///////////////////////////////////////////////////////////////////////

// File:        reconfig.h

// Description: Network layer that reconfigures the scaling vs feature

//              depth.

// Author:      Ray Smith

//

// (C) Copyright 2014, Google Inc.

// 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.

///////////////////////////////////////////////////////////////////////

#ifndef TESSERACT_LSTM_RECONFIG_H_

#define TESSERACT_LSTM_RECONFIG_H_

#include "matrix.h"

#include "network.h"

namespace tesseract {

// Reconfigures (Shrinks) the inputs by concatenating an x_scale by y_scale tile

// of inputs together, producing a single, deeper output per tile.

// Note that fractional parts are truncated for efficiency, so make sure the

// input stride is a multiple of the y_scale factor!

class Reconfig : public Network {

public:

  TESS_API

  Reconfig(const std::string &name, int ni, int x_scale, int y_scale);

  ~Reconfig() override = default;

  // Returns the shape output from the network given an input shape (which may

  // be partially unknown ie zero).

  StaticShape OutputShape(const StaticShape &input_shape) const override;

  std::string spec() const override {

    return "S" + std::to_string(y_scale_) + "," + std::to_string(x_scale_);

  }

  // Returns an integer reduction factor that the network applies to the

  // time sequence. Assumes that any 2-d is already eliminated. Used for

  // scaling bounding boxes of truth data.

  // WARNING: if GlobalMinimax is used to vary the scale, this will return

  // the last used scale factor. Call it before any forward, and it will return

  // the minimum scale factor of the paths through the GlobalMinimax.

  int XScaleFactor() const override;

  // Writes to the given file. Returns false in case of error.

  bool Serialize(TFile *fp) const override;

  // Reads from the given file. Returns false in case of error.

  bool DeSerialize(TFile *fp) override;

  // Runs forward propagation of activations on the input line.

  // See Network for a detailed discussion of the arguments.

  void Forward(bool debug, const NetworkIO &input, const TransposedArray *input_transpose,

               NetworkScratch *scratch, NetworkIO *output) override;

  // Runs backward propagation of errors on the deltas line.

  // See Network for a detailed discussion of the arguments.

  bool Backward(bool debug, const NetworkIO &fwd_deltas, NetworkScratch *scratch,

                NetworkIO *back_deltas) override;

private:

  void DebugWeights() override {

    tprintf("Must override Network::DebugWeights for type %d\n", type_);

  }

protected:

  // Non-serialized data used to store parameters between forward and back.

  StrideMap back_map_;

  // Serialized data.

  int32_t x_scale_;

  int32_t y_scale_;

};

} // namespace tesseract.

#endif // TESSERACT_LSTM_SUBSAMPLE_H_