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 { MedicationStatement } from 'fhir/r4';
import {
    useMedicationStatementServiceContext,
    usePatientServiceContext
} from '../services';
import { FhirMedicationStatement } from '../components';
import { useFhirMedicationStatementTargetedBroadcast } from '../hooks';
import { describeWriteFailure } from '../utils/fetchFailureMessage';
import { invalidSubmitMessage } from '../utils/forms/invalidSubmitMessage';

interface MedicationStatementModalProps {
    isOpen: boolean;
    onClose: () => void;
    medicationStatement?: MedicationStatement;
    onSuccess?: (medicationStatement: MedicationStatement) => void;
    onError?: (error: string) => void;
    title?: string;
}

export const MedicationStatementModal: React.FC<MedicationStatementModalProps> = ({
                                                                                      isOpen,
                                                                                      onClose,
                                                                                      medicationStatement,
                                                                                      onSuccess,
                                                                                      onError,
                                                                                      title
                                                                                  }) => {
    const { patientState, encounterState } = usePatientServiceContext();
    const {
        transformToFhirMedicationStatement,
        transformFromFhirMedicationStatement,
        createMedicationStatement,
        updateMedicationStatement
    } = useMedicationStatementServiceContext();

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

    const isNew = !medicationStatement;
    const modalTitle = title || `${isNew ? 'Create' : 'Edit'} Medication Statement`;

    const methods = useForm({
        defaultValues: {
            status: '',
            statusReason: null,
            category: null,
            medicationCodeableConcept: null,
            effectiveType: 'dateTime',
            effectiveDateTime: '',
            dateAsserted: '',
            informationSource: null,
            reasonCode: [],
            reasonReference: [],
            context: [],
            partOf: [],
            basedOn: [],
            note: [],
            dosage: []
        }
    });

    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((medicationStatement: MedicationStatement) => {
        reset(transformFromFhirMedicationStatement(medicationStatement));
    }, [transformFromFhirMedicationStatement, reset]);

    useFhirMedicationStatementTargetedBroadcast({
        medicationStatement,
        isOpen,
        onUpdate: init,
        onDelete: onClose
    });

    useEffect(() => {
        if (medicationStatement) {
            init(medicationStatement);
        }
    }, [medicationStatement, 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: MedicationStatement;

            if (isNew) {
                result = await createMedicationStatement(transformToFhirMedicationStatement(data, patientState, encounterState));
            } else {
                result = await updateMedicationStatement({
                    id: medicationStatement?.id,
                    ...transformToFhirMedicationStatement(data, patientState)
                }, medicationStatement?.meta?.versionId);
            }

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

            setTimeout(() => {
                setSuccess(undefined);
                onClose();
            }, 1500);
        } catch (err: any) {
            console.error(`Error ${isNew ? 'creating' : 'updating'} medication statement:`, err);
            const errorMsg = describeWriteFailure(err, `Failed to ${isNew ? 'create' : 'update'} medication statement`);
            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>
                        <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 }}>
                        <FhirMedicationStatement elevated={false}
                                                 disabled={submitting}
                                                 enableInlineActions={false}/>
                    </div>
                </form>
            </FormProvider>
        </Modal>
    );
};