/** Accumulate deltas and render at most once per animation frame. */
export function createStreamRenderer({onReply, onThinking, schedule = callback => requestAnimationFrame(callback), cancel = id => cancelAnimationFrame(id)}) {
    const text = {reply: "", thinking: ""};
    const dirty = new Set();
    let frame = null;
    const flush = () => {
        if (frame !== null) cancel(frame);
        frame = null;
        if (dirty.has("thinking")) onThinking?.(text.thinking);
        if (dirty.has("reply")) onReply?.(text.reply);
        dirty.clear();
    };
    const update = (target, value, replace = false) => {
        text[target] = replace ? value : text[target] + value;
        dirty.add(target);
        if (frame === null) frame = schedule(flush);
    };
    return {
        onChunk: ({chunk, fullReply}) => update("reply", typeof fullReply === "string" ? fullReply : chunk, typeof fullReply === "string"),
        onThinking: ({chunk, fullThinking}) => update("thinking", typeof fullThinking === "string" ? fullThinking : chunk, typeof fullThinking === "string"),
        onReplace: ({target, text: value}) => update(target, value, true),
        flush,
        dispose() {
            if (frame !== null) cancel(frame);
            frame = null;
            dirty.clear();
        }
    };
}