#include "mlir/Dialect/SparseTensor/Utils/Merger.h"
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include <memory>

using namespace mlir;
using namespace mlir::sparse_tensor;

namespace {

/// Simple recursive data structure used to match expressions in Mergers.
struct Pattern {
  Kind kind;

  /// Expressions representing tensors simply have a tensor number.
  unsigned tensorNum;

  /// Tensor operations point to their children.
  std::shared_ptr<Pattern> e0;
  std::shared_ptr<Pattern> e1;

  /// Constructors.
  /// Rather than using these, please use the readable helper constructor
  /// functions below to make tests more readable.
  Pattern(unsigned tensorNum) : kind(Kind::kTensor), tensorNum(tensorNum) {}
  Pattern(Kind kind, const std::shared_ptr<Pattern> &e0,
          const std::shared_ptr<Pattern> &e1)
      : kind(kind), e0(e0), e1(e1) {
    assert(kind >= Kind::kMulF);
    assert(e0 && e1);
  }
};

///
/// Readable Pattern builder functions.
/// These should be preferred over the actual constructors.
///

static std::shared_ptr<Pattern> tensorPattern(unsigned tensorNum) {
  return std::make_shared<Pattern>(tensorNum);
}

static std::shared_ptr<Pattern>
addfPattern(const std::shared_ptr<Pattern> &e0,
            const std::shared_ptr<Pattern> &e1) {
  return std::make_shared<Pattern>(Kind::kAddF, e0, e1);
}

static std::shared_ptr<Pattern>
mulfPattern(const std::shared_ptr<Pattern> &e0,
            const std::shared_ptr<Pattern> &e1) {
  return std::make_shared<Pattern>(Kind::kMulF, e0, e1);
}

class MergerTestBase : public ::testing::Test {
protected:
  MergerTestBase(unsigned numTensors, unsigned numLoops)
      : numTensors(numTensors), numLoops(numLoops),
        merger(numTensors, numLoops) {}

  ///
  /// Expression construction helpers.
  ///

  unsigned tensor(unsigned tensor) {
    return merger.addExp(Kind::kTensor, tensor);
  }

  unsigned addf(unsigned e0, unsigned e1) {
    return merger.addExp(Kind::kAddF, e0, e1);
  }

  unsigned mulf(unsigned e0, unsigned e1) {
    return merger.addExp(Kind::kMulF, e0, e1);
  }

  ///
  /// Comparison helpers.
  ///

  /// For readability of tests.
  unsigned lat(unsigned lat) { return lat; }

  /// Returns true if a lattice point with an expression matching the given
  /// pattern and bits matching the given bits is present in lattice points
  /// [p, p+n) of lattice set s. This is useful for testing partial ordering
  /// constraints between lattice points. We generally know how contiguous
  /// groups of lattice points should be ordered with respect to other groups,
  /// but there is no required ordering within groups.
  bool latPointWithinRange(unsigned s, unsigned p, unsigned n,
                           const std::shared_ptr<Pattern> &pattern,
                           const BitVector &bits) {
    for (unsigned i = p; i < p + n; ++i) {
      if (compareExpression(merger.lat(merger.set(s)[i]).exp, pattern) &&
          compareBits(s, i, bits))
        return true;
    }
    return false;
  }

  /// Wrapper over latPointWithinRange for readability of tests.
  void expectLatPointWithinRange(unsigned s, unsigned p, unsigned n,
                                 const std::shared_ptr<Pattern> &pattern,
                                 const BitVector &bits) {
    EXPECT_TRUE(latPointWithinRange(s, p, n, pattern, bits));
  }

  /// Wrapper over expectLatPointWithinRange for a single lat point.
  void expectLatPoint(unsigned s, unsigned p,
                      const std::shared_ptr<Pattern> &pattern,
                      const BitVector &bits) {
    EXPECT_TRUE(latPointWithinRange(s, p, 1, pattern, bits));
  }

  /// Converts a vector of (loop, tensor) pairs to a bitvector with the
  /// corresponding bits set.
  BitVector
  loopsToBits(const std::vector<std::pair<unsigned, unsigned>> &loops) {
    BitVector testBits = BitVector(numTensors + 1, false);
    for (auto l : loops) {
      auto loop = std::get<0>(l);
      auto tensor = std::get<1>(l);
      testBits.set(numTensors * loop + tensor);
    }
    return testBits;
  }

  /// Returns true if the bits of lattice point p in set s match the given bits.
  bool compareBits(unsigned s, unsigned p, const BitVector &bits) {
    return merger.lat(merger.set(s)[p]).bits == bits;
  }

  /// Check that there are n lattice points in set s.
  void expectNumLatPoints(unsigned s, unsigned n) {
    EXPECT_THAT(merger.set(s).size(), n);
  }

  /// Compares expressions for equality. Equality is defined recursively as:
  /// - Operations are equal if they have the same kind and children.
  /// - Leaf tensors are equal if they refer to the same tensor.
  bool compareExpression(unsigned e, const std::shared_ptr<Pattern> &pattern) {
    auto tensorExp = merger.exp(e);
    if (tensorExp.kind != pattern->kind)
      return false;
    switch (tensorExp.kind) {
    // Leaf.
    case kTensor:
      return tensorExp.tensor == pattern->tensorNum;
    case kInvariant:
    case kIndex:
      llvm_unreachable("invariant not handled yet");
    // Unary operations.
    case kAbsF:
    case kAbsC:
    case kCeilF:
    case kFloorF:
    case kSqrtF:
    case kSqrtC:
    case kExpm1F:
    case kExpm1C:
    case kLog1pF:
    case kLog1pC:
    case kSinF:
    case kSinC:
    case kTanhF:
    case kTanhC:
    case kNegF:
    case kNegC:
    case kNegI:
    case kTruncF:
    case kExtF:
    case kCastFS:
    case kCastFU:
    case kCastSF:
    case kCastUF:
    case kCastS:
    case kCastU:
    case kCastIdx:
    case kTruncI:
    case kCIm:
    case kCRe:
    case kBitCast:
    case kBinaryBranch:
    case kUnary:
    case kShlI:
    case kBinary:
      return compareExpression(tensorExp.children.e0, pattern->e0);
    // Binary operations.
    case kMulF:
    case kMulC:
    case kMulI:
    case kDivF:
    case kDivC:
    case kDivS:
    case kDivU:
    case kAddF:
    case kAddC:
    case kAddI:
    case kSubF:
    case kSubC:
    case kSubI:
    case kAndI:
    case kOrI:
    case kXorI:
    case kShrS:
    case kShrU:
      return compareExpression(tensorExp.children.e0, pattern->e0) &&
             compareExpression(tensorExp.children.e1, pattern->e1);
    }
    llvm_unreachable("unexpected kind");
  }

  unsigned numTensors;
  unsigned numLoops;
  Merger merger;
};

class MergerTest3T1L : public MergerTestBase {
protected:
  // Our three tensors (two inputs, one output).
  const unsigned t0 = 0, t1 = 1, t2 = 2;

  // Our single loop.
  const unsigned l0 = 0;

  MergerTest3T1L() : MergerTestBase(3, 1) {
    // Tensor 0: sparse input vector.
    merger.addExp(Kind::kTensor, t0, -1u);
    merger.setDim(t0, l0, Dim::kSparse);

    // Tensor 1: sparse input vector.
    merger.addExp(Kind::kTensor, t1, -1u);
    merger.setDim(t1, l0, Dim::kSparse);

    // Tensor 2: dense output vector.
    merger.addExp(Kind::kTensor, t2, -1u);
    merger.setDim(t2, l0, Dim::kDense);
  }
};

} // namespace

/// Vector addition of 2 vectors, i.e.:
///   a(i) = b(i) + c(i)
/// which should form the 3 lattice points
/// {
///   lat( i_00 i_01 / (tensor_0 + tensor_1) )
///   lat( i_00 / tensor_0 )
///   lat( i_01 / tensor_1 )
/// }
/// and after optimization, will reduce to the 2 lattice points
/// {
///   lat( i_00 i_01 / (tensor_0 + tensor_1) )
///   lat( i_00 / tensor_0 )
/// }
TEST_F(MergerTest3T1L, VectorAdd2) {
  // Construct expression.
  auto e = addf(tensor(t0), tensor(t1));

  // Build lattices and check.
  auto s = merger.buildLattices(e, l0);
  expectNumLatPoints(s, 3);
  expectLatPoint(s, lat(0), addfPattern(tensorPattern(t0), tensorPattern(t1)),
                 loopsToBits({{l0, t0}, {l0, t1}}));
  expectLatPointWithinRange(s, lat(1), 2, tensorPattern(t0),
                            loopsToBits({{l0, t0}}));
  expectLatPointWithinRange(s, lat(1), 2, tensorPattern(t1),
                            loopsToBits({{l0, t1}}));

  // Optimize lattices and check.
  s = merger.optimizeSet(s);
  expectNumLatPoints(s, 3);
  expectLatPoint(s, lat(0), addfPattern(tensorPattern(t0), tensorPattern(t1)),
                 loopsToBits({{l0, t0}, {l0, t1}}));
  expectLatPointWithinRange(s, lat(1), 2, tensorPattern(t0),
                            loopsToBits({{l0, t0}}));
  expectLatPointWithinRange(s, lat(1), 2, tensorPattern(t1),
                            loopsToBits({{l0, t1}}));
}

/// Vector multiplication of 2 vectors, i.e.:
///   a(i) = b(i) * c(i)
/// which should form the single lattice point
/// {
///   lat( i_00 i_01 / (tensor_0 * tensor_1) )
/// }
TEST_F(MergerTest3T1L, VectorMul2) {
  // Construct expression.
  auto e = mulf(t0, t1);

  // Build lattices and check.
  auto s = merger.buildLattices(e, l0);
  expectNumLatPoints(s, 1);
  expectLatPoint(s, lat(0), mulfPattern(tensorPattern(t0), tensorPattern(t1)),
                 loopsToBits({{l0, t0}, {l0, t1}}));

  // Optimize lattices and check.
  s = merger.optimizeSet(s);
  expectNumLatPoints(s, 1);
  expectLatPoint(s, lat(0), mulfPattern(tensorPattern(t0), tensorPattern(t1)),
                 loopsToBits({{l0, t0}, {l0, t1}}));
}