npm package: @ikarha/emecef
Description: Node.js client library for interacting with the Benin e-MCF API for normalized invoicing
Author: Ologou François-Jean de Dieu ASSOGBA
Latest version: 1.0.0

## eMCF API Client
A TypeScript client library for interacting with the e-MCF (MACHINES ELECTRONIQUES CERTIFIEES DE FACTURATION) API for normalized invoicing.
This library provides a simple and typed interface to manage invoices and retrieve information from the e-MCF API.

### Features

- Billing API: 
  - Create, 
  - finalize, 
  - and retrieve invoice details.
- Info API: 
  - Fetch e-MCF status, 
  - tax groups, 
  - invoice types, 
  - and payment types.
- TypeScript Support: Fully typed with TypeScript interfaces for robust development.
      Environment Configuration: Configurable via environment variables for security and flexibility.
      Error Handling: Comprehensive error handling with meaningful messages.

### Installation
Install the package using npm:

```bash
 npm install @ikarha/emecef
```

### Prerequisites

- Node.js (>= 14.x)
- A valid JWT token provided by the DGI for e-MCF API access
- An active internet connection :)

### Configuration
The library uses environment variables for configuration. Create a .env file in your project root based on the provided .env.example:

```bash

# .example.env file

EMECEF_BASE_URL=https://developer.impots.bj/sygmef-emcf/api
EMECEF_TOKEN=your-jwt-token
```

Ensure you have dotenv installed and load it at the start of your application:

```bash
npm install dotenv
````

Then, load the environment variables in your application:

```typescript

import * as dotenv from 'dotenv';
dotenv.config();

```

### Usage
Initialize the Services

```typescript
import { BillingService, InfoService } from '@ikarha/emecef';

// Initialize services (environment variables must be set)
const billingService = new BillingService();
const infoService = new InfoService();
```

#### Example: Create and Finalize an Invoice

```typescript
import { BillingService } from '@ikarha/emecef';
import { InvoiceRequestDataDto, InvoiceTypeEnum, PaymentTypeEnum, TaxGroupTypeEnum } from 'emcf-api-client/dist/types/billing';
import * as dotenv from 'dotenv';

dotenv.config();

async function main() {
const billingService = new BillingService();

try {
// Check API status
const status = await billingService.getStatus();
console.log('API Status:', status);

    // Create an invoice
    const invoiceData: InvoiceRequestDataDto = {
      ifu: '9999900000001',
      type: InvoiceTypeEnum.FV,
      items: [
        {
          name: 'Jus d\'orange',
          price: 1800,
          quantity: 2,
          taxGroup: TaxGroupTypeEnum.B
        },
        {
          name: 'Lait 1/1 EX',
          price: 450,
          quantity: 3,
          taxGroup: TaxGroupTypeEnum.A
        }
      ],
      client: {
        contact: '45661122',
        ifu: '9999900000002',
        name: 'Nom du client',
        address: 'Rue d\'ananas 23'
      },
      operator: {
        id: '',
        name: 'Jacques'
      },
      payment: [
        {
          name: PaymentTypeEnum.ESPECES,
          amount: 4950
        }
      ]
    };
    const invoiceResponse = await billingService.createInvoice(invoiceData);
    console.log('Invoice Response:', invoiceResponse);

    // Finalize the invoice
    const finalizeResponse = await billingService.finalizeInvoice(invoiceResponse.uid, 'confirm');
    console.log('Finalization:', finalizeResponse);
} catch (error) {
console.error('Error:', error instanceof Error ? error.message : 'Unknown error');
}
}

main().catch(console.error);
```


#### Available Methods
- BillingService
  - getInvoiceStatus(): Retrieves the API status and pending invoice requests.
  - createInvoice(data: InvoiceRequestDataDto): Submits a new invoice and retrieves calculated totals.
  - finalizeInvoice(uid: string, action: 'confirm' | 'annuler'): Confirms or cancels an invoice.
  - getInvoiceDetails(uid: string): Retrieves details of a pending invoice.

- InfoService 
  - getEmeCefInfo(): Retrieves information about e-MCF instances.
  - getTaxGroups(): Retrieves available tax groups and their rates.
  - getInvoiceTypes(): Retrieves available invoice types.
  - getPaymentTypes(): Retrieves available payment types.

### Environment Variables

| Variable      | Description                          | Required | Example                                     |
|---------------|--------------------------------------|----------|---------------------------------------------|
| EMECEF_BASE_URL | Base URL of the e-MCF API            | Yes      | https://developer.impots.bj/sygmef-emcf/api |
| EMECEF_TOKEN    | JWT token for API authentication     | Yes      | your-jwt-token                              |


### Error Handling
The library throws ApiError instances with meaningful error messages based on the API's error codes. Check the error documentation in the e-MCF API specification for details.


### Development
#### Build the Project

```bash
 npm run build
```

#### Run Tests

Tests are implemented with Jest. Run them with:
```bash
npm test
```

#### Project Structure

- ```src/api/```: Contains service classes for billing and info APIs.
- ```src/types/```: TypeScript interfaces for API data transfer objects (DTOs).
- ```src/errors/```: Custom error handling logic.
- ```dist/```: Compiled JavaScript and TypeScript declaration files.

### Contributing
Contributions are welcome! Please open an issue or submit a pull request on the GitHub repository.

### License
This project is licensed under the MIT License. See the LICENSE file for details.