feat: add pretty-printing options

Closes #35

README.md

@@ -9,6 +9,24 @@ var json2toml = require('json2toml');
 
 json2toml({simple: true});
 // => 'simple = true\n'
+
+// Also supports pretty-printing options
+json2toml(
+  {
+    deeply: {
+      option: false,
+      nested: {
+        option: true
+      }
+    }
+  },
+  { indent: 2, newlineAfterSection: true }
+);
+// => [deeply]
+// =>   option = false
+// =>
+// => [deeply.nested]
+// =>   option = true
 ```
 
 ## Installation
@@ -23,6 +41,10 @@ $ npm install json2toml
 var json2toml = require('json2toml');
 ```
 
-### json2toml(hash)
+### json2toml(hash, options = {})
 
 Converts an _Object_ `hash` to TOML, and returns the result as a _String_.
+
+- `options.indent`: Number of spaces for indentation.
+- `options.newlineAfterSection`: Whether or not to output a newline after the
+  last pair in a hash if that hash wasn't empty.

index.js

@@ -11,27 +11,34 @@ function format(obj) {
     : JSON.stringify(obj);
 }
 
-module.exports = function(hash) {
+module.exports = function(hash, options = {}) {
   function visit(hash, prefix) {
     var nestedPairs = [];
     var simplePairs = [];
 
+    var indentStr = '';
+
     forEach(keys(hash).sort(), function(key) {
       var value = hash[key];
       (isPlainObject(value) ? nestedPairs : simplePairs).push([key, value]);
     });
 
     if (!(isEmpty(prefix) || isEmpty(simplePairs))) {
       toml += '[' + prefix + ']\n';
+      indentStr = ''.padStart(options.indent, ' ');
     }
 
     forEach(simplePairs, function(array) {
       var key = array[0];
       var value = array[1];
 
-      toml += key + ' = ' + format(value) + '\n';
+      toml += indentStr + key + ' = ' + format(value) + '\n';
     });
 
+    if (!isEmpty(simplePairs) && options.newlineAfterSection) {
+      toml += '\n';
+    }
+
     forEach(nestedPairs, function(array) {
       var key = array[0];
       var value = array[1];

test/index.js

@@ -49,3 +49,15 @@ test('nested', function(t) {
              + 'again = "it never ends"\n';
   t.equal(json2toml(hash), toml);
 });
+
+test('pretty', function(t) {
+  t.plan(1);
+
+  var hash = { nested: { hash: { deep: true } } };
+  var toml = '[nested.hash]\n  deep = true';
+
+  t.equal(
+    json2toml(hash, { indent: 2, newlineAfterSection: true }).trim(),
+    toml
+  );
+});