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

// File:        series.h

// Description: Runs networks in series on the same input.

// Author:      Ray Smith

//

// (C) Copyright 2013, 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_SERIES_H_

#define TESSERACT_LSTM_SERIES_H_

#include "plumbing.h"

namespace tesseract {

// Runs two or more networks in series (layers) on the same input.

class Series : public Plumbing {

public:

  // ni_ and no_ will be set by AddToStack.

  TESS_API

  explicit Series(const std::string &name);

  ~Series() 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 {

    std::string spec("[");

    for (auto &it : stack_) {

      spec += it->spec();

    }

    spec += "]";

    return spec;

  }

  // Sets up the network for training. Initializes weights using weights of

  // scale `range` picked according to the random number generator `randomizer`.

  // Returns the number of weights initialized.

  int InitWeights(float range, TRand *randomizer) override;

  // Recursively searches the network for softmaxes with old_no outputs,

  // and remaps their outputs according to code_map. See network.h for details.

  int RemapOutputs(int old_no, const std::vector<int> &code_map) override;

  // Sets needs_to_backprop_ to needs_backprop and returns true if

  // needs_backprop || any weights in this network so the next layer forward

  // can be told to produce backprop for this layer if needed.

  bool SetupNeedsBackprop(bool needs_backprop) override;

  // 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;

  // Provides the (minimum) x scale factor to the network (of interest only to

  // input units) so they can determine how to scale bounding boxes.

  void CacheXScaleFactor(int factor) 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;

  // Splits the series after the given index, returning the two parts and

  // deletes itself. The first part, up to network with index last_start, goes

  // into start, and the rest goes into end.

  TESS_API

  void SplitAt(unsigned last_start, Series **start, Series **end);

  // Appends the elements of the src series to this, removing from src and

  // deleting it.

  TESS_API

  void AppendSeries(Network *src);

};

} // namespace tesseract.

#endif // TESSERACT_LSTM_SERIES_H_