import React, { useState, useEffect, useCallback } from 'react';
import { Flex, FlexItem } from '../components/ui/flex';
import { DismissibleAlert } from '../components/ui/dismissible-alert';
import { Modal } from '../components/ui/wp-modal-shim';
import { useForm, FormProvider } from 'react-hook-form';
import { Procedure } from 'fhir/r4';
import {
    useProcedureServiceContext,
    useAuthServiceContext,
    usePatientServiceContext
} from '../services';
import { FhirProcedure, FhirProcedureDisplay } from '../components';
import { PrintableRegion, PrintRecord } from '../components/ui/print-record';
import { useFhirProcedureTargetedBroadcast, useActiveEncounterReference } from '../hooks';
import { describeWriteFailure } from '../utils/fetchFailureMessage';
import { invalidSubmitMessage } from '../utils/forms/invalidSubmitMessage';

interface ProcedureModalProps {
    isOpen: boolean;
    onClose: () => void;
    procedure?: Procedure;
    onSuccess?: (procedure: Procedure) => void;
    onError?: (error: string) => void;
    title?: string;
}

export const ProcedureModal: React.FC<ProcedureModalProps> = ({
                                                                  isOpen,
                                                                  onClose,
                                                                  procedure,
                                                                  onSuccess,
                                                                  onError,
                                                                  title
                                                              }) => {
    const { currentUser, userRole, USER_ROLES } = useAuthServiceContext();

    // THIS MODAL HAD NO PATIENT GUARD AT ALL - see the note in ClinicalImpressionModal.
    const isPatient = [USER_ROLES.PATIENT, USER_ROLES.RELATED_PERSON].includes(userRole as string);
    const { patientState, encounterState } = usePatientServiceContext();
    const activeEncounter = useActiveEncounterReference();
    const {
        transformToFhirProcedure,
        transformFromFhirProcedure,
        createProcedure,
        updateProcedure
    } = useProcedureServiceContext();

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

    const isNew = !procedure;
    const modalTitle = title || `${isNew ? 'Create' : 'Edit'} Procedure`;

    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;

    // A REFUSED CLICK SAYS SO WHERE IT HAPPENED. The button is in the modal header, above a form that
    // can be several screens tall, and react-hook-form reports each problem inline beside its field -
    // so somebody scrolled past the first card saw nothing change at all. This fills the error slot
    // this modal already has, at the top of the form, next to the button they pressed.
    const onInvalid = (errors: unknown) => setError(invalidSubmitMessage(errors));

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

    useFhirProcedureTargetedBroadcast({
        procedure,
        isOpen,
        onUpdate: init,
        onDelete: onClose
    });

    useEffect(() => {
        if (procedure) {
            init(procedure);
        }
    }, [procedure, init]);

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

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

        try {
            let result: Procedure;

            if (isNew) {
                result = await createProcedure(transformToFhirProcedure(data, patientState, encounterState, currentUser?.fhir));
            } else {
                result = await updateProcedure({
                    id: procedure?.id,
                    ...transformToFhirProcedure(data)
                });
            }

            const successMsg = `Procedure ${isNew ? 'created' : 'updated'} successfully.`;
            setSuccess(successMsg);
            onSuccess?.(result);

            setTimeout(() => {
                setSuccess(undefined);
                onClose();
            }, 1500);
        } catch (err: any) {
            console.error(`Error ${isNew ? 'creating' : 'updating'} procedure:`, err);
            const errorMsg = describeWriteFailure(err, `Failed to ${isNew ? 'create' : 'update'} procedure`);
            setError(errorMsg);
            onError?.(errorMsg);
        } finally {
            setSubmitting(false);
        }
    };

    if (!isOpen) return null;

    return (
        <Modal
            title={modalTitle}
            onRequestClose={onClose}
            size="large"
            style={{ maxWidth: '900px' }}
            headerActions={[
                <Flex justify="end">
                    <FlexItem>
                        {/* A READER GETS PRINT WHERE A WRITER GETS SAVE. A patient reading a record has no use
                            for a Create/Update button - live it lies, disabled it tells them what they may not
                            do, and neither answers the question they have: how do I get this to somebody who
                            is not on Akashic. */}
                        {isPatient ? (
                            <PrintRecord/>
                        ) : (
                            <button
                                type="button"
                                className={`btn btn-green${submitting ? ' btn-busy' : ''}`}
                                onClick={handleSubmit(onSubmit, onInvalid)}
                                disabled={submitting}
                            >
                                {isNew ? 'Create' : 'Update'}
                            </button>
                        )}
                    </FlexItem>
                </Flex>
            ]}
        >
            <FormProvider {...methods}>
                <form>
                    {success && (
                        <DismissibleAlert status="success" onDismiss={() => setSuccess(undefined)} className="mb-4">
                            {success}
                        </DismissibleAlert>
                    )}

                    {error && (
                        <DismissibleAlert status="error" onDismiss={() => setError(undefined)} className="mb-4">
                            {error}
                        </DismissibleAlert>
                    )}

                    <div style={{ paddingBottom: 16 }}>
{/* 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}/>
                            </PrintableRegion>
                        ) : (
                            <FhirProcedure elevated={false}
                                           disabled={submitting}
                                           enableInlineActions={false}/>
                        )}
                    </div>
                </form>
            </FormProvider>
        </Modal>
    );
};