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 { AdverseEvent } from 'fhir/r4';
import { Check, FileText } from 'lucide-react';
import {
    useAdverseEventServiceContext,
    usePatientServiceContext,
    useAuthServiceContext
} from '../../../../../services';
import { AppHeader, AppSpinner, ProfileLayoutContainer, ScrollableTab, FhirAdverseEvent, HistoryNavigator } from '../../../../../components';
import { useFhirAdverseEventTargetedBroadcast, useActiveEncounterReference } from '../../../../../hooks';
import { useArchive } from '../../../../../hooks/useArchive';
import ArchiveConfirmModal from '../../../../../components/ArchiveConfirmModal/ArchiveConfirmModal';
import { describeWriteFailure } from '../../../../../utils/fetchFailureMessage';
import { patientCacheGuard } from '../../../../../utils/cacheOwner';

const EditAdverseEventPage: React.FC = () => {
    const { adverseEventId } = useParams<{ adverseEventId: string }>();
    const navigate = useNavigate();
    const { currentUser } = useAuthServiceContext();
    const { patientState, encounterState } = usePatientServiceContext();
    const {
        cachedForPatientId: adverseEventsOwner,
        fetchAdverseEvent,
        transformToFhirAdverseEvent,
        transformFromFhirAdverseEvent,
        createAdverseEvent,
        updateAdverseEvent,
        archiveAdverseEvent,
        adverseEventsList: rawAdverseEventsList,
    } = useAdverseEventServiceContext();
    // The cache outlives a change of patient: read only the patient on screen.
    const adverseEventsGuard = patientCacheGuard(adverseEventsOwner, patientState?.id);
    const adverseEventsList = adverseEventsGuard.list(rawAdverseEventsList);

    const [loading, setLoading] = useState(false);
    const [submitting, setSubmitting] = useState(false);
    const [success, setSuccess] = useState<string | undefined>();
    const [error, setError] = useState<string | undefined>();
    const [adverseEvent, setAdverseEvent] = useState<AdverseEvent | undefined>();

    const isNew = adverseEventId === 'new';
    const spacerMargin = '24px';

    // THE FIELD AGREES WITH THE SAVE NOW. The service already applied the active encounter whether or
    // not this field was touched, so the record filed against the visit correctly while the control
    // read "Select...". A clinician reading that is told their record is unattached when it is not, and
    // the natural correction is to open a list of every past visit and pick one - which is how a wrong
    // visit gets attached to a clinical fact.
    //
    // The same hook the eight clinical modals use, so there is one rule rather than a second copy. It
    // returns undefined outside a visit, which is what keeps the plain chart route opening empty.
    const activeEncounter = useActiveEncounterReference();

    const methods = useForm({
        defaultValues: {
            identifier: [],
            actuality: '',
            category: [],
            event: null,
            subject: null,
            encounter: activeEncounter ?? null,
            date: '',
            detected: '',
            recordedDate: '',
            resultingCondition: [],
            location: null,
            seriousness: null,
            severity: null,
            outcome: null,
            recorder: null,
            contributor: [],
            suspectEntity: [],
            subjectMedicalHistory: [],
            referenceDocument: [],
            study: [],
        }
    });

    const { handleSubmit, reset } = methods;

    const init = useCallback((adverseEvent: AdverseEvent) => {
        reset(transformFromFhirAdverseEvent(adverseEvent));
        setAdverseEvent(adverseEvent);
    }, [transformFromFhirAdverseEvent]);

    useFhirAdverseEventTargetedBroadcast({
        adverseEvent,
        adverseEventId,
        onUpdate: init,
        onDelete: () => navigate('..', { relative: 'path' })
    });

    const archive = useArchive((reason, note) => archiveAdverseEvent(adverseEvent!, reason, note));

    useEffect(() => {
        const loadAdverseEvent = async () => {
            if (isNew || adverseEvent) return;

            const foundAdverseEvent = adverseEventsList?.find(ae => ae.id === adverseEventId);

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

            setLoading(true);

            try {
                const fetchedAdverseEvent = await fetchAdverseEvent(adverseEventId as string);
                init(fetchedAdverseEvent);
            } catch (err) {
                console.error('Error loading adverse event:', err);
                setError('Could not load adverse event. Try again.');
            } finally {
                setLoading(false);
            }
        };

        loadAdverseEvent();
    }, [adverseEventId, fetchAdverseEvent, transformFromFhirAdverseEvent]);

    const onSubmit = async (data: any) => {
        if (!patientState) {
            setError('Patient information is missing. Please try again.');
            return;
        }

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

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

                navigate('..', { relative: 'path' });
            } else {
                await updateAdverseEvent({
                    id: adverseEvent?.id,
                    ...transformToFhirAdverseEvent(data)
                });
            }

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

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

    return (
        <HistoryNavigator<AdverseEvent> resourceType="AdverseEvent" resourceId={adverseEventId || ''}>
            {(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>
                            )}

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

                            {!isNew && (
                                <button type="button" className="btn btn-green" onClick={archive.open}>
                                    Archive
                                </button>
                            )}
                        </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>
                                <FhirAdverseEvent elevated={true} disabled={submitting} enableInlineActions={false}/>
                            </ProfileLayoutContainer>
                        </ScrollableTab>

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

export default EditAdverseEventPage;