@claudebernard/fhir-mapper/README.md

A simple FHIR / BCB resource mapper to help stay interoperable while still using the Claude Bernard intelligence

# @claudebernard/fhir-mapper
This library will be composed of several bidirectional mapping entities between Claude Bernard (alias BCB) interfaces and FHIR specifications.

Each mapper will contain at the very least a _fhirToBcb_ and a _bcbToFhir_ functions, will return a **MappingResponse** object and is expected to work offline.

```ts
interface MappingResponse<T = unknown> {
    result: T | undefined;
    errors?: MappingError[];
}
type MappingError = {
    field: string;
    message: string;
}
```

Some of those mappers can accept optional **CodificationFunction** parameters which are meant to provide a way for the user to be able to choose how the mapping between a fhir resource's [Coding](https://www.hl7.org/fhir/datatypes.html#Coding) field and the corresponding Claude Bernard class codification property is done.

Of course, if the value of the respective fields is not provided or if they use the Claude Bernard codification already, those parameters should be omitted.

**CodificationFunction** type :

```ts
type CodificationFunction = ((coding : Coding) => SimpleCodification) | undefined;

type SimpleCodification = {
    code: string;
    label: string;
};
```
The **CodificationFunction** type expects a fhir r5 **Coding** resource as input and a **SimpleCodification** object as output.

## Dependencies
The library uses the _@types/fhir_ lib to gain access to fhir r5 official objects and methods.

## Installation

```sh
npm install --save @claudebernard/fhir-mapper
```

## Mappers list

Below the list of all mappers currently comprised in this library :
- A [**Dosage**](https://www.hl7.org/fhir/dosage.html#Dosage) mapper exported as _dosageMapper_.
- A [**Patient**](https://www.hl7.org/fhir/patient.html#Patient) mapper exported as _patientMapper_.

## Mappers details

### Dosage mapper : functions

#### - fhirToBcb

```ts
function fhirToBcb(
    dosageInstructions: Dosage[],
    indicationMapper?: CodificationFunction,
    routeMapper?: CodificationFunction,
    intakeMapper?: CodificationFunction
) : MappingResponse<BCBPosologieStructuree2>[] {} 
```

The function takes 4 parameters : 
- 1 mandatory parameter 'dosageInstructions' which will be the fhir r5 [Dosage](https://www.hl7.org/fhir/dosage.html#Dosage) resources that need to be mapped.
- 3 optional parameters of type **CodificationFunction**.

Those optional parameters are meant to be used to map fhir (asNeededFor, route, doseAndRate) fields to (codeIndication, codeVoie, codeUnitePrise) **BCBPosologieStructuree2** class properties.

##### Usage

```ts
import { dosageMapper } from '@claudebernard/fhir-mapper';
// other imports ... 

const fhirDosages = [];
const routeMapper = (coding : Coding) => {
    // some api call or logic implemented by yourself ...
    return {
        code : routeCode,
        label : routeLabel
    }
}

// ...

const bcbDosages = dosageMapper.fhirToBcb(fhirDosages, undefined, routeMapper, undefined);

// ...
```

#### - bcbToFhir

```ts
function bcbToFhir(bcbDosages: BCBPosologieStructuree2[]): MappingResponse<Dosage>[] {} 
```

This function takes only one parameter, an array of **BCBPosologieStructuree2** objects and returns a **MappingResponse** containing the corresponding fhir **Dosage** resources.

It will for now by default keep the Claude Bernard codification for the **Coding** fields in the output fhir **Dosage** resources.

##### Usage

```ts
import { dosageMapper } from '@claudebernard/fhir-mapper';
// other imports ... 

const bcbDosages = [];

// ...

const fhirDosages = dosageMapper.bcbToFhir(bcbDosages);

// ...
```

#### Dosage mapper : current limitations 
Even though the mapper works and allows us to transform Dosage resources in Claude Bernard resources, there are some caveats : - some fields are currently unmapped due to a lack of overlap between the two structures.
- some fields are only partially mapped due to the fact that on one side (fhir) they are arrays and on the other (claude bernard), they are unitary values.

## Claude Bernard codifications
Below is listed the different Claude Bernard coding systems or valuesets that will be used internally by the mappers.
- https://platform.claudebernard.fr/fhir/ImplementationGuides/ValueSet/routes
- https://platform.claudebernard.fr/fhir/ImplementationGuides/ValueSet/intake-units
- https://platform.claudebernard.fr/fhir/ImplementationGuides/ValueSet/indications

### Patient mapper : functions

#### - fhirToBcb

```ts
function fhirToBcb(
  fhirPatient: BundleEntry[],
  allergiesMapper?: CodificationFunction,
  snomedPathologiesMapper?: CodificationFunction,
): MappingResponse<BCBPatient> {}
```
The function takes 3 parameters : 
- 1 mandatory parameter 'fhirPatient' which will be an array of r5 [BundleEntry](https://www.hl7.org/fhir/bundle.html) resources that need to be mapped.
- 2 optional parameters of type **CodificationFunction**.

Those optional parameters are meant to be used to map fhir (Condition.code.coding, AllergyIntolerance.code.coding) fields to (lstPathologiesAMM, lstIdComposantAllergie) **BCBPatient** class properties.

##### Usage

```ts
import { patientMapper } from '@claudebernard/fhir-mapper';
// other imports ... 

const fhirPatient = [];
const allergiesMapper = (coding : Coding) => {
    // some api call or logic implemented by yourself ...
    return {
        code : allergyCode,
        label : allergyLabel
    }
}

const snomedPathologiesMapper = (coding : Coding) => {
    // some api call or logic implemented by yourself ...
    return {
        code : pathologyCode,
        label : pathologyLabel
    }
}

// ...

const bcbPatient = patientMapper.fhirToBcb(fhirPatient, allergiesMapper, snomedPathologiesMapper);

// ...
```

#### - bcbToFhir

```ts
function bcbToFhir(
  bcbPatient: BCBPatient,
): MappingResponse<BundleEntry[]> {}
```
The function takes 1 parameter of type BCBPatient and returns a **MappingResponse** containing the an array of the corresponding fhir **BundleEntry** resources.

##### Usage

```ts
import { patientMapper } from '@claudebernard/fhir-mapper';
// other imports ... 

const bcbPatient = [];

// ...

const fhirPatient = patientMapper.bcbToFhir(bcbPatient);

// ...
```

#### - fhirTocb

```ts
function fhirTocb(
  fhirPatient: BundleEntry[],
  allergiesMapper?: CodificationFunction,
  snomedPathologiesMapper?: CodificationFunction,
): MappingResponse<BCBPatient> {}
```
The function takes 3 parameters : 
- 1 mandatory parameter 'fhirPatient' which will be an array of r5 [BundleEntry](https://www.hl7.org/fhir/bundle.html) resources that need to be mapped.
- 2 optional parameters of type **CodificationFunction**.

Those optional parameters are meant to be used to map fhir (Condition.code.coding, AllergyIntolerance.code.coding) fields to (lstPathologiesAMM, lstIdComposantAllergie) **CBPatient** class properties.

##### Usage

```ts
import { patientMapper } from '@claudebernard/fhir-mapper';
// other imports ... 

const fhirPatient = [];
const allergiesMapper = (coding : Coding) => {
    // some api call or logic implemented by yourself ...
    return {
        code : allergyCode,
        label : allergyLabel
    }
}

const snomedPathologiesMapper = (coding : Coding) => {
    // some api call or logic implemented by yourself ...
    return {
        code : pathologyCode,
        label : pathologyLabel
    }
}

// ...

const cbPatient = patientMapper.fhirTocb(fhirPatient, allergiesMapper, snomedPathologiesMapper);

// ...
```

#### - cbToFhir

```ts
function cbToFhir(
  cbPatient: CBPatient,
): MappingResponse<BundleEntry[]> {}
```
The function takes 1 parameter of type BCBPatient and returns a **MappingResponse** containing the an array of the corresponding fhir **BundleEntry** resources.

##### Usage

```ts
import { patientMapper } from '@claudebernard/fhir-mapper';
// other imports ... 

const cbPatient = [];

// ...

const fhirPatient = patientMapper.cbToFhir(cbPatient);

// ...
```

## Browser support
- [x] Chrome
- [x] Firefox
- [x] Safari
- [x] Microsoft Edge

## License

Copyright of Cegedim. See [LICENSE](LICENSE.md) for details.