// See LICENSE for license details.

package Chisel

import scala.collection.immutable.ListMap
import scala.collection.mutable.{ArrayBuffer, HashSet, LinkedHashMap}

import internal._
import internal.Builder.pushCommand
import internal.firrtl._

/** An abstract class for data types that solely consist of (are an aggregate
  * of) other Data objects.
  */
sealed abstract class Aggregate(dirArg: Direction) extends Data(dirArg) {
  private[Chisel] def cloneTypeWidth(width: Width): this.type = cloneType
  def width: Width = flatten.map(_.width).reduce(_ + _)
}

object Vec {
  /** Creates a new [[Vec]] with `n` entries of the specified data type.
    *
    * @note elements are NOT assigned by default and have no value
    */
  def apply[T <: Data](n: Int, gen: T): Vec[T] = new Vec(gen.cloneType, n)

  @deprecated("Vec argument order should be size, t; this will be removed by the official release", "chisel3")
  def apply[T <: Data](gen: T, n: Int): Vec[T] = new Vec(gen.cloneType, n)

  /** Creates a new [[Vec]] composed of elements of the input Seq of [[Data]]
    * nodes.
    *
    * @note input elements should be of the same type (this is checked at the
    * FIRRTL level, but not at the Scala / Chisel level)
    * @note the width of all output elements is the width of the largest input
    * element
    * @note output elements are connected from the input elements
    */
  def apply[T <: Data](elts: Seq[T]): Vec[T] = {
    // REVIEW TODO: this should be removed in favor of the apply(elts: T*)
    // varargs constructor, which is more in line with the style of the Scala
    // collection API. However, a deprecation phase isn't possible, since
    // changing apply(elt0, elts*) to apply(elts*) causes a function collision
    // with apply(Seq) after type erasure. Workarounds by either introducing a
    // DummyImplicit or additional type parameter will break some code.

    require(!elts.isEmpty)
    val width = elts.map(_.width).reduce(_ max _)
    val vec = Wire(new Vec(elts.head.cloneTypeWidth(width), elts.length))
    for ((v, e) <- vec zip elts)
      v := e
    vec
  }

  /** Creates a new [[Vec]] composed of the input [[Data]] nodes.
    *
    * @note input elements should be of the same type (this is checked at the
    * FIRRTL level, but not at the Scala / Chisel level)
    * @note the width of all output elements is the width of the largest input
    * element
    * @note output elements are connected from the input elements
    */
  def apply[T <: Data](elt0: T, elts: T*): Vec[T] =
    apply(elt0 +: elts.toSeq)

  /** Creates a new [[Vec]] of length `n` composed of the results of the given
    * function applied over a range of integer values starting from 0.
    *
    * @param n number of elements in the vector (the function is applied from
    * 0 to `n-1`)
    * @param gen function that takes in an Int (the index) and returns a
    * [[Data]] that becomes the output element
    */
  def tabulate[T <: Data](n: Int)(gen: (Int) => T): Vec[T] =
    apply((0 until n).map(i => gen(i)))

  /** Creates a new [[Vec]] of length `n` composed of the result of the given
    * function repeatedly applied.
    *
    * @param n number of elements (amd the number of times the function is
    * called)
    * @param gen function that generates the [[Data]] that becomes the output
    * element
    */
  def fill[T <: Data](n: Int)(gen: => T): Vec[T] = apply(Seq.fill(n)(gen))
}

/** A vector (array) of [[Data]] elements. Provides hardware versions of various
  * collection transformation functions found in software array implementations.
  *
  * @tparam T type of elements
  * @note when multiple conflicting assignments are performed on a Vec element,
  * the last one takes effect (unlike Mem, where the result is undefined)
  * @note Vecs, unlike classes in Scala's collection library, are propagated
  * intact to FIRRTL as a vector type, which may make debugging easier
  */
sealed class Vec[T <: Data] private (gen: => T, val length: Int)
    extends Aggregate(gen.dir) with VecLike[T] {
  // Note: the constructor takes a gen() function instead of a Seq to enforce
  // that all elements must be the same and because it makes FIRRTL generation
  // simpler.

  private val self = IndexedSeq.fill(length)(gen)

  override def <> (that: Data): Unit = this := that

  /** Strong bulk connect, assigning elements in this Vec from elements in a Seq.
    *
    * @note the length of this Vec must match the length of the input Seq
    */
  def <> (that: Seq[T]): Unit = this := that

  // TODO: eliminate once assign(Seq) isn't ambiguous with assign(Data) since Vec extends Seq and Data
  def <> (that: Vec[T]): Unit = this := that.asInstanceOf[Data]

  override def := (that: Data): Unit = that match {
    case _: Vec[_] => this connect that
    case _ => this badConnect that
  }

  /** Strong bulk connect, assigning elements in this Vec from elements in a Seq.
    *
    * @note the length of this Vec must match the length of the input Seq
    */
  def := (that: Seq[T]): Unit = {
    require(this.length == that.length)
    for ((a, b) <- this zip that)
      a := b
  }

  // TODO: eliminate once assign(Seq) isn't ambiguous with assign(Data) since Vec extends Seq and Data
  def := (that: Vec[T]): Unit = this connect that

  /** Creates a dynamically indexed read or write accessor into the array.
    */
  def apply(idx: UInt): T = {
    val x = gen
    x.setRef(this, idx)
    x
  }

  /** Creates a statically indexed read or write accessor into the array.
    */
  def apply(idx: Int): T = self(idx)

  @deprecated("Use Vec.apply instead", "chisel3")
  def read(idx: UInt): T = apply(idx)

  @deprecated("Use Vec.apply instead", "chisel3")
  def write(idx: UInt, data: T): Unit = apply(idx) := data

  override def cloneType: this.type =
    Vec(length, gen).asInstanceOf[this.type]

  private val t = gen
  private[Chisel] def toType: String = s"${t.toType}[$length]"
  private[Chisel] lazy val flatten: IndexedSeq[Bits] =
    (0 until length).flatMap(i => this.apply(i).flatten)

  for ((elt, i) <- self zipWithIndex)
    elt.setRef(this, i)
}

/** A trait for [[Vec]]s containing common hardware generators for collection
  * operations.
  */
trait VecLike[T <: Data] extends collection.IndexedSeq[T] {
  def apply(idx: UInt): T

  @deprecated("Use Vec.apply instead", "chisel3")
  def read(idx: UInt): T

  @deprecated("Use Vec.apply instead", "chisel3")
  def write(idx: UInt, data: T): Unit

  /** Outputs true if p outputs true for every element.
    */
  def forall(p: T => Bool): Bool = (this map p).fold(Bool(true))(_ && _)

  /** Outputs true if p outputs true for at least one element.
    */
  def exists(p: T => Bool): Bool = (this map p).fold(Bool(false))(_ || _)

  /** Outputs true if the vector contains at least one element equal to x (using
    * the === operator).
    */
  def contains(x: T)(implicit evidence: T <:< UInt): Bool = this.exists(_ === x)

  /** Outputs the number of elements for which p is true.
    */
  def count(p: T => Bool): UInt = SeqUtils.count(this map p)

  /** Helper function that appends an index (literal value) to each element,
    * useful for hardware generators which output an index.
    */
  private def indexWhereHelper(p: T => Bool) = this map p zip (0 until length).map(i => UInt(i))

  /** Outputs the index of the first element for which p outputs true.
    */
  def indexWhere(p: T => Bool): UInt = SeqUtils.priorityMux(indexWhereHelper(p))

  /** Outputs the index of the last element for which p outputs true.
    */
  def lastIndexWhere(p: T => Bool): UInt = SeqUtils.priorityMux(indexWhereHelper(p).reverse)

  /** Outputs the index of the element for which p outputs true, assuming that
    * the there is exactly one such element.
    *
    * The implementation may be more efficient than a priority mux, but
    * incorrect results are possible if there is not exactly one true element.
    *
    * @note the assumption that there is only one element for which p outputs
    * true is NOT checked (useful in cases where the condition doesn't always
    * hold, but the results are not used in those cases)
    */
  def onlyIndexWhere(p: T => Bool): UInt = SeqUtils.oneHotMux(indexWhereHelper(p))
}

/** Base class for data types defined as a bundle of other data types.
  *
  * Usage: extend this class (either as an anonymous or named class) and define
  * members variables of [[Data]] subtypes to be elements in the Bundle.
  */
class Bundle extends Aggregate(NO_DIR) {
  private val _namespace = Builder.globalNamespace.child

  // TODO: replace with better defined FIRRTL weak-connect operator
  /** Connect elements in this Bundle to elements in `that` on a best-effort
    * (weak) basis, matching by type, orientation, and name.
    *
    * @note unconnected elements will NOT generate errors or warnings
    *
    * @example
    * {{{
    * // Pass through wires in this module's io to those mySubModule's io,
    * // matching by type, orientation, and name, and ignoring extra wires.
    * mySubModule.io <> io
    * }}}
    */
  override def <> (that: Data): Unit = that match {
    case _: Bundle => this bulkConnect that
    case _ => this badConnect that
  }

  // TODO: replace with better defined FIRRTL strong-connect operator
  override def := (that: Data): Unit = this <> that

  lazy val elements: ListMap[String, Data] = ListMap(namedElts:_*)

  /** Returns a best guess at whether a field in this Bundle is a user-defined
    * Bundle element without looking at type signatures.
    */
  private def isBundleField(m: java.lang.reflect.Method) =
    m.getParameterTypes.isEmpty &&
    !java.lang.reflect.Modifier.isStatic(m.getModifiers) &&
    !(Bundle.keywords contains m.getName) && !(m.getName contains '$')

  /** Returns a field's contained user-defined Bundle element if it appears to
    * be one, otherwise returns None.
    */
  private def getBundleField(m: java.lang.reflect.Method): Option[Data] = {
    if (isBundleField(m) &&
        (classOf[Data].isAssignableFrom(m.getReturnType) ||
         classOf[Option[_]].isAssignableFrom(m.getReturnType))) {
      m.invoke(this) match {
        case d: Data =>
          Some(d)
        case o: Option[_] =>
          o.getOrElse(None) match {
            case d: Data =>
              Some(d)
            case _ => None
          }
        case _ => None
      }
    } else {
      None
    }
  }

  /** Returns a list of elements in this Bundle.
    */
  private[Chisel] lazy val namedElts = {
    val nameMap = LinkedHashMap[String, Data]()
    val seen = HashSet[Data]()
    for (m <- getClass.getMethods.sortWith(_.getName < _.getName)) {
      getBundleField(m) match {
        case Some(d) =>
          if (nameMap contains m.getName) {
            require(nameMap(m.getName) eq d)
          } else if (!seen(d)) {
            nameMap(m.getName) = d; seen += d
          }
        case None =>
      }
    }
    ArrayBuffer(nameMap.toSeq:_*) sortWith {case ((an, a), (bn, b)) => (a._id > b._id) || ((a eq b) && (an > bn))}
  }
  private[Chisel] def toType = {
    def eltPort(elt: Data): String = {
      val flipStr = if (elt.isFlip) "flip " else ""
      s"${flipStr}${elt.getRef.name} : ${elt.toType}"
    }
    s"{${namedElts.reverse.map(e => eltPort(e._2)).mkString(", ")}}"
  }
  private[Chisel] lazy val flatten = namedElts.flatMap(_._2.flatten)
  private[Chisel] def addElt(name: String, elt: Data): Unit =
    namedElts += name -> elt
  private[Chisel] override def _onModuleClose: Unit = // scalastyle:ignore method.name
    for ((name, elt) <- namedElts) { elt.setRef(this, _namespace.name(name)) }

  override def cloneType : this.type = {
    // If the user did not provide a cloneType method, try invoking one of
    // the following constructors, not all of which necessarily exist:
    // - A zero-parameter constructor
    // - A one-paramater constructor, with null as the argument
    // - A one-parameter constructor for a nested Bundle, with the enclosing
    //   parent Module as the argument
    val constructor = this.getClass.getConstructors.head
    try {
      val args = Seq.fill(constructor.getParameterTypes.size)(null)
      constructor.newInstance(args:_*).asInstanceOf[this.type]
    } catch {
      case e: java.lang.reflect.InvocationTargetException if e.getCause.isInstanceOf[java.lang.NullPointerException] =>
        try {
          constructor.newInstance(_parent.get).asInstanceOf[this.type]
        } catch {
          case _: java.lang.reflect.InvocationTargetException | _: java.lang.IllegalArgumentException =>
            Builder.error(s"Parameterized Bundle ${this.getClass} needs cloneType method. You are probably using " +
              "an anonymous Bundle object that captures external state and hence is un-cloneTypeable")
            this
        }
      case _: java.lang.reflect.InvocationTargetException | _: java.lang.IllegalArgumentException =>
        Builder.error(s"Parameterized Bundle ${this.getClass} needs cloneType method")
        this
    }
  }
}

private[Chisel] object Bundle {
  val keywords = List("flip", "asInput", "asOutput", "cloneType", "toBits")
}