declare const TextEncoder: any | undefined;
declare const TextDecoder: any | undefined;

function isValidUtf8(data: Uint8Array): boolean {
    const toStringAndBack = Buffer.from(Buffer.from(data).toString('utf8'), 'utf8');
    return Buffer.compare(Buffer.from(data), toStringAndBack) === 0;
}

export function toUtf8(str: string): Uint8Array {
    if (typeof TextEncoder !== 'undefined') {
        return new TextEncoder().encode(str);
    }

    // Use Buffer hack instead of nodejs util.TextEncoder to ensure
    // webpack does not bundle the util module for browsers.
    return new Uint8Array(Buffer.from(str, 'utf8'));
}

export function fromUtf8(data: Uint8Array): string {
    if (typeof TextDecoder !== 'undefined') {
        return new TextDecoder('utf-8', { fatal: true }).decode(data);
    }

    // Use Buffer hack instead of nodejs util.TextDecoder to ensure
    // webpack does not bundle the util module for browsers.
    // Buffer.toString has no fatal option
    if (!isValidUtf8(data)) {
        throw new Error('Invalid UTF8 data');
    }
    return Buffer.from(data).toString('utf8');
}