import {throwError as observableThrowError} from 'rxjs';

import {catchError, map} from 'rxjs/operators';
import {Sort} from './sort';
import {ArrayInterface} from './array-interface';
import {ResourceHelper} from './resource-helper';
import {Resource} from './resource';
import * as url from 'url';
import {Observable} from 'rxjs/internal/Observable';

export class ResourceArray<T extends Resource> implements ArrayInterface<T> {
    public sortInfo: Sort[];

    public proxyUrl: string;
    public rootUrl: string;

    public self_uri: string;
    public next_uri: string;
    public prev_uri: string;
    public first_uri: string;
    public last_uri: string;

    public _embedded;

    public totalElements = 0;
    public totalPages = 1;
    public pageNumber = 1;
    public pageSize: number;

    public result: T[] = [];

    push = (el: T) => {
        this.result.push(el);
    };

    length = (): number => {
        return this.result.length;
    };

    private init = (type: { new(): T }, response: any, sortInfo: Sort[]): ResourceArray<T> => {
        const result: ResourceArray<T> = ResourceHelper.createEmptyResult<T>(this._embedded);
        result.sortInfo = sortInfo;
        ResourceHelper.instantiateResourceCollection(type, response, result);
        return result;
    };

// Load next page
    next = (type: { new(): T }): Observable<ResourceArray<T>> => {
        if (this.next_uri) {
            return ResourceHelper.getHttp().get(ResourceHelper.getProxy(this.next_uri), {headers: ResourceHelper.headers}).pipe(
                map(response => this.init(type, response, this.sortInfo)),
                catchError(error => observableThrowError(error)),);
        }
        return observableThrowError('no next defined');
    };

    prev = (type: { new(): T }): Observable<ResourceArray<T>> => {
        if (this.prev_uri) {
            return ResourceHelper.getHttp().get(ResourceHelper.getProxy(this.prev_uri), {headers: ResourceHelper.headers}).pipe(
                map(response => this.init(type, response, this.sortInfo)),
                catchError(error => observableThrowError(error)),);
        }
        return observableThrowError('no prev defined');
    };

// Load first page

    first = (type: { new(): T }): Observable<ResourceArray<T>> => {
        if (this.first_uri) {
            return ResourceHelper.getHttp().get(ResourceHelper.getProxy(this.first_uri), {headers: ResourceHelper.headers}).pipe(
                map(response => this.init(type, response, this.sortInfo)),
                catchError(error => observableThrowError(error)),);
        }
        return observableThrowError('no first defined');
    };

// Load last page

    last = (type: { new(): T }): Observable<ResourceArray<T>> => {
        if (this.last_uri) {
            return ResourceHelper.getHttp().get(ResourceHelper.getProxy(this.last_uri), {headers: ResourceHelper.headers}).pipe(
                map(response => this.init(type, response, this.sortInfo)),
                catchError(error => observableThrowError(error)),);
        }
        return observableThrowError('no last defined');
    };

// Load page with given pageNumber

    page = (type: { new(): T }, pageNumber: number): Observable<ResourceArray<T>> => {
        this.self_uri = this.self_uri.replace('{?page,size,sort}', '');
        this.self_uri = this.self_uri.replace('{&sort}', '');
        let urlParsed = url.parse(ResourceHelper.getProxy(this.self_uri));
        let query: string = ResourceArray.replaceOrAdd(urlParsed.query, 'size', this.pageSize.toString());
        query = ResourceArray.replaceOrAdd(query, 'page', pageNumber.toString());


        let uri = urlParsed.query ?
            ResourceHelper.getProxy(this.self_uri).replace(urlParsed.query, query) : ResourceHelper.getProxy(this.self_uri).concat(query);
        uri = this.addSortInfo(uri);
        return ResourceHelper.getHttp().get(uri, {headers: ResourceHelper.headers}).pipe(
            map(response => this.init(type, response, this.sortInfo)),
            catchError(error => observableThrowError(error)),);
    };

// Sort collection based on given sort attribute


    sortElements = (type: { new(): T }, ...sort: Sort[]): Observable<ResourceArray<T>> => {
        this.self_uri = this.self_uri.replace('{?page,size,sort}', '');
        this.self_uri = this.self_uri.replace('{&sort}', '');
        let uri = ResourceHelper.getProxy(this.self_uri).concat('?', 'size=', this.pageSize.toString(), '&page=', this.pageNumber.toString());
        uri = this.addSortInfo(uri);
        return ResourceHelper.getHttp().get(uri, {headers: ResourceHelper.headers}).pipe(
            map(response => this.init(type, response, sort)),
            catchError(error => observableThrowError(error)),);
    };

// Load page with given size

    size = (type: { new(): T }, size: number): Observable<ResourceArray<T>> => {
        let uri = ResourceHelper.getProxy(this.self_uri).concat('?', 'size=', size.toString());
        uri = this.addSortInfo(uri);
        return ResourceHelper.getHttp().get(uri, {headers: ResourceHelper.headers}).pipe(
            map(response => this.init(type, response, this.sortInfo)),
            catchError(error => observableThrowError(error)),);
    };

    private addSortInfo(uri: string) {
        if (this.sortInfo) {
            for (const item of this.sortInfo) {
                uri = uri.concat('&sort=', item.path, ',', item.order);
            }
        }
        return uri;
    }

    private static replaceOrAdd(query: string, field: string, value: string): string {
        if (query) {
            let idx: number = query.indexOf(field);
            let idxNextAmp: number = query.indexOf('&', idx) == -1 ? query.indexOf('/', idx) : query.indexOf('&', idx);

            if (idx != -1) {
                let seachValue = query.substring(idx, idxNextAmp);
                query = query.replace(seachValue, field + '=' + value);
            } else {
                query = query.concat("&" + field + '=' + value);
            }
        } else {
            query = "?" + field + '=' + value;
        }
        return query;
    }
}