export const topicUrl = (baseUrl, topic) => `${baseUrl}/${topic}`;
export const topicUrlWs = (baseUrl, topic) => `${topicUrl(baseUrl, topic)}/ws`
    .replaceAll("https://", "wss://")
    .replaceAll("http://", "ws://");
export const topicUrlWsWithSince = (baseUrl, topic, since) => `${topicUrlWs(baseUrl, topic)}?since=${since}`;
export const topicUrlJson = (baseUrl, topic) => `${topicUrl(baseUrl, topic)}/json`;
export const topicUrlJsonPoll = (baseUrl, topic) => `${topicUrlJson(baseUrl, topic)}?poll=1`;
export const shortUrl = (url) => url.replaceAll(/https?:\/\//g, "");
export const shortTopicUrl = (baseUrl, topic) => shortUrl(topicUrl(baseUrl, topic));

// From: https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch
export async function* fetchLinesIterator(fileURL) {
    const utf8Decoder = new TextDecoder('utf-8');
    const response = await fetch(fileURL);
    const reader = response.body.getReader();
    let { value: chunk, done: readerDone } = await reader.read();
    chunk = chunk ? utf8Decoder.decode(chunk) : '';

    const re = /\n|\r|\r\n/gm;
    let startIndex = 0;
    let result;

    for (;;) {
        let result = re.exec(chunk);
        if (!result) {
            if (readerDone) {
                break;
            }
            let remainder = chunk.substr(startIndex);
            ({ value: chunk, done: readerDone } = await reader.read());
            chunk = remainder + (chunk ? utf8Decoder.decode(chunk) : '');
            startIndex = re.lastIndex = 0;
            continue;
        }
        yield chunk.substring(startIndex, result.index);
        startIndex = re.lastIndex;
    }
    if (startIndex < chunk.length) {
        yield chunk.substr(startIndex); // last line didn't end in a newline char
    }
}