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/*
 * Copyright 2014 Twitter inc.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */

package com.twitter.storehaus.algebra

import com.twitter.algebird.{ Semigroup, StatefulSummer }
import com.twitter.bijection.ImplicitBijection

/**
  * Enrichment on the [[com.twitter.storehaus.algebra.MergeableStore]]
  * trait. Storehaus uses the enrichment pattern instead of adding
  * these methods directly to the trait because many of the functions
  * (mapValues, for example) have different meanings for
  * ReadableStore, Store and MergeableStore.
  *
  * {{{ import MergeableStore.enrich }}}
  *
  * to get access to these methods.
  *
  * TODO: in scala 2.10 this should be a value class
  */
class EnrichedMergeableStore[K, V](store: MergeableStore[K, V]) {
  def unpivot[CombinedK, InnerK, InnerV](split: CombinedK => (K, InnerK))
    (implicit ev: V <:< Map[InnerK, InnerV], monoid: Semigroup[InnerV])
      : MergeableStore[CombinedK, InnerV] =
    MergeableStore.unpivot(store.asInstanceOf[MergeableStore[K, Map[InnerK, InnerV]]])(split)

  def withSummer(summerCons: SummerConstructor[K]): MergeableStore[K, V] =
    MergeableStore.withSummer(store)(summerCons)

  def composeKeyMapping[K1](fn: K1 => K): MergeableStore[K1, V] =
    MergeableStore.convert(store)(fn)

  def mapValues[V1](implicit bij: ImplicitBijection[V1, V]): MergeableStore[K, V1] =
    MergeableStore.convert(store)(identity[K])

  def convert[K1, V1](fn: K1 => K)(implicit bij: ImplicitBijection[V1, V]): MergeableStore[K1, V1] =
    MergeableStore.convert(store)(fn)

  def onMergeFailure(rescueException: Throwable => Unit): MergeableStore[K, V] =
    new MergeableStoreProxy[K, V] {
      override def self = store
      override def merge(kv: (K, V)) = store.merge(kv).onFailure(rescueException)
      override def multiMerge[K1 <: K](kvs: Map[K1, V]) =
        store.multiMerge(kvs).map { case (key, value) => (key, value.onFailure(rescueException)) }
    }
}