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package pimpathon

import pimpathon.multiMap.IgnoreFromCBF

import scala.collection.generic.CanBuildFrom
import scala.collection.{mutable ⇒ M, breakOut}

import pimpathon.map._


object nestedMap {
  type NestedMap[K1, K2, V] = Map[K1, Map[K2, V]]
  type NMCBF[K1, K2, V] = CanBuildFrom[Nothing, (K1, K2, V), NestedMap[K1, K2, V]]

  implicit def build[K1, K2, V]: NMCBF[K1, K2, V] = new NestedMapCanBuilderFrom[K1, K2, V]

  implicit def nestedMapPimps[K1, K2, V](nestedMap: NestedMap[K1, K2, V]): NestedMapPimps[K1, K2, V] =
    new NestedMapPimps[K1, K2, V](nestedMap)

  class NestedMapPimps[K1, K2, V](value: NestedMap[K1, K2, V]) {
    def flipNesting: NestedMap[K2, K1, V] = value.flatMap(o ⇒ o._2.map(i ⇒ (i._1, o._1, i._2)))(breakOut)
    def nestedMap: NestedMapConflictingPimps[K1, K2, V] = new NestedMapConflictingPimps[K1, K2, V](value)
    def +(kkv: (K1, K2, V)): NestedMap[K1, K2, V] = append(kkv._1, kkv._2, kkv._3)
    def append(k1: K1, k2: K2, v: V): NestedMap[K1, K2, V] = value + ((k1, value.getOrEmpty(k1) + ((k2, v))))
    def getOrEmpty(k1: K1): Map[K2, V] = value.getOrElse(k1, Map.empty[K2, V])
  }

  class NestedMapConflictingPimps[K1, K2, V](value: NestedMap[K1, K2, V]) {
    def mapValuesEagerly[W](f: V ⇒ W): NestedMap[K1, K2, W] = value.mapValuesEagerly(_.mapValuesEagerly(f))
    def mapKeysEagerly[C](f: K2 ⇒ C): NestedMap[K1, C, V]   = value.mapValuesEagerly(_.mapKeysEagerly(f))
  }

  object NestedMap {
    def build[K1, K2, V]: NMCBF[K1, K2, V] = new NestedMapCanBuilderFrom[K1, K2, V]
    def empty[K1, K2, V]: NestedMap[K1, K2, V] = Map.empty[K1, Map[K2, V]]
  }

  class NestedMapCanBuilderFrom[K1, K2, V] extends NMCBF[K1, K2, V]
    with IgnoreFromCBF[Nothing, (K1, K2, V), NestedMap[K1, K2, V]] {

    def apply(): M.Builder[(K1, K2, V), NestedMap[K1, K2, V]] = new NestedMapBuilder[K1, K2, V]()
  }

  class NestedMapBuilder[K1, K2, V](map: M.Map[K1, Map[K2, V]] = M.Map.empty[K1, Map[K2, V]])
    extends M.Builder[(K1, K2, V), NestedMap[K1, K2, V]] {

    def +=(elem: (K1, K2, V)): this.type = { add(elem._1, elem._2, elem._3); this}
    def result(): NestedMap[K1, K2, V] = map.map(entry ⇒ entry)(breakOut)
    def clear(): Unit = map.clear()

    private def add(k1: K1, k2: K2, v: V): Unit = map.put(k1, map.getOrElse(k1, Map.empty[K2, V]) + ((k2, v)))
  }
}