import { Injectable } from '@angular/core';
import { Http, Response, Headers, RequestOptions } from '@angular/http';
import { environment } from '../../../environments/environment';
import { Observable } from 'rxjs/Rx';

import { contentHeaders } from '../headers';

import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';

@Injectable()
export abstract class RestService<T> {
    protected model;

    constructor(public authHttp: Http) {

    }

    get url() : string {
        return environment.api + this.model;
    }

    private handleError(error: any) {
        return error.json().message || error.json()[0].message || 'Server error';
    }

    index(): Observable<T[]> {
        return this.authHttp.get(this.url)
            .map((res: Response) => res.json())
            .catch((error: any) => Observable.throw(this.handleError(error)));
    }

    view(id: number): Observable<T> {
        return this.authHttp.get(`${this.url}/${id}`)
            .map((res: Response) => res.json())
            .catch((error: any) => Observable.throw(this.handleError(error)));
    }

    create(body: Object): Observable<T> {
        let options = new RequestOptions({ headers: contentHeaders });
        return this.authHttp.post(this.url, body, options)
            .map((res: Response) => res.json())
            .catch((error: any) => Observable.throw(this.handleError(error)));
    }

    update(body: Object): Observable<T> {
        let options = new RequestOptions({ headers: contentHeaders });
        return this.authHttp.put(`${this.url}/${body['id']}`, body, options)
            .map((res: Response) => res.json())
            .catch((error: any) => Observable.throw(this.handleError(error)));
    }

    delete(id: number): Observable<void> {
        return this.authHttp.delete(`${this.url}/${id}`)
            .map((res: Response) => res.json())
            .catch((error: any) => Observable.throw(this.handleError(error)));
    }
}