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

// File:        associate.cpp

// Description: Functions for scoring segmentation paths according to

//              their character widths, gap widths and seam cuts.

// Author:      Daria Antonova

// Created:     Mon Mar 8 11:26:43 PDT 2010

//

// (C) Copyright 2010, 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.

//

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

#include <cmath>

#include <cstdio>

#include "associate.h"

#include "normalis.h"

#include "pageres.h"

namespace tesseract {

const float AssociateUtils::kMaxFixedPitchCharAspectRatio = 2.0f;

const float AssociateUtils::kMinGap = 0.03f;

void AssociateUtils::ComputeStats(int col, int row, const AssociateStats *parent_stats,

                                  int parent_path_length, bool fixed_pitch, float max_char_wh_ratio,

                                  WERD_RES *word_res, bool debug, AssociateStats *stats) {

  stats->Clear();

  ASSERT_HOST(word_res != nullptr);

  if (word_res->blob_widths.empty()) {

    return;

  }

  if (debug) {

    tprintf("AssociateUtils::ComputeStats() for col=%d, row=%d%s\n", col, row,

            fixed_pitch ? " (fixed pitch)" : "");

  }

  float normalizing_height = kBlnXHeight;

  ROW *blob_row = word_res->blob_row;

  // TODO(rays/daria) Can unicharset.script_has_xheight be useful here?

  if (fixed_pitch && blob_row != nullptr) {

    // For fixed pitch language like CJK, we use the full text height

    // as the normalizing factor so we are not dependent on xheight

    // calculation.

    if (blob_row->body_size() > 0.0f) {

      normalizing_height = word_res->denorm.y_scale() * blob_row->body_size();

    } else {

      normalizing_height =

          word_res->denorm.y_scale() * (blob_row->x_height() + blob_row->ascenders());

    }

    if (debug) {

      tprintf("normalizing height = %g (scale %g xheight %g ascenders %g)\n", normalizing_height,

              word_res->denorm.y_scale(), blob_row->x_height(), blob_row->ascenders());

    }

  }

  float wh_ratio = word_res->GetBlobsWidth(col, row) / normalizing_height;

  if (wh_ratio > max_char_wh_ratio) {

    stats->bad_shape = true;

  }

  // Compute the gap sum for this shape. If there are only negative or only

  // positive gaps, record their sum in stats->gap_sum. However, if there is

  // a mixture, record only the sum of the positive gaps.

  // TODO(antonova): explain fragment.

  int negative_gap_sum = 0;

  for (int c = col; c < row; ++c) {

    int gap = word_res->GetBlobsGap(c);

    (gap > 0) ? stats->gap_sum += gap : negative_gap_sum += gap;

  }

  if (stats->gap_sum == 0) {

    stats->gap_sum = negative_gap_sum;

  }

  if (debug) {

    tprintf("wh_ratio=%g (max_char_wh_ratio=%g) gap_sum=%d %s\n", wh_ratio, max_char_wh_ratio,

            stats->gap_sum, stats->bad_shape ? "bad_shape" : "");

  }

  // Compute shape_cost (for fixed pitch mode).

  if (fixed_pitch) {

    bool end_row = (row == (word_res->ratings->dimension() - 1));

    // Ensure that the blob has gaps on the left and the right sides

    // (except for beginning and ending punctuation) and that there is

    // no cutting through ink at the blob boundaries.

    if (col > 0) {

      float left_gap = word_res->GetBlobsGap(col - 1) / normalizing_height;

      SEAM *left_seam = word_res->seam_array[col - 1];

      if ((!end_row && left_gap < kMinGap) || left_seam->priority() > 0.0f) {

        stats->bad_shape = true;

      }

      if (debug) {

        tprintf("left_gap %g, left_seam %g %s\n", left_gap, left_seam->priority(),

                stats->bad_shape ? "bad_shape" : "");

      }

    }

    float right_gap = 0.0f;

    if (!end_row) {

      right_gap = word_res->GetBlobsGap(row) / normalizing_height;

      SEAM *right_seam = word_res->seam_array[row];

      if (right_gap < kMinGap || right_seam->priority() > 0.0f) {

        stats->bad_shape = true;

        if (right_gap < kMinGap) {

          stats->bad_fixed_pitch_right_gap = true;

        }

      }

      if (debug) {

        tprintf("right_gap %g right_seam %g %s\n", right_gap, right_seam->priority(),

                stats->bad_shape ? "bad_shape" : "");

      }

    }

    // Impose additional segmentation penalties if blob widths or gaps

    // distribution don't fit a fixed-pitch model.

    // Since we only know the widths and gaps of the path explored so far,

    // the means and variances are computed for the path so far (not

    // considering characters to the right of the last character on the path).

    stats->full_wh_ratio = wh_ratio + right_gap;

    if (parent_stats != nullptr) {

      stats->full_wh_ratio_total = (parent_stats->full_wh_ratio_total + stats->full_wh_ratio);

      float mean = stats->full_wh_ratio_total / static_cast<float>(parent_path_length + 1);

      stats->full_wh_ratio_var =

          parent_stats->full_wh_ratio_var + pow(mean - stats->full_wh_ratio, 2);

    } else {

      stats->full_wh_ratio_total = stats->full_wh_ratio;

    }

    if (debug) {

      tprintf("full_wh_ratio %g full_wh_ratio_total %g full_wh_ratio_var %g\n",

              stats->full_wh_ratio, stats->full_wh_ratio_total, stats->full_wh_ratio_var);

    }

    stats->shape_cost = FixedPitchWidthCost(wh_ratio, right_gap, end_row, max_char_wh_ratio);

    // For some reason Tesseract prefers to treat the whole CJ words

    // as one blob when the initial segmentation is particularly bad.

    // This hack is to avoid favoring such states.

    if (col == 0 && end_row && wh_ratio > max_char_wh_ratio) {

      stats->shape_cost += 10;

    }

    stats->shape_cost += stats->full_wh_ratio_var;

    if (debug) {

      tprintf("shape_cost %g\n", stats->shape_cost);

    }

  }

}

float AssociateUtils::FixedPitchWidthCost(float norm_width, float right_gap, bool end_pos,

                                          float max_char_wh_ratio) {

  float cost = 0.0f;

  if (norm_width > max_char_wh_ratio) {

    cost += norm_width;

  }

  if (norm_width > kMaxFixedPitchCharAspectRatio) {

    cost += norm_width * norm_width; // extra penalty for merging CJK chars

  }

  // Penalize skinny blobs, except for punctuation in the last position.

  if (norm_width + right_gap < 0.5f && !end_pos) {

    cost += 1.0f - (norm_width + right_gap);

  }

  return cost;

}

} // namespace tesseract