spy.ts

import { globalState } from "./globalstate"
import { once, Lambda } from "../utils/utils"

export function isSpyEnabled() {
    return !!globalState.spyListeners.length
}

export function spyReport(event) {
    if (!globalState.spyListeners.length) return
    const listeners = globalState.spyListeners
    for (let i = 0, l = listeners.length; i < l; i++) listeners[i](event)
}

export function spyReportStart(event) {
    const change = { ...event, spyReportStart: true }
    spyReport(change)
}

const END_EVENT = { spyReportEnd: true }

export function spyReportEnd(change?) {
    if (change) spyReport({ ...change, spyReportEnd: true })
    else spyReport(END_EVENT)
}

export function spy(listener: (change: any) => void): Lambda {
    globalState.spyListeners.push(listener)
    return once(() => {
        const idx = globalState.spyListeners.indexOf(listener)
        if (idx !== -1) globalState.spyListeners.splice(idx, 1)
    })
}