import { arrayContentDidChange, arrayContentWillChange } from './array_events';
import { addListener, removeListener } from './events';
import { notifyPropertyChange } from './property_events';
import { get } from './property_get';
const EMPTY_ARRAY = Object.freeze([]);
export function objectAt(array, index) {
    if (Array.isArray(array)) {
        return array[index];
    }
    else {
        return array.objectAt(index);
    }
}
export function replace(array, start, deleteCount, items = EMPTY_ARRAY) {
    if (Array.isArray(array)) {
        replaceInNativeArray(array, start, deleteCount, items);
    }
    else {
        array.replace(start, deleteCount, items);
    }
}
const CHUNK_SIZE = 60000;
// To avoid overflowing the stack, we splice up to CHUNK_SIZE items at a time.
// See https://code.google.com/p/chromium/issues/detail?id=56588 for more details.
export function replaceInNativeArray(array, start, deleteCount, items) {
    arrayContentWillChange(array, start, deleteCount, items.length);
    if (items.length <= CHUNK_SIZE) {
        array.splice(start, deleteCount, ...items);
    }
    else {
        array.splice(start, deleteCount);
        for (let i = 0; i < items.length; i += CHUNK_SIZE) {
            let chunk = items.slice(i, i + CHUNK_SIZE);
            array.splice(start + i, 0, ...chunk);
        }
    }
    arrayContentDidChange(array, start, deleteCount, items.length);
}
function arrayObserversHelper(obj, target, opts, operation, notify) {
    let willChange = (opts && opts.willChange) || 'arrayWillChange';
    let didChange = (opts && opts.didChange) || 'arrayDidChange';
    let hasObservers = get(obj, 'hasArrayObservers');
    operation(obj, '@array:before', target, willChange);
    operation(obj, '@array:change', target, didChange);
    if (hasObservers === notify) {
        notifyPropertyChange(obj, 'hasArrayObservers');
    }
    return obj;
}
export function addArrayObserver(array, target, opts) {
    return arrayObserversHelper(array, target, opts, addListener, false);
}
export function removeArrayObserver(array, target, opts) {
    return arrayObserversHelper(array, target, opts, removeListener, true);
}