// tslint:disable: object-literal-sort-keys
import { TransformOptions } from '@babel/core';
import { merge } from '../lib';

export interface BabelRegisterOptions extends TransformOptions {
    extensions?: string[];
    cache?: boolean;
}

const defaultExtensions = ['.es6', '.es', '.jsx', '.js', '.mjs', '.ts', '.tsx'];

const defaultRegisterOptions: BabelRegisterOptions = {
    presets: [
        [
            '@babel/preset-env',
            {
                targets: {
                    node: true,
                },
            },
        ],
        '@babel/typescript',
    ],
    plugins: [
        '@babel/plugin-proposal-class-properties',
        '@babel/plugin-proposal-object-rest-spread',
        '@babel/plugin-transform-object-assign',
    ],

    extensions: defaultExtensions,
};

export const initBabel = (rootPathPaths?: string | string[], options?: BabelRegisterOptions, mergeDefault = false) => {
    let registerOptions: BabelRegisterOptions = options || defaultRegisterOptions;

    if (options && mergeDefault) {
        registerOptions = merge<BabelRegisterOptions>([defaultRegisterOptions, options], { concatArrays: true });
    }

    // confine to specified root paths if passed
    if (rootPathPaths) {
        rootPathPaths = Array.isArray(rootPathPaths) ? rootPathPaths : [rootPathPaths];
        registerOptions.only = rootPathPaths;
        registerOptions.babelrcRoots = rootPathPaths;
    }

    require('@babel/register')(registerOptions);
};