common-ui/src/lib/services/generic.service.ts

import { HttpClient, HttpEvent, HttpParams } from '@angular/common/http';
import { Injector } from '@angular/core';
import { Observable } from 'rxjs';
import { CustomHttpUrlEncodingCodec, HeadersConfiguration, List, RequiredParam, Validate } from '../utils';
import { map, tap } from 'rxjs/operators';

const ROOT_CHANGES_KEY = 'root';

export interface HeaderOptions {
    readonly authorization?: boolean;
    readonly accept?: boolean;
    readonly contentType?: boolean;
}

export interface QueryParam {
    readonly key: string;
    readonly value: string | number | boolean;
}

/**
 * I for interface
 * R for response
 */
export abstract class GenericService<I> {
    protected readonly _http = this._injector.get(HttpClient);
    protected readonly _lastCheckedForChanges = new Map<string, string>([[ROOT_CHANGES_KEY, '0']]);

    protected constructor(protected readonly _injector: Injector, protected readonly _defaultModelPath: string) {}

    get<T = I[]>(): Observable<T>;
    // eslint-disable-next-line @typescript-eslint/unified-signatures
    get<T = I>(id: string, ...args: unknown[]): Observable<T>;
    // eslint-disable-next-line @typescript-eslint/no-unused-vars
    get<T>(id?: string, ...args: unknown[]): Observable<T> {
        return id ? this._getOne<T>([id]) : this.getAll<T>();
    }

    getAll<R = I[]>(modelPath = this._defaultModelPath, queryParams?: List<QueryParam>): Observable<R> {
        return this._http
            .get<R>(`/${encodeURI(modelPath)}`, {
                headers: HeadersConfiguration.getHeaders({ contentType: false }),
                observe: 'body',
                params: this._queryParams(queryParams),
            })
            .pipe(tap(() => this._updateLastChanged()));
    }

    getFor<R = I[]>(entityId: string, queryParams?: List<QueryParam>): Observable<R> {
        return this.getAll<R>(`${this._defaultModelPath}/${entityId}`, queryParams).pipe(tap(() => this._updateLastChanged(entityId)));
    }

    @Validate()
    delete(@RequiredParam() body: unknown, modelPath = this._defaultModelPath, queryParams?: List<QueryParam>): Observable<unknown> {
        let path = `/${encodeURI(modelPath)}`;

        if (typeof body === 'string') {
            path += `/${encodeURIComponent(body)}`;
        }

        return this._http.delete(path, {
            body: body,
            params: this._queryParams(queryParams),
            headers: HeadersConfiguration.getHeaders({ contentType: false }),
            observe: 'body',
        });
    }

    @Validate()
    upload<R = I>(data?: Blob, modelPath = this._defaultModelPath): Observable<HttpEvent<R>> {
        const formParams = new FormData();

        if (data !== undefined) {
            formParams.append('file', data);
        }

        const headers = HeadersConfiguration.getHeaders({ contentType: false });

        return this._http.post<R>(`/${encodeURI(modelPath)}`, formParams, {
            headers,
            observe: 'events',
            reportProgress: true,
        });
    }

    hasChanges$(key = ROOT_CHANGES_KEY): Observable<boolean> {
        const modelPath = key === ROOT_CHANGES_KEY ? '' : `${key}/`;
        const body = { value: this._lastCheckedForChanges.get(key) ?? '0' };
        return this._post<{ value: boolean }>(body, `${this._defaultModelPath}/${modelPath}changes`).pipe(
            map((res: { value: boolean }) => res.value),
        );
    }

    @Validate()
    protected _post<R = I>(
        @RequiredParam() body: unknown,
        modelPath = this._defaultModelPath,
        queryParams?: List<QueryParam>,
    ): Observable<R> {
        return this._http.post<R>(`/${encodeURI(modelPath)}`, body, {
            params: this._queryParams(queryParams),
            headers: HeadersConfiguration.getHeaders(),
            observe: 'body',
        });
    }

    @Validate()
    protected _put<R = I>(
        @RequiredParam() body: unknown,
        modelPath = this._defaultModelPath,
        queryParams?: List<QueryParam>,
    ): Observable<R> {
        return this._http.put<R>(`/${encodeURI(modelPath)}`, body, {
            params: this._queryParams(queryParams),
            headers: HeadersConfiguration.getHeaders(),
            observe: 'body',
        });
    }

    @Validate()
    protected _getOne<R = I>(
        @RequiredParam() path: List,
        modelPath = this._defaultModelPath,
        queryParams?: List<QueryParam>,
    ): Observable<R> {
        const entityPath = path.map(item => encodeURIComponent(item)).join('/');

        return this._http.get<R>(`/${encodeURI(modelPath)}/${entityPath}`, {
            headers: HeadersConfiguration.getHeaders({ contentType: false }),
            params: this._queryParams(queryParams),
            observe: 'body',
        });
    }

    protected _queryParams(queryParams?: List<QueryParam>): HttpParams {
        let queryParameters = new HttpParams({ encoder: new CustomHttpUrlEncodingCodec() });
        queryParams?.forEach(param => {
            if (param?.value !== undefined && param?.value !== null) {
                queryParameters = queryParameters.append(param.key, param.value);
            }
        });

        return queryParameters;
    }

    protected _updateLastChanged(key = ROOT_CHANGES_KEY): void {
        this._lastCheckedForChanges.set(key, new Date().toISOString());
    }
}