@tsailab/xai/dist/esm/node/xstreamable/xnode.sse.fetch.js

The loto-xai is an openai nodejs sdk compatible extension library.

import { createParser } from 'eventsource-parser';
import { XSseProxyError } from './xnode.sse.error';
import { fetch as globalFetch, } from './xnode.sse.types';
import { asyncStreamIterable } from './xnode.sse.util';
export async function xnodeSseFetchProxy(url, options, fetch = globalFetch) {
    const { eventType = 'message', onconnected, onend, onerror, onmessage, logwarn, ...fetchOptions } = options;
    if (!url?.length) {
        throw XSseProxyError.createError(`Illegal parameter of url.`);
    }
    const res = await fetch(url, fetchOptions);
    // error catched
    if (!res.ok) {
        let reason = '';
        try {
            reason = await res.text();
        }
        catch (err) {
            reason = err?.message ?? res.statusText;
            logwarn?.(err, reason);
        }
        const e = XSseProxyError.createError(reason, res);
        if (onerror) {
            onerror(e);
        }
        else {
            throw XSseProxyError.createError(reason, res);
        }
    }
    const parser = createParser({
        onEvent: (em) => {
            if (em.event === eventType && em.data) {
                onmessage(em.data);
            }
            else {
                // ignore
                logwarn?.(em);
            }
        },
        onError: (err) => {
            logwarn?.(err);
            onerror?.(err);
        },
        onComment: (comment) => {
            logwarn?.(comment);
            onend?.(comment);
        },
    });
    const feed = (chunk) => {
        parser.feed(chunk);
    };
    if (!res.body?.getReader) {
        // Vercel polyfills `fetch` with `node-fetch`, which doesn't conform to
        // web standards, so this is a workaround...
        const body = res.body;
        if (!body.on || !body.read) {
            throw new XSseProxyError(`Unsupport 'fetch' implemention`);
        }
        body.on('readable', () => {
            let chunk;
            while (null !== (chunk = body.read())) {
                feed(chunk.toString());
            }
        });
    }
    else {
        for await (const chunk of asyncStreamIterable(res.body)) {
            const str = new TextDecoder().decode(chunk);
            feed(str);
        }
    }
}
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