/*-
 * ============LICENSE_START=======================================================
 * SDC
 * ================================================================================
 * Copyright (C) 2017 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * ============LICENSE_END=========================================================
 */

import { Pipe, PipeTransform } from '@angular/core';
import { ITranslateArgs, TranslateService } from './translate.service';

// tslint:disable-next-line:interface-name
interface ITranslateParams {
    phrase: string;
    args: ITranslateArgs;
    language: string;
}

@Pipe({
    name: 'translate',
    pure: false
})
export class TranslatePipe implements PipeTransform {
    private translated: string;
    private lastParams: ITranslateParams = {
        phrase: undefined,
        args: undefined,
        language: undefined
    };

    constructor(private translateService: TranslateService) {
    }

    public transform(phrase: string, args: ITranslateArgs, language: string = this.translateService.activeLanguage): string {
        const curParams: ITranslateParams = { phrase, args, language };
        if (this.shouldUpdate(curParams)) {
            this.lastParams = curParams;
            this.translated = this.translateService.translate(phrase, args, language);
        }

        return this.translated;
    }

    private shouldUpdate(curParams: ITranslateParams): boolean {
        return (
            curParams.language !== this.lastParams.language ||
            curParams.args !== this.lastParams.args ||
            curParams.phrase !== this.lastParams.phrase
        );
    }
}