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

// File:        tabvector.h

// Description: Class to hold a near-vertical vector representing a tab-stop.

// Author:      Ray Smith

//

// (C) Copyright 2008, 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_TEXTORD_TABVECTOR_H_

#define TESSERACT_TEXTORD_TABVECTOR_H_

#include "bbgrid.h"

#include "blobgrid.h"

#include "clst.h"

#include "elst.h"

#include "elst2.h"

#include "rect.h"

#include <algorithm>

class BLOBNBOX;

class ScrollView;

namespace tesseract {

extern double_VAR_H(textord_tabvector_vertical_gap_fraction);

extern double_VAR_H(textord_tabvector_vertical_box_ratio);

// The alignment type that a tab vector represents.

// Keep this enum synced with kAlignmentNames in tabvector.cpp.

enum TabAlignment {

  TA_LEFT_ALIGNED,

  TA_LEFT_RAGGED,

  TA_CENTER_JUSTIFIED,

  TA_RIGHT_ALIGNED,

  TA_RIGHT_RAGGED,

  TA_SEPARATOR,

  TA_COUNT

};

// Forward declarations. The classes use their own list types, so we

// need to make the list types first.

class TabFind;

class TabVector;

class TabConstraint;

ELIST2IZEH(TabVector)

CLISTIZEH(TabVector)

ELISTIZEH(TabConstraint)

// TabConstraint is a totally self-contained class to maintain

// a list of [min,max] constraints, each referring to a TabVector.

// The constraints are manipulated through static methods that act

// on a list of constraints. The list itself is cooperatively owned

// by the TabVectors of the constraints on the list and managed

// by implicit reference counting via the elements of the list.

class TabConstraint : public ELIST<TabConstraint>::LINK {

public:

  // This empty constructor is here only so that the class can be ELISTIZED.

  // TODO(rays) change deep_copy in elst.h line 955 to take a callback copier

  // and eliminate CLASSNAME##_copier.

  TabConstraint() = default;

  // Create a constraint for the top or bottom of this TabVector.

  static void CreateConstraint(TabVector *vector, bool is_top);

  // Test to see if the constraints are compatible enough to merge.

  static bool CompatibleConstraints(TabConstraint_LIST *list1, TabConstraint_LIST *list2);

  // Merge the lists of constraints and update the TabVector pointers.

  // The second list is deleted.

  static void MergeConstraints(TabConstraint_LIST *list1, TabConstraint_LIST *list2);

  // Set all the tops and bottoms as appropriate to a mean of the

  // constrained range. Delete all the constraints and list.

  static void ApplyConstraints(TabConstraint_LIST *constraints);

private:

  TabConstraint(TabVector *vector, bool is_top);

  // Get the max of the mins and the min of the maxes.

  static void GetConstraints(TabConstraint_LIST *constraints, int *y_min, int *y_max);

  // The TabVector this constraint applies to.

  TabVector *vector_;

  // If true then we refer to the top of the vector_.

  bool is_top_;

  // The allowed range of this vector_.

  int y_min_;

  int y_max_;

};

// Class to hold information about a single vector

// that represents a tab stop or a rule line.

class TabVector : public ELIST2<TabVector>::LINK {

public:

  // TODO(rays) fix this in elst.h line 1076, where it should use the

  // copy constructor instead of operator=.

  TabVector() = default;

  ~TabVector() = default;

  // Public factory to build a TabVector from a list of boxes.

  // The TabVector will be of the given alignment type.

  // The input vertical vector is used in fitting, and the output

  // vertical_x, vertical_y have the resulting line vector added to them

  // if the alignment is not ragged.

  // The extended_start_y and extended_end_y are the maximum possible

  // extension to the line segment that can be used to align with others.

  // The input CLIST of BLOBNBOX good_points is consumed and taken over.

  static TabVector *FitVector(TabAlignment alignment, ICOORD vertical, int extended_start_y,

                              int extended_end_y, BLOBNBOX_CLIST *good_points, int *vertical_x,

                              int *vertical_y);

  // Build a ragged TabVector by copying another's direction, shifting it

  // to match the given blob, and making its initial extent the height

  // of the blob, but its extended bounds from the bounds of the original.

  TabVector(const TabVector &src, TabAlignment alignment, const ICOORD &vertical_skew,

            BLOBNBOX *blob);

  // Copies basic attributes of a tab vector for simple operations.

  // Copies things such startpt, endpt, range, width.

  // Does not copy things such as partners, boxes, or constraints.

  // This is useful if you only need vector information for processing, such

  // as in the table detection code.

  TabVector *ShallowCopy() const;

  // Simple accessors.

  const ICOORD &startpt() const {

    return startpt_;

  }

  const ICOORD &endpt() const {

    return endpt_;

  }

  int extended_ymax() const {

    return extended_ymax_;

  }

  int extended_ymin() const {

    return extended_ymin_;

  }

  int sort_key() const {

    return sort_key_;

  }

  int mean_width() const {

    return mean_width_;

  }

  void set_top_constraints(TabConstraint_LIST *constraints) {

    top_constraints_ = constraints;

  }

  void set_bottom_constraints(TabConstraint_LIST *constraints) {

    bottom_constraints_ = constraints;

  }

  TabVector_CLIST *partners() {

    return &partners_;

  }

  void set_startpt(const ICOORD &start) {

    startpt_ = start;

  }

  void set_endpt(const ICOORD &end) {

    endpt_ = end;

  }

  bool intersects_other_lines() const {

    return intersects_other_lines_;

  }

  void set_intersects_other_lines(bool value) {

    intersects_other_lines_ = value;

  }

  // Inline quasi-accessors that require some computation.

  // Compute the x coordinate at the given y coordinate.

  int XAtY(int y) const {

    int height = endpt_.y() - startpt_.y();

    if (height != 0) {

      return (y - startpt_.y()) * (endpt_.x() - startpt_.x()) / height + startpt_.x();

    } else {

      return startpt_.x();

    }

  }

  // Compute the vertical overlap with the other TabVector.

  int VOverlap(const TabVector &other) const {

    return std::min(other.endpt_.y(), endpt_.y()) - std::max(other.startpt_.y(), startpt_.y());

  }

  // Compute the vertical overlap with the given y bounds.

  int VOverlap(int top_y, int bottom_y) const {

    return std::min(top_y, static_cast<int>(endpt_.y())) -

           std::max(bottom_y, static_cast<int>(startpt_.y()));

  }

  // Compute the extended vertical overlap with the given y bounds.

  int ExtendedOverlap(int top_y, int bottom_y) const {

    return std::min(top_y, extended_ymax_) - std::max(bottom_y, extended_ymin_);

  }

  // Return true if this is a left tab stop, either aligned, or ragged.

  bool IsLeftTab() const {

    return alignment_ == TA_LEFT_ALIGNED || alignment_ == TA_LEFT_RAGGED;

  }

  // Return true if this is a right tab stop, either aligned, or ragged.

  bool IsRightTab() const {

    return alignment_ == TA_RIGHT_ALIGNED || alignment_ == TA_RIGHT_RAGGED;

  }

  // Return true if this is a separator.

  bool IsSeparator() const {

    return alignment_ == TA_SEPARATOR;

  }

  // Return true if this is a center aligned tab stop.

  bool IsCenterTab() const {

    return alignment_ == TA_CENTER_JUSTIFIED;

  }

  // Return true if this is a ragged tab top, either left or right.

  bool IsRagged() const {

    return alignment_ == TA_LEFT_RAGGED || alignment_ == TA_RIGHT_RAGGED;

  }

  // Return true if this vector is to the left of the other in terms

  // of sort_key_.

  bool IsLeftOf(const TabVector &other) const {

    return sort_key_ < other.sort_key_;

  }

  // Return true if the vector has no partners.

  bool Partnerless() {

    return partners_.empty();

  }

  // Return the number of tab boxes in this vector.

  int BoxCount() {

    return boxes_.length();

  }

  // Lock the vector from refits by clearing the boxes_ list.

  void Freeze() {

    boxes_.shallow_clear();

  }

  // Flip x and y on the ends so a vector can be created from flipped input.

  void XYFlip() {

    int x = startpt_.y();

    startpt_.set_y(startpt_.x());

    startpt_.set_x(x);

    x = endpt_.y();

    endpt_.set_y(endpt_.x());

    endpt_.set_x(x);

  }

  // Reflect the tab vector in the y-axis.

  void ReflectInYAxis() {

    startpt_.set_x(-startpt_.x());

    endpt_.set_x(-endpt_.x());

    sort_key_ = -sort_key_;

    if (alignment_ == TA_LEFT_ALIGNED) {

      alignment_ = TA_RIGHT_ALIGNED;

    } else if (alignment_ == TA_RIGHT_ALIGNED) {

      alignment_ = TA_LEFT_ALIGNED;

    }

    if (alignment_ == TA_LEFT_RAGGED) {

      alignment_ = TA_RIGHT_RAGGED;

    } else if (alignment_ == TA_RIGHT_RAGGED) {

      alignment_ = TA_LEFT_RAGGED;

    }

  }

  // Separate function to compute the sort key for a given coordinate pair.

  static int SortKey(const ICOORD &vertical, int x, int y) {

    ICOORD pt(x, y);

    return pt * vertical;

  }

  // Return the x at the given y for the given sort key.

  static int XAtY(const ICOORD &vertical, int sort_key, int y) {

    if (vertical.y() != 0) {

      return (vertical.x() * y + sort_key) / vertical.y();

    } else {

      return sort_key;

    }

  }

  // Sort function for E2LIST::sort to sort by sort_key_.

  static int SortVectorsByKey(const TabVector *tv1, const TabVector *tv2) {

    return tv1->sort_key_ - tv2->sort_key_;

  }

  // More complex members.

  // Extend this vector to include the supplied blob if it doesn't

  // already have it.

  void ExtendToBox(BLOBNBOX *blob);

  // Set the ycoord of the start and move the xcoord to match.

  void SetYStart(int start_y);

  // Set the ycoord of the end and move the xcoord to match.

  void SetYEnd(int end_y);

  // Rotate the ends by the given vector.

  void Rotate(const FCOORD &rotation);

  // Setup the initial constraints, being the limits of

  // the vector and the extended ends.

  void SetupConstraints();

  // Setup the constraints between the partners of this TabVector.

  void SetupPartnerConstraints();

  // Setup the constraints between this and its partner.

  void SetupPartnerConstraints(TabVector *partner);

  // Use the constraints to modify the top and bottom.

  void ApplyConstraints();

  // Merge close tab vectors of the same side that overlap.

  static void MergeSimilarTabVectors(const ICOORD &vertical, TabVector_LIST *vectors,

                                     BlobGrid *grid);

  // Return true if this vector is the same side, overlaps, and close

  // enough to the other to be merged.

  bool SimilarTo(const ICOORD &vertical, const TabVector &other, BlobGrid *grid) const;

  // Eat the other TabVector into this and delete it.

  void MergeWith(const ICOORD &vertical, TabVector *other);

  // Add a new element to the list of partner TabVectors.

  // Partners must be added in order of increasing y coordinate of the text line

  // that makes them partners.

  // Groups of identical partners are merged into one.

  void AddPartner(TabVector *partner);

  // Return true if other is a partner of this.

  bool IsAPartner(const TabVector *other);

  // Print basic information about this tab vector.

  void Print(const char *prefix);

  // Print basic information about this tab vector and every box in it.

  void Debug(const char *prefix);

  // Draw this tabvector in place in the given window.

  void Display(ScrollView *tab_win);

  // Refit the line and/or re-evaluate the vector if the dirty flags are set.

  void FitAndEvaluateIfNeeded(const ICOORD &vertical, TabFind *finder);

  // Evaluate the vector in terms of coverage of its length by good-looking

  // box edges. A good looking box is one where its nearest neighbour on the

  // inside is nearer than half the distance its nearest neighbour on the

  // outside of the putative column. Bad boxes are removed from the line.

  // A second pass then further filters boxes by requiring that the gutter

  // width be a minimum fraction of the mean gutter along the line.

  void Evaluate(const ICOORD &vertical, TabFind *finder);

  // (Re)Fit a line to the stored points. Returns false if the line

  // is degenerate. Although the TabVector code mostly doesn't care about the

  // direction of lines, XAtY would give silly results for a horizontal line.

  // The class is mostly aimed at use for vertical lines representing

  // horizontal tab stops.

  bool Fit(ICOORD vertical, bool force_parallel);

  // Return the partner of this TabVector if the vector qualifies as

  // being a vertical text line, otherwise nullptr.

  TabVector *VerticalTextlinePartner();

  // Return the matching tabvector if there is exactly one partner, or

  // nullptr otherwise.  This can be used after matching is done, eg. by

  // VerticalTextlinePartner(), without checking if the line is vertical.

  TabVector *GetSinglePartner();

private:

  // Constructor is private as the static factory is the external way

  // to build a TabVector.

  TabVector(int extended_ymin, int extended_ymax, TabAlignment alignment, BLOBNBOX_CLIST *boxes);

  // Delete this, but first, repoint all the partners to point to

  // replacement. If replacement is nullptr, then partner relationships

  // are removed.

  void Delete(TabVector *replacement);

private:

  // The bottom of the tab line.

  ICOORD startpt_;

  // The top of the tab line.

  ICOORD endpt_;

  // The lowest y that the vector might extend to.

  int extended_ymin_ = 0;

  // The highest y that the vector might extend to.

  int extended_ymax_ = 0;

  // Perpendicular distance of vector from a given vertical for sorting.

  int sort_key_ = 0;

  // Result of Evaluate 0-100. Coverage of line with good boxes.

  int percent_score_ = 0;

  // The mean width of the blobs. Meaningful only for separator lines.

  int mean_width_ = 0;

  // True if the boxes_ list has been modified, so a refit is needed.

  bool needs_refit_ = false;

  // True if a fit has been done, so re-evaluation is needed.

  bool needs_evaluation_ = false;

  // True if a separator line intersects at least 2 other lines.

  bool intersects_other_lines_ = false;

  // The type of this TabVector.

  TabAlignment alignment_ = TA_LEFT_ALIGNED;

  // The list of boxes whose edges are aligned at this TabVector.

  BLOBNBOX_CLIST boxes_;

  // List of TabVectors that have a connection with this via a text line.

  TabVector_CLIST partners_;

  // Constraints used to resolve the exact location of the top and bottom

  // of the tab line.

  TabConstraint_LIST *top_constraints_ = nullptr;

  TabConstraint_LIST *bottom_constraints_ = nullptr;

};

} // namespace tesseract.

#endif // TESSERACT_TEXTORD_TABVECTOR_H_