import { useCallback } from 'react';
import { environment } from '../environments/environment.ts';
import { useHttpService } from './HttpService.tsx';

// apiUrl, NOT fhirClinicalApi. `/R4/imaging/*` is declared in api.yaml, on the gateway that
// resolves to environment.apiUrl - the same base Stage 1's ImagingUploadService.tsx uses for
// /R4/imaging/import. environment.fhirClinicalApi is a DIFFERENT gateway serving FHIR resource types
// (/R4/ImagingStudy and friends, in templates/fhir/03-fhir-clinical.yaml); it declares no imaging
// path at all. Pointing here would make API Gateway return 403 "Missing Authentication Token" for an
// unmatched resource BEFORE the authorizer runs - which reads like an auth failure, not a wrong host,
// and would show as "This imaging study could not be loaded" for every user with no frame ever fetched.
//
// Already ends in /R4 - do not append another. And never environment.healthLakeEndpoint: that key does
// not exist on environment.
const API_URL = environment.apiUrl;

// The shape AWS HealthImaging returns from GetImageSetMetadata, narrowed to the fields this feature
// reads. Deliberately permissive Record<string, unknown> for the DICOM blocks rather than an
// enumeration of every tag: the converter in healthImagingToWadoRs.ts reads a known handful by name
// and narrows each at the point of use, so declaring 400 optional DICOM keywords here would buy
// nothing and rot immediately.
export interface HealthImagingInstance {
    DICOM?: Record<string, unknown>;
    ImageFrames?: { ID: string }[];
    // Sits on the instance, NOT inside DICOM - and is NOT the same value as
    // DICOM.TransferSyntaxUID. That one is the uploaded file's syntax; this is what HealthImaging
    // actually stores and hands back from GetImageFrame. Verified live on the imported CT:
    // DICOM.TransferSyntaxUID = 1.2.840.10008.1.2 (Implicit VR LE) while
    // StoredTransferSyntaxUID = 1.2.840.10008.1.2.4.202 (HTJ2K), for the same instance.
    StoredTransferSyntaxUID?: string;
}

export interface HealthImagingSeries {
    DICOM?: Record<string, unknown>;
    Instances?: Record<string, HealthImagingInstance>;
}

export interface HealthImagingMetadata {
    Study?: {
        DICOM?: Record<string, unknown>;
        Series?: Record<string, HealthImagingSeries>;
    };
}

// Exported as a plain function, not a hook method, because the Cornerstone image loader builds these
// urls from inside a callback that is not a React render - see dicomLoader.ts.
export const frameUrl = (imageSetId: string, studyId: string, frameId: string): string =>
    `${API_URL}/imaging/imageset/${encodeURIComponent(imageSetId)}/frame`
    + `?study=${encodeURIComponent(studyId)}&frameId=${encodeURIComponent(frameId)}`;

export const metadataUrl = (imageSetId: string, studyId: string): string =>
    `${API_URL}/imaging/imageset/${encodeURIComponent(imageSetId)}/metadata`
    + `?study=${encodeURIComponent(studyId)}`;

export const useImagingFrameService = () => {
    const { get } = useHttpService();

    const fetchImageSetMetadata = useCallback(
        (imageSetId: string, studyId: string): Promise<HealthImagingMetadata> =>
            get<HealthImagingMetadata>(metadataUrl(imageSetId, studyId)),
        [get]
    );

    return { fetchImageSetMetadata };
};