/*!
 * devextreme-angular-test
 * Version: 17.2.8
 * Build date: Mon Feb 05 2018
 *
 * Copyright (c) 2012 - 2018 Developer Express Inc. ALL RIGHTS RESERVED
 *
 * This software may be modified and distributed under the terms
 * of the MIT license. See the LICENSE file in the root of the project for details.
 *
 * https://github.com/DevExpress/devextreme-angular
 */

import {
    Injectable,
    SimpleChanges,
    IterableDiffers
} from '@angular/core';

import {
    DxComponent
} from './component';

@Injectable()
export class IterableDifferHelper {

    private _host: DxComponent;
    private _propertyDiffers: { [id: string]: any; } = {};

    constructor(private _differs: IterableDiffers) { }

    setHost(host: DxComponent) {
        this._host = host;
    }

    setup(prop: string, changes: SimpleChanges) {
        if (prop in changes) {
            const value = changes[prop].currentValue;
            this.setupSingle(prop, value);
        }
    }

    setupSingle(prop: string, value: any) {
        if (value && Array.isArray(value)) {
            if (!this._propertyDiffers[prop]) {
                try {
                    this._propertyDiffers[prop] = this._differs.find(value).create(null);
                    return true;
                } catch (e) { }
            }
        } else {
            delete this._propertyDiffers[prop];
        }

        return false;
    }

    getChanges(prop: string, value: any) {
        if (this._propertyDiffers[prop]) {
            return this._propertyDiffers[prop].diff(value);
        }
    }

    doCheck(prop: string) {
        if (this._propertyDiffers[prop]) {
            const changes = this.getChanges(prop, this._host[prop]);
            if (changes && this._host.instance) {
                this._host.lockWidgetUpdate();
                this._host.instance.option(prop, this._host[prop]);
            }
        }
    }

}