import Foundation
import PathKit

/// A class representing a template
public class Template {
  public let parser:TokenParser

  /// Create a template with the given name inside the main bundle
  public convenience init?(named:String) throws {
    try self.init(named:named, inBundle:nil)
  }

  /// Create a template with the given name inside the given bundle
  public convenience init?(named:String, inBundle bundle:NSBundle?) throws {
    var url:NSURL?

    if let bundle = bundle {
      url = bundle.URLForResource(named, withExtension: nil)
    } else {
      url = NSBundle.mainBundle().URLForResource(named, withExtension: nil)
    }

    try self.init(URL:url!)
  }

  /// Create a template with a file found at the given URL
  public convenience init(URL:NSURL) throws {
    let templateString = try NSString(contentsOfURL: URL, encoding: NSUTF8StringEncoding)
    self.init(templateString: templateString as String)
  }

  /// Create a template with a file found at the given path
  public convenience init?(path:Path) throws {
    self.init(templateString: path.read() ?? "")
  }

  /// Create a template with a template string
  public init(templateString:String) {
    let lexer = Lexer(templateString: templateString)
    let tokens = lexer.tokenize()
    parser = TokenParser(tokens: tokens)
  }

  /// Render the given template in a context
  public func render(context:Context) -> Result {
    switch parser.parse() {
    case .Success(let nodes):
      return renderNodes(nodes, context: context)

    case .Error(let error):
      return .Error(error)
    }
  }

  /// Render the given template without a context
  public func render() -> Result {
    let context = Context()
    return render(context)
  }
}