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 { Procedure } from 'fhir/r4';
import { Check, FileText } from 'lucide-react';
import {
    useAuthServiceContext,
    usePatientServiceContext,
    useProcedureServiceContext
} from '../../../../../services';
import { AppHeader, AppSpinner, FhirProcedure, HistoryNavigator, ProfileLayoutContainer, ScrollableTab, FhirProcedureDisplay } from '../../../../../components';
import { PrintableRegion, PrintRecord } from '../../../../../components/ui/print-record';
import { useFhirProcedureBroadcast, useFhirProcedures, useFhirProcedureTargetedBroadcast, useActiveEncounterReference, useRequestRecordCorrection } from '../../../../../hooks';
import { resolveProcedureAuthorReference } from '../../../../../utils/messaging/requestCorrection';
import { useArchive } from '../../../../../hooks/useArchive';
import ArchiveConfirmModal from '../../../../../components/ArchiveConfirmModal/ArchiveConfirmModal';
import { describeWriteFailure } from '../../../../../utils/fetchFailureMessage';
import { formatFhirCodeableConcept } from '../../../../../utils/fhirCodeableConcept.tsx';
import { patientCacheGuard } from '../../../../../utils/cacheOwner';

const EditProcedurePage: React.FC = () => {
    const { procedureId } = useParams<{ procedureId: string }>();
    const navigate = useNavigate();
    const { currentUser, userRole, USER_ROLES } = useAuthServiceContext();
    const { patientState, encounterState } = usePatientServiceContext();
    const {
        cachedForPatientId: proceduresOwner,
        fetchProcedure,
        transformToFhirProcedure,
        transformFromFhirProcedure,
        createProcedure,
        updateProcedure,
        archiveProcedure,
        proceduresList: rawProceduresList
    } = useProcedureServiceContext();
    // The cache outlives a change of patient: read only the patient on screen.
    const proceduresGuard = patientCacheGuard(proceduresOwner, patientState?.id);
    const proceduresList = proceduresGuard.list(rawProceduresList);

    const [loading, setLoading] = useState(false);
    const [submitting, setSubmitting] = useState(false);
    const [success, setSuccess] = useState<string | undefined>();
    const [error, setError] = useState<string | undefined>();
    const [procedure, setProcedure] = useState<Procedure | undefined>(undefined);

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

    useFhirProcedureBroadcast();
    useFhirProcedures();

    // 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: {
            encounter: activeEncounter,
            status: '',
            category: null,
            code: null,
            bodySite: [],
            outcome: null,
            followUp: [],
            performedType: '',
            performedDateTime: '',
            performedString: '',
            performedAge: null,
            performedRange: { low: null, high: null },
            recorder: null,
            asserter: null,
            performer: [],
            reasonCode: [],
            reasonReference: [],
            note: []
        }
    });

    const { handleSubmit, reset } = methods;

    const init = useCallback((procedure: Procedure) => {
        reset(transformFromFhirProcedure(procedure));
        setProcedure(procedure);
    }, [transformFromFhirProcedure, reset]);

    useFhirProcedureTargetedBroadcast({
        procedure,
        procedureId,
        onUpdate: init,
        onDelete: () => navigate('..', { relative: 'path' })
    });

    const archive = useArchive((reason, note) => archiveProcedure(procedure!, reason, note));

    const { requestCorrection, error: correctionError, recovery: correctionRecovery } = useRequestRecordCorrection(
        procedure ? resolveProcedureAuthorReference(procedure) : undefined);
    const handleRequestCorrection = async (note: string) => {
        if (!procedure) return { ok: false };
        const label = formatFhirCodeableConcept(procedure.code) || 'this procedure';
        return requestCorrection(resolveProcedureAuthorReference(procedure), label, note);
    };

    useEffect(() => {
        const loadProcedure = async () => {
            if (isNew || procedure) return;

            const foundProcedure = proceduresList?.find(p => p.id === procedureId);

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

            setLoading(true);

            try {
                const fetchedProcedure = await fetchProcedure(procedureId as string);
                init(fetchedProcedure);
            } catch (err) {
                console.error('Error loading procedure:', err);
                setError('Could not load procedure. Try again.');
            } finally {
                setLoading(false);
            }
        };

        loadProcedure();
    }, [procedure, proceduresList, procedureId, fetchProcedure, init]);

    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 createProcedure(transformToFhirProcedure(data, patientState, encounterState, currentUser?.fhir));

                navigate('..', { relative: 'path' });
            } else {
                await updateProcedure({
                    id: procedure?.id,
                    ...transformToFhirProcedure(data)
                });
            }

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

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

    return (
        <HistoryNavigator<Procedure> resourceType="Procedure" resourceId={procedureId || ''}>
            {(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 && procedure && <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. `FhirProcedureDisplay`
                                    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 && procedure ? (
                                    <PrintableRegion>
                                        <FhirProcedureDisplay procedure={procedure}
                                                           isOpen={true}
                                                           onClose={() => undefined}
                                                           onRequestCorrection={handleRequestCorrection}
                                                           correctionError={correctionError}
                                                           correctionRecovery={correctionRecovery}/>
                                    </PrintableRegion>
                                ) : (
                                    <FhirProcedure elevated={true}
                                                   disabled={submitting}/>
                                )}
                            </ProfileLayoutContainer>
                        </ScrollableTab>

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

export default EditProcedurePage;