import { errorLog, log } from "./logger";

export interface Arg {
  key: string;
  value: string | number | boolean;
  help: string;
}

export class ArgsParser<T extends Record<string, Arg>> {
  readonly rest: string[] = [];

  constructor(public args: T) {}
  
  parse(): T | undefined {
    const rawArgs = process.argv.slice(2);
  
    let allGood = true;
  
    for (let i=0; i<rawArgs.length; i++) {
      const arg = rawArgs[i];
  
      if (arg.startsWith('-')) {
        const argAfterHyphen = arg.startsWith('--') ? arg.substring(2) : arg.substring(1);
        const argObj = Object.values(this.args).find((a) => a.key === argAfterHyphen);
        if (argObj) {
          const argValue = (i < rawArgs.length-1) ? rawArgs[i+1] : '';
          switch (typeof argObj.value) {
            case 'boolean': argObj.value = true; break;
            case 'string': argObj.value = argValue; i++; break;
            case 'number': argObj.value = Number.parseFloat(argValue); i++; break;
          }
        } else {
          errorLog(`Unknown option: ${arg}`);
          allGood = false;
        }
      } else {
        this.rest.push(arg);
      }
    }
  
    return allGood ? this.args : undefined;
  }

  printArgUsage() {
    Object.values(this.args).forEach((a) => {
      const needValue = typeof a.value !== 'boolean';
      const hyphen = a.key.length == 1 ? '-' : '--';
      if (needValue) {
        log(` ${hyphen}${a.key} <${typeof a.value}>: ${a.help}`);
      } else {
        log(` ${hyphen}${a.key}: ${a.help}`);
      }
    });
  }
}