import { 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 { Immunization } from 'fhir/r4';
import { Check, FileText } from 'lucide-react';
import {
    useAuthServiceContext,
    useImmunizationServiceContext,
    usePatientServiceContext
} from '../../../../../services';
import { AppHeader, AppSpinner, ProfileLayoutContainer, ScrollableTab, HistoryNavigator, FhirImmunization, FhirImmunizationDisplay } from '../../../../../components';
import { PrintableRegion, PrintRecord } from '../../../../../components/ui/print-record';
import { useFhirImmunizationTargetedBroadcast } from '../../../../../hooks';
import { useArchive } from '../../../../../hooks/useArchive';
import ArchiveConfirmModal from '../../../../../components/ArchiveConfirmModal/ArchiveConfirmModal';
import { describeWriteFailure } from '../../../../../utils/fetchFailureMessage';
import { patientCacheGuard } from '../../../../../utils/cacheOwner';

const EditImmunizationPage: React.FC = () => {
    const { immunizationId } = useParams<{ immunizationId: string }>();
    const navigate = useNavigate();
    const { userRole, USER_ROLES } = useAuthServiceContext();
    const { patientState, encounterState } = usePatientServiceContext();
    const {
        cachedForPatientId: immunizationsOwner,
        fetchImmunization,
        transformToFhirImmunization,
        transformFromFhirImmunization,
        createImmunization,
        updateImmunization,
        archiveImmunization,
        immunizationsList: rawImmunizationsList
    } = useImmunizationServiceContext();
    // The cache outlives a change of patient: read only the patient on screen.
    const immunizationsGuard = patientCacheGuard(immunizationsOwner, patientState?.id);
    const immunizationsList = immunizationsGuard.list(rawImmunizationsList);

    const [loading, setLoading] = useState(false);
    const [submitting, setSubmitting] = useState(false);
    const [success, setSuccess] = useState<string | undefined>();
    const [error, setError] = useState<string | undefined>();
    const [immunization, setImmunization] = useState<Immunization | undefined>();

    const isPatient = [USER_ROLES.PATIENT, USER_ROLES.RELATED_PERSON].includes(userRole as string);
    const isNew = immunizationId === 'new';
    const spacerMargin = '24px';

    const methods = useForm({
        defaultValues: {
            status: '',
            statusReason: null,
            vaccineCode: null,
            encounter: null,
            occurrenceDateTime: '',
            recorded: '',
            primarySource: true,
            reportOrigin: null,
            location: null,
            manufacturer: null,
            lotNumber: '',
            expirationDate: '',
            site: null,
            route: null,
            doseQuantity: null,
            performer: [],
            note: [],
            reasonCode: [],
            isSubpotent: false,
            subpotentReason: [],
            programEligibility: [],
            fundingSource: null,
            reaction: [],
            protocolApplied: []
        }
    });

    const { handleSubmit, reset } = methods;

    const init = useCallback((immunization: Immunization) => {
        reset(transformFromFhirImmunization(immunization));
        setImmunization(immunization);
    }, [transformFromFhirImmunization]);

    useFhirImmunizationTargetedBroadcast({
        immunization,
        immunizationId,
        onUpdate: init,
        onDelete: () => navigate('..', { relative: 'path' })
    });

    const archive = useArchive((reason, note) => archiveImmunization(immunization!, reason, note));

    useEffect(() => {
        const loadImmunization = async () => {
            if (isNew || immunization) return;

            const foundImmunization = immunizationsList?.find(i => i.id === immunizationId);

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

            setLoading(true);
            try {
                const fetchedImmunization = await fetchImmunization(immunizationId as string);
                init(fetchedImmunization);
            } catch (err) {
                console.error('Error loading immunization:', err);
                setError('Could not load immunization. Try again.');
            } finally {
                setLoading(false);
            }
        };

        loadImmunization();
    }, [immunization, immunizationsList, immunizationId, fetchImmunization, 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 createImmunization(transformToFhirImmunization(data, patientState, encounterState));

                navigate('..', { relative: 'path' });
            } else {
                await updateImmunization({
                    id: immunization?.id,
                    ...transformToFhirImmunization(data, patientState, encounterState)
                });
            }

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

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

    return (
        <HistoryNavigator<Immunization> resourceType="Immunization" resourceId={immunizationId || ''}>
            {(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>
                            )}

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

                            {!isNew && !isPatient && (
                                <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. */}
                            {isPatient && immunization && <PrintRecord/>}
                        </AppHeader>

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

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

                        {error && (
                            <>
                                <DismissibleAlert status="error" onDismiss={() => setError(undefined)}>
                                    <div className="whitespace-pre-line">{error}</div>
                                </DismissibleAlert>

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

                        <ScrollableTab>
                            <ProfileLayoutContainer>
                                {/* THE READER GETS THE RECORD, NOT THE FORM SWITCHED OFF. `FhirImmunizationDisplay`
                                    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. */}
                                {isPatient && immunization ? (
                                    <PrintableRegion>
                                        <FhirImmunizationDisplay immunization={immunization}
                                                              isOpen={true}
                                                              onClose={() => undefined}/>
                                    </PrintableRegion>
                                ) : (
                                    <FhirImmunization elevated={true}
                                                      disabled={submitting}/>
                                )}
                            </ProfileLayoutContainer>
                        </ScrollableTab>

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

export default EditImmunizationPage;