import React, { useState, useEffect, useCallback } from 'react';
import { useNavigate, useParams } from 'react-router-dom';
import { DismissibleAlert } from '../../../../../components/ui/dismissible-alert';
import { Spacer } from '../../../../../components/ui/spacer';
import { useForm, FormProvider } from 'react-hook-form';
import { DeviceRequest } from 'fhir/r4';
import { Check, FileText } from 'lucide-react';

import { AppHeader, AppSpinner, ProfileLayoutContainer, ScrollableTab, HistoryNavigator, FhirDeviceRequest, FhirDeviceRequestDisplay } from '../../../../../components';
import { PrintableRegion, PrintRecord } from '../../../../../components/ui/print-record';
import {
    useAuthServiceContext,
    useDeviceRequestServiceContext,
    usePatientServiceContext
} from '../../../../../services';
import { useFhirDeviceRequestTargetedBroadcast } from '../../../../../hooks';
import { useArchive } from '../../../../../hooks/useArchive';
import ArchiveConfirmModal from '../../../../../components/ArchiveConfirmModal/ArchiveConfirmModal';
import { describeWriteFailure } from '../../../../../utils/fetchFailureMessage';
import { mayEditRecord } from '../../../../../utils/recordEditability';
import { useSeatStanding } from '../../../../../utils/seatStanding';
import { patientCacheGuard } from '../../../../../utils/cacheOwner';

const EditDeviceRequestPage: React.FC = () => {
    const { deviceRequestId } = useParams<{ deviceRequestId: string }>();
    const navigate = useNavigate();
    const { currentUser, userRole, USER_ROLES, practitionerRoles } = useAuthServiceContext();
    const seatStanding = useSeatStanding();
    const { patientState, encounterState } = usePatientServiceContext();
    const {
        cachedForPatientId: deviceRequestsOwner,
        fetchDeviceRequest,
        transformToFhirDeviceRequest,
        transformFromFhirDeviceRequest,
        createDeviceRequest,
        updateDeviceRequest,
        archiveDeviceRequest,
        deviceRequestsList: rawDeviceRequestsList
    } = useDeviceRequestServiceContext();
    // The cache outlives a change of patient: read only the patient on screen.
    const deviceRequestsGuard = patientCacheGuard(deviceRequestsOwner, patientState?.id);
    const deviceRequestsList = deviceRequestsGuard.list(rawDeviceRequestsList);

    const [loading, setLoading] = useState(false);
    const [submitting, setSubmitting] = useState(false);
    const [success, setSuccess] = useState<string | undefined>();
    const [error, setError] = useState<string | undefined>();
    const [deviceRequest, setDeviceRequest] = useState<DeviceRequest | undefined>();

    const archive = useArchive((reason, note) => archiveDeviceRequest(deviceRequest!, reason, note));

    const isPatient = [USER_ROLES.PATIENT, USER_ROLES.RELATED_PERSON].includes(userRole as string);

    /*
     * MAY THIS VIEWER EDIT THIS RECORD - the question the page below is drawn from.
     *
     * It used to ask `isPatient`, which is one case of it. Writing a DeviceRequest needs a paid clinician seat,
     * resolved per request by the server's `callerMayWrite`, and an unseated practitioner passed every
     * check here: the form opened populated, with Save and Archive, and the write came back refused. A
     * refusal that arrives after the typing has already spent the work.
     *
     * THE LIST IS NOT ENOUGH ON ITS OWN. A control removed only from the list is a client gate with a
     * door beside it - this page is reachable by URL - so the same question is asked again here.
     */
    const seat = mayEditRecord({ seatStanding,
        resourceType: 'DeviceRequest',
        viewerIsStaff: !isPatient,
        practitionerRoles,
    });

    const mayWrite = !isPatient && seat.mayEdit;
    const isNew = deviceRequestId === 'new';
    const spacerMargin = '24px';

    const methods = useForm({
        defaultValues: {
            status: '',
            intent: '',
            priority: '',
            codeCodeableConcept: null,
            occurrenceType: '',
            occurrenceDateTime: '',
            occurrenceTiming: null,
            reasonCode: [],
            reasonReference: [],
            supportingInfo: [],
            performerType: null,
            performer: null,
            note: []
        }
    });

    const { handleSubmit, reset } = methods;

    const init = useCallback((deviceRequest: DeviceRequest) => {
        reset(transformFromFhirDeviceRequest(deviceRequest));
        setDeviceRequest(deviceRequest);
    }, [transformFromFhirDeviceRequest]);

    useFhirDeviceRequestTargetedBroadcast({
        deviceRequest,
        deviceRequestId,
        onUpdate: init,
        onDelete: () => navigate('..', { relative: 'path' })
    });

    useEffect(() => {
        const loadDeviceRequest = async () => {
            if (isNew || deviceRequest) return;

            const foundDeviceRequest = deviceRequestsList?.find(dr => dr.id === deviceRequestId);

            if (foundDeviceRequest) {
                init(foundDeviceRequest);
                return;
            }

            setLoading(true);
            try {
                const fetchedDeviceRequest = await fetchDeviceRequest(deviceRequestId as string);
                init(fetchedDeviceRequest);
            } catch (err) {
                console.error('Error loading device request:', err);
                setError('Could not load device request. Try again.');
            } finally {
                setLoading(false);
            }
        };
        loadDeviceRequest();
    }, [deviceRequest, deviceRequestsList, deviceRequestId, fetchDeviceRequest, init]);

    const onSubmit = async (data: any) => {
        if (isPatient) return;

        if (!patientState) {
            setError('Patient information is missing. Please try again.');
            return;
        }

        setSubmitting(true);
        setSuccess(undefined);
        setError(undefined);

        try {
            if (isNew) {
                await createDeviceRequest(transformToFhirDeviceRequest(data, patientState, encounterState, currentUser?.fhir));

                navigate('..', { relative: 'path' });
            } else {
                await updateDeviceRequest({
                    id: deviceRequest?.id,
                    ...transformToFhirDeviceRequest(data)
                });
            }

            setSuccess(`Allergy/intolerance ${isNew ? 'created' : 'updated'} successfully.`);
            setTimeout(() => setSuccess(undefined), 3_000);
        } catch (err: any) {
            console.error(`Error ${isNew ? 'creating' : 'updating'} device request:`, err);
            setError(describeWriteFailure(err, `Failed to ${isNew ? 'create' : 'update'} device request`));
        } finally {
            setSubmitting(false);
        }
    };

    if (loading) {
        return <AppSpinner/>;
    }

    return (
        <HistoryNavigator<DeviceRequest> resourceType="DeviceRequest" resourceId={deviceRequestId || ''}>
            {(showHistory) => (
                <FormProvider {...methods}>

                    <form onSubmit={handleSubmit(onSubmit)}>
                        <AppHeader showBackButton={true}>

                            {!isNew && (
                                <button
                                    type="button"
                                    className="btn btn-blue"
                                    disabled={submitting}
                                    onClick={showHistory}
                                >
                                    <FileText />
                                    History
                                </button>
                            )}

                            {/* SAID, NOT WITHHELD. A Save that simply disappears reads as a broken screen or as a
                                permission the reader has lost, and both send them to an administrator to check permissions
                                that are already correct. A seat is nameable, and a practice can enable one in a minute. */}
                            {!isPatient && !seat.mayEdit && (
                                <p className="text-sm text-secondary max-w-[22rem]">{seat.reason}</p>
                            )}

                            {mayWrite && (
                                <button
                                    className={`btn btn-green${submitting ? ' btn-busy' : ''}`}
                                    disabled={submitting}
                                    type="submit"
                                >
                                    <Check />
                                    Save
                                </button>
                            )}

                            {!isNew && mayWrite && (
                                <button type="button"
                                        className="btn btn-green"
                                        onClick={archive.open}>
                                    Archive
                                </button>
                            )}

                            {/* The record has to be able to leave the screen. Without this a
                                patient sending it to somebody not on Akashic photographs a scrolling
                                page or prints the browser window, navigation and all. */}
                            {!mayWrite && deviceRequest && <PrintRecord/>}
                        </AppHeader>

                        {success && (
                            <>
                                <DismissibleAlert status="success" onDismiss={() => setSuccess(undefined)}>
                                    {success}
                                </DismissibleAlert>

                                <Spacer margin={spacerMargin}/>
                            </>
                        )}

                        {error && (
                            <>
                                <DismissibleAlert status="error" onDismiss={() => setError(undefined)}>
                                    <div style={{ whiteSpace: 'pre-line' }}>{error}</div>
                                </DismissibleAlert>

                                <Spacer margin={spacerMargin}/>
                            </>
                        )}

                        <ScrollableTab>
                            <ProfileLayoutContainer>
                                {/* THE READER GETS THE RECORD, NOT THE FORM SWITCHED OFF. `FhirDeviceRequestDisplay`
                                    already renders this resource for the history viewer, the reference
                                    preview and the patient snapshot, so a patient was the one audience shown
                                    the edit form instead of the view written for reading it. The old shape
                                    wrapped the form in `inert`, which is worse than it looks: the fields stay
                                    in the accessibility tree, so a screen reader still reads them as inputs,
                                    and a text range over the subtree returns an EMPTY STRING - a patient
                                    could not select or copy their own record. */}
                                {!mayWrite && deviceRequest ? (
                                    <PrintableRegion>
                                        <FhirDeviceRequestDisplay deviceRequest={deviceRequest}
                                                               isOpen={true}
                                                               onClose={() => undefined}/>
                                    </PrintableRegion>
                                ) : (
                                    <FhirDeviceRequest elevated={true}
                                                       disabled={submitting}/>
                                )}
                            </ProfileLayoutContainer>
                        </ScrollableTab>

                        {mayWrite && (
                            <ArchiveConfirmModal
                                open={archive.isOpen}
                                onOpenChange={(o) => { if (!o) archive.close(); }}
                                resourceLabel="Device Request"
                                submitting={archive.submitting}
                                error={archive.error}
                                onConfirm={async (reason, note) => {
                                    if (await archive.submit(reason, note)) {
                                        navigate('..', { relative: 'path' });
                                    }
                                }}
                            />
                        )}
                    </form>
                </FormProvider>
            )}
        </HistoryNavigator>
    );
};

export default EditDeviceRequestPage;