src/config/config.ts

import * as fs from "fs";
import * as path from "path";

export class Config {
    private readonly data: Record<string, string | object | number | []>;

    constructor(data: Record<string, any>) {
        this.data = data;
    }

    public static load(fileName = "config.json"): Config {
        const configPath = Config.findConfigFile(fileName);

        if (!configPath) {
            throw new Error(`Could not find ${fileName}`);
        }

        const contents = fs.readFileSync(configPath, "utf8");
        const data = JSON.parse(contents);

        return new Config(data);
    }

    public get<T>(key: string): T {
        if (!(key in this.data)) {
            throw new Error(`Missing configuration key: ${key}`);
        }

        return this.data[key] as T;
    }

    public has(key: string): boolean {
        return key in this.data;
    }

    private static findConfigFile(fileName: string): string | null {
        let currentDir = process.cwd();

        while (true) {
            const candidate = path.join(currentDir, fileName);

            if (fs.existsSync(candidate)) {
                return candidate;
            }

            const parentDir = path.dirname(currentDir);

            if (parentDir === currentDir) {
                return null;
            }

            currentDir = parentDir;
        }
    }
}