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/*
 *  Copyright 2021-2024 Disney Streaming
 *
 *  Licensed under the Tomorrow Open Source Technology License, Version 1.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *     https://disneystreaming.github.io/TOST-1.0.txt
 *
 *  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 smithy4s
package schema

/**
  * Represents a member of product type (case class)
  */
final case class Field[S, A](
    label: String,
    schema: Schema[A],
    get: S => A
) {

  /**
    * Returns the hints that are only relative to the field
    * (typically derived from member-level traits)
    */
  final def memberHints: Hints = schema.hints.memberHints

  /**
    * Returns all hints : the ones defined directly on the field, and the ones
    * defined on the target of the field.
    */
  final def hints: Hints = schema.hints

  @deprecated("use .schema instead", since = "0.18.0")
  final def instance: Schema[A] = schema

  lazy val getDefaultValue: Option[A] =
    schema.getDefaultValue

  def isDefaultValue(a: A): Boolean = getDefaultValue.contains(a)

  /**
   * If the field is marked as required (using `smithy.api#required`) OR
   * if the field value is different from its default, returns the value.
   * Otherwise returns None.
   */
  def getUnlessDefault(s: S): Option[A] = {
    val a = get(s)
    if (isRequired) Some(a)
    else
      getDefaultValue match {
        case Some(`a`) => None
        case _         => Some(a)
      }
  }

  /**
   * Applies a side-effecting lambda if the field is marked as required (using `smithy.api#required`),
   * OR if the field value is different from its default. Otherwise nothing happens.
   */
  def foreachUnlessDefault(s: S)(f: A => Unit): Unit = {
    // duplicates logic from getUnlessDefault in order to avoid unnecessary Option allocation
    val a = get(s)
    if (isDefaultValue(a) && !isRequired) () else f(a)
  }

  def hasDefaultValue: Boolean = getDefaultValue.isDefined
  def isRequired: Boolean = hints.has(smithy.api.Required)

  @deprecated("use !hasDefaultValue instead", since = "0.18.4")
  def isStrictlyRequired: Boolean = !hasDefaultValue

  def transformHintsLocally(f: Hints => Hints): Field[S, A] =
    copy(schema = schema.transformHintsLocally(f))

  def transformHintsTransitively(f: Hints => Hints) =
    copy(schema = schema.transformHintsTransitively(f))

  def contramap[S0](f: S0 => S): Field[S0, A] =
    Field(label, schema, get.compose(f))

  def addHints(newHints: Hint*): Field[S, A] =
    copy(schema = schema.addMemberHints(newHints: _*))

  def addHints(newHints: Hints): Field[S, A] =
    copy(schema = schema.addMemberHints(newHints))
}

object Field {

  def required[S, A](
      label: String,
      schema: Schema[A],
      get: S => A
  ): Field[S, A] =
    Field(label, schema, get).addHints(smithy.api.Required())

  def optional[S, A](
      label: String,
      schema: Schema[A],
      get: S => Option[A]
  ): Field[S, Option[A]] =
    Field(label, schema.option, get)

}