KnodesCommunity/typedoc-plugins

import { textUtils } from '../../utils';

interface ISourceEdit {
    from: number;
    source: string;
    replacement: string;
}

export interface ISourceMap {
    line: number;
    column: number;
    layers: SourceMapLayer[];
    pos: number;
}

export class SourceMapLayer {
    public readonly editions: ISourceEdit[] = [];
    private _resultingText = this.originalText;
    public get resultingText(){
        return this._resultingText;
    }
    public constructor(
        public readonly label: string,
        public readonly originalText: string,
        private readonly _parentLayer?: SourceMapLayer,
    ){}

    /**
     * Add a new edition to this layer.
     *
     * @param from - The position where the edit starts.
     * @param source - The original content.
     * @param replacement - The replacement content.
     */
    public addEdition( from: number, source: string, replacement: string ){
        const edition = { from, replacement, source };
        const deltaPos = this._remapSelfEditPos( from ).delta;
        this.editions.push( edition );
        this._resultingText = this._resultingText.slice( 0, from + deltaPos ) + replacement + this._resultingText.slice( from + source.length + deltaPos );
    }

    /**
     * Return a string describing the position of the given index in the source file.
     *
     * @param sourceFile - The source file name.
     * @param index - The char index.
     * @returns a string like `"hello.ts:42:84" (in expansion of @tag1 ⇒ @tag2)"
     */
    public sourceHint( sourceFile: string | undefined, index: number ){
        if( !sourceFile ){
            return 'UNKNOWN SOURCE';
        }
        const { line, column, layers: expansions } = this._getSourceMap( index, false );
        const posStr = line && column ? `:${line}:${column}` : '';
        const expansionContext = ` (in expansion of ${expansions.map( e => e.label ).join( ' ⇒ ' )})`;
        return `"${sourceFile}${posStr}"${expansionContext}`;
    }

    /**
     * Map the given {@link pos} in the 1st layer's content.
     *
     * @param pos - The character index.
     * @param mapSelf - A flag indicating if this layer's editions should be mapped.
     * @returns the source map.
     */
    private _getSourceMap( pos: number, mapSelf = true ){
        const { offsetedPos, isExpansionApplied } = mapSelf ? this._remapSelfEditPos( pos ) : { offsetedPos: pos, isExpansionApplied: true };
        const editionContext: ISourceMap = this._parentLayer?._getSourceMap( offsetedPos ) ?? {
            ...textUtils.getCoordinates( this.originalText, offsetedPos ),
            pos: offsetedPos,
            layers: [],
        };
        if( isExpansionApplied ){
            editionContext.layers = [ ...editionContext.layers, this ];
        }
        return editionContext;
    }

    /**
     * Remap the given position in this layer's editions.
     *
     * @param pos - The character position.
     * @returns the mapped position.
     */
    private _remapSelfEditPos( pos: number ) {
        const remap = this.editions.reduce(
            ( acc, edit ) => {
                const isAfterEdit = edit.from <= acc.offsetedPos;
                if( !isAfterEdit ){
                    return acc;
                }
                const _isExpansionApplied = edit.from + edit.replacement.length > acc.offsetedPos;
                const isOffsettedPosInEdit = edit.from <= acc.offsetedPos && edit.from + edit.replacement.length >= acc.offsetedPos;
                const newAcc = {
                    offsetedPos: isOffsettedPosInEdit ?
                        edit.from :
                        acc.offsetedPos - ( edit.replacement.length - edit.source.length ),
                    isExpansionApplied: _isExpansionApplied || acc.isExpansionApplied,
                };
                return newAcc;
            },
            { offsetedPos: pos, isExpansionApplied: false } );
        return {
            ...remap,
            delta: remap.offsetedPos - pos,
        };
    }
}