/* Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.

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. */

#ifdef PADDLE_WITH_XPU

#include <algorithm>
#include <utility>
#include <vector>
#include "paddle/fluid/framework/op_registry.h"
#include "paddle/fluid/operators/math/blas.h"

namespace paddle {
namespace operators {

static framework::DDim RowMatrixFromVector(const framework::DDim &x_dim) {
  if (x_dim.size() > 1) {
    return x_dim;
  }
  return framework::make_ddim({1, x_dim[0]});
}

static framework::Tensor FoldInitDims(const framework::Tensor &input) {
  auto output = input;
  auto in_dims = input.dims();
  if (in_dims.size() == 3) {
    output.Resize({in_dims[0] * in_dims[1], in_dims[2]});
  }
  return output;
}
/**
 * Get column matrix shape from a vector shape. If the ran of y_dim > 1, the
 * original y_dim is returned.
 */
static framework::DDim ColumnMatrixFromVector(const framework::DDim &y_dim) {
  if (y_dim.size() > 1) {
    return y_dim;
  }
  return framework::make_ddim({y_dim[0], 1});
}

static void ReshapeTensorIntoMatrixSequence(
    framework::Tensor *x, const math::MatDescriptor &descriptor) {
  int64_t h, w;
  h = descriptor.height_;
  w = descriptor.width_;
  if (descriptor.trans_) {
    std::swap(w, h);
  }
  if (descriptor.batch_size_) {
    x->Resize({descriptor.batch_size_, h, w});
  } else {
    x->Resize({h, w});
  }
}
/**
 * Reshape the x,y,out tensor to 3-D or 2-D tensor by matrix descriptor
 * Out = matmul(x, y)
 *
 * This method will first calculate X,Y matrix sequence, and then calculate
 * the out shape.
 *
 * Assume X = [BatchSize, H1, W1], Y = [BatchSize, H2, W2]
 * The out = [BatchSize, H1, W2]
 *
 * If there is no batch size in `X` and `Y`, the out will be [H1, W2]
 * If any of `X` and `Y` has batch size BatchSize, the out will have the
 * BatchSize.
 */
static void ReshapeXYOutIntoMatrixSequence(framework::Tensor *x,
                                           framework::Tensor *y,
                                           framework::Tensor *out, bool trans_x,
                                           bool trans_y) {
  auto x_dim = RowMatrixFromVector(x->dims());
  auto y_dim = ColumnMatrixFromVector(y->dims());
  auto mat_dim_x = math::CreateMatrixDescriptor(x_dim, 0, trans_x);
  auto mat_dim_y = math::CreateMatrixDescriptor(y_dim, 0, trans_y);
  if (mat_dim_x.batch_size_ == 0 && mat_dim_y.batch_size_ == 0) {
    out->Resize({mat_dim_x.height_, mat_dim_y.width_});
  } else {
    out->Resize({std::max(mat_dim_x.batch_size_, mat_dim_y.batch_size_),
                 mat_dim_x.height_, mat_dim_y.width_});
  }

  ReshapeTensorIntoMatrixSequence(x, mat_dim_x);
  ReshapeTensorIntoMatrixSequence(y, mat_dim_y);
}

template <typename DeviceContext, typename T>
class MatMulXPUKernel : public framework::OpKernel<T> {
 public:
  void Compute(const framework::ExecutionContext &context) const override {
    auto *x = context.Input<framework::Tensor>("X");
    auto *y = context.Input<framework::Tensor>("Y");
    auto *out = context.Output<framework::Tensor>("Out");
    out->mutable_data<T>(context.GetPlace());

    auto mat_dim_a = math::CreateMatrixDescriptor(
        RowMatrixFromVector(x->dims()), 0, context.Attr<bool>("transpose_X"));
    auto mat_dim_b =
        math::CreateMatrixDescriptor(ColumnMatrixFromVector(y->dims()), 0,
                                     context.Attr<bool>("transpose_Y"));
    PADDLE_ENFORCE_EQ(
        mat_dim_a.width_, mat_dim_b.height_,
        platform::errors::InvalidArgument("Shape mistake in matmul_op"));
    PADDLE_ENFORCE_EQ(
        mat_dim_a.batch_size_, mat_dim_b.batch_size_,
        platform::errors::InvalidArgument("Shape mistake in matmul_op"));
    T alpha = static_cast<T>(context.Attr<float>("alpha"));

    auto &dev_ctx = context.template device_context<DeviceContext>();
    float *data_c = out->data<T>();
    if (mat_dim_a.batch_size_ == 0 || mat_dim_a.batch_size_ == 1) {
      int r =
          xpu::fc_int16(dev_ctx.x_context(), mat_dim_a.trans_, mat_dim_b.trans_,
                        mat_dim_a.height_, mat_dim_b.width_, mat_dim_a.width_,
                        alpha, x->data<T>(), y->data<T>(), 0.0f, data_c);
      PADDLE_ENFORCE_EQ(
          r, XPU_SUCCESS,
          platform::errors::External(
              "XPU API return wrong value[%d], please check whether "
              "Baidu Kunlun Card is properly installed.",
              r));
    } else {
      // batch matmul
      int r = xpu::batched_gemm_int16(dev_ctx.x_context(), mat_dim_a.trans_,
                                      mat_dim_b.trans_, mat_dim_a.batch_size_,
                                      mat_dim_a.height_, mat_dim_b.width_,
                                      mat_dim_a.width_, alpha, x->data<T>(),
                                      y->data<T>(), data_c, nullptr, nullptr);
      PADDLE_ENFORCE_EQ(
          r, XPU_SUCCESS,
          platform::errors::External(
              "XPU API return wrong value[%d], please check whether "
              "Baidu Kunlun Card is properly installed.",
              r));
    }
  }
};

// Reshape a rank-3 tensor from P x M x N to M x (P * N).
// (Warning: This requires transposing data and writes into new memory.)
// Identity op if the tensor is not of rank 3.
template <typename DeviceContext, typename T>
static framework::Tensor XPUFoldHeadAndLastDims(
    const DeviceContext &context, const framework::Tensor &input) {
  auto in_dims = input.dims();
  if (in_dims.size() != 3) {
    return input;
  }

  framework::Tensor output;
  output.Resize({in_dims[1], in_dims[0], in_dims[2]});
  output.mutable_data<T>(context.GetPlace());
  std::vector<int> in_shape_host = {static_cast<int>(in_dims[0]),
                                    static_cast<int>(in_dims[1]),
                                    static_cast<int>(in_dims[2])};
  std::vector<int> axis_host = {1, 0, 2};

  int r = xpu::transpose(context.x_context(), input.data<T>(), output.data<T>(),
                         in_shape_host.data(), axis_host.data(), /*ndims=*/3);
  PADDLE_ENFORCE_EQ(r, XPU_SUCCESS,
                    platform::errors::External(
                        "XPU API return wrong value[%d], please check whether "
                        "Baidu Kunlun Card is properly installed.",
                        r));
  output.Resize({in_dims[1], in_dims[0] * in_dims[2]});

  return output;
}

// Using dimensional constraints on matrix multiplication, it is
// straight-forward to check the following table for when X and Y
// are both matrices.
//
// transpose_X | False    | True     | False    | True
// transpose_Y | False    | False    | True     | True
// -----------+----------+----------+----------+-----------
//        dX = | dOut Y^T | Y dOut^T | dOut Y   | Y^T dOut^T
//        dY = | X^T dOut | X dOut   | dOut^T X | dOut^T X^T
//
// When X is a vector of size K, we treat it instead as a matrix of shape
// (1, K). Similarly, when Y is a vector of size K, we treat it instead as
// a matrix of shape (K, 1).
//
// When X and Y are both 3-dimensional tensors, then the first dimension
// the batch dimension can be ignored and the exact same formulas apply
// as for two matrices.
//
// Finally, when, e.g., X is a 3-dimensional tensor but Y is a matrix, we end
// up with formulas like
//
//   dY_{ij} = \sum_{p, m} X_{pmi} dOut_{pmj}
//
// To handle this sort of scenario, we reshape X : P x M x K, dOut: P x M x N
// to X: (P * M) x K, dOut: (P * M) x N.
template <typename DeviceContext, typename T>
class MatMulGradXPUKernel : public framework::OpKernel<T> {
 public:
  void MatMul(const framework::ExecutionContext &context,
              const framework::Tensor &a, bool trans_a,
              const framework::Tensor &b, bool trans_b,
              framework::Tensor *out) const {
    out->mutable_data<T>(context.GetPlace());
    auto mat_dim_a = math::CreateMatrixDescriptor(a.dims(), 0, trans_a);
    auto mat_dim_b = math::CreateMatrixDescriptor(b.dims(), 0, trans_b);
    PADDLE_ENFORCE_EQ(
        mat_dim_a.width_, mat_dim_b.height_,
        platform::errors::InvalidArgument("Shape mistake in matmul_grad_op"));
    PADDLE_ENFORCE_EQ(
        mat_dim_a.batch_size_, mat_dim_b.batch_size_,
        platform::errors::InvalidArgument("Shape mistake in matmul_grad_op"));
    T alpha = static_cast<T>(context.Attr<float>("alpha"));

    auto &dev_ctx = context.template device_context<DeviceContext>();
    float *data_c = out->data<T>();
    if (mat_dim_a.batch_size_ == 0 || mat_dim_a.batch_size_ == 1) {
      int r =
          xpu::fc_int16(dev_ctx.x_context(), mat_dim_a.trans_, mat_dim_b.trans_,
                        mat_dim_a.height_, mat_dim_b.width_, mat_dim_a.width_,
                        alpha, a.data<T>(), b.data<T>(), 0.0f, data_c);
      PADDLE_ENFORCE_EQ(
          r, XPU_SUCCESS,
          platform::errors::External(
              "XPU API return wrong value[%d], please check whether "
              "Baidu Kunlun Card is properly installed.",
              r));
    } else {
      // batch matmul
      int r = xpu::batched_gemm_int16(dev_ctx.x_context(), mat_dim_a.trans_,
                                      mat_dim_b.trans_, mat_dim_a.batch_size_,
                                      mat_dim_a.height_, mat_dim_b.width_,
                                      mat_dim_a.width_, alpha, a.data<T>(),
                                      b.data<T>(), data_c, nullptr, nullptr);
      PADDLE_ENFORCE_EQ(
          r, XPU_SUCCESS,
          platform::errors::External(
              "XPU API return wrong value[%d], please check whether "
              "Baidu Kunlun Card is properly installed.",
              r));
    }
  }

  void CalcInputGrad(const framework::ExecutionContext &context,
                     const framework::Tensor &a, bool trans_a,
                     bool is_fold_init_dims_a, const framework::Tensor &b,
                     bool trans_b, bool is_fold_init_dims_b,
                     framework::Tensor *out) const {
    if (out == nullptr) return;
    bool need_combine = (a.dims().size() == 3 || b.dims().size() == 3) &&
                        out->dims().size() == 2;
    if (!need_combine) {
      MatMul(context, a, trans_a, b, trans_b, out);
    } else {
      auto &dev_ctx = context.template device_context<DeviceContext>();
      MatMul(
          context, is_fold_init_dims_a
                       ? FoldInitDims(a)
                       : XPUFoldHeadAndLastDims<DeviceContext, T>(dev_ctx, a),
          trans_a, is_fold_init_dims_b
                       ? FoldInitDims(b)
                       : XPUFoldHeadAndLastDims<DeviceContext, T>(dev_ctx, b),
          trans_b, out);
    }
  }

  void Compute(const framework::ExecutionContext &context) const override {
    auto x = *context.Input<framework::Tensor>("X");
    auto y = *context.Input<framework::Tensor>("Y");
    auto dout =
        *context.Input<framework::Tensor>(framework::GradVarName("Out"));
    auto *dx = context.Output<framework::Tensor>(framework::GradVarName("X"));
    auto *dy = context.Output<framework::Tensor>(framework::GradVarName("Y"));
    bool transpose_x = context.Attr<bool>("transpose_X");
    bool transpose_y = context.Attr<bool>("transpose_Y");

    ReshapeXYOutIntoMatrixSequence(&x, &y, &dout, transpose_x, transpose_y);

    framework::DDim dx_dims;
    if (dx) {
      dx_dims = dx->dims();
      if (dx_dims != x.dims()) {
        dx->Resize(x.dims());
      }
    }

    framework::DDim dy_dims;
    if (dy) {
      dy_dims = dy->dims();
      if (dy_dims != y.dims()) {
        dy->Resize(y.dims());
      }
    }

    if (transpose_x && transpose_y) {
      CalcInputGrad(context, y, true, true, dout, true, false, dx);
      CalcInputGrad(context, dout, true, true, x, true, false, dy);
    } else if (transpose_x) {
      CalcInputGrad(context, y, false, false, dout, true, false, dx);
      CalcInputGrad(context, x, false, false, dout, false, true, dy);
    } else if (transpose_y) {
      CalcInputGrad(context, dout, false, false, y, false, true, dx);
      CalcInputGrad(context, dout, true, true, x, false, true, dy);
    } else {
      CalcInputGrad(context, dout, false, false, y, true, false, dx);
      CalcInputGrad(context, x, true, true, dout, false, true, dy);
    }

    if (dx) {
      if (dx_dims != x.dims()) {
        dx->Resize(dx_dims);
      }
    }

    if (dy) {
      if (dy_dims != y.dims()) {
        dy->Resize(dy_dims);
      }
    }
  }
};

}  // namespace operators
}  // namespace paddle

namespace ops = paddle::operators;

REGISTER_OP_XPU_KERNEL(
    matmul, ops::MatMulXPUKernel<paddle::platform::XPUDeviceContext, float>);
REGISTER_OP_XPU_KERNEL(
    matmul_grad,
    ops::MatMulGradXPUKernel<paddle::platform::XPUDeviceContext, float>);
#endif
