[Node] Introduce formats to now node

Closes #8

Stencil/Node.swift

@@ -98,13 +98,43 @@ public class VariableNode : Node {
 }
 
 public class NowNode : Node {
+    public let format:Variable
+
     public class func parse(parser:TokenParser, token:Token) -> (node:Node?, error:Error?) {
-        return (NowNode(), nil)
+        var format:Variable?
+
+        let components = token.components()
+        if components.count == 2 {
+            format = Variable(components[1])
+        }
+
+        return (NowNode(format:format), nil)
+    }
+
+    public init(format:Variable?) {
+        if let format = format {
+            self.format = format
+        } else {
+            self.format = Variable("\"yyyy-MM-dd 'at' HH:mm\"")
+        }
     }
 
     public func render(context: Context) -> (String?, Error?) {
         let date = NSDate()
-        return ("\(date)", nil)
+        let format: AnyObject? = self.format.resolve(context)
+        var formatter:NSDateFormatter?
+
+        if let format = format as? NSDateFormatter {
+            formatter = format
+        } else if let format = format as? String {
+            formatter = NSDateFormatter()
+            formatter!.dateFormat = format
+        } else {
+            // TODO Error
+            return (nil, nil)
+        }
+
+        return ("\(formatter!.stringFromDate(date))", nil)
     }
 }
 

StencilTests/NodeTests.swift

@@ -180,3 +180,47 @@ class IfNodeTests: NodeTests {
     }
 
 }
+
+class NowNodeTests: NodeTests {
+
+    // MARK: Parsing
+
+    func testParseDefaultNow() {
+        let tokens = [ Token.Block(value: "now") ]
+        let parser = TokenParser(tokens: tokens)
+        let (nodes, error) = parser.parse()
+
+        let node = nodes!.first! as NowNode
+
+        XCTAssertTrue(error == nil)
+        XCTAssertEqual(nodes!.count, 1)
+        XCTAssertEqual(node.format.variable, "\"yyyy-MM-dd 'at' HH:mm\"")
+    }
+
+    func testParseNowWithFormat() {
+        let tokens = [ Token.Block(value: "now \"HH:mm\"") ]
+        let parser = TokenParser(tokens: tokens)
+        let (nodes, error) = parser.parse()
+
+        let node = nodes!.first! as NowNode
+
+        XCTAssertTrue(error == nil)
+        XCTAssertEqual(nodes!.count, 1)
+        XCTAssertEqual(node.format.variable, "\"HH:mm\"")
+    }
+
+    // MARK: Rendering
+
+    func testRenderNowNode() {
+        let node = NowNode(format: Variable("\"yyyy-MM-dd\""))
+        let result = node.render(context)
+
+        let formatter = NSDateFormatter()
+        formatter.dateFormat = "yyyy-MM-dd"
+        let date = formatter.stringFromDate(NSDate())
+
+        XCTAssertEqual(result.0!, date)
+    }
+
+}
+