import {promisify} from './lang/promise';
import {writeFile} from 'fs';

const writeFilePromise = promisify(writeFile);

const DEFAULT_ENCODING = 'utf8';

export class FileWriter {
    private readonly path: string;
    private readonly encoding: string;
    private append: boolean;

    constructor(path: string, append: boolean, encoding?: string) {
        this.path = path;
        this.append = append;
        this.encoding = encoding || DEFAULT_ENCODING;
    }

    async write(string: string): Promise<void> {
        await writeFilePromise(this.path, string, this.getWriteOption());
        this.append = true;
    }

    private getWriteOption() {
        return {
            encoding: this.encoding,
            flag: this.append ? 'a' : 'w'
        };
    }
}