function imageItem(url, index) {
    return {url, src: url, index, attempt: 0, failed: false, settled: false}
}

export function startImages(urls) {
    return urls.length ? [imageItem(urls[0], 0)] : []
}

export function settleImage(items, urls, item, failed = false) {
    // Ignore events from images removed by a page change or dialog close.
    if (!items.includes(item)) return
    item.failed = failed
    if (item.settled) return
    item.settled = true
    if (items.length < urls.length)
        items.push(imageItem(urls[items.length], items.length))
}

export function retryImage(item) {
    item.failed = false
    item.attempt++
    item.src = item.url + (item.url.includes('?') ? '&' : '?') + 'retry=' + item.attempt
}