Recipie-Book/app/models/Unit.scala

package models

class ConversionException(from: Unit, to: Unit) extends
    RuntimeException(s"Cannot convert from $from to $to.", null)

sealed trait Unit {
  def productPrefix: String
  protected def conversion: Float
  def name: String = this.productPrefix.split("\\.").last
  protected def abreviation: String
  def measure: Measure
  def convertToPrimary(v: Float): Float = v/conversion
  def convertFromPrimary(v: Float): Float = v*conversion
  def convertTo(v: Float, other: Unit) = {
    if (measure == other.measure)
      other.convertFromPrimary(convertToPrimary(v))
    else
      throw new ConversionException(this, other)
  }
}

case object Gram extends Unit
{
  protected val conversion: Float = 1f
  val measure: Measure = Mass
  val abreviation: String = "g"
}

case object Kilogram extends Unit
{
  protected val conversion: Float = 0.001f
  val measure: Measure = Mass
  val abreviation: String = "kg"
}

case object Ounce extends Unit
{
  protected val conversion: Float = 0.03527396f
  val measure: Measure = Mass
  val abreviation: String = "oz"
}

case object Pound extends Unit
{
  protected val conversion: Float = 0.00220462249993f
  val measure: Measure = Mass
  val abreviation: String = "lb"
}

case object Mililiter extends Unit
{
  protected val conversion: Float = 1000f
  val measure: Measure = Volume
  val abreviation: String = "mL"
}

case object Liter extends Unit
{
  protected val conversion: Float = 1f
  val measure: Measure = Volume
  val abreviation: String = "L"
}

case object Teaspoon extends Unit
{
  protected val conversion: Float = 202.8842218965f
  val measure: Measure = Volume
  val abreviation: String = "tsp"
}

case object Tablespoon extends Unit
{
  protected val conversion: Float = 67.627891024f
  val measure: Measure = Volume
  val abreviation: String = "Tbsp"
}

case object Cup extends Unit
{
  protected val conversion: Float = 4.166666f
  val measure: Measure = Volume
  val abreviation: String = "cups"
}

case object Gallon extends Unit
{
  protected val conversion: Float = 0.26417290088f
  val measure: Measure = Volume
  val abreviation: String = "gallons"
}

case object Count extends Unit
{
  protected val conversion: Float = 1f
  val measure: Measure = Number
  val abreviation: String = ""
}