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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// Google Mock - a framework for writing C++ mock classes.

//

// This file implements Matcher<const string&>, Matcher<string>, and

// utilities for defining matchers.

#include "gmock/gmock-matchers.h"

#include <string.h>

#include <iostream>

#include <sstream>

#include <string>

#include <vector>

namespace testing {

namespace internal {

// Returns the description for a matcher defined using the MATCHER*()

// macro where the user-supplied description string is "", if

// 'negation' is false; otherwise returns the description of the

// negation of the matcher.  'param_values' contains a list of strings

// that are the print-out of the matcher's parameters.

GTEST_API_ std::string FormatMatcherDescription(

    bool negation, const char* matcher_name,

    const std::vector<const char*>& param_names, const Strings& param_values) {

  std::string result = ConvertIdentifierNameToWords(matcher_name);

  if (!param_values.empty()) {

    result += " " + JoinAsKeyValueTuple(param_names, param_values);

  }

  return negation ? "not (" + result + ")" : result;

}

// FindMaxBipartiteMatching and its helper class.

//

// Uses the well-known Ford-Fulkerson max flow method to find a maximum

// bipartite matching. Flow is considered to be from left to right.

// There is an implicit source node that is connected to all of the left

// nodes, and an implicit sink node that is connected to all of the

// right nodes. All edges have unit capacity.

//

// Neither the flow graph nor the residual flow graph are represented

// explicitly. Instead, they are implied by the information in 'graph' and

// a vector<int> called 'left_' whose elements are initialized to the

// value kUnused. This represents the initial state of the algorithm,

// where the flow graph is empty, and the residual flow graph has the

// following edges:

//   - An edge from source to each left_ node

//   - An edge from each right_ node to sink

//   - An edge from each left_ node to each right_ node, if the

//     corresponding edge exists in 'graph'.

//

// When the TryAugment() method adds a flow, it sets left_[l] = r for some

// nodes l and r. This induces the following changes:

//   - The edges (source, l), (l, r), and (r, sink) are added to the

//     flow graph.

//   - The same three edges are removed from the residual flow graph.

//   - The reverse edges (l, source), (r, l), and (sink, r) are added

//     to the residual flow graph, which is a directional graph

//     representing unused flow capacity.

//

// When the method augments a flow (moving left_[l] from some r1 to some

// other r2), this can be thought of as "undoing" the above steps with

// respect to r1 and "redoing" them with respect to r2.

//

// It bears repeating that the flow graph and residual flow graph are

// never represented explicitly, but can be derived by looking at the

// information in 'graph' and in left_.

//

// As an optimization, there is a second vector<int> called right_ which

// does not provide any new information. Instead, it enables more

// efficient queries about edges entering or leaving the right-side nodes

// of the flow or residual flow graphs. The following invariants are

// maintained:

//

// left[l] == kUnused or right[left[l]] == l

// right[r] == kUnused or left[right[r]] == r

//

// . [ source ]                                        .

// .   |||                                             .

// .   |||                                             .

// .   ||\--> left[0]=1  ---\    right[0]=-1 ----\     .

// .   ||                   |                    |     .

// .   |\---> left[1]=-1    \--> right[1]=0  ---\|     .

// .   |                                        ||     .

// .   \----> left[2]=2  ------> right[2]=2  --\||     .

// .                                           |||     .

// .         elements           matchers       vvv     .

// .                                         [ sink ]  .

//

// See Also:

//   [1] Cormen, et al (2001). "Section 26.2: The Ford-Fulkerson method".

//       "Introduction to Algorithms (Second ed.)", pp. 651-664.

//   [2] "Ford-Fulkerson algorithm", Wikipedia,

//       'https://en.wikipedia.org/wiki/Ford%E2%80%93Fulkerson_algorithm'

class MaxBipartiteMatchState {

 public:

  explicit MaxBipartiteMatchState(const MatchMatrix& graph)

      : graph_(&graph),

        left_(graph_->LhsSize(), kUnused),

        right_(graph_->RhsSize(), kUnused) {}

  // Returns the edges of a maximal match, each in the form {left, right}.

  ElementMatcherPairs Compute() {

    // 'seen' is used for path finding { 0: unseen, 1: seen }.

    ::std::vector<char> seen;

    // Searches the residual flow graph for a path from each left node to

    // the sink in the residual flow graph, and if one is found, add flow

    // to the graph. It's okay to search through the left nodes once. The

    // edge from the implicit source node to each previously-visited left

    // node will have flow if that left node has any path to the sink

    // whatsoever. Subsequent augmentations can only add flow to the

    // network, and cannot take away that previous flow unit from the source.

    // Since the source-to-left edge can only carry one flow unit (or,

    // each element can be matched to only one matcher), there is no need

    // to visit the left nodes more than once looking for augmented paths.

    // The flow is known to be possible or impossible by looking at the

    // node once.

    for (size_t ilhs = 0; ilhs < graph_->LhsSize(); ++ilhs) {

      // Reset the path-marking vector and try to find a path from

      // source to sink starting at the left_[ilhs] node.

      GTEST_CHECK_(left_[ilhs] == kUnused)

          << "ilhs: " << ilhs << ", left_[ilhs]: " << left_[ilhs];

      // 'seen' initialized to 'graph_->RhsSize()' copies of 0.

      seen.assign(graph_->RhsSize(), 0);

      TryAugment(ilhs, &seen);

    }

    ElementMatcherPairs result;

    for (size_t ilhs = 0; ilhs < left_.size(); ++ilhs) {

      size_t irhs = left_[ilhs];

      if (irhs == kUnused) continue;

      result.push_back(ElementMatcherPair(ilhs, irhs));

    }

    return result;

  }

 private:

  static const size_t kUnused = static_cast<size_t>(-1);

  // Perform a depth-first search from left node ilhs to the sink.  If a

  // path is found, flow is added to the network by linking the left and

  // right vector elements corresponding each segment of the path.

  // Returns true if a path to sink was found, which means that a unit of

  // flow was added to the network. The 'seen' vector elements correspond

  // to right nodes and are marked to eliminate cycles from the search.

  //

  // Left nodes will only be explored at most once because they

  // are accessible from at most one right node in the residual flow

  // graph.

  //

  // Note that left_[ilhs] is the only element of left_ that TryAugment will

  // potentially transition from kUnused to another value. Any other

  // left_ element holding kUnused before TryAugment will be holding it

  // when TryAugment returns.

  //

  bool TryAugment(size_t ilhs, ::std::vector<char>* seen) {

    for (size_t irhs = 0; irhs < graph_->RhsSize(); ++irhs) {

      if ((*seen)[irhs]) continue;

      if (!graph_->HasEdge(ilhs, irhs)) continue;

      // There's an available edge from ilhs to irhs.

      (*seen)[irhs] = 1;

      // Next a search is performed to determine whether

      // this edge is a dead end or leads to the sink.

      //

      // right_[irhs] == kUnused means that there is residual flow from

      // right node irhs to the sink, so we can use that to finish this

      // flow path and return success.

      //

      // Otherwise there is residual flow to some ilhs. We push flow

      // along that path and call ourselves recursively to see if this

      // ultimately leads to sink.

      if (right_[irhs] == kUnused || TryAugment(right_[irhs], seen)) {

        // Add flow from left_[ilhs] to right_[irhs].

        left_[ilhs] = irhs;

        right_[irhs] = ilhs;

        return true;

      }

    }

    return false;

  }

  const MatchMatrix* graph_;  // not owned

  // Each element of the left_ vector represents a left hand side node

  // (i.e. an element) and each element of right_ is a right hand side

  // node (i.e. a matcher). The values in the left_ vector indicate

  // outflow from that node to a node on the right_ side. The values

  // in the right_ indicate inflow, and specify which left_ node is

  // feeding that right_ node, if any. For example, left_[3] == 1 means

  // there's a flow from element #3 to matcher #1. Such a flow would also

  // be redundantly represented in the right_ vector as right_[1] == 3.

  // Elements of left_ and right_ are either kUnused or mutually

  // referent. Mutually referent means that left_[right_[i]] = i and

  // right_[left_[i]] = i.

  ::std::vector<size_t> left_;

  ::std::vector<size_t> right_;

};

const size_t MaxBipartiteMatchState::kUnused;

GTEST_API_ ElementMatcherPairs FindMaxBipartiteMatching(const MatchMatrix& g) {

  return MaxBipartiteMatchState(g).Compute();

}

static void LogElementMatcherPairVec(const ElementMatcherPairs& pairs,

                                     ::std::ostream* stream) {

  typedef ElementMatcherPairs::const_iterator Iter;

  ::std::ostream& os = *stream;

  os << "{";

  const char* sep = "";

  for (Iter it = pairs.begin(); it != pairs.end(); ++it) {

    os << sep << "\n  (" << "element #" << it->first << ", " << "matcher #"

       << it->second << ")";

    sep = ",";

  }

  os << "\n}";

}

bool MatchMatrix::NextGraph() {

  for (size_t ilhs = 0; ilhs < LhsSize(); ++ilhs) {

    for (size_t irhs = 0; irhs < RhsSize(); ++irhs) {

      char& b = matched_[SpaceIndex(ilhs, irhs)];

      if (!b) {

        b = 1;

        return true;

      }

      b = 0;

    }

  }

  return false;

}

void MatchMatrix::Randomize() {

  for (size_t ilhs = 0; ilhs < LhsSize(); ++ilhs) {

    for (size_t irhs = 0; irhs < RhsSize(); ++irhs) {

      char& b = matched_[SpaceIndex(ilhs, irhs)];

      b = static_cast<char>(rand() & 1);  // NOLINT

    }

  }

}

std::string MatchMatrix::DebugString() const {

  ::std::stringstream ss;

  const char* sep = "";

  for (size_t i = 0; i < LhsSize(); ++i) {

    ss << sep;

    for (size_t j = 0; j < RhsSize(); ++j) {

      ss << HasEdge(i, j);

    }

    sep = ";";

  }

  return ss.str();

}

void UnorderedElementsAreMatcherImplBase::DescribeToImpl(

    ::std::ostream* os) const {

  switch (match_flags()) {

    case UnorderedMatcherRequire::ExactMatch:

      if (matcher_describers_.empty()) {

        *os << "is empty";

        return;

      }

      if (matcher_describers_.size() == 1) {

        *os << "has " << Elements(1) << " and that element ";

        matcher_describers_[0]->DescribeTo(os);

        return;

      }

      *os << "has " << Elements(matcher_describers_.size())

          << " and there exists some permutation of elements such that:\n";

      break;

    case UnorderedMatcherRequire::Superset:

      *os << "a surjection from elements to requirements exists such that:\n";

      break;

    case UnorderedMatcherRequire::Subset:

      *os << "an injection from elements to requirements exists such that:\n";

      break;

  }

  const char* sep = "";

  for (size_t i = 0; i != matcher_describers_.size(); ++i) {

    *os << sep;

    if (match_flags() == UnorderedMatcherRequire::ExactMatch) {

      *os << " - element #" << i << " ";

    } else {

      *os << " - an element ";

    }

    matcher_describers_[i]->DescribeTo(os);

    if (match_flags() == UnorderedMatcherRequire::ExactMatch) {

      sep = ", and\n";

    } else {

      sep = "\n";

    }

  }

}

void UnorderedElementsAreMatcherImplBase::DescribeNegationToImpl(

    ::std::ostream* os) const {

  switch (match_flags()) {

    case UnorderedMatcherRequire::ExactMatch:

      if (matcher_describers_.empty()) {

        *os << "isn't empty";

        return;

      }

      if (matcher_describers_.size() == 1) {

        *os << "doesn't have " << Elements(1) << ", or has " << Elements(1)

            << " that ";

        matcher_describers_[0]->DescribeNegationTo(os);

        return;

      }

      *os << "doesn't have " << Elements(matcher_describers_.size())

          << ", or there exists no permutation of elements such that:\n";

      break;

    case UnorderedMatcherRequire::Superset:

      *os << "no surjection from elements to requirements exists such that:\n";

      break;

    case UnorderedMatcherRequire::Subset:

      *os << "no injection from elements to requirements exists such that:\n";

      break;

  }

  const char* sep = "";

  for (size_t i = 0; i != matcher_describers_.size(); ++i) {

    *os << sep;

    if (match_flags() == UnorderedMatcherRequire::ExactMatch) {

      *os << " - element #" << i << " ";

    } else {

      *os << " - an element ";

    }

    matcher_describers_[i]->DescribeTo(os);

    if (match_flags() == UnorderedMatcherRequire::ExactMatch) {

      sep = ", and\n";

    } else {

      sep = "\n";

    }

  }

}

// Checks that all matchers match at least one element, and that all

// elements match at least one matcher. This enables faster matching

// and better error reporting.

// Returns false, writing an explanation to 'listener', if and only

// if the success criteria are not met.

bool UnorderedElementsAreMatcherImplBase::VerifyMatchMatrix(

    const ::std::vector<std::string>& element_printouts,

    const MatchMatrix& matrix, MatchResultListener* listener) const {

  if (matrix.LhsSize() == 0 && matrix.RhsSize() == 0) {

    return true;

  }

  const bool is_exact_match_with_size_discrepency =

      match_flags() == UnorderedMatcherRequire::ExactMatch &&

      matrix.LhsSize() != matrix.RhsSize();

  if (is_exact_match_with_size_discrepency) {

    // The element count doesn't match.  If the container is empty,

    // there's no need to explain anything as Google Mock already

    // prints the empty container. Otherwise we just need to show

    // how many elements there actually are.

    if (matrix.LhsSize() != 0 && listener->IsInterested()) {

      *listener << "which has " << Elements(matrix.LhsSize()) << "\n";

    }

  }

  bool result = !is_exact_match_with_size_discrepency;

  ::std::vector<char> element_matched(matrix.LhsSize(), 0);

  ::std::vector<char> matcher_matched(matrix.RhsSize(), 0);

  for (size_t ilhs = 0; ilhs < matrix.LhsSize(); ilhs++) {

    for (size_t irhs = 0; irhs < matrix.RhsSize(); irhs++) {

      char matched = matrix.HasEdge(ilhs, irhs);

      element_matched[ilhs] |= matched;

      matcher_matched[irhs] |= matched;

    }

  }

  if (match_flags() & UnorderedMatcherRequire::Superset) {

    const char* sep =

        "where the following matchers don't match any elements:\n";

    for (size_t mi = 0; mi < matcher_matched.size(); ++mi) {

      if (matcher_matched[mi]) continue;

      result = false;

      if (listener->IsInterested()) {

        *listener << sep << "matcher #" << mi << ": ";

        matcher_describers_[mi]->DescribeTo(listener->stream());

        sep = ",\n";

      }

    }

  }

  if (match_flags() & UnorderedMatcherRequire::Subset) {

    const char* sep =

        "where the following elements don't match any matchers:\n";

    const char* outer_sep = "";

    if (!result) {

      outer_sep = "\nand ";

    }

    for (size_t ei = 0; ei < element_matched.size(); ++ei) {

      if (element_matched[ei]) continue;

      result = false;

      if (listener->IsInterested()) {

        *listener << outer_sep << sep << "element #" << ei << ": "

                  << element_printouts[ei];

        sep = ",\n";

        outer_sep = "";

      }

    }

  }

  return result;

}

bool UnorderedElementsAreMatcherImplBase::FindPairing(

    const MatchMatrix& matrix, MatchResultListener* listener) const {

  ElementMatcherPairs matches = FindMaxBipartiteMatching(matrix);

  size_t max_flow = matches.size();

  if ((match_flags() & UnorderedMatcherRequire::Superset) &&

      max_flow < matrix.RhsSize()) {

    if (listener->IsInterested()) {

      *listener << "where no permutation of the elements can satisfy all "

                   "matchers, and the closest match is "

                << max_flow << " of " << matrix.RhsSize()

                << " matchers with the pairings:\n";

      LogElementMatcherPairVec(matches, listener->stream());

    }

    return false;

  }

  if ((match_flags() & UnorderedMatcherRequire::Subset) &&

      max_flow < matrix.LhsSize()) {

    if (listener->IsInterested()) {

      *listener

          << "where not all elements can be matched, and the closest match is "

          << max_flow << " of " << matrix.RhsSize()

          << " matchers with the pairings:\n";

      LogElementMatcherPairVec(matches, listener->stream());

    }

    return false;

  }

  if (matches.size() > 1) {

    if (listener->IsInterested()) {

      const char* sep = "where:\n";

      for (size_t mi = 0; mi < matches.size(); ++mi) {

        *listener << sep << " - element #" << matches[mi].first

                  << " is matched by matcher #" << matches[mi].second;

        sep = ",\n";

      }

    }

  }

  return true;

}

}  // namespace internal

}  // namespace testing