// 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: kushalav@google.com (Avanish Kushal)

//         sameeragarwal@google.com (Sameer Agarwal)

#include "ceres/visibility.h"

#include <set>

#include <vector>

#include "ceres/block_structure.h"

#include "ceres/graph.h"

#include "ceres/internal/scoped_ptr.h"

#include "glog/logging.h"

#include "gtest/gtest.h"

namespace ceres {

namespace internal {

using std::set;

using std::vector;

class VisibilityTest : public ::testing::Test {

};

TEST(VisibilityTest, SimpleMatrix) {

  //   A = [1 0 0 0 0 1

  //        1 0 0 1 0 0

  //        0 1 1 0 0 0

  //        0 1 0 0 1 0]

  int num_cols = 6;

  int num_eliminate_blocks = 2;

  CompressedRowBlockStructure bs;

  // Row 1

  {

    bs.rows.push_back(CompressedRow());

    CompressedRow& row = bs.rows.back();

    row.block.size = 2;

    row.block.position = 0;

    row.cells.push_back(Cell(0, 0));

    row.cells.push_back(Cell(5, 0));

  }

  // Row 2

  {

    bs.rows.push_back(CompressedRow());

    CompressedRow& row = bs.rows.back();

    row.block.size = 2;

    row.block.position = 2;

    row.cells.push_back(Cell(0, 1));

    row.cells.push_back(Cell(3, 1));

  }

  // Row 3

  {

    bs.rows.push_back(CompressedRow());

    CompressedRow& row = bs.rows.back();

    row.block.size = 2;

    row.block.position = 4;

    row.cells.push_back(Cell(1, 2));

    row.cells.push_back(Cell(2, 2));

  }

  // Row 4

  {

    bs.rows.push_back(CompressedRow());

    CompressedRow& row = bs.rows.back();

    row.block.size = 2;

    row.block.position = 6;

    row.cells.push_back(Cell(1, 3));

    row.cells.push_back(Cell(4, 3));

  }

  bs.cols.resize(num_cols);

  vector< set<int> > visibility;

  ComputeVisibility(bs, num_eliminate_blocks, &visibility);

  ASSERT_EQ(visibility.size(), num_cols - num_eliminate_blocks);

  for (int i = 0; i < visibility.size(); ++i) {

    ASSERT_EQ(visibility[i].size(), 1);

  }

  scoped_ptr<WeightedGraph<int> > graph(CreateSchurComplementGraph(visibility));

  EXPECT_EQ(graph->vertices().size(), visibility.size());

  for (int i = 0; i < visibility.size(); ++i) {

    EXPECT_EQ(graph->VertexWeight(i), 1.0);

  }

  for (int i = 0; i < visibility.size(); ++i) {

    for (int j = i; j < visibility.size(); ++j) {

      double edge_weight = 0.0;

      if ((i == 1 && j == 3) || (i == 0 && j == 2) || (i == j)) {

        edge_weight = 1.0;

      }

      EXPECT_EQ(graph->EdgeWeight(i, j), edge_weight)

          << "Edge: " << i << " " << j

          << " weight: " << graph->EdgeWeight(i, j)

          << " expected weight: " << edge_weight;

    }

  }

}

TEST(VisibilityTest, NoEBlocks) {

  //   A = [1 0 0 0 0 0

  //        1 0 0 0 0 0

  //        0 1 0 0 0 0

  //        0 1 0 0 0 0]

  int num_cols = 6;

  int num_eliminate_blocks = 2;

  CompressedRowBlockStructure bs;

  // Row 1

  {

    bs.rows.push_back(CompressedRow());

    CompressedRow& row = bs.rows.back();

    row.block.size = 2;

    row.block.position = 0;

    row.cells.push_back(Cell(0, 0));

  }

  // Row 2

  {

    bs.rows.push_back(CompressedRow());

    CompressedRow& row = bs.rows.back();

    row.block.size = 2;

    row.block.position = 2;

    row.cells.push_back(Cell(0, 1));

  }

  // Row 3

  {

    bs.rows.push_back(CompressedRow());

    CompressedRow& row = bs.rows.back();

    row.block.size = 2;

    row.block.position = 4;

    row.cells.push_back(Cell(1, 2));

  }

  // Row 4

  {

    bs.rows.push_back(CompressedRow());

    CompressedRow& row = bs.rows.back();

    row.block.size = 2;

    row.block.position = 6;

    row.cells.push_back(Cell(1, 3));

  }

  bs.cols.resize(num_cols);

  vector<set<int> > visibility;

  ComputeVisibility(bs, num_eliminate_blocks, &visibility);

  ASSERT_EQ(visibility.size(), num_cols - num_eliminate_blocks);

  for (int i = 0; i < visibility.size(); ++i) {

    ASSERT_EQ(visibility[i].size(), 0);

  }

  scoped_ptr<WeightedGraph<int> > graph(CreateSchurComplementGraph(visibility));

  EXPECT_EQ(graph->vertices().size(), visibility.size());

  for (int i = 0; i < visibility.size(); ++i) {

    EXPECT_EQ(graph->VertexWeight(i), 1.0);

  }

  for (int i = 0; i < visibility.size(); ++i) {

    for (int j = i; j < visibility.size(); ++j) {

      double edge_weight = 0.0;

      if (i == j) {

        edge_weight = 1.0;

      }

      EXPECT_EQ(graph->EdgeWeight(i, j), edge_weight)

          << "Edge: " << i << " " << j

          << " weight: " << graph->EdgeWeight(i, j)

          << " expected weight: " << edge_weight;

    }

  }

}

}  // namespace internal

}  // namespace ceres