import { meta, peekMeta } from '@ember/-internals/meta';
import { assert } from '@ember/debug';
import { objectAt } from './array';
import { EACH_PROXIES } from './each_proxy_events';
import { addObserver, removeObserver } from './observer';
import { notifyPropertyChange } from './property_events';
export function eachProxyFor(array) {
    let eachProxy = EACH_PROXIES.get(array);
    if (eachProxy === undefined) {
        eachProxy = new EachProxy(array);
        EACH_PROXIES.set(array, eachProxy);
    }
    return eachProxy;
}
class EachProxy {
    constructor(content) {
        this._content = content;
        this._keys = undefined;
        meta(this);
    }
    // ..........................................................
    // ARRAY CHANGES
    // Invokes whenever the content array itself changes.
    arrayWillChange(content, idx, removedCnt /*, addedCnt */) {
        // eslint-disable-line no-unused-vars
        let keys = this._keys;
        if (!keys) {
            return;
        }
        let lim = removedCnt > 0 ? idx + removedCnt : -1;
        if (lim > 0) {
            for (let key in keys) {
                removeObserverForContentKey(content, key, this, idx, lim);
            }
        }
    }
    arrayDidChange(content, idx, _removedCnt, addedCnt) {
        let keys = this._keys;
        if (!keys) {
            return;
        }
        let lim = addedCnt > 0 ? idx + addedCnt : -1;
        let meta = peekMeta(this);
        for (let key in keys) {
            if (lim > 0) {
                addObserverForContentKey(content, key, this, idx, lim);
            }
            notifyPropertyChange(this, key, meta);
        }
    }
    // ..........................................................
    // LISTEN FOR NEW OBSERVERS AND OTHER EVENT LISTENERS
    // Start monitoring keys based on who is listening...
    willWatchProperty(property) {
        this.beginObservingContentKey(property);
    }
    didUnwatchProperty(property) {
        this.stopObservingContentKey(property);
    }
    // ..........................................................
    // CONTENT KEY OBSERVING
    // Actual watch keys on the source content.
    beginObservingContentKey(keyName) {
        let keys = this._keys;
        if (keys === undefined) {
            keys = this._keys = Object.create(null);
        }
        if (!keys[keyName]) {
            keys[keyName] = 1;
            let content = this._content;
            let len = content.length;
            addObserverForContentKey(content, keyName, this, 0, len);
        }
        else {
            keys[keyName]++;
        }
    }
    stopObservingContentKey(keyName) {
        let keys = this._keys;
        if (keys !== undefined && keys[keyName] > 0 && --keys[keyName] <= 0) {
            let content = this._content;
            let len = content.length;
            removeObserverForContentKey(content, keyName, this, 0, len);
        }
    }
    contentKeyDidChange(_obj, keyName) {
        notifyPropertyChange(this, keyName);
    }
}
function addObserverForContentKey(content, keyName, proxy, idx, loc) {
    while (--loc >= idx) {
        let item = objectAt(content, loc);
        if (item) {
            assert(`When using @each to observe the array \`${content.toString()}\`, the array must return an object`, typeof item === 'object');
            addObserver(item, keyName, proxy, 'contentKeyDidChange');
        }
    }
}
function removeObserverForContentKey(content, keyName, proxy, idx, loc) {
    while (--loc >= idx) {
        let item = objectAt(content, loc);
        if (item) {
            removeObserver(item, keyName, proxy, 'contentKeyDidChange');
        }
    }
}