.log('Selection element not found');
        return null;
    }

    if (!(startTag instanceof Element)) {
        console.log('StartTag is not instance of Element');
        return null;
    }
    if (!(endTag instanceof Element)) {
        console.log('EndTag is not instance of Element');
        return null;
    }

    let startElement = startTag as Element;
    let endElement = endTag as Element;

    let startId: number =
        Number(startElement.getAttribute(DOCUMENT_TAG_ID_ATTRIBUTE_NAME)) ?? -1;
    let endId: number =
        Number(endElement.getAttribute(DOCUMENT_TAG_ID_ATTRIBUTE_NAME)) ?? -1;

    let startPosition =
        annotation.tagStartPositions[startId] +
        annotation.tagLengths[startId] +
        selection.anchorOffset;
    let endPosition =
        annotation.tagStartPositions[endId] +
        annotation.tagLengths[endId] +
        selection.focusOffset -
        1;

    // need to switch start and end elements (selection was in the opposite way then expected)
    if (startPosition > endPosition) {
        let temp = startPosition;
        startPosition = endPosition;
        endPosition = temp;

        temp = startId;
        startId = endId;
        endId = temp;

        const tempElement = startElement;
        startElement = endElement;
        endElement = tempElement;
    }

    const length = endPosition - startPosition + 1;
    const text = selection.toString();

    return {
        endElementId: endId,
        startElementId: startId,
        startPositionOriginalDocument: startPosition,
        endPositionOriginalDocument: endPosition,
        selectionLengthOriginalDocument: length,
        selectedText: text,
    };
}