1 files changed, 59 insertions, 16 deletions

diff --git a/src/main/scala/xyz/driver/core/date.scala b/src/main/scala/xyz/driver/core/date.scala
index 5a6f736..d6f64e4 100644
--- a/src/main/scala/xyz/driver/core/date.scala
+++ b/src/main/scala/xyz/driver/core/date.scala
@@ -2,24 +2,67 @@ package xyz.driver.core
 
 import java.util.Calendar
 
+import scala.util.Try
+
+import scalaz.std.anyVal._
+import scalaz.syntax.equal._
+
+/**
+  * Driver Date type and related validators/extractors.
+  * Day, Month, and Year extractors are from ISO 8601 strings => driver...Date integers.
+  * TODO: Decouple extractors from ISO 8601, as we might want to parse other formats.
+  */
 object date {
 
+  type Day = Int @@ Day.type
+
+  object Day {
+    def apply(value: Int): Day = {
+      require(1 to 31 contains value, "Day must be in range 1 <= value <= 31")
+      value.asInstanceOf[Day]
+    }
+
+    def unapply(dayString: String): Option[Int] = {
+      require(dayString.length === 2, s"ISO 8601 day string, DD, must have length 2: $dayString")
+      Try(dayString.toInt).toOption.map(apply)
+    }
+  }
+
   type Month = Int @@ Month.type
-  private[core] def tagMonth(value: Int): Month = value.asInstanceOf[Month]
 
   object Month {
-    val JANUARY   = tagMonth(Calendar.JANUARY)
-    val FEBRUARY  = tagMonth(Calendar.FEBRUARY)
-    val MARCH     = tagMonth(Calendar.MARCH)
-    val APRIL     = tagMonth(Calendar.APRIL)
-    val MAY       = tagMonth(Calendar.MAY)
-    val JUNE      = tagMonth(Calendar.JUNE)
-    val JULY      = tagMonth(Calendar.JULY)
-    val AUGUST    = tagMonth(Calendar.AUGUST)
-    val SEPTEMBER = tagMonth(Calendar.SEPTEMBER)
-    val OCTOBER   = tagMonth(Calendar.OCTOBER)
-    val NOVEMBER  = tagMonth(Calendar.NOVEMBER)
-    val DECEMBER  = tagMonth(Calendar.DECEMBER)
+    def apply(value: Int): Month = {
+      require(0 to 11 contains value, "Month is zero-indexed: 0 <= value <= 11")
+      value.asInstanceOf[Month]
+    }
+    val JANUARY   = Month(Calendar.JANUARY)
+    val FEBRUARY  = Month(Calendar.FEBRUARY)
+    val MARCH     = Month(Calendar.MARCH)
+    val APRIL     = Month(Calendar.APRIL)
+    val MAY       = Month(Calendar.MAY)
+    val JUNE      = Month(Calendar.JUNE)
+    val JULY      = Month(Calendar.JULY)
+    val AUGUST    = Month(Calendar.AUGUST)
+    val SEPTEMBER = Month(Calendar.SEPTEMBER)
+    val OCTOBER   = Month(Calendar.OCTOBER)
+    val NOVEMBER  = Month(Calendar.NOVEMBER)
+    val DECEMBER  = Month(Calendar.DECEMBER)
+
+    def unapply(monthString: String): Option[Month] = {
+      require(monthString.length === 2, s"ISO 8601 month string, MM, must have length 2: $monthString")
+      Try(monthString.toInt).toOption.map(isoM => apply(isoM - 1))
+    }
+  }
+
+  type Year = Int @@ Year.type
+
+  object Year {
+    def apply(value: Int): Year = value.asInstanceOf[Year]
+
+    def unapply(yearString: String): Option[Int] = {
+      require(yearString.length === 4, s"ISO 8601 year string, YYYY, must have length 4: $yearString")
+      Try(yearString.toInt).toOption.map(apply)
+    }
   }
 
   final case class Date(year: Int, month: Month, day: Int) {
@@ -38,9 +81,9 @@ object date {
     }
 
     def fromString(dateString: String): Option[Date] = {
-      util.Try(dateString.split("-").map(_.toInt)).toOption collect {
-        case Array(year, month, day) if (1 to 12 contains month) && (1 to 31 contains day) =>
-          Date(year, tagMonth(month - 1), day)
+      dateString.split('-') match {
+        case Array(Year(year), Month(month), Day(day)) => Some(Date(year, month, day))
+        case _                                         => None
       }
     }
   }