import { Injectable } from '@angular/core';
import { HttpClient, HttpErrorResponse, HttpRequest } from '@angular/common/http';

import { Observable, throwError } from 'rxjs';
import { catchError, tap } from 'rxjs/operators';

import { Sermon, MultipleSermonResponse, SingleSermonResponse } from '../interfaces/sermon';
import { SERMONS_BY_ID,
         SERMONS_BY_PAGE_URL, 
         SERMON_MP3_BASE_URL,
         SERMONS_BY_SEARCH_URL,
         SERMON_ADD_URL,
         SERMON_DELETE_URL,
         SERMON_UPDATE_URL } from '../constants/urls';

@Injectable()
export class SermonService {    
    private pageSize: number = 10;

    constructor(private httpClient: HttpClient){ 

    }

    getSermons(count: number): Observable<MultipleSermonResponse> {
        let url = SERMONS_BY_PAGE_URL + 1 + "?pageSize=" + 5;
        return this.httpClient.get<MultipleSermonResponse>(url).pipe(tap(e => this.setMultipleDates(e)), catchError(this.handleError));
    };

    getSermonsByPage(page: number): Observable<MultipleSermonResponse>{
        let url = SERMONS_BY_PAGE_URL + page + "?pageSize=" + this.pageSize;
        return this.httpClient.get<MultipleSermonResponse>(url).pipe(tap(e => this.setMultipleDates(e)), catchError(this.handleError));
    }

    getSermonById(id: number): Observable<SingleSermonResponse>{
        let url = SERMONS_BY_ID + id + "?pageSize=" + this.pageSize;
        return this.httpClient.get<SingleSermonResponse>(url).pipe(tap(e => this.setSingleDate(e)), catchError(this.handleError));
    }

    searchSermons(searchTerm: string, page: number): Observable<MultipleSermonResponse>{
        let url = SERMONS_BY_SEARCH_URL + "?searchTerm=" + searchTerm + "&page=" + page + "&pageSize=" + this.pageSize;
        return this.httpClient.get<MultipleSermonResponse>(url).pipe(tap(e => this.setMultipleDates(e)), catchError(this.handleError));
    }

    addSermon(sermon: Sermon, sermonFile: File){
        let fd = new FormData();
        fd.append("title",sermon.title);
        fd.append("description",sermon.description);
        fd.append("date",new Date(sermon.date).getTime().toString()); //Pas date as milliseconds since 1970
        fd.append("author",sermon.author);
        fd.append("file",sermonFile);
        fd.append("timezoneOffset",new Date().getTimezoneOffset().toString());
        const req = new HttpRequest('POST', SERMON_ADD_URL, fd, {
            reportProgress: true,
            withCredentials: true
          });
          return this.httpClient.request(req).pipe(
            catchError(this.handleError)
          );
    }

    updateSermon(sermon: Sermon){
        let fd = new FormData();
        fd.append("id",sermon.id.toString());
        fd.append("title",sermon.title);
        fd.append("description",sermon.description);
        fd.append("date",new Date(sermon.date).toUTCString());
        fd.append("author",sermon.author);
        fd.append("timezoneOffset",new Date().getTimezoneOffset().toString());
        return this.httpClient.put<Sermon>(SERMON_UPDATE_URL,fd,{withCredentials:true})
                              .pipe(catchError(this.handleError));
    }
    

    deleteSermon(sermonId: number){
        let options = {
            withCredentials: true,
            body: {
                "id" : sermonId
            }
        };
        return this.httpClient.delete(SERMON_DELETE_URL,options)
                        .pipe(catchError(this.handleError));
    }

    setSingleDate(e : SingleSermonResponse): SingleSermonResponse {
        e.sermon = this.setDates(e.sermon);
        return e;
    }

    setMultipleDates(e : MultipleSermonResponse) : MultipleSermonResponse {
        e.sermons.forEach(s => {
            s = this.setDates(s);
        });
        return e;
    }

    setDates(sermon: Sermon): Sermon {
        sermon.date = new Date(sermon.date);
        sermon.uploadDate = new Date(sermon.uploadDate);
        return sermon;
    }

    private handleError(error: HttpErrorResponse) {
        if (error.error instanceof ErrorEvent) {
          // A client-side or network error occurred. Handle it accordingly.
          console.error('An error occurred:', error.error.message);
        } else {
          // The backend returned an unsuccessful response code.
          // The response body may contain clues as to what went wrong,
          console.error(
            `Backend returned code ${error.status}, ` +
            `body was: ${error.error}`);
        }
        // return an observable with a user-facing error message
        return throwError(
          'Something bad happened; please try again later.');
    };
}