# Install
`npm install blockchain-payments`

# About
Blockchain.info payment api (v2) module

# Example
## Creation of an address

```js
const BlockchainPayments = require("blockchain-payments");
const express = require("express");
const app = express();

const xpub = "xpub"; // xpub
const key = "key"; // blockchain key
const notifySecret = "secret"; // secret key for notification

const blockchain = new BlockchainPayments(xpub, key, notifySecret);

// Create an address for the payment
app.post('/payments/bitcoin/address/', (req, res, next) => {    
  blockchain.createAddress({
      callback: 'http://example.com'
  }, {
      someCallbackField1: '1',
      someCallbackFieldw2: '2',
  }).then((data) => {
      console.log(data) // {address: ..., index: ..., callback: ...}
  })
});
```

## Conversation of currencies

```js
BlockchainPayments.toBTC(500, 'USD').then((amountInBTC) => {
    // converting USD(or other) to BTC;
});
```

## Handling of a notification

```js
const successHandler = (data, callback) => {
  // data === req.query    
  // save payment info into db e.t.c    
  // callback() or return promise
};

const errorHandler = (err, meta) => {
  // you can save something to a file, db e.t.c.
  // operation must be synchronous or in the background
};

let confirmationsCount = 8; // count of confirmations for acception, default 6

app.get('payments/notification/', blockchain.notify(successHandler, errorHandler, confirmationsCount));
```

# Description  
You can write custom notification handler, but library version includes data/authentication validation and automatically sends all headers in the necessary format

# API
### .constructor(xpub, key, notifySecret, [notifyCallback])  
you can find __xpub__ and __key__ in your blockchain account, __notifySecret__ you have to come up yourself

### .createAddress(query, [callbackQuery])
returns promise, creates bitcoin address for client payment  
you can set callback url query params with callbackQuery as js object

### .notify(fn, onError, [confirmationsCount])
notification handler, it is "connect" middleware

# Class methods
### .toBTC(amount, currency)
converts an amount from a given currency to BTC, returns promise