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/*
 * Copyright 2001-2013 Artima, 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 org.scalautils

/**
 * Provides decidedBy and whenBothAre syntax, which facilitates the
 * explicit specification of Equality[T] and/or Uniformity[T] where
 * Equality[T] is taken implicitly.
 *
 * @author Bill Venners
 */
trait Explicitly {

  class DecidedWord {
    def by[A](equality: Equality[A]): DecidedByEquality[A] = new DecidedByEquality[A](equality)
  }

  val decided = new DecidedWord

  class DeterminedWord {
    def by[A](equivalence: Equivalence[A]): DeterminedByEquivalence[A] = new DeterminedByEquivalence[A](equivalence)
  }

  val determined = new DeterminedWord

  class DecidedByEquality[A](equality: Equality[A]) extends Equality[A] {
  
    /**
     * Indicates whether the objects passed as a and b are equal.
     *
     * @param a a left-hand-side object being compared with another (right-hand-side one) for equality (e.g., a == b)
     * @param b a right-hand-side object being compared with another (left-hand-side one) for equality (e.g., a == b)
     * @return true if the passed objects are "equal," as defined by this Equality instance
     */
    def areEqual(a: A, b: Any): Boolean = equality.areEqual(a, b)
  
    def afterBeing(uniformity: Uniformity[A]): NormalizingEquality[A] =
      new ComposedNormalizingEquality[A](equality, uniformity)
  } 
  
  class DeterminedByEquivalence[T](equivalence: Equivalence[T]) extends Equivalence[T] {
  
    /**
     * Indicates whether the objects passed as a and b are equal.
     *
     * @param a a left-hand-side object being compared with another (right-hand-side one) for equality (e.g., a == b)
     * @param b a right-hand-side object being compared with another (left-hand-side one) for equality (e.g., a == b)
     * @return true if the passed objects are "equal," as defined by this Equality instance
     */
    def areEquivalent(a: T, b: T): Boolean = equivalence.areEquivalent(a, b)
  
    def afterBeing(normalization: Normalization[T]): NormalizingEquivalence[T] =
      new ComposedNormalizingEquivalence[T](equivalence, normalization)
  } 

  class TheAfterWord {
    def being[N](uniformity: Uniformity[N])(implicit equality: Equality[N]): NormalizingEquality[N] =
      new ComposedNormalizingEquality[N](equality, uniformity)
    def being[N](normalization: Normalization[N])(implicit equivalence: Equivalence[N]): NormalizingEquivalence[N] =
      new ComposedNormalizingEquivalence[N](equivalence, normalization)
  }

  val after = new TheAfterWord
}

object Explicitly extends Explicitly