import { useEffect, useState, useCallback } from 'react';
import { usePatientServiceContext, useCarePlanServiceContext } from '../services';

import { describeFetchFailure, isRefusedRead } from '../utils/fetchFailureMessage';

interface UseFhirCarePlansOptions {
    autoLoad?: boolean;
    errorMessage?: string;
    forceReload?: boolean;
}

interface UseFhirCarePlansReturn {
    loading: boolean;
    error: string | undefined;
    /** The last load was answered with a 403: refused, not lost. */
    refused: boolean;
    /** This patient's read has answered, one way or the other. Until then an empty list is unknown. */
    answered: boolean;
    loadCarePlans: () => Promise<void>;
    clearError: () => void;
    carePlansBundle: ReturnType<typeof useCarePlanServiceContext>['carePlansBundle'];
    carePlansList: ReturnType<typeof useCarePlanServiceContext>['carePlansList'];
}

export const useFhirCarePlans = (options: UseFhirCarePlansOptions = {}): UseFhirCarePlansReturn => {
    const {
        autoLoad = true,
        errorMessage = "Failed to load care plans",
        forceReload = false
    } = options;

    const { patientState } = usePatientServiceContext();
    const {
        cachedForPatientId,
        fetchCarePlansWithPolling,
        carePlansBundle,
        carePlansList
    } = useCarePlanServiceContext();

    const [loading, setLoading] = useState(false);
    const [error, setError] = useState<string | undefined>();
    const [refused, setRefused] = useState(false);

    const loadCarePlans = useCallback(async () => {
        if (!patientState) {
            return;
        }

        setLoading(true);
        setError(undefined);
        setRefused(false);

        try {
            await fetchCarePlansWithPolling(patientState);
        } catch (err) {
            console.error('Failed to load care plans:', err);
            setError(describeFetchFailure(err, errorMessage));
            setRefused(isRefusedRead(err));
        } finally {
            setLoading(false);
        }
    }, [patientState, fetchCarePlansWithPolling, errorMessage]);

    const clearError = useCallback(() => {
        setError(undefined);
    }, []);

    useEffect(() => {
        if (!autoLoad) return;
        if (!patientState) return;

        // A bundle belonging to SOMEBODY ELSE is not a reason not to ask. This used to fire only when
        // there was no bundle at all, so moving between two charts left the previous patient's list in
        // place, with no request and nothing on screen to say it was not theirs.
        // NOT a refetch on every navigation: same patient, bundle loaded, no request.
        if (!carePlansBundle || cachedForPatientId !== patientState.id || forceReload) {
            loadCarePlans();
        }
    }, [autoLoad, patientState, carePlansBundle, cachedForPatientId, forceReload, loadCarePlans]);

    return {
        loading,
        error,
        refused,
        answered: Boolean(error) || (Boolean(carePlansBundle) && cachedForPatientId === patientState?.id),
        loadCarePlans,
        clearError,
        carePlansBundle,
        carePlansList
    };
};