gistfile1.scala

package com.cammy.firehose.domain

import java.io.File
import java.nio.file.attribute.BasicFileAttributeView
import java.nio.file.{Paths, Files}
import org.joda.time.Instant
import scalaz._
import Scalaz._

sealed trait CameraImageTimestamp {
  def value: Instant
}
case class UploadedTimestamp(value: Instant) extends CameraImageTimestamp
case class CanonicalTimestamp(value: Instant) extends CameraImageTimestamp
case class CameraImageTimestamps(canonical: Option[CanonicalTimestamp], uploaded: UploadedTimestamp) {
  def timestamp: CameraImageTimestamp = canonical.getOrElse(uploaded)
}

object CameraImageTimestamps {
  def fromFile(file: File): TimestampParseException \/ CameraImageTimestamps = {
    for {
      uploaded  <- getUploadedTimestampFromFile(file)
      canonical <- getCanonicalTimestampFromFile(file)
    } yield CameraImageTimestamps(canonical, uploaded)
  }

  private def getUploadedTimestampFromFile(file: File): TimestampParseException \/ UploadedTimestamp = {
    try {
      val view = Files.getFileAttributeView(Paths.get(file.getAbsolutePath), classOf[BasicFileAttributeView]).readAttributes();
      \/-(UploadedTimestamp(instantFromLong(view.creationTime().toMillis)))
    } catch {
      case e: Exception => -\/(TimestampParseException("Tried to read the CTime from the file and failed."))
    }
  }

  private def getCanonicalTimestampFromFile(file: File): TimestampParseException \/ Option[CanonicalTimestamp] = {
    // Would be parsing based on some filename stuff
    -\/(TimestampParseException("Cannot parse timestamp"))
  }

  private def instantFromLong(v: Long) = new Instant(v)
}