javascript-obfuscator/src/node/NodeUtils.ts

import * as escodegen from 'escodegen-wallaby';
import * as esprima from 'esprima';
import * as estraverse from 'estraverse';
import * as ESTree from 'estree';

import { TNodeWithBlockScope } from '../types/node/TNodeWithBlockScope';
import { TNodeWithScope } from '../types/node/TNodeWithScope';
import { TObject } from '../types/TObject';
import { TStatement } from '../types/node/TStatement';

import { NodeGuards } from './NodeGuards';

export class NodeUtils {
    /**
     * @param {T} astTree
     * @returns {T}
     */
    public static addXVerbatimPropertyToLiterals <T extends ESTree.Node = ESTree.Node> (astTree: T): T {
        estraverse.replace(astTree, {
            leave: (node: ESTree.Node) => {
                if (NodeGuards.isLiteralNode(node)) {
                    node['x-verbatim-property'] = {
                        content: node.raw,
                        precedence: escodegen.Precedence.Primary
                    };
                }
            }
        });

        return astTree;
    }

    /**
     * @param {T} astTree
     * @returns {T}
     */
    public static clone <T extends ESTree.Node = ESTree.Node> (astTree: T): T {
        return NodeUtils.parentize(NodeUtils.cloneRecursive(astTree));
    }

    /**
     * @param {string} code
     * @returns {TStatement[]}
     */
    public static convertCodeToStructure (code: string): TStatement[] {
        let structure: ESTree.Program = esprima.parseScript(code);

        structure = NodeUtils.addXVerbatimPropertyToLiterals(structure);
        structure = NodeUtils.parentize(structure);

        return structure.body;
    }

    /**
     * @param {NodeGuards[]} structure
     * @returns {string}
     */
    public static convertStructureToCode (structure: ESTree.Node[]): string {
        return structure.reduce((code: string, node: ESTree.Node) => {
            return code + escodegen.generate(node, {
                sourceMapWithCode: true
            }).code;
        }, '');
    }

    /**
     * @param {Node} targetNode
     * @returns {TNodeWithBlockScope[]}
     */
    public static getBlockScopesOfNode (targetNode: ESTree.Node): TNodeWithBlockScope[] {
        return NodeUtils.getBlockScopesOfNodeRecursive(targetNode);
    }

    /**
     * @param {Statement} node
     * @returns {TStatement | null}
     */
    public static getNextSiblingStatementNode (node: ESTree.Statement): TStatement | null {
        return NodeUtils.getSiblingStatementNodeByOffset(node, 1);
    }

    /**
     * @param {Statement} node
     * @returns {TStatement | null}
     */
    public static getPreviousSiblingStatementNode (node: ESTree.Statement): TStatement | null {
        return NodeUtils.getSiblingStatementNodeByOffset(node, -1);
    }

    /**
     * @param {NodeGuards} node
     * @returns {TNodeWithScope}
     */
    public static getScopeOfNode (node: ESTree.Node): TNodeWithScope {
        const parentNode: ESTree.Node | undefined = node.parentNode;

        if (!parentNode) {
            throw new ReferenceError('`parentNode` property of given node is `undefined`');
        }

        if (!NodeGuards.isNodeHasScope(parentNode)) {
            return NodeUtils.getScopeOfNode(parentNode);
        }

        return parentNode;
    }

    /**
     * @param {UnaryExpression} unaryExpressionNode
     * @returns {NodeGuards}
     */
    public static getUnaryExpressionArgumentNode (unaryExpressionNode: ESTree.UnaryExpression): ESTree.Node {
        if (NodeGuards.isUnaryExpressionNode(unaryExpressionNode.argument)) {
            return NodeUtils.getUnaryExpressionArgumentNode(unaryExpressionNode.argument);
        }

        return unaryExpressionNode.argument;
    }

    /**
     * @param {T} astTree
     * @returns {T}
     */
    public static parentize <T extends ESTree.Node = ESTree.Node> (astTree: T): T {
        estraverse.replace(astTree, {
            enter: NodeUtils.parentizeNode
        });

        return astTree;
    }

    /**
     * @param {T} node
     * @param {Node} parentNode
     * @returns {T}
     */
    public static parentizeNode <T extends ESTree.Node = ESTree.Node> (node: T, parentNode: ESTree.Node | null): T {
        node.parentNode = parentNode || node;
        node.obfuscatedNode = false;

        return node;
    }

    /**
     * @param {T} node
     * @returns {T}
     */
    private static cloneRecursive <T> (node: T): T {
        if (node === null) {
            return node;
        }

        const copy: TObject = {};

        for (const property in node) {
            if (!node.hasOwnProperty(property) || property === 'parentNode') {
                continue;
            }

            const value: any = node[property];

            let clonedValue: any | null;

            if (value === null || value instanceof RegExp) {
                clonedValue = value;
            } else if (Array.isArray(value)) {
                clonedValue = value.map(NodeUtils.cloneRecursive);
            } else if (typeof value === 'object') {
                clonedValue = NodeUtils.cloneRecursive(value);
            } else {
                clonedValue = value;
            }

            copy[property] = clonedValue;
        }

        return <T>copy;
    }

    /**
     * @param {Node} node
     * @param {TNodeWithBlockScope[]} blockScopes
     * @param {number} depth
     * @returns {TNodeWithBlockScope[]}
     */
    private static getBlockScopesOfNodeRecursive (
        node: ESTree.Node,
        blockScopes: TNodeWithBlockScope[] = [],
        depth: number = 0
    ): TNodeWithBlockScope[] {
        const parentNode: ESTree.Node | undefined = node.parentNode;

        if (!parentNode) {
            throw new ReferenceError('`parentNode` property of given node is `undefined`');
        }

        /**
         * Stage 1: process root block statement node of the slice of AST-tree
         */
        if (NodeGuards.isBlockStatementNode(node) && parentNode === node) {
            blockScopes.push(node);
        }

        /**
         * Stage 2: process any other nodes
         */
        if (
            /**
             * we can add program node instantly
             */
            NodeGuards.isProgramNode(node) ||
            /**
             * we shouldn't add to the array input node that is node with block scope itself
             * so, on depth 0 we will skip push to the array of block scopes
             */
            (depth && NodeGuards.isNodeHasBlockScope(node, parentNode))
        ) {
            blockScopes.push(node);
        }

        if (node !== parentNode) {
            return NodeUtils.getBlockScopesOfNodeRecursive(parentNode, blockScopes, ++depth);
        }

        return blockScopes;
    }

    /**
     * @param {Statement} node
     * @param {number} offset
     * @returns {TStatement | null}
     */
    private static getSiblingStatementNodeByOffset (node: ESTree.Statement, offset: number): TStatement | null {
        const scopeNode: TNodeWithScope = NodeUtils.getScopeOfNode(node);
        const scopeBody: TStatement[] = !NodeGuards.isSwitchCaseNode(scopeNode)
            ? scopeNode.body
            : scopeNode.consequent;
        const indexInScope: number = scopeBody.indexOf(node);

        return scopeBody[indexInScope + offset] || null;
    }
}