improve toBTC and fromBTC while ensuring safety.

lib/bcoin/utils.js

@@ -451,7 +451,18 @@ utils.assert.equal = function assertEqual(l, r, msg) {
     throw new Error(msg || ('Assertion failed: ' + l + ' != ' + r));
 };
 
-utils.toBTC = function toBTC(satoshi) {
+utils.toBTC = function toBTC(satoshi, strict) {
+  if (typeof satoshi === 'string' && /^\d+(?:\.\d+)?$/.test(satoshi)) {
+    satoshi = new bn(satoshi, 10);
+  } else if (typeof satoshi === 'number') {
+    // XXX Dangerous precision - do not use for any real txes
+    if (!strict)
+      satoshi = new bn(Math.floor(+satoshi || 0).toString(16), 16);
+  }
+
+  if (!(satoshi instanceof bn))
+    throw new Error('could not calculate btc');
+
   var m = new bn(10000000).mul(new bn(10));
   var lo = satoshi.mod(m);
   if (lo.cmpn(0) !== 0) {
@@ -462,9 +473,35 @@ utils.toBTC = function toBTC(satoshi) {
   } else {
     lo = '';
   }
+
   return satoshi.div(m).toString(10) + lo.replace(/0+$/, '');
 };
 
+utils.fromBTC = function(btc, strict) {
+  var satoshi;
+
+  if (typeof btc === 'string' && /^\d+(?:\.\d+)?$/.test(btc)) {
+    var parts = btc.split('.');
+    parts[0] = parts[0] || '0';
+    parts[1] = parts[1] || '0';
+    while (parts[1].length < 8)
+      parts[1] += '0';
+    parts[0] = parts[0].replace(/^0+/, '');
+    satoshi = new bn(parts[0] + parts[1], 10);
+  } else if (typeof btc === 'number') {
+    // XXX Dangerous precision - do not use for any real txes
+    if (!strict)
+      satoshi = new bn(+btc || 0);
+  }
+
+  if (!(satoshi instanceof bn))
+    throw new Error('could not calculate satoshis');
+
+  var m = new bn(10000000).mul(new bn(10));
+  satoshi.imuln(m);
+  return satoshi;
+};
+
 utils.isIP = function(ip) {
   if (typeof ip !== 'string')
     return 0;
@@ -519,14 +556,3 @@ utils.merge = function(target) {
   });
   return target;
 };
-
-utils.fromBTC = function(btc) {
-  var satoshi = new bn(+btc || 0);
-  satoshi.imuln(100000000);
-  return satoshi;
-};
-
-utils.ntoBTC = function(satoshi) {
-  satoshi = new bn(Math.floor(+satoshi || 0).toString(16), 16);
-  return bcoin.utils.toBTC(satoshi);
-};