Q

q.scala

// o for original t for translated
// basically a translation table
val reference = Map("schema1" -> Map("oa1" -> "ta1", "ob1" -> "tb1"),
  "schema2" -> Map("oa2" -> "ta2", "ob2" -> "tb2"))

// given data with the original names and values
// v for value
val given = Map("ob2" -> "vb2", "oa1" -> "va1")

val wanted = Map("schema1" -> Map("ta1" -> "va1"), "schema2" -> Map("tb2" -> "vb2"))

// 1. brute
// check for every key in `given` if it is a value in one of the schema in `reference`
// cost: N*M

// 2. moar maps
// create an intermediary table ("reverse" of `reference`)
val intermediary = Map("oa1" -> "schema1", "ob1" -> "schema1", "oa2" -> "schema2", "ob2" -> "schema2")
// build the list of needed schemas `needed` from `intermediary` and `given`
// index `reference` on schema and field to get to the translation
// cost: N ?
val indirect = reference.flatMap { case (k, v) => v.keys.map(_ -> k) }                              
                                                                                                    
given.foldLeft(Map.empty[String, Map[String, String]]) { (m, e) =>                                  
  indirect.get(e._1).map { s =>                                                                     
    val ref = reference(s)(e._1)                                                                    
    val tr = m.getOrElse(s, Map.empty) + (ref -> e._2)                                          
    m + (s -> tr)                                                                                   
  }                                                                                                 
  .getOrElse(m)                                                                                     
}