// burst-broadcast.js  (CommonJS)
function createBurstBroadcaster(broadcast, {
    event = 'message',      // 要广播的事件名
    idleMs = 10_000,        // 静默阈值
    startPayload = 'start', // 静默后先发的内容
    startOnFirst = true,    // 首条是否也先发 start
} = {}) {
    let lastTs = 0;

    return function burstSend(data) {
        const now = Date.now();
        const idleTooLong = (now - lastTs) >= idleMs;
        const isFirst = lastTs === 0;

        if ((startOnFirst && isFirst) || idleTooLong) {
            broadcast(event, startPayload); // 先发“start”
        }

        broadcast(event, data);           // 再发真实数据
        lastTs = now;
    };
}

module.exports = { createBurstBroadcaster };