javascript-obfuscator/src/generators/identifier-names-generators/MangledIdentifierNamesGenerator.ts

import { inject, injectable } from 'inversify';
import { ServiceIdentifiers } from '../../container/ServiceIdentifiers';

import { TNodeWithLexicalScope } from '../../types/node/TNodeWithLexicalScope';

import { IOptions } from '../../interfaces/options/IOptions';
import { IRandomGenerator } from '../../interfaces/utils/IRandomGenerator';
import { ISetUtils } from '../../interfaces/utils/ISetUtils';

import { alphabetString } from '../../constants/AlphabetString';
import { alphabetStringUppercase } from '../../constants/AlphabetStringUppercase';
import { numbersString } from '../../constants/NumbersString';
import { reservedIdentifierNames } from '../../constants/ReservedIdentifierNames';

import { AbstractIdentifierNamesGenerator } from './AbstractIdentifierNamesGenerator';
import { NodeLexicalScopeUtils } from '../../node/NodeLexicalScopeUtils';

@injectable()
export class MangledIdentifierNamesGenerator extends AbstractIdentifierNamesGenerator {
    /**
     * @type {number}
     */
    private static readonly maxRegenerationAttempts: number = 20;

    /**
     * @type {string}
     */
    private static readonly initMangledNameCharacter: string = '9';

    /**
     * @type {string[]}
     */
    private static readonly nameSequence: string[] = [
        ...`${numbersString}${alphabetString}${alphabetStringUppercase}`
    ];

    /**
     * Reserved JS words with length of 2-4 symbols that can be possible generated with this replacer
     * + reserved DOM names like `Set`, `Map`, `Date`, etc
     *
     * @type {Set<string>}
     */
    private static readonly reservedNamesSet: Set<string> = new Set(reservedIdentifierNames);

    /**
     * @type {string}
     */
    private lastMangledName: string = MangledIdentifierNamesGenerator.initMangledNameCharacter;

    /**
     * @type {WeakMap<TNodeWithLexicalScope, string>}
     */
    private readonly lastMangledNameForScopeMap: WeakMap <TNodeWithLexicalScope, string> = new WeakMap();

    /**
     * @type {WeakMap<string, string>}
     */
    private readonly lastMangledNameForLabelMap: Map <string, string> = new Map();

    /**
     * @type {ISetUtils}
     */
    private readonly setUtils: ISetUtils;

    /**
     * @param {IRandomGenerator} randomGenerator
     * @param {IOptions} options
     * @param {ISetUtils} setUtils
     */
    public constructor (
        @inject(ServiceIdentifiers.IRandomGenerator) randomGenerator: IRandomGenerator,
        @inject(ServiceIdentifiers.IOptions) options: IOptions,
        @inject(ServiceIdentifiers.ISetUtils) setUtils: ISetUtils,
    ) {
        super(randomGenerator, options);

        this.setUtils = setUtils;
    }

    /**
     * Generates next name based on a global previous mangled name
     * We can ignore nameLength parameter here, it hasn't sense with this generator
     *
     * @param {number} nameLength
     * @returns {string}
     */
    public generateNext (nameLength?: number): string {
        const identifierName: string = this.generateNewMangledName(this.lastMangledName);

        this.updatePreviousMangledName(identifierName);
        this.preserveName(identifierName);

        return identifierName;
    }

    /**
     * @param {number} nameLength
     * @returns {string}
     */
    public generateForGlobalScope (nameLength?: number): string {
        const prefix: string = this.options.identifiersPrefix ?
            `${this.options.identifiersPrefix}`
            : '';

        const identifierName: string = this.generateNewMangledName(
            this.lastMangledName,
            (newIdentifierName: string) => {
                const identifierNameWithPrefix: string = `${prefix}${newIdentifierName}`;

                return this.isValidIdentifierName(identifierNameWithPrefix);
            }
        );
        const identifierNameWithPrefix: string = `${prefix}${identifierName}`;

        this.updatePreviousMangledName(identifierName);
        this.preserveName(identifierNameWithPrefix);

        return identifierNameWithPrefix;
    }

    /**
     * @param {TNodeWithLexicalScope} lexicalScopeNode
     * @param {number} nameLength
     * @returns {string}
     */
    public generateForLexicalScope (lexicalScopeNode: TNodeWithLexicalScope, nameLength?: number): string {
        const lexicalScopes: TNodeWithLexicalScope[] = [
            lexicalScopeNode,
            ...NodeLexicalScopeUtils.getLexicalScopes(lexicalScopeNode)
        ];

        const lastMangledNameForScope: string = this.getLastMangledNameForScopes(lexicalScopes);
        const identifierName: string = this.generateNewMangledName(
            lastMangledNameForScope,
            (newIdentifierName: string) =>
                this.isValidIdentifierNameInLexicalScopes(newIdentifierName, lexicalScopes)
        );

        this.lastMangledNameForScopeMap.set(lexicalScopeNode, identifierName);

        this.updatePreviousMangledName(identifierName);
        this.preserveNameForLexicalScope(identifierName, lexicalScopeNode);

        return identifierName;
    }

    /**
     * @param {string} label
     * @param {number} nameLength
     * @returns {string}
     */
    public generateForLabel (label: string, nameLength?: number): string {
        const lastMangledNameForLabel: string = this.getLastMangledNameForLabel(label);

        const identifierName: string = this.generateNewMangledName(lastMangledNameForLabel);

        this.updatePreviousMangledNameForLabel(identifierName, label, lastMangledNameForLabel);

        return identifierName;
    }

    /**
     * @param {string} nextName
     * @param {string} prevName
     * @returns {boolean}
     */
    // eslint-disable-next-line complexity
    public isIncrementedMangledName (nextName: string, prevName: string): boolean {
        if (nextName === prevName) {
            return false;
        }

        const nextNameLength: number = nextName.length;
        const prevNameLength: number = prevName.length;

        if (nextNameLength !== prevNameLength) {
            return nextNameLength > prevNameLength;
        }

        const nameSequence: string[] = this.getNameSequence();

        for (let i: number = 0; i < nextNameLength; i++) {
            const nextNameCharacter: string = nextName[i];
            const prevNameCharacter: string = prevName[i];

            if (nextNameCharacter === prevNameCharacter) {
                continue;
            }

            const indexOfNextNameCharacter: number = nameSequence.indexOf(nextNameCharacter);
            const indexOfPrevNameCharacter: number = nameSequence.indexOf(prevNameCharacter);

            return indexOfNextNameCharacter > indexOfPrevNameCharacter;
        }

        throw new Error('Something goes wrong during comparison of mangled names');
    }

    /**
     * @param {string} mangledName
     * @returns {boolean}
     */
    public override isValidIdentifierName (mangledName: string): boolean {
        return super.isValidIdentifierName(mangledName)
            && !MangledIdentifierNamesGenerator.reservedNamesSet.has(mangledName);
    }

    /**
     * @returns {string[]}
     */
    protected getNameSequence (): string[] {
        return MangledIdentifierNamesGenerator.nameSequence;
    }

    /**
     * @param {string} name
     */
    protected updatePreviousMangledName (name: string): void {
        if (!this.isIncrementedMangledName(name, this.lastMangledName)) {
            return;
        }

        this.lastMangledName = name;
    }

    /**
     * @param {string} name
     * @param {string} label
     * @param {string} lastMangledNameForLabel
     */
    protected updatePreviousMangledNameForLabel (name: string, label: string, lastMangledNameForLabel: string): void {
        if (!this.isIncrementedMangledName(name, lastMangledNameForLabel)) {
            return;
        }

        this.lastMangledNameForLabelMap.set(label, name);
    }

    /**
     * @param {string} previousMangledName
     * @param {(newIdentifierName: string) => boolean} validationFunction
     * @returns {string}
     */
    protected generateNewMangledName (
        previousMangledName: string,
        validationFunction?: (newIdentifierName: string) => boolean
    ): string {
        const generateNewMangledName = (name: string, regenerationAttempt: number = 0): string => {
            /**
             * Attempt to decrease amount of regeneration tries because of large preserved names set
             * When we reached the limit, we're trying to generate next mangled name based on the latest
             * preserved name
             */
            if (regenerationAttempt > MangledIdentifierNamesGenerator.maxRegenerationAttempts) {
                const lastPreservedName = this.setUtils.getLastElement(this.preservedNamesSet);

                if (lastPreservedName) {
                    return this.generateNewMangledName(lastPreservedName);
                }
            }

            const nameSequence: string[] = this.getNameSequence();
            const nameSequenceLength: number = nameSequence.length;
            const nameLength: number = name.length;

            const zeroSequence: (num: number) => string = (num: number): string => {
                return '0'.repeat(num);
            };

            let index: number = nameLength - 1;

            do {
                const character: string = name[index];
                const indexInSequence: number = nameSequence.indexOf(character);
                const lastNameSequenceIndex: number = nameSequenceLength - 1;

                if (indexInSequence !== lastNameSequenceIndex) {
                    const previousNamePart: string = name.slice(0, index);
                    const nextCharacter: string = nameSequence[indexInSequence + 1];
                    const zeroSequenceLength: number = nameLength - (index + 1);
                    const zeroSequenceCharacters: string = zeroSequence(zeroSequenceLength);

                    return previousNamePart + nextCharacter + zeroSequenceCharacters;
                }

                --index;
            } while (index >= 0);

            const firstLetterCharacter: string = nameSequence[numbersString.length];

            return `${firstLetterCharacter}${zeroSequence(nameLength)}`;
        };

        let identifierName: string = previousMangledName;
        let isValidIdentifierName: boolean;

        do {
            identifierName = generateNewMangledName(identifierName);
            isValidIdentifierName = validationFunction?.(identifierName)
                ?? this.isValidIdentifierName(identifierName);
        } while (!isValidIdentifierName);

        return identifierName;
    }

    /**
     * @param {TNodeWithLexicalScope[]} lexicalScopeNodes
     * @returns {string}
     */
    private getLastMangledNameForScopes (lexicalScopeNodes: TNodeWithLexicalScope[]): string {
        for (const lexicalScope of lexicalScopeNodes) {
            const lastMangledName: string | null = this.lastMangledNameForScopeMap.get(lexicalScope) ?? null;

            if (!lastMangledName) {
                continue;
            }

            return lastMangledName;
        }

        return MangledIdentifierNamesGenerator.initMangledNameCharacter;
    }

    /**
     * @param {string} label
     * @returns {string}
     */
    private getLastMangledNameForLabel (label: string): string {
        const lastMangledName: string | null = this.lastMangledNameForLabelMap.get(label) ?? null;

        return lastMangledName ?? MangledIdentifierNamesGenerator.initMangledNameCharacter;
    }
}