// SPDX-License-Identifier: Apache-2.0

package chiselTests

import circt.stage.ChiselStage
import chisel3._
import chisel3.testers.{BasicTester, TesterDriver}
import chisel3.util._
import org.scalacheck._

import scala.annotation.{nowarn, tailrec}

class LitTesterMod(vecSize: Int) extends Module {
  val io = IO(new Bundle {
    val out = Output(Vec(vecSize, UInt()))
  })
  io.out := VecInit(Seq.fill(vecSize) { 0.U })
}

class RegTesterMod(vecSize: Int) extends Module {
  val io = IO(new Bundle {
    val in = Input(Vec(vecSize, UInt()))
    val out = Output(Vec(vecSize, UInt()))
  })
  val vecReg = RegNext(io.in, VecInit(Seq.fill(vecSize) { 0.U }))
  io.out := vecReg
}

class IOTesterMod(vecSize: Int) extends Module {
  val io = IO(new Bundle {
    val in = Input(Vec(vecSize, UInt()))
    val out = Output(Vec(vecSize, UInt()))
  })
  io.out := io.in
}

class OneBitUnitRegVec extends Module {
  val io = IO(new Bundle {
    val out = Output(UInt(1.W))
  })
  val oneBitUnitRegVec = Reg(Vec(1, UInt(1.W)))
  oneBitUnitRegVec(0) := 1.U(1.W)
  io.out := oneBitUnitRegVec(0)
}

class LitTester(w: Int, values: List[Int]) extends BasicTester {
  val dut = Module(new LitTesterMod(values.length))
  for (a <- dut.io.out)
    assert(a === 0.U)
  stop()
}

class RegTester(w: Int, values: List[Int]) extends BasicTester {
  val v = VecInit(values.map(_.U(w.W)))
  val dut = Module(new RegTesterMod(values.length))
  val doneReg = RegInit(false.B)
  dut.io.in := v
  when(doneReg) {
    for ((a, b) <- dut.io.out.zip(values))
      assert(a === b.U)
    stop()
  }.otherwise {
    doneReg := true.B
    for (a <- dut.io.out)
      assert(a === 0.U)
  }
}

class IOTester(w: Int, values: List[Int]) extends BasicTester {
  val v = VecInit(values.map(_.U(w.W))) // Does this need a Wire? No. It's a Vec of Lits and hence synthesizeable.
  val dut = Module(new IOTesterMod(values.length))
  dut.io.in := v
  for ((a, b) <- dut.io.out.zip(values)) {
    assert(a === b.U)
  }
  stop()
}

class IOTesterModFill(vecSize: Int) extends Module {
  // This should generate a BindingException when we attempt to wire up the Vec.fill elements
  //  since they're pure types and hence unsynthesizeable.
  val io = IO(new Bundle {
    val in = Input(VecInit(Seq.fill(vecSize) { UInt() }))
    val out = Output(VecInit(Seq.fill(vecSize) { UInt() }))
  })
  io.out := io.in
}

class ValueTester(w: Int, values: List[Int]) extends BasicTester {
  val v = VecInit(values.map(_.asUInt(w.W)))
  for ((a, b) <- v.zip(values)) {
    assert(a === b.asUInt)
  }
  stop()
}

class TabulateTester(n: Int) extends BasicTester {
  val v = VecInit(Range(0, n).map(i => (i * 2).asUInt))
  val x = VecInit(Array.tabulate(n) { i => (i * 2).asUInt }.toIndexedSeq)
  val u = VecInit.tabulate(n)(i => (i * 2).asUInt)

  assert(v.asUInt === x.asUInt)
  assert(v.asUInt === u.asUInt)
  assert(x.asUInt === u.asUInt)

  stop()
}

class FillTester(n: Int, value: Int) extends BasicTester {
  val x = VecInit(Array.fill(n)(value.U).toIndexedSeq)
  val u = VecInit.fill(n)(value.U)

  assert(x.asUInt === u.asUInt, cf"Expected Vec to be filled like $x, instead VecInit.fill created $u")
  stop()
}

object VecMultiDimTester {

  @tailrec
  private def assert2DIsCorrect(n: Int, arr: Vec[Vec[UInt]], compArr: Seq[Seq[Int]]): Unit = {
    val compareRow = arr(n).zip(compArr(n))
    compareRow.foreach(x => assert(x._1 === x._2.U))
    if (n != 0) assert2DIsCorrect(n - 1, arr, compArr)
  }

  @tailrec
  private def assert3DIsCorrect(n: Int, m: Int, arr: Vec[Vec[Vec[UInt]]], compArr: Seq[Seq[Seq[Int]]]): Unit = {
    assert2DIsCorrect(m - 1, arr(n), compArr(n))
    if (n != 0) assert3DIsCorrect(n - 1, m, arr, compArr)
  }

  class TabulateTester2D(n: Int, m: Int) extends BasicTester {
    def gen(x:        Int, y: Int): UInt = (x + y).asUInt
    def genCompVec(x: Int, y: Int): Int = x + y
    val vec = VecInit.tabulate(n, m) { gen }
    val compArr = Seq.tabulate(n, m) { genCompVec }

    assert2DIsCorrect(n - 1, vec, compArr)
    stop()
  }

  class TabulateTester3D(n: Int, m: Int, p: Int) extends BasicTester {
    def gen(x:        Int, y: Int, z: Int): UInt = (x + y + z).asUInt
    def genCompVec(x: Int, y: Int, z: Int): Int = x + y + z
    val vec = VecInit.tabulate(n, m, p) { gen }
    val compArr = Seq.tabulate(n, m, p) { genCompVec }

    assert3DIsCorrect(n - 1, m, vec, compArr)
    stop()
  }

  class Fill2DTester(n: Int, m: Int, value: Int) extends BasicTester {
    val u = VecInit.fill(n, m)(value.U)
    val compareArr = Seq.fill(n, m)(value)

    assert2DIsCorrect(n - 1, u, compareArr)
    stop()
  }

  class Fill3DTester(n: Int, m: Int, p: Int, value: Int) extends BasicTester {
    val u = VecInit.fill(n, m, p)(value.U)
    val compareArr = Seq.fill(n, m, p)(value)

    assert3DIsCorrect(n - 1, m, u, compareArr)
    stop()
  }

  class BidirectionalTester2DFill(n: Int, m: Int) extends BasicTester {
    val mod = Module(new PassthroughModule)
    val vec2D = VecInit.fill(n, m)(mod.io)
    for {
      vec1D <- vec2D
      module <- vec1D
    } yield {
      module <> Module(new PassthroughModuleTester).io
    }
    stop()
  }

  class BidirectionalTester3DFill(n: Int, m: Int, p: Int) extends BasicTester {
    val mod = Module(new PassthroughModule)
    val vec3D = VecInit.fill(n, m, p)(mod.io)

    for {
      vec2D <- vec3D
      vec1D <- vec2D
      module <- vec1D
    } yield {
      module <> (Module(new PassthroughModuleTester).io)
    }
    stop()
  }

  class TabulateModuleTester(value: Int) extends Module {
    val io = IO(Flipped(new PassthroughModuleIO))
    // This drives the input of a PassthroughModule
    io.in := value.U
  }

  class BidirectionalTester2DTabulate(n: Int, m: Int) extends BasicTester {
    val vec2D = VecInit.tabulate(n, m) { (x, y) => Module(new TabulateModuleTester(x + y + 1)).io }

    for {
      x <- 0 until n
      y <- 0 until m
    } yield {
      val value = x + y + 1
      val receiveMod = Module(new PassthroughModule).io
      vec2D(x)(y) <> receiveMod
      assert(receiveMod.out === value.U)
    }
    stop()
  }

  class BidirectionalTester3DTabulate(n: Int, m: Int, p: Int) extends BasicTester {
    val vec3D = VecInit.tabulate(n, m, p) { (x, y, z) => Module(new TabulateModuleTester(x + y + z + 1)).io }

    for {
      x <- 0 until n
      y <- 0 until m
      z <- 0 until p
    } yield {
      val value = x + y + z + 1
      val receiveMod = Module(new PassthroughModule).io
      vec3D(x)(y)(z) <> receiveMod
      assert(receiveMod.out === value.U)
    }
    stop()
  }
}

class IterateTester(start: Int, len: Int)(f: UInt => UInt) extends BasicTester {
  val controlVec = VecInit(Seq.iterate(start.U, len)(f))
  val testVec = VecInit.iterate(start.U, len)(f)
  assert(
    controlVec.asUInt === testVec.asUInt,
    cf"Expected Vec to be filled like $controlVec, instead created $testVec\n"
  )
  stop()
}

class ShiftRegisterTester(n: Int) extends BasicTester {
  val (cnt, wrap) = Counter(true.B, n * 2)
  val shifter = Reg(Vec(n, UInt((log2Ceil(n).max(1)).W)))
  shifter.zip(shifter.drop(1)).foreach { case (l, r) => l := r }
  shifter(n - 1) := cnt
  when(cnt >= n.asUInt) {
    val expected = cnt - n.asUInt
    assert(shifter(0) === expected)
  }
  when(wrap) {
    stop()
  }
}

class HugeVecTester(n: Int) extends BasicTester {
  require(n > 0)
  val myVec = Wire(Vec(n, UInt()))
  myVec.foreach { x =>
    x := 123.U
    assert(x === 123.U)
  }
  stop()
}

class OneBitUnitRegVecTester extends BasicTester {
  val dut = Module(new OneBitUnitRegVec)
  assert(dut.io.out === 1.U)
  stop()
}

class ZeroEntryVecTester extends BasicTester {
  require(Vec(0, Bool()).getWidth == 0)

  val bundleWithZeroEntryVec = new Bundle {
    val foo = Bool()
    val bar = Vec(0, Bool())
  }
  require(0.U.asTypeOf(bundleWithZeroEntryVec).getWidth == 1)
  require(bundleWithZeroEntryVec.asUInt.getWidth == 1)

  val m = Module(new Module {
    val io = IO(Output(bundleWithZeroEntryVec))
    io.foo := false.B
  })
  WireDefault(m.io.bar)

  stop()
}

class PassthroughModuleTester extends Module {
  val io = IO(Flipped(new PassthroughModuleIO))
  // This drives the input of a PassthroughModule
  io.in := 123.U
  assert(io.out === 123.U)
}

class ModuleIODynamicIndexTester(n: Int) extends BasicTester {
  val duts = VecInit.fill(n)(Module(new PassthroughModule).io)
  val tester = Module(new PassthroughModuleTester)

  val (cycle, done) = Counter(true.B, n)
  for ((m, i) <- duts.zipWithIndex) {
    when(cycle =/= i.U) {
      m.in := 0.U // default
      assert(m.out === 0.U)
    }.otherwise {
      m.in := DontCare
    }
  }
  // only connect one dut per cycle
  duts(cycle) <> tester.io
  assert(duts(cycle).out === 123.U)

  when(done) { stop() }
}

class ReduceTreeTester() extends BasicTester {
  class FooIO[T <: Data](n: Int, private val gen: T) extends Bundle {
    val in = Flipped(Vec(n, new DecoupledIO(gen)))
    val out = new DecoupledIO(gen)
  }

  class Foo[T <: Data](n: Int, private val gen: T) extends Module {
    val io = IO(new FooIO(n, gen))

    def foo(a: DecoupledIO[T], b: DecoupledIO[T]) = {
      a.ready := true.B
      b.ready := true.B
      val out = Wire(new DecoupledIO(gen))

      out.valid := true.B

      val regSel = RegInit(false.B)
      out.bits := Mux(regSel, a.bits, b.bits)
      out.ready := a.ready
      out
    }

    io.out <> io.in.reduceTree(foo)
  }

  val dut = Module(new Foo(5, UInt(5.W)))
  dut.io := DontCare
  stop()
}

class VecSpec extends ChiselPropSpec with Utils {

  property("Vecs should be assignable") {
    forAll(safeUIntN(8)) {
      case (w: Int, v: List[Int]) =>
        assertTesterPasses { new ValueTester(w, v) }
    }
  }

  property("Vecs should be passed through vec IO") {
    forAll(safeUIntN(8)) {
      case (w: Int, v: List[Int]) =>
        assertTesterPasses { new IOTester(w, v) }
    }
  }

  property("Vec.fill with a pure type should generate an exception") {
    // We don't really need a sequence of random widths here, since any should throw an exception.
    forAll(safeUIntWidth) {
      case (w: Int) =>
        an[BindingException] should be thrownBy extractCause[BindingException] {
          ChiselStage.elaborate(new IOTesterModFill(w))
        }
    }
  }

  property("A Reg of a Vec should operate correctly") {
    forAll(safeUIntN(8)) {
      case (w: Int, v: List[Int]) =>
        assertTesterPasses { new RegTester(w, v) }
    }
  }

  property("A Vec of lit should operate correctly") {
    forAll(safeUIntN(8)) {
      case (w: Int, v: List[Int]) =>
        assertTesterPasses { new LitTester(w, v) }
    }
  }

  property("VecInit should tabulate correctly") {
    forAll(smallPosInts) { (n: Int) => assertTesterPasses { new TabulateTester(n) } }
  }

  property("VecInit should tabulate 2D vec correctly") {
    forAll(smallPosInts, smallPosInts) { (n: Int, m: Int) =>
      assertTesterPasses { new VecMultiDimTester.TabulateTester2D(n, m) }
    }
  }

  property("VecInit should tabulate 3D vec correctly") {
    forAll(smallPosInts, smallPosInts, smallPosInts) { (n: Int, m: Int, p: Int) =>
      assertTesterPasses { new VecMultiDimTester.TabulateTester3D(n, m, p) }
    }
  }

  property("VecInit should fill correctly") {
    forAll(smallPosInts, Gen.choose(0, 50)) { (n: Int, value: Int) => assertTesterPasses { new FillTester(n, value) } }
  }

  property("VecInit should fill 2D vec correctly") {
    forAll(smallPosInts, smallPosInts, Gen.choose(0, 50)) { (n: Int, m: Int, value: Int) =>
      assertTesterPasses { new VecMultiDimTester.Fill2DTester(n, m, value) }
    }
  }

  property("VecInit should fill 3D vec correctly") {
    forAll(smallPosInts, smallPosInts, smallPosInts, Gen.choose(0, 50)) { (n: Int, m: Int, p: Int, value: Int) =>
      assertTesterPasses { new VecMultiDimTester.Fill3DTester(n, m, p, value) }
    }
  }

  property("VecInit should support 2D fill bidirectional wire connection") {
    forAll(smallPosInts, smallPosInts) { (n: Int, m: Int) =>
      assertTesterPasses { new VecMultiDimTester.BidirectionalTester2DFill(n, m) }
    }
  }

  property("VecInit should support 3D fill bidirectional wire connection") {
    forAll(smallPosInts, smallPosInts, smallPosInts) { (n: Int, m: Int, p: Int) =>
      assertTesterPasses { new VecMultiDimTester.BidirectionalTester3DFill(n, m, p) }
    }
  }

  property("VecInit should support 2D tabulate bidirectional wire connection") {
    forAll(smallPosInts, smallPosInts) { (n: Int, m: Int) =>
      assertTesterPasses { new VecMultiDimTester.BidirectionalTester2DTabulate(n, m) }
    }
  }

  property("VecInit should support 3D tabulate bidirectional wire connection") {
    forAll(smallPosInts, smallPosInts, smallPosInts) { (n: Int, m: Int, p: Int) =>
      assertTesterPasses { new VecMultiDimTester.BidirectionalTester3DTabulate(n, m, p) }
    }
  }

  property("VecInit should iterate correctly") {
    forAll(Gen.choose(1, 10), smallPosInts) { (start: Int, len: Int) =>
      assertTesterPasses { new IterateTester(start, len)(x => x + 50.U) }
    }
  }

  property("Regs of vecs should be usable as shift registers") {
    forAll(smallPosInts) { (n: Int) => assertTesterPasses { new ShiftRegisterTester(n) } }
  }

  property("Infering widths on huge Vecs should not cause a stack overflow") {
    assertTesterPasses(new HugeVecTester(10000), annotations = TesterDriver.verilatorOnly)
  }

  property("A Reg of a Vec of a single 1 bit element should compile and work") {
    assertTesterPasses { new OneBitUnitRegVecTester }
  }

  property("A Vec with zero entries should compile and have zero width") {
    assertTesterPasses { new ZeroEntryVecTester }
  }

  property("Dynamic indexing of a Vec of Module IOs should work") {
    assertTesterPasses { new ModuleIODynamicIndexTester(4) }
  }

  property("It should be possible to bulk connect a Vec and a Seq") {
    ChiselStage.elaborate(new Module {
      val io = IO(new Bundle {
        val out = Output(Vec(4, UInt(8.W)))
      })
      val seq = Seq.fill(4)(0.U)
      io.out <> seq
    })
  }

  property("Bulk connecting a Vec and Seq of different sizes should report a ChiselException") {
    a[ChiselException] should be thrownBy extractCause[ChiselException] {
      ChiselStage.elaborate(new Module {
        val io = IO(new Bundle {
          val out = Output(Vec(4, UInt(8.W)))
        })
        val seq = Seq.fill(5)(0.U)
        io.out <> seq
      })
    }
  }

  property("It should be possible to initialize a Vec with DontCare") {
    ChiselStage.elaborate(new Module {
      val io = IO(new Bundle {
        val out = Output(Vec(4, UInt(8.W)))
      })
      io.out := VecInit(Seq(4.U, 5.U, DontCare, 2.U))
    })
  }

  property("Indexing a Chisel type Vec by a hardware type should give a sane error message") {
    a[ExpectedHardwareException] should be thrownBy extractCause[ChiselException] {
      ChiselStage.elaborate {
        new Module {
          val io = IO(new Bundle {})
          val foo = Vec(2, Bool())
          foo(0.U) := false.B
        }
      }
    }
  }

  property("reduceTree should preserve input/output type") {
    assertTesterPasses { new ReduceTreeTester() }
  }

  property("Vecs of empty Bundles and empty Records should work") {
    class MyModule(gen: Record) extends Module {
      val idx = IO(Input(UInt(2.W)))
      val in = IO(Input(gen))
      val out = IO(Output(gen))

      val reg = RegInit(0.U.asTypeOf(Vec(4, gen)))
      reg(idx) := in
      out := reg(idx)
    }
    class EmptyBundle extends Bundle
    class EmptyRecord extends Record {
      val elements = collection.immutable.ListMap.empty
    }
    for (gen <- List(new EmptyBundle, new EmptyRecord)) {
      val chirrtl = ChiselStage.emitCHIRRTL(new MyModule(gen))
      chirrtl should include("input in : { }")
      chirrtl should include("reg reg : { }[4]")
    }
  }
}
