/*
  ==============================================================================

   This file is part of the JUCE library.
   Copyright (c) 2015 - ROLI Ltd.

   Permission is granted to use this software under the terms of either:
   a) the GPL v2 (or any later version)
   b) the Affero GPL v3

   Details of these licenses can be found at: www.gnu.org/licenses

   JUCE 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.

   ------------------------------------------------------------------------------

   To release a closed-source product which uses JUCE, commercial licenses are
   available: visit www.juce.com for more information.

  ==============================================================================
*/

PathStrokeType::PathStrokeType (float strokeThickness) noexcept
    : thickness (strokeThickness), jointStyle (mitered), endStyle (butt)
{
}

PathStrokeType::PathStrokeType (float strokeThickness, JointStyle joint, EndCapStyle end) noexcept
    : thickness (strokeThickness), jointStyle (joint), endStyle (end)
{
}

PathStrokeType::PathStrokeType (const PathStrokeType& other) noexcept
    : thickness (other.thickness),
      jointStyle (other.jointStyle),
      endStyle (other.endStyle)
{
}

PathStrokeType& PathStrokeType::operator= (const PathStrokeType& other) noexcept
{
    thickness = other.thickness;
    jointStyle = other.jointStyle;
    endStyle = other.endStyle;
    return *this;
}

PathStrokeType::~PathStrokeType() noexcept
{
}

bool PathStrokeType::operator== (const PathStrokeType& other) const noexcept
{
    return thickness == other.thickness
        && jointStyle == other.jointStyle
        && endStyle == other.endStyle;
}

bool PathStrokeType::operator!= (const PathStrokeType& other) const noexcept
{
    return ! operator== (other);
}

//==============================================================================
namespace PathStrokeHelpers
{
    static bool lineIntersection (const float x1, const float y1,
                                  const float x2, const float y2,
                                  const float x3, const float y3,
                                  const float x4, const float y4,
                                  float& intersectionX,
                                  float& intersectionY,
                                  float& distanceBeyondLine1EndSquared) noexcept
    {
        if (x2 != x3 || y2 != y3)
        {
            const float dx1 = x2 - x1;
            const float dy1 = y2 - y1;
            const float dx2 = x4 - x3;
            const float dy2 = y4 - y3;
            const float divisor = dx1 * dy2 - dx2 * dy1;

            if (divisor == 0)
            {
                if (! ((dx1 == 0 && dy1 == 0) || (dx2 == 0 && dy2 == 0)))
                {
                    if (dy1 == 0 && dy2 != 0)
                    {
                        const float along = (y1 - y3) / dy2;
                        intersectionX = x3 + along * dx2;
                        intersectionY = y1;

                        distanceBeyondLine1EndSquared = intersectionX - x2;
                        distanceBeyondLine1EndSquared *= distanceBeyondLine1EndSquared;
                        if ((x2 > x1) == (intersectionX < x2))
                            distanceBeyondLine1EndSquared = -distanceBeyondLine1EndSquared;

                        return along >= 0 && along <= 1.0f;
                    }

                    if (dy2 == 0 && dy1 != 0)
                    {
                        const float along = (y3 - y1) / dy1;
                        intersectionX = x1 + along * dx1;
                        intersectionY = y3;

                        distanceBeyondLine1EndSquared = (along - 1.0f) * dx1;
                        distanceBeyondLine1EndSquared *= distanceBeyondLine1EndSquared;
                        if (along < 1.0f)
                            distanceBeyondLine1EndSquared = -distanceBeyondLine1EndSquared;

                        return along >= 0 && along <= 1.0f;
                    }

                    if (dx1 == 0 && dx2 != 0)
                    {
                        const float along = (x1 - x3) / dx2;
                        intersectionX = x1;
                        intersectionY = y3 + along * dy2;

                        distanceBeyondLine1EndSquared = intersectionY - y2;
                        distanceBeyondLine1EndSquared *= distanceBeyondLine1EndSquared;

                        if ((y2 > y1) == (intersectionY < y2))
                            distanceBeyondLine1EndSquared = -distanceBeyondLine1EndSquared;

                        return along >= 0 && along <= 1.0f;
                    }

                    if (dx2 == 0 && dx1 != 0)
                    {
                        const float along = (x3 - x1) / dx1;
                        intersectionX = x3;
                        intersectionY = y1 + along * dy1;

                        distanceBeyondLine1EndSquared = (along - 1.0f) * dy1;
                        distanceBeyondLine1EndSquared *= distanceBeyondLine1EndSquared;
                        if (along < 1.0f)
                            distanceBeyondLine1EndSquared = -distanceBeyondLine1EndSquared;

                        return along >= 0 && along <= 1.0f;
                    }
                }

                intersectionX = 0.5f * (x2 + x3);
                intersectionY = 0.5f * (y2 + y3);

                distanceBeyondLine1EndSquared = 0.0f;
                return false;
            }

            const float along1 = ((y1 - y3) * dx2 - (x1 - x3) * dy2) / divisor;

            intersectionX = x1 + along1 * dx1;
            intersectionY = y1 + along1 * dy1;

            if (along1 >= 0 && along1 <= 1.0f)
            {
                const float along2 = ((y1 - y3) * dx1 - (x1 - x3) * dy1) / divisor;

                if (along2 >= 0 && along2 <= 1.0f)
                {
                    distanceBeyondLine1EndSquared = 0.0f;
                    return true;
                }
            }

            distanceBeyondLine1EndSquared = along1 - 1.0f;
            distanceBeyondLine1EndSquared *= distanceBeyondLine1EndSquared;
            distanceBeyondLine1EndSquared *= (dx1 * dx1 + dy1 * dy1);

            if (along1 < 1.0f)
                distanceBeyondLine1EndSquared = -distanceBeyondLine1EndSquared;

            return false;
        }

        intersectionX = x2;
        intersectionY = y2;

        distanceBeyondLine1EndSquared = 0.0f;
        return true;
    }

    static void addEdgeAndJoint (Path& destPath,
                                 const PathStrokeType::JointStyle style,
                                 const float maxMiterExtensionSquared, const float width,
                                 const float x1, const float y1,
                                 const float x2, const float y2,
                                 const float x3, const float y3,
                                 const float x4, const float y4,
                                 const float midX, const float midY)
    {
        if (style == PathStrokeType::beveled
            || (x3 == x4 && y3 == y4)
            || (x1 == x2 && y1 == y2))
        {
            destPath.lineTo (x2, y2);
            destPath.lineTo (x3, y3);
        }
        else
        {
            float jx, jy, distanceBeyondLine1EndSquared;

            // if they intersect, use this point..
            if (lineIntersection (x1, y1, x2, y2,
                                  x3, y3, x4, y4,
                                  jx, jy, distanceBeyondLine1EndSquared))
            {
                destPath.lineTo (jx, jy);
            }
            else
            {
                if (style == PathStrokeType::mitered)
                {
                    if (distanceBeyondLine1EndSquared < maxMiterExtensionSquared
                        && distanceBeyondLine1EndSquared > 0.0f)
                    {
                        destPath.lineTo (jx, jy);
                    }
                    else
                    {
                        // the end sticks out too far, so just use a blunt joint
                        destPath.lineTo (x2, y2);
                        destPath.lineTo (x3, y3);
                    }
                }
                else
                {
                    // curved joints
                    float angle1 = std::atan2 (x2 - midX, y2 - midY);
                    float angle2 = std::atan2 (x3 - midX, y3 - midY);
                    const float angleIncrement = 0.1f;

                    destPath.lineTo (x2, y2);

                    if (std::abs (angle1 - angle2) > angleIncrement)
                    {
                        if (angle2 > angle1 + float_Pi
                             || (angle2 < angle1 && angle2 >= angle1 - float_Pi))
                        {
                            if (angle2 > angle1)
                                angle2 -= float_Pi * 2.0f;

                            jassert (angle1 <= angle2 + float_Pi);

                            angle1 -= angleIncrement;
                            while (angle1 > angle2)
                            {
                                destPath.lineTo (midX + width * std::sin (angle1),
                                                 midY + width * std::cos (angle1));

                                angle1 -= angleIncrement;
                            }
                        }
                        else
                        {
                            if (angle1 > angle2)
                                angle1 -= float_Pi * 2.0f;

                            jassert (angle1 >= angle2 - float_Pi);

                            angle1 += angleIncrement;
                            while (angle1 < angle2)
                            {
                                destPath.lineTo (midX + width * std::sin (angle1),
                                                 midY + width * std::cos (angle1));

                                angle1 += angleIncrement;
                            }
                        }
                    }

                    destPath.lineTo (x3, y3);
                }
            }
        }
    }

    static void addLineEnd (Path& destPath,
                            const PathStrokeType::EndCapStyle style,
                            const float x1, const float y1,
                            const float x2, const float y2,
                            const float width)
    {
        if (style == PathStrokeType::butt)
        {
            destPath.lineTo (x2, y2);
        }
        else
        {
            float offx1, offy1, offx2, offy2;

            float dx = x2 - x1;
            float dy = y2 - y1;
            const float len = juce_hypot (dx, dy);

            if (len == 0)
            {
                offx1 = offx2 = x1;
                offy1 = offy2 = y1;
            }
            else
            {
                const float offset = width / len;
                dx *= offset;
                dy *= offset;

                offx1 = x1 + dy;
                offy1 = y1 - dx;
                offx2 = x2 + dy;
                offy2 = y2 - dx;
            }

            if (style == PathStrokeType::square)
            {
                // square ends
                destPath.lineTo (offx1, offy1);
                destPath.lineTo (offx2, offy2);
                destPath.lineTo (x2, y2);
            }
            else
            {
                // rounded ends
                const float midx = (offx1 + offx2) * 0.5f;
                const float midy = (offy1 + offy2) * 0.5f;

                destPath.cubicTo (x1 + (offx1 - x1) * 0.55f, y1 + (offy1 - y1) * 0.55f,
                                  offx1 + (midx - offx1) * 0.45f, offy1 + (midy - offy1) * 0.45f,
                                  midx, midy);

                destPath.cubicTo (midx + (offx2 - midx) * 0.55f, midy + (offy2 - midy) * 0.55f,
                                  offx2 + (x2 - offx2) * 0.45f, offy2 + (y2 - offy2) * 0.45f,
                                  x2, y2);
            }
        }
    }

    struct Arrowhead
    {
        float startWidth, startLength;
        float endWidth, endLength;
    };

    static void addArrowhead (Path& destPath,
                              const float x1, const float y1,
                              const float x2, const float y2,
                              const float tipX, const float tipY,
                              const float width,
                              const float arrowheadWidth)
    {
        Line<float> line (x1, y1, x2, y2);
        destPath.lineTo (line.getPointAlongLine (-(arrowheadWidth / 2.0f - width), 0));
        destPath.lineTo (tipX, tipY);
        destPath.lineTo (line.getPointAlongLine (arrowheadWidth - (arrowheadWidth / 2.0f - width), 0));
        destPath.lineTo (x2, y2);
    }

    struct LineSection
    {
        float x1, y1, x2, y2;      // original line
        float lx1, ly1, lx2, ly2;  // the left-hand stroke
        float rx1, ry1, rx2, ry2;  // the right-hand stroke
    };

    static void shortenSubPath (Array<LineSection>& subPath, float amountAtStart, float amountAtEnd)
    {
        while (amountAtEnd > 0 && subPath.size() > 0)
        {
            LineSection& l = subPath.getReference (subPath.size() - 1);
            float dx = l.rx2 - l.rx1;
            float dy = l.ry2 - l.ry1;
            const float len = juce_hypot (dx, dy);

            if (len <= amountAtEnd && subPath.size() > 1)
            {
                LineSection& prev = subPath.getReference (subPath.size() - 2);
                prev.x2 = l.x2;
                prev.y2 = l.y2;
                subPath.removeLast();
                amountAtEnd -= len;
            }
            else
            {
                const float prop = jmin (0.9999f, amountAtEnd / len);
                dx *= prop;
                dy *= prop;
                l.rx1 += dx;
                l.ry1 += dy;
                l.lx2 += dx;
                l.ly2 += dy;
                break;
            }
        }

        while (amountAtStart > 0 && subPath.size() > 0)
        {
            LineSection& l = subPath.getReference (0);
            float dx = l.rx2 - l.rx1;
            float dy = l.ry2 - l.ry1;
            const float len = juce_hypot (dx, dy);

            if (len <= amountAtStart && subPath.size() > 1)
            {
                LineSection& next = subPath.getReference (1);
                next.x1 = l.x1;
                next.y1 = l.y1;
                subPath.remove (0);
                amountAtStart -= len;
            }
            else
            {
                const float prop = jmin (0.9999f, amountAtStart / len);
                dx *= prop;
                dy *= prop;
                l.rx2 -= dx;
                l.ry2 -= dy;
                l.lx1 -= dx;
                l.ly1 -= dy;
                break;
            }
        }
    }

    static void addSubPath (Path& destPath, Array<LineSection>& subPath,
                            const bool isClosed, const float width, const float maxMiterExtensionSquared,
                            const PathStrokeType::JointStyle jointStyle, const PathStrokeType::EndCapStyle endStyle,
                            const Arrowhead* const arrowhead)
    {
        jassert (subPath.size() > 0);

        if (arrowhead != nullptr)
            shortenSubPath (subPath, arrowhead->startLength, arrowhead->endLength);

        const LineSection& firstLine = subPath.getReference (0);

        float lastX1 = firstLine.lx1;
        float lastY1 = firstLine.ly1;
        float lastX2 = firstLine.lx2;
        float lastY2 = firstLine.ly2;

        if (isClosed)
        {
            destPath.startNewSubPath (lastX1, lastY1);
        }
        else
        {
            destPath.startNewSubPath (firstLine.rx2, firstLine.ry2);

            if (arrowhead != nullptr)
                addArrowhead (destPath, firstLine.rx2, firstLine.ry2, lastX1, lastY1, firstLine.x1, firstLine.y1,
                              width, arrowhead->startWidth);
            else
                addLineEnd (destPath, endStyle, firstLine.rx2, firstLine.ry2, lastX1, lastY1, width);
        }

        for (int i = 1; i < subPath.size(); ++i)
        {
            const LineSection& l = subPath.getReference (i);

            addEdgeAndJoint (destPath, jointStyle,
                             maxMiterExtensionSquared, width,
                             lastX1, lastY1, lastX2, lastY2,
                             l.lx1, l.ly1, l.lx2, l.ly2,
                             l.x1, l.y1);

            lastX1 = l.lx1;
            lastY1 = l.ly1;
            lastX2 = l.lx2;
            lastY2 = l.ly2;
        }

        const LineSection& lastLine = subPath.getReference (subPath.size() - 1);

        if (isClosed)
        {
            const LineSection& l = subPath.getReference (0);

            addEdgeAndJoint (destPath, jointStyle,
                             maxMiterExtensionSquared, width,
                             lastX1, lastY1, lastX2, lastY2,
                             l.lx1, l.ly1, l.lx2, l.ly2,
                             l.x1, l.y1);

            destPath.closeSubPath();
            destPath.startNewSubPath (lastLine.rx1, lastLine.ry1);
        }
        else
        {
            destPath.lineTo (lastX2, lastY2);

            if (arrowhead != nullptr)
                addArrowhead (destPath, lastX2, lastY2, lastLine.rx1, lastLine.ry1, lastLine.x2, lastLine.y2,
                              width, arrowhead->endWidth);
            else
                addLineEnd (destPath, endStyle, lastX2, lastY2, lastLine.rx1, lastLine.ry1, width);
        }

        lastX1 = lastLine.rx1;
        lastY1 = lastLine.ry1;
        lastX2 = lastLine.rx2;
        lastY2 = lastLine.ry2;

        for (int i = subPath.size() - 1; --i >= 0;)
        {
            const LineSection& l = subPath.getReference (i);

            addEdgeAndJoint (destPath, jointStyle,
                             maxMiterExtensionSquared, width,
                             lastX1, lastY1, lastX2, lastY2,
                             l.rx1, l.ry1, l.rx2, l.ry2,
                             l.x2, l.y2);

            lastX1 = l.rx1;
            lastY1 = l.ry1;
            lastX2 = l.rx2;
            lastY2 = l.ry2;
        }

        if (isClosed)
        {
            addEdgeAndJoint (destPath, jointStyle,
                             maxMiterExtensionSquared, width,
                             lastX1, lastY1, lastX2, lastY2,
                             lastLine.rx1, lastLine.ry1, lastLine.rx2, lastLine.ry2,
                             lastLine.x2, lastLine.y2);
        }
        else
        {
            // do the last line
            destPath.lineTo (lastX2, lastY2);
        }

        destPath.closeSubPath();
    }

    static void createStroke (const float thickness, const PathStrokeType::JointStyle jointStyle,
                              const PathStrokeType::EndCapStyle endStyle,
                              Path& destPath, const Path& source,
                              const AffineTransform& transform,
                              const float extraAccuracy, const Arrowhead* const arrowhead)
    {
        jassert (extraAccuracy > 0);

        if (thickness <= 0)
        {
            destPath.clear();
            return;
        }

        const Path* sourcePath = &source;
        Path temp;

        if (sourcePath == &destPath)
        {
            destPath.swapWithPath (temp);
            sourcePath = &temp;
        }
        else
        {
            destPath.clear();
        }

        destPath.setUsingNonZeroWinding (true);

        const float maxMiterExtensionSquared = 9.0f * thickness * thickness;
        const float width = 0.5f * thickness;

        // Iterate the path, creating a list of the
        // left/right-hand lines along either side of it...
        PathFlatteningIterator it (*sourcePath, transform, Path::defaultToleranceForMeasurement / extraAccuracy);

        Array <LineSection> subPath;
        subPath.ensureStorageAllocated (512);
        LineSection l;
        l.x1 = 0;
        l.y1 = 0;

        const float minSegmentLength = 0.0001f;

        while (it.next())
        {
            if (it.subPathIndex == 0)
            {
                if (subPath.size() > 0)
                {
                    addSubPath (destPath, subPath, false, width, maxMiterExtensionSquared, jointStyle, endStyle, arrowhead);
                    subPath.clearQuick();
                }

                l.x1 = it.x1;
                l.y1 = it.y1;
            }

            l.x2 = it.x2;
            l.y2 = it.y2;

            float dx = l.x2 - l.x1;
            float dy = l.y2 - l.y1;

            const float hypotSquared = dx*dx + dy*dy;

            if (it.closesSubPath || hypotSquared > minSegmentLength || it.isLastInSubpath())
            {
                const float len = std::sqrt (hypotSquared);

                if (len == 0)
                {
                    l.rx1 = l.rx2 = l.lx1 = l.lx2 = l.x1;
                    l.ry1 = l.ry2 = l.ly1 = l.ly2 = l.y1;
                }
                else
                {
                    const float offset = width / len;
                    dx *= offset;
                    dy *= offset;

                    l.rx2 = l.x1 - dy;
                    l.ry2 = l.y1 + dx;
                    l.lx1 = l.x1 + dy;
                    l.ly1 = l.y1 - dx;

                    l.lx2 = l.x2 + dy;
                    l.ly2 = l.y2 - dx;
                    l.rx1 = l.x2 - dy;
                    l.ry1 = l.y2 + dx;
                }

                subPath.add (l);

                if (it.closesSubPath)
                {
                    addSubPath (destPath, subPath, true, width, maxMiterExtensionSquared, jointStyle, endStyle, arrowhead);
                    subPath.clearQuick();
                }
                else
                {
                    l.x1 = it.x2;
                    l.y1 = it.y2;
                }
            }
        }

        if (subPath.size() > 0)
            addSubPath (destPath, subPath, false, width, maxMiterExtensionSquared, jointStyle, endStyle, arrowhead);
    }
}

void PathStrokeType::createStrokedPath (Path& destPath, const Path& sourcePath,
                                        const AffineTransform& transform, const float extraAccuracy) const
{
    PathStrokeHelpers::createStroke (thickness, jointStyle, endStyle, destPath, sourcePath,
                                     transform, extraAccuracy, 0);
}

void PathStrokeType::createDashedStroke (Path& destPath,
                                         const Path& sourcePath,
                                         const float* dashLengths,
                                         int numDashLengths,
                                         const AffineTransform& transform,
                                         const float extraAccuracy) const
{
    jassert (extraAccuracy > 0);

    if (thickness <= 0)
        return;

    Path newDestPath;
    PathFlatteningIterator it (sourcePath, transform, Path::defaultToleranceForMeasurement / extraAccuracy);

    bool first = true;
    int dashNum = 0;
    float pos = 0.0f, lineLen = 0.0f, lineEndPos = 0.0f;
    float dx = 0.0f, dy = 0.0f;

    for (;;)
    {
        const bool isSolid = ((dashNum & 1) == 0);
        const float dashLen = dashLengths [dashNum++ % numDashLengths];

        jassert (dashLen > 0); // must be a positive increment!
        if (dashLen <= 0)
            break;

        pos += dashLen;

        while (pos > lineEndPos)
        {
            if (! it.next())
            {
                if (isSolid && ! first)
                    newDestPath.lineTo (it.x2, it.y2);

                createStrokedPath (destPath, newDestPath, AffineTransform(), extraAccuracy);
                return;
            }

            if (isSolid && ! first)
                newDestPath.lineTo (it.x1, it.y1);
            else
                newDestPath.startNewSubPath (it.x1, it.y1);

            dx = it.x2 - it.x1;
            dy = it.y2 - it.y1;
            lineLen = juce_hypot (dx, dy);
            lineEndPos += lineLen;
            first = it.closesSubPath;
        }

        const float alpha = (pos - (lineEndPos - lineLen)) / lineLen;

        if (isSolid)
            newDestPath.lineTo (it.x1 + dx * alpha,
                                it.y1 + dy * alpha);
        else
            newDestPath.startNewSubPath (it.x1 + dx * alpha,
                                         it.y1 + dy * alpha);
    }
}

void PathStrokeType::createStrokeWithArrowheads (Path& destPath,
                                                 const Path& sourcePath,
                                                 const float arrowheadStartWidth, const float arrowheadStartLength,
                                                 const float arrowheadEndWidth, const float arrowheadEndLength,
                                                 const AffineTransform& transform,
                                                 const float extraAccuracy) const
{
    PathStrokeHelpers::Arrowhead head;
    head.startWidth = arrowheadStartWidth;
    head.startLength = arrowheadStartLength;
    head.endWidth = arrowheadEndWidth;
    head.endLength = arrowheadEndLength;

    PathStrokeHelpers::createStroke (thickness, jointStyle, endStyle,
                                     destPath, sourcePath, transform, extraAccuracy, &head);
}
