// Ceres Solver - A fast non-linear least squares minimizer

// Copyright 2015 Google Inc. All rights reserved.

// http://ceres-solver.org/

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// Author: sameeragarwal@google.com (Sameer Agarwal)

#ifndef CERES_INTERNAL_BLOCK_RANDOM_ACCESS_DIAGONAL_MATRIX_H_

#define CERES_INTERNAL_BLOCK_RANDOM_ACCESS_DIAGONAL_MATRIX_H_

#include <set>

#include <vector>

#include <utility>

#include "ceres/mutex.h"

#include "ceres/block_random_access_matrix.h"

#include "ceres/collections_port.h"

#include "ceres/triplet_sparse_matrix.h"

#include "ceres/integral_types.h"

#include "ceres/internal/macros.h"

#include "ceres/internal/port.h"

#include "ceres/internal/scoped_ptr.h"

#include "ceres/types.h"

namespace ceres {

namespace internal {

// A thread safe block diagonal matrix implementation of

// BlockRandomAccessMatrix.

class BlockRandomAccessDiagonalMatrix : public BlockRandomAccessMatrix {

 public:

  // blocks is an array of block sizes.

  explicit BlockRandomAccessDiagonalMatrix(const std::vector<int>& blocks);

  // The destructor is not thread safe. It assumes that no one is

  // modifying any cells when the matrix is being destroyed.

  virtual ~BlockRandomAccessDiagonalMatrix();

  // BlockRandomAccessMatrix Interface.

  virtual CellInfo* GetCell(int row_block_id,

                            int col_block_id,

                            int* row,

                            int* col,

                            int* row_stride,

                            int* col_stride);

  // This is not a thread safe method, it assumes that no cell is

  // locked.

  virtual void SetZero();

  // Invert the matrix assuming that each block is positive definite.

  void Invert();

  // y += S * x

  void RightMultiply(const double* x, double* y) const;

  // Since the matrix is square, num_rows() == num_cols().

  virtual int num_rows() const { return tsm_->num_rows(); }

  virtual int num_cols() const { return tsm_->num_cols(); }

  const TripletSparseMatrix* matrix() const { return tsm_.get(); }

  TripletSparseMatrix* mutable_matrix() { return tsm_.get(); }

 private:

  // row/column block sizes.

  const std::vector<int> blocks_;

  std::vector<CellInfo*> layout_;

  // The underlying matrix object which actually stores the cells.

  scoped_ptr<TripletSparseMatrix> tsm_;

  friend class BlockRandomAccessDiagonalMatrixTest;

  CERES_DISALLOW_COPY_AND_ASSIGN(BlockRandomAccessDiagonalMatrix);

};

}  // namespace internal

}  // namespace ceres

#endif  // CERES_INTERNAL_BLOCK_RANDOM_ACCESS_DIAGONAL_MATRIX_H_