Sidecar.scala

import scala.util.matching.Regex

    val in = """# Systems
               |
               |## System 1
               |
               |- Foo: bar
               |- Baz: qux
               |- Bla:
               |  1. Bla
               |  2. Bla
               |  3. Bla
               |
               |### Header
               |
               |askdjfalskdjfalsdf
               |
               |### Another header
               |
               |Content
               |
               |## System 2
               |
               |### Property
               |
               |- value
               |- value
               |
               |## System 3
               |
               |- foo: bar""".stripMargin

    def systemNameToPropertyMap(input: String): Map[String, Map[String, String]] = {
      val system   = raw"(?m)^## (.*)\n{2}((?:.|\n)*?)(?=^## |\z)".r
      val item     = raw"(?m)^- (.*):((?:.|\n)*?)\s*(?=^- |^#{2,3} |\z)".r
      val block    = raw"(?m)^### (.*)\n\s*((?:.|\n)*?)\s*(?=^#{2,3} |\z)".r
      val inline   = raw"(?m)\A (.*)\z".r
      val indented = raw"(?m)\A(\n {2}.*)*\z".r

      def content(rawValue: String) =
        rawValue match {
          case inline(value) => value
          case indented(_*)  => rawValue.replaceFirst("\n {2}", "").replaceAll("\n {2}", "\n")
        }
      def groups(regex: Regex, input: String) = regex.findAllMatchIn(input).map(_.subgroups)

      (for {
        name :: body :: Nil <- groups(system, input)
        items  = for (k :: v :: Nil <- groups(item, body)) yield k -> content(v)
        blocks = for (k :: v :: Nil <- groups(block, body)) yield k -> v
      } yield name -> (items ++ blocks).toMap).toMap
    }

    println(systemNameToPropertyMap(in))