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 { Task, Organization, Practitioner } from 'fhir/r4';
import {
    useTaskServiceContext,
    useAuthServiceContext,
    usePatientServiceContext
} from '../services';
import { FhirTask, FhirTaskDisplay } from '../components';
import { PrintableRegion, PrintRecord } from '../components/ui/print-record';
import { useFhirTaskTargetedBroadcast, useActiveEncounterReference } from '../hooks';
import { describeWriteFailure } from '../utils/fetchFailureMessage';
import { invalidSubmitMessage } from '../utils/forms/invalidSubmitMessage';

interface TaskModalProps {
    isOpen: boolean;
    onClose: () => void;
    task?: Task;
    onSuccess?: (task: Task) => void;
    onError?: (error: string) => void;
    title?: string;
}

export const TaskModal: React.FC<TaskModalProps> = ({
                                                        isOpen,
                                                        onClose,
                                                        task,
                                                        onSuccess,
                                                        onError,
                                                        title
                                                    }) => {
    const { currentUser, userRole, USER_ROLES, wpOrganization } = useAuthServiceContext();
    const { patientState, encounterState } = usePatientServiceContext();
    const activeEncounter = useActiveEncounterReference();
    const {
        transformToFhirTask,
        transformFromFhirTask,
        createTask,
        updateTask
    } = useTaskServiceContext();

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

    const isNew = !task;
    // A RELATED PERSON IS A PATIENT VIEWER. This read
    // `userRole === USER_ROLES.PATIENT`, so a parent acting for a child was treated as
    // staff here while the matching page and FhirTask itself both counted them.
    // It now decides which of the two renders below the reader gets, so a narrow
    // predicate would put a proxy into the edit form rather than the record.
    const isPatient = [USER_ROLES.PATIENT, USER_ROLES.RELATED_PERSON].includes(userRole as string);
    const modalTitle = title || `${isNew ? 'Create' : 'Edit'} Task`;

    const methods = useForm({
        defaultValues: {
            encounter: activeEncounter,
            identifier: [],
            instantiatesCanonical: [],
            instantiatesUri: [],
            basedOn: [],
            groupIdentifier: null,
            partOf: [],
            status: '',
            statusReason: null,
            businessStatus: null,
            intent: '',
            priority: '',
            code: null,
            description: '',
            focus: [{}],
            for: null,
            authoredOn: '',
            lastModified: '',
            requester: null,
            performerType: [],
            owner: null,
            location: null,
            reasonCode: [],
            reasonReference: [],
            insurance: [],
            note: [],
            relevantHistory: []
        }
    });

    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((task: Task) => {
        reset(transformFromFhirTask(task));
    }, [transformFromFhirTask, reset]);

    useFhirTaskTargetedBroadcast({
        task,
        isOpen,
        onUpdate: init,
        onDelete: onClose
    });

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

    const onSubmit = async (data: any) => {
        if (isPatient) return;

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

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

        try {
            const practitioner: Practitioner = currentUser?.fhir as Practitioner;
            let result: Task;

            if (isNew) {
                result = await createTask(transformToFhirTask(data, patientState, practitioner, encounterState, wpOrganization.current as Organization));
            } else {
                result = await updateTask({
                    id: task?.id,
                    ...transformToFhirTask(data)
                });
            }

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

            setTimeout(() => {
                setSuccess(undefined);
                onClose();
            }, 1500);
        } catch (err: any) {
            console.error(`Error ${isNew ? 'creating' : 'updating'} task:`, err);
            const errorMsg = describeWriteFailure(err, `Failed to ${isNew ? 'create' : 'update'} task`);
            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>
                           {/* No Cancel: this Modal's X already calls onClose. */}
                           {/* 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. `FhirTaskDisplay`
                            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 && task ? (
                            <PrintableRegion>
                                <FhirTaskDisplay task={task}
                                              isOpen={true}
                                              onClose={() => undefined}/>
                            </PrintableRegion>
                        ) : (
                            <FhirTask elevated={false}
                                      disabled={submitting}
                                      enableInlineActions={false}/>
                        )}
                    </div>
                </form>
            </FormProvider>
        </Modal>
    );
};