import { useCallback } from "react";

import { environment } from "../environments/environment.ts";
import { useHttpService } from "./HttpService.tsx";

/**
 * The in-product help assistant., slices 4 and 5.
 *
 * `fhirBaseApi`, NOT `apiUrl` - `/R4/assistant/ask` is declared in `templates/fhir/02-fhir-base.yaml`,
 * and that template's gateway is the one `environment.fhirBaseApi` resolves to. Already ends in `/R4`;
 * do not append another.
 *
 * THIS COMMENT PREVIOUSLY SAID `apiUrl` AND WAS WRONG, WHICH IS WORTH KEEPING RATHER THAN QUIETLY
 * CORRECTING. It named the right template and then drew the wrong host from it - `02-fhir-base.yaml`
 * serves `fhir-base....`, not `api....`. **A confident comment asserting the exact thing it got wrong is
 * worse than no comment**, because the next reader checks it and moves on.
 *
 * HOW IT WAS CAUGHT, and it is the cheap probe worth reusing: POST the path to each candidate host
 * unauthenticated and read the STATUS, not the body.
 *
 * api.staging... 403 <- empty body: API Gateway's "no such resource", before any authorizer
 * fhir-base.staging... 401 <- the route EXISTS and the authorizer refused an anonymous caller
 * fhir-clinical.staging... 403
 *
 * **401 means the route is there; a bare 403 means it is not.** In a browser the wrong host surfaces
 * only as a failed CORS preflight and `net::ERR_FAILED`, which reads like a network or CORS problem and
 * sends you to the wrong place entirely - exactly what `ImagingFrameService` documents about this trap.
 */
const API_URL = environment.fhirBaseApi;

/** A place in the product the answer points at. The server resolved it; the client only renders it. */
export interface AssistantDestinationLink {
    id: string;
    label: string;
    path: string;
    /**
 * Resolved by the server from the record it read. Only ever ids it fetched itself, never anything
 * the model wrote - it picks a numbered entry and the server turns that into this.
 */
    params?: { visitId?: string };
}

export interface AssistantReply {
    answer: string;
    /**
 * `clinical` when the question needed a practitioner, `unknown` when the assistant could not answer.
 * Worth rendering differently from an ordinary answer: a refusal is a real outcome the reader
 * should recognise as deliberate, not as the assistant trailing off.
 */
    refusal: "clinical" | "unknown" | null;
    destinations: AssistantDestinationLink[];
}

/**
 * THE PAGE IS SENT AS A ROUTE AND NOTHING ELSE. The server drops it unless it is route-shaped, so
 * anything else is discarded there too - but sending a title, a patient name or a search term "for
 * context" is the client half of the same mistake, and it is the half that is easy to add later.
 */
export interface AssistantQuestion {
    question: string;
    page?: string;
}

export const useAssistantService = () => {
    const { post } = useHttpService();

    const ask = useCallback(
        (input: AssistantQuestion): Promise<AssistantReply> =>
            post<AssistantReply>(`${API_URL}/assistant/ask`, input),
        [post],
    );

    return { ask };
};