public with sharing class SalesforceReportApi {

    private final static String REPORTS_RESOURCE = '/services/data/v44.0/analytics/reports/';

    private static HttpResponse execute(String method, String restResource) {

        HttpRequest request = new HttpRequest();

        request.setMethod(method);
        request.setEndpoint(endpoint + restResource);
        request.setTimeout(120000); // 2 Minutes

        request.setHeader('Accept', 'application/json');
        request.setHeader('Content-Type',  'application/json');
        request.setHeader('Authorization', 'OAuth ' + UserInfo.getSessionID());
        request.setHeader('Authorization', 'Bearer ' + UserInfo.getSessionID());
        request.setCompressed(false);

        HttpResponse httpResponse = new Http().send(request);

        return httpResponse;
    }

    private static String endpoint {
        get {
            return URL.getOrgDomainUrl().toExternalForm();
        }
    }

    public static MatrixReport getMatrixReport(Id reportId) {

        HttpResponse response = execute(HttpMethod.GET, REPORTS_RESOURCE + reportId);

        return (MatrixReport) JSON.deserialize(response.getBody(), MatrixReport.class);
    }
}