dotEnv.sbt

lazy val dotEnvFile = taskKey[String]("Defines the file to load environment variables from")

dotEnvFile := ".env"

// The task returns the loaded dotEnv file and a map of the loaded variables, in case it would need to be manipulated somewhere else
lazy val loadEnv = taskKey[(File, Map[String, String])]("""Loads the environment variables from file defined by task `dotEnvFile` (they must follow the format "export X=Y")""")

loadEnv := {
  val logger = ConsoleLogger()
  val sourceFileName = dotEnvFile.value
  val sourceFile = file(sourceFileName)
  val export = """^export\s+([^=]+)="?(.*?)"?$""".r

  logger.info(s"""Loading environment variables from file "$sourceFileName" ...""")

  val propertiesMap = scala.io.Source.fromFile(sourceFile).getLines() map {
    _.trim
  } flatMap {
    case export(key, value) =>
      logger.info(s"""Loaded variable "$key"="$value"""")
      Some((key, value))

    case _ => None
  } toMap

  propertiesMap.foreach((java.lang.System.setProperty _).tupled)

  logger.info("Environment variables loaded.")

  (sourceFile, propertiesMap)
}