:(

import Foundation
import ImageIO

infix operator >>= { associativity left }

func >>=<A,B>(l: A?, r: A -> B?) -> B? {
  if let x = l {
    return r(x)
  }
  return nil
}

func flatMap<A,B>(list: [A], f: A -> B?) -> [B] {
  var result : [B] = []
  for x in list {
    if let value = f(x) {
      result.append(value)
    }
  }
  return result
}

typealias rn_CGPropDictionary = Dictionary<String, AnyObject>

func string(input: rn_CGPropDictionary, key: String) -> String? {
  return input[key] as? String
}

func dictionary(input: rn_CGPropDictionary, key: String) -> rn_CGPropDictionary? {
  return input[key] as? rn_CGPropDictionary
}

func datesFromImagesInDir(dir: String) -> [NSDate] {
  let fm = NSFileManager.defaultManager()
  var error: NSError?
  
  let df = NSDateFormatter()
  df.dateFormat = "yyyy:MM:dd HH:mm:ss"
  
  
  let options = [String(kCGImageSourceShouldCache) : false]
  
  let dateTimeOriginal = { string($0, kCGImagePropertyExifDateTimeOriginal) }
  let exif             = { dictionary($0, kCGImagePropertyExifDictionary) }
  let imageProperties  = { CGImageSourceCopyPropertiesAtIndex($0, 0, options) }
  let imageSource      = { CGImageSourceCreateWithURL($0, nil) }
  let absoluteURL      = { (fileName: String) in NSURL(fileURLWithPath: dir)?.URLByAppendingPathComponent(fileName) }
  
  let directoryContents = fm.contentsOfDirectoryAtPath(dir, error: &error) as? [String]
  
  return directoryContents.map  {
    return flatMap($0) { fileName in
      absoluteURL(fileName) >>= imageSource >>= imageProperties >>= exif >>= dateTimeOriginal >>= df.dateFromString
    }
    } ?? []
}