count.ts

import * as fs from 'fs';

/**
 * Returns an array of file names in the root directory.
 * @param root A path to root directory.
 */
function getFolders(root: string): string[] {
    return fs.readdirSync(root);
}

/**
 * Returns a filtered array of folders by name.
 * @param folders A string of folder names.
 * @param name A substring to filter by.
 */
function filterFolders(folders: string[], name: string): string[] {
    return folders.filter((item) => item.includes(name));
}

interface FilesObject {
    [k: string]: number;
}

/**
 * Returns an object, where keys are folder names
 * and values are number of subfolders.
 * @param folders A string of folder names.
 */
function getFilesObj(folders: string[]): FilesObject {
    return folders.reduce((obj, path) => {
        const innerFolders = getFolders(path);
        // @ts-ignore
        obj[path] = innerFolders.filter(folder => !folder.includes('_example')).length;
        return obj;
    }, {});
}

/**
 * Returns a sum of all files in every folder.
 * and values are number of subfolders.
 * @param filesObj An object, where keys are subfolders
 */
function getTotalFiles(filesObj: FilesObject) {
    let total = 0;
    for (let key in filesObj) {
        total += filesObj[key];
    }
    return total;
}

/**
 * Reads and returns a string from a file.
 * @param filePath
 */
function getFileString(filePath: string): string {
    return fs.readFileSync(filePath, { encoding: 'utf8' });
}

/**
 * Returns a string with new amounts of kata solved
 * @param  str A string from readme.
 * @param filesObj An object, where keys are subfolders
 */
function refreshFilesCount(str: string, filesObj: FilesObject): string {
    const re = (value: string) => {
        const regex = `(?<=${value}.+: )\\d+`;

        return new RegExp(regex, 'g');
    };

    for (let path in filesObj) {
        str = str.replace(re(path), () => filesObj[path].toString());
    }

    str = str.replace(re('Total'), () => getTotalFiles(filesObj).toString());

    return str;
}

/**
 * Writes new data to a file
 * @param filePath A path to file.
 * @param str New string to write.
 */
function writeFileString(filePath: string, str: string): void {
    fs.writeFileSync(filePath, str);
}

function main(): void {
    const folders = getFolders('./');
    const filteredFolders = filterFolders(folders, 'kyu');
    const filesObj = getFilesObj(filteredFolders);
    const oldReadme = getFileString('./README.md');
    const newReadme = refreshFilesCount(oldReadme, filesObj);
    writeFileString('./README.md', newReadme);
}

main();