fix(POST electrumx/balance): Implemented with unit and integration tests

src/routes/v3/electrumx.js

@@ -51,6 +51,7 @@ class Electrum {
     _this.router.get('/utxos/:address', _this.getUtxos)
     _this.router.post('/utxos', _this.utxosBulk)
     _this.router.get('/balance/:address', _this.getBalance)
+    _this.router.post('/balance', _this.balanceBulk)
     _this.router.get('/transactions/:address', _this.getTransactions)
   }
 
@@ -423,26 +424,93 @@ class Electrum {
     }
   }
 
-  // Convert a 'bitcoincash:...' address to a script hash used by ElectrumX.
-  addressToScripthash (addrStr) {
+  /**
+   * @api {post} /electrumx/balance Get balances for an array of addresses.
+   * @apiName  Balances for an array of addresses
+   * @apiGroup ElectrumX / Fulcrum
+   * @apiDescription Returns an array of balanes associated with an array of address.
+   * Limited to 20 items per request.
+   *
+   * @apiExample Example usage:
+   * curl -X POST "https://api.fullstack.cash/v3/electrumx/balance" -H "accept: application/json" -H "Content-Type: application/json" -d '{"addresses":["bitcoincash:qrdka2205f4hyukutc2g0s6lykperc8nsu5u2ddpqf","bitcoincash:qrdka2205f4hyukutc2g0s6lykperc8nsu5u2ddpqf"]}'
+   *
+   *
+   */
+  // POST handler for bulk queries on address balance
+  async balanceBulk (req, res, next) {
     try {
-      // console.log(`addrStr: ${addrStr}`)
+      let addresses = req.body.addresses
 
-      const address = _this.bitcore.Address.fromString(addrStr)
-      // console.log(`address: ${address}`)
+      // Reject if addresses is not an array.
+      if (!Array.isArray(addresses)) {
+        res.status(400)
+        return res.json({
+          error: 'addresses needs to be an array. Use GET for single address.'
+        })
+      }
 
-      const script = _this.bitcore.Script.buildPublicKeyHashOut(address)
-      // console.log(`script: ${script}`)
+      // Enforce array size rate limits
+      if (!_this.routeUtils.validateArraySize(req, addresses)) {
+        res.status(429) // https://github.com/Bitcoin-com/rest.bitcoin.com/issues/330
+        return res.json({
+          error: 'Array too large.'
+        })
+      }
 
-      const scripthash = _this.bitcore.crypto.Hash.sha256(script.toBuffer())
-        .reverse()
-        .toString('hex')
-      // console.log(`scripthash: ${scripthash}`)
+      wlogger.debug(
+        'Executing electrumx.js/balanceBulk with these addresses: ',
+        addresses
+      )
 
-      return scripthash
+      // Validate each element in the address array.
+      for (let i = 0; i < addresses.length; i++) {
+        const thisAddress = addresses[i]
+
+        // Ensure the input is a valid BCH address.
+        try {
+          _this.bchjs.Address.toLegacyAddress(thisAddress)
+        } catch (err) {
+          res.status(400)
+          return res.json({
+            error: `Invalid BCH address. Double check your address is valid: ${thisAddress}`
+          })
+        }
+
+        // Prevent a common user error. Ensure they are using the correct network address.
+        const networkIsValid = _this.routeUtils.validateNetwork(thisAddress)
+        if (!networkIsValid) {
+          res.status(400)
+          return res.json({
+            error: `Invalid network for address ${thisAddress}. Trying to use a testnet address on mainnet, or vice versa.`
+          })
+        }
+      }
+
+      // Loops through each address and creates an array of Promises, querying
+      // ElectrumX API in parallel.
+      addresses = addresses.map(async (address, index) => {
+        // console.log(`address: ${address}`)
+        const balance = await _this._balanceFromElectrumx(address)
+
+        return {
+          balance,
+          address
+        }
+      })
+
+      // Wait for all parallel Insight requests to return.
+      const result = await Promise.all(addresses)
+
+      // Return the array of retrieved address information.
+      res.status(200)
+      return res.json({
+        success: true,
+        balances: result
+      })
     } catch (err) {
-      wlogger.error('Error in electrumx.js/addressToScripthash()')
-      throw err
+      wlogger.error('Error in electrumx.js/balanceBulk().', err)
+
+      return _this.errorHandler(err, res)
     }
   }
 
@@ -548,6 +616,29 @@ class Electrum {
       return _this.errorHandler(err, res)
     }
   }
+
+  // Convert a 'bitcoincash:...' address to a script hash used by ElectrumX.
+  addressToScripthash (addrStr) {
+    try {
+      // console.log(`addrStr: ${addrStr}`)
+
+      const address = _this.bitcore.Address.fromString(addrStr)
+      // console.log(`address: ${address}`)
+
+      const script = _this.bitcore.Script.buildPublicKeyHashOut(address)
+      // console.log(`script: ${script}`)
+
+      const scripthash = _this.bitcore.crypto.Hash.sha256(script.toBuffer())
+        .reverse()
+        .toString('hex')
+      // console.log(`scripthash: ${scripthash}`)
+
+      return scripthash
+    } catch (err) {
+      wlogger.error('Error in electrumx.js/addressToScripthash()')
+      throw err
+    }
+  }
 }
 
 module.exports = Electrum