/****************************************************************************
**
Various utility computation methods

Copyright (C) 2024 LibreCAD.org
Copyright (C) 2024 sand1024

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
**********************************************************************/
#include <algorithm>
#include <cmath>

#include "lc_linemath.h"
#include "rs.h"
#include "rs_information.h"
#include "rs_line.h"
#include "rs_math.h"
#include "rs_vector.h"

namespace {

// Compare by coordinates
// points within RS_TOLERANCE distance are considered equal
bool compareCoordinates(const RS_Vector& p0, const RS_Vector& p1)
{
    return p0.distanceTo(p1) >= RS_TOLERANCE && (
               p0.x < p1.x || (p0.x <= p1.x && p0.y < p1.y));
}

/**
 * @brief isCounterclockwise v3 - v1, v2 - v1, if ordered as counterclockwise
 * @param v1
 * @param v2
 * @param v3
 * @return
 */
bool isCounterClockwise (const RS_Vector& v1, const RS_Vector& v2, const RS_Vector& v3)
{
    double res = RS_Vector::crossP((v2 - v1).normalized(), (v3 - v1).normalized()).z;

    return res >= RS_TOLERANCE;
}
}

/**
 * Calculates point located on specified distance and angle from given starting point
 * @param startPoint start point
 * @param angleValueDegree angle in degrees
 * @param distance distance for vector
 * @return resulting point
 */
RS_Vector LC_LineMath::getEndOfLineSegment(const RS_Vector &startPoint, double angleValueDegree, double distance){
    double angle = RS_Math::deg2rad(angleValueDegree);
    RS_Vector line = RS_Vector::polar(distance, angle);
    RS_Vector result  = startPoint + line;
    return result;
}


/**
 * Return points that is located by specified distance and angle from given start point
 * @param startPoint start point
 * @param angleValueRad angle to target end point from start point (in radians)
 * @param distance  distance between start and end point
 * @return resulting point
 */
RS_Vector LC_LineMath::relativePoint(const RS_Vector &startPoint, double distance, double angleValueRad){
    RS_Vector offsetVector = RS_Vector::polar(distance, angleValueRad);
    RS_Vector result  = startPoint + offsetVector;
    return result;
}

RS_Vector LC_LineMath::calculateAngleSegment(const RS_Vector& startPoint, const RS_Vector& previousLineStart,
                                             const RS_Vector& previousLineEnd, double angleValueDegree,
                                             bool angleRelative, double distance) {
    double angle = RS_Math::deg2rad(angleValueDegree);
    double realAngle = defineActualSegmentAngle(angle, angleRelative, previousLineStart, previousLineEnd);
    RS_Vector line = RS_Vector::polar(distance, realAngle);
    RS_Vector result = startPoint + line;
    return result;
}

/**
 * Defines actual angle to provide line segment. If angle value is relative, adds that angle to own angle of line segment
 * @param angle specified angle
 * @param angleIsRelative if true, angle value is related
 * @param previousLineStart previous line segment start
 * @param previousLineEnd previous line segment end
 * @return
 */
double LC_LineMath::defineActualSegmentAngle(double angle, bool angleIsRelative, const RS_Vector& previousLineStart,
                                             const RS_Vector& previousLineEnd) {
    double result = angle;
    if (angleIsRelative) {
        RS_Vector line = previousLineEnd - previousLineStart;
        double previousSegmentAngle = line.angle();
        result = angle + previousSegmentAngle;
    }
    return result;
}

/**
 * Calculates projection of given point to infinite line (ray), that extends lines provided by coordinates
 * @param coord point coordinates
 * @param lineStartPoint line start
 * @param lineEndPoint  line end
 * @return projectsion coordinates
 */
RS_Vector LC_LineMath::getNearestPointOnInfiniteLine(const RS_Vector& coord, const RS_Vector& lineStartPoint,
                                                     const RS_Vector& lineEndPoint) {
    RS_Vector ae = lineEndPoint - lineStartPoint;
    RS_Vector ea = lineStartPoint - lineEndPoint;
    RS_Vector ap = coord - lineStartPoint;

    double magnitude = ae.magnitude();
    if (magnitude < RS_TOLERANCE || ea.magnitude() < RS_TOLERANCE) {
        return RS_Vector(false);
    }

    // Orthogonal projection from both sides:
    RS_Vector ba = ae * RS_Vector::dotP(ae, ap) / (magnitude * magnitude);

    return lineStartPoint + ba;
}

/**
 * Calculates actual endpoint of line segment, that starts from given point by provided angle and is controlled by provided
 * snap point. Actually, the endpoint of segment is projection of snap point to infinite line that has specified angle and starts
 * from given starting point.
 * @param angleValueDegree angle value in degrees
 * @param startPoint start point of line segment
 * @param toSnapPoint snap point
 * @return end point for the segment
 */
RS_Vector LC_LineMath::calculateEndpointForAngleDirection(double wcsAngleRad, const RS_Vector& startPoint,
                                                          const RS_Vector& toSnapPoint) {
    RS_Vector possibleEndPoint;

    RS_Vector infiniteTickStartPoint = startPoint;
    RS_Vector infiniteTickEndPoint = infiniteTickStartPoint.relative(10.0, wcsAngleRad);
    RS_Vector pointOnInfiniteTick = getNearestPointOnInfiniteLine(toSnapPoint, infiniteTickStartPoint,
                                                                  infiniteTickEndPoint);

    possibleEndPoint = pointOnInfiniteTick;
    return possibleEndPoint;
}

RS_Vector LC_LineMath::calculateEndpointForAngleDirection(double angleValueDegree, bool angleIsRelative,
                                                          const RS_Vector& fromPoint, const RS_Vector& toSnapPoint,
                                                          const RS_Vector& previousLineStart,
                                                          const RS_Vector& previousLineEnd) {
    double angle = RS_Math::deg2rad(angleValueDegree);
    RS_Vector infiniteTickStartPoint = fromPoint;
    double realAngle = defineActualSegmentAngle(angle, angleIsRelative, previousLineStart, previousLineEnd);

    RS_Vector infiniteTickVector = RS_Vector::polar(10.0, realAngle);
    RS_Vector infiniteTickEndPoint = infiniteTickStartPoint + infiniteTickVector;
    RS_Vector pointOnInfiniteTick = getNearestPointOnInfiniteLine(toSnapPoint, infiniteTickStartPoint,
                                                                  infiniteTickEndPoint);

    return pointOnInfiniteTick;
}

/**
 * Returns nearest projection of point to given line
 * @param line  line
 * @param coord point
 * @param infiniteLine if true, given line is considered to be infinite
 * @return point
 */
RS_Vector LC_LineMath::getNearestPointOnLine(const RS_Line* line, const RS_Vector& coord, bool infiniteLine){
    // For infinite lines, find the nearest point is not limited by start/end points
    bool onEntity = ! infiniteLine;
    return line != nullptr ? line->getNearestPointOnEntity(coord, onEntity, nullptr) : RS_Vector{false};
}

/**
 * Determines point that lies on circle of provided center and radius and with specific angle to point
 * @param radius circle radius
 * @param arcAngle  circle angle
 * @param centerCircle center of circle
 * @return point coordinates
 */
RS_Vector LC_LineMath::findPointOnCircle(double radius, double arcAngle, const RS_Vector& centerCircle){
    RS_Vector radiusVector = RS_Vector::polar(radius, arcAngle);
    RS_Vector pointPos = centerCircle + radiusVector;
    return pointPos;
}

/**
 * Determines how given point relates to provided line
 * @param startPos start point of line
 * @param endPos end point of line
 * @param point  point to check
 * @return point position
 */
int LC_LineMath::getPointPosition(const RS_Vector &startPos, const RS_Vector &endPos, const RS_Vector &point){
    RS_Vector a = endPos - startPos; // 1
    RS_Vector b = point - startPos; // 2
    double sa = a. x * b.y - b.x * a.y; // 3
    if (sa > 0.0) {
        return LEFT;
    }
    if (sa < 0.0) {
        return RIGHT;
    }
    if ((a.x * b.x < 0.0) || (a.y * b.y < 0.0)) {
        return BEHIND;
    }
    if (a.magnitude() < b.magnitude()) {
        return BEYOND;
    }
    if (startPos == point) {
        return ORIGIN;
    }
    if (endPos == point) {
        return DESTINATION;
    }
    return BETWEEN;
}

/**
 * Checks whether two lines defined by their edge points lay on the same ray vector
 * @param line1Start
 * @param line1End
 * @param line2Start
 * @param line2End
 * @return
 */
bool LC_LineMath::areLinesOnSameRay(const RS_Vector& line1Start, const RS_Vector& line1End, const RS_Vector& line2Start,
                                    const RS_Vector& line2End) {
    // TODO: create a generic algorithm to find whether points are collinear
    // Find the rank of the matrix formed by point homogeneous coordinates:
    // coincidence: rank = 1
    // collinear:   rank = 2
    // coplanar:    rank = 3
    double angle1 = line1Start.angleTo(line1End);
    double angle2 = line1Start.angleTo(line2End);
    double angle3 = line1Start.angleTo(line2Start);

    // if all points are on the same ray, the angles from first point to remaining 3 points will be the same

    angle1 = RS_Math::correctAngle0ToPi(angle1);
    angle2 = RS_Math::correctAngle0ToPi(angle2);
    angle3 = RS_Math::correctAngle0ToPi(angle3);

    bool sameLine = false;
    if (std::abs(angle1 - angle2) < RS_TOLERANCE_ANGLE && std::abs(angle1 - angle3) < RS_TOLERANCE_ANGLE) {
        sameLine = true;
    }
    return sameLine;
}

/**
 * Check whether distance between points is meaningful
 * @param startPoint
 * @param endPoint
 * @return
 */
bool LC_LineMath::isNonZeroLineLength(const RS_Vector &startPoint, const RS_Vector &endPoint){
    return (endPoint - startPoint).squared() > RS_TOLERANCE;
}

/**
 * Returns meaningful value. If provided candidate is not meaningful, returns replacement value
 * @param candidate
 * @param replacementValue
 * @return
 */
double LC_LineMath::getMeaningful(double candidate, double replacementValue){
    return (std::abs(candidate) < RS_TOLERANCE) ? replacementValue : candidate;
}


double LC_LineMath::getMeaningfulPositive(double candidate, double replacementValue){
    return (candidate < RS_TOLERANCE) ? replacementValue : candidate;
}

/**
 * Checks and returns meaningful angle - if provided value is not meaningful, returns replacement value
 * @param candidate
 * @param replacementValue
 * @return
 */
double LC_LineMath::getMeaningfulAngle(double candidate, double replacementValue){
    return (std::abs(candidate) < RS_TOLERANCE_ANGLE) ? replacementValue : candidate;
}

/**
 * Returns true if value is meaningful
 * @param value
 * @return
 */
bool LC_LineMath::isMeaningful(double value){
    return std::abs(value) >= RS_TOLERANCE;
}

/**
 * Return true if angle value is not meaningful
 * @param value
 * @return
 */
bool LC_LineMath::isNotMeaningful(double value){
    return std::abs(value) < RS_TOLERANCE;
}

/**
 * Returns true if angle value is meaningful
 * @param value
 * @return
 */
bool LC_LineMath::isMeaningfulAngle(double value){
    return std::abs(value) >= RS_TOLERANCE_ANGLE;
}

bool LC_LineMath::isSameAngle(double angle1, double angle2) {
    return std::abs(angle1 - angle2) < RS_TOLERANCE_ANGLE;
}

/**
 * Return true if distance between two points is meaningful and so these are
 * different points
 * @param v1 first point
 * @param v2 second point
 * @return true if points are different
 */
bool LC_LineMath::isMeaningfulDistance(const RS_Vector &v1, const RS_Vector &v2){
    double distance = v1.distanceTo(v2);
    return distance >= RS_TOLERANCE;
}
/**
 * Return true if distance between two points is not meaningful (close to zero
 * and less than RS_TOLERANCE) - so basically these to points may be considered as
 * the same point
 * @param v1 first point
 * @param v2 second point
 * @return true if distance not meaningful, false otherwise
 */
bool LC_LineMath::isNotMeaningfulDistance(const RS_Vector &v1, const RS_Vector &v2){
    double distance = v1.distanceTo(v2);
    return distance < RS_TOLERANCE;
}

/**
 * Creates line that is parallel to given original line (defined by start and and point), that is located
 * on given distance
 * @param start start of original line
 * @param end end of original line
 * @param distance distance for parallel line
 * @return line data that describes parallel line
 */
RS_LineData LC_LineMath::createParallel(const RS_Vector &start, const RS_Vector &end, double distance){
    RS_Line line{nullptr, {start, end}};
    double ang = line.getDirection1() + M_PI_2;
    // calculate 1st parallel:
    line.move(RS_Vector::polar(distance, ang));
    return line.getData();
}

/**
 * Determines intersection point for two lines defined by provided start and end vectors
 * @param s1  start of line 1
 * @param e1  end of line 1
 * @param s2  start of line 2
 * @param e2  end of line 2
 * @return intersection point, invalid vector if no intersection point found
 */
RS_Vector LC_LineMath::getIntersectionLineLine(const RS_Vector& s1, const RS_Vector& e1, const RS_Vector& s2,
                                               const RS_Vector& e2) {
    RS_Line line1{nullptr, {s1, e1}};
    RS_Line line2{nullptr, {s2, e2}};
    RS_VectorSolutions sol = RS_Information::getIntersectionLineLine(&line1, &line2);
    return sol.empty() ? RS_Vector{false} : sol.at(0);
}

RS_Vector LC_LineMath::getIntersectionLineLineFast(const RS_Vector& s1, const RS_Vector& e1, const RS_Vector& s2,
                                                   const RS_Vector& e2) {
    RS_Vector ret;

    double num = ((e2.x - s2.x) * (s1.y - s2.y) - (e2.y - s2.y) * (s1.x - s2.x));
    double div = ((e2.y - s2.y) * (e1.x - s1.x) - (e2.x - s2.x) * (e1.y - s1.y));

    double angle1 = s1.angleTo(e1);
    double angle2 = s2.angleTo(e2);

    if (fabs(div)>RS_TOLERANCE &&
        fabs(remainder(angle1-angle2, M_PI))>=RS_TOLERANCE*10.) {
        double u = num / div;

        double xs = s1.x + u * (e1.x - s1.x);
        double ys = s1.y + u * (e1.y - s1.y);
        ret = RS_Vector(xs, ys);
    }
    else {
        // lines are parallel
        ret = RS_Vector(false);
    }
    return ret;
}

RS_Vector LC_LineMath::getIntersectionInfiniteLineLineFast(const RS_Vector& s1, const RS_Vector& e1, const RS_Vector& s2, const RS_Vector& e2, double offsetX, double offsetY) {

    RS_Vector ret;

    double num = ((e2.x - s2.x) * (s1.y - s2.y) - (e2.y - s2.y) * (s1.x - s2.x));
    double div = ((e2.y - s2.y) * (e1.x - s1.x) - (e2.x - s2.x) * (e1.y - s1.y));

    double angle1 = s1.angleTo(e1);
    double angle2 = s2.angleTo(e2);

    if (fabs(div)>RS_TOLERANCE &&
        fabs(remainder(angle1-angle2, M_PI))>=RS_TOLERANCE*10.) {
        double u = num / div;

        double xs = s1.x + u * (e1.x - s1.x);
        double ys = s1.y + u * (e1.y - s1.y);
        // check that intersection is within finite line, here we expect that start/end is properly orderred (from min to max)
        if ((xs >= (s2.x-offsetX)) && (xs <= (e2.x+offsetX)) && (ys >= (s2.y-offsetY)) && (ys <= (e2.y+offsetY))){
            ret = RS_Vector(xs, ys);
        }
        else {
            ret = RS_Vector(false);
        }
    }
    else {
        // lines are parallel
        ret = RS_Vector(false);
    }
    return ret;
}

bool LC_LineMath::hasIntersectionLineRect(const RS_Vector& lineStart, const RS_Vector& lineEnd, const RS_Vector& rectMin, const RS_Vector& rectMax) {
    RS_Vector direction =  lineEnd - lineStart;
    // fixme - rewrite to faster implementation as it is used in rendering pipeline!!
    // here we check intersection of infinite line and two diagonals of given rect with edges parallel to axis.

    if (hasLineIntersection(lineStart, direction, rectMin, rectMax)){ // intersection with first diagonal
        return true;
    }
    else{
        return hasLineIntersection(lineStart, direction, {rectMin.x, rectMax.y}, {rectMax.x, rectMin.y}); // intersection with second diagnonal
    }
}

/*
 * check whether there is intersection of infinite line and segment
 */
bool LC_LineMath::hasLineIntersection(RS_Vector p0, RS_Vector direction, RS_Vector p2, RS_Vector p3)
{
    RS_Vector P = p2;
    RS_Vector R = p3 - p2;
    RS_Vector Q = p0;
    RS_Vector S = direction;

    RS_Vector N = RS_Vector(S.y, -S.x);
//    float t = dot(Q-P, N) / dot(R, N);

    RS_Vector tmp = Q-P;
    double t = tmp.dotP(N) / R.dotP(N);

    if (t >= 0.0 && t <= 1.0){
        return true;
//        return P + R * t;
    }
    return false;
//    return RS_Vector(-1.0);
}


/**
 * @brief convexHull - find the convex hull by Graham's scan
 * @param points - input points
 * @return - the convex hull found
 */
RS_VectorSolutions LC_LineMath::convexHull(const RS_VectorSolutions& points){
    RS_VectorSolutions sol = points;
    // ignore invalid points
    auto it = std::remove_if(sol.begin(), sol.end(), [](const RS_Vector& p) {
        return ! p.valid;});
    sol = {{sol.begin(), it}};

    if (sol.size() <= 1) {
        return sol;
    }

    // find the left-most and lowest corner
    std::sort(sol.begin(), sol.end(), compareCoordinates);

    // avoid duplicates
    RS_VectorSolutions hull{{sol.at(0)}};
    for(size_t i = 1; i < sol.size(); ++i) {
        if (hull.back().distanceTo(sol.at(i)) > RS_TOLERANCE) {
            hull.push_back(sol.at(i));
        }
    }

    if (hull.size() <= 2) {
        return hull;
    }

    // soft by the angle to the corner
    std::sort(hull.begin() + 1, hull.end(),
              [lowerLeft=hull.at(0)](const RS_Vector& lhs, const RS_Vector& rhs) {
                  return lowerLeft.angleTo(lhs) < lowerLeft.angleTo(rhs);
              });

    // keep the farthest for the same angle
    sol = {hull.at(0), hull.at(1)};
    for (size_t i = 2; i < hull.size(); ++i) {
        const double angle0 = sol.at(0).angleTo(sol.back());
        const double angle1 = sol.at(0).angleTo(hull.at(i));
        if (RS_Math::equal(angle0, angle1, RS_TOLERANCE)) {
            if (sol.at(0).distanceTo(hull.at(i)) < sol.at(0).distanceTo(sol.back())) {
                sol.back() = hull.at(i);
            }
        } else {
            sol.push_back(hull.at(i));
        }
    }

    // only keep left turns
    hull = {sol.at(0), sol.at(1)};
    for (size_t i = 2; i < sol.size(); ++i) {
        const size_t j = hull.size() - 1;
        if (isCounterClockwise(hull.at(j-1), hull.at(j), sol.at(i))) {
            hull.push_back(sol.at(i));
        }
        else {
            hull.at(j) = sol.at(i);
        }
    }
    return hull;
}

double LC_LineMath::angleFor3Points(const RS_Vector& edgePoint1, const RS_Vector& intersection, const RS_Vector& edgePoint2) {
    double angle1 = intersection.angleTo(edgePoint1);
    double angle2 = intersection.angleTo(edgePoint2);
    double angle = RS_Math::getAngleDifference(angle1, angle2, false);
    angle = RS_Math::correctAngle0ToPi(angle);
    // double angle = RS_Math::correctAngle(angle1-angle2);
    return angle;
}