/*
 * This program source code file is part of KICAD, a free EDA CAD application.
 *
 * Copyright (C) 2017-2020 Kicad Developers, see AUTHORS.txt for contributors.
 *
 * 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, you may find one here:
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * or you may search the http://www.gnu.org website for the version 2 license,
 * or you may write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 */
#include <limits>
#include <vector>

#include <preview_items/polygon_geom_manager.h>

#include <geometry/geometry_utils.h>
#include <geometry/shape_line_chain.h>


POLYGON_GEOM_MANAGER::POLYGON_GEOM_MANAGER( CLIENT& aClient ):
    m_client( aClient ),
    m_leaderMode( LEADER_MODE::DIRECT ),
    m_intersectionsAllowed( true )
{}


bool POLYGON_GEOM_MANAGER::AddPoint( const VECTOR2I& aPt )
{
    // if this is the first point, make sure the client is happy
    // for us to continue
    if( !IsPolygonInProgress() && !m_client.OnFirstPoint( *this ) )
        return false;

    if( m_leaderPts.PointCount() > 1 )
    {
        // there are enough leader points - the next
        // locked-in point is the end of the first leader
        // segment
        m_lockedPoints.Append( m_leaderPts.CPoint( 1 ) );
    }
    else
    {
        // no leader lines, directly add the cursor
        m_lockedPoints.Append( aPt );
    }

    // check for self-intersections
    if( !m_intersectionsAllowed && IsSelfIntersecting( false ) )
    {
        m_lockedPoints.Remove( m_lockedPoints.PointCount() - 1 );
        return false;
    }

    m_client.OnGeometryChange( *this );
    return true;
}


void POLYGON_GEOM_MANAGER::SetFinished()
{

    m_client.OnComplete( *this );
}


void POLYGON_GEOM_MANAGER::SetLeaderMode( LEADER_MODE aMode )
{
    m_leaderMode = aMode;
}


bool POLYGON_GEOM_MANAGER::IsSelfIntersecting( bool aIncludeLeaderPts ) const
{
    SHAPE_LINE_CHAIN pts( m_lockedPoints );

    if( aIncludeLeaderPts )
    {
        for( int i = 0; i < m_leaderPts.PointCount(); ++i )
        {
            if( m_leaderPts.CPoint( i ) != pts.CPoint( 0 ) )
                pts.Append( m_leaderPts.CPoint( i ) );
        }
    }

    // line chain needs to be set as closed for proper checks
    pts.SetClosed( true );

    return !!pts.SelfIntersecting();
}


void POLYGON_GEOM_MANAGER::SetCursorPosition( const VECTOR2I& aPos )
{
    updateLeaderPoints( aPos );
}


bool POLYGON_GEOM_MANAGER::IsPolygonInProgress() const
{
    return m_lockedPoints.PointCount() > 0;
}


bool POLYGON_GEOM_MANAGER::NewPointClosesOutline( const VECTOR2I& aPt ) const
{
    return m_lockedPoints.PointCount() > 0 && m_lockedPoints.CPoint( 0 ) == aPt;
}


void POLYGON_GEOM_MANAGER::DeleteLastCorner()
{
    if( m_lockedPoints.PointCount() > 0 )
        m_lockedPoints.Remove( m_lockedPoints.PointCount() - 1 );

    // update the new last segment (was previously
    // locked in), reusing last constraints
    if( m_lockedPoints.PointCount() > 0 )
        updateLeaderPoints( m_leaderPts.CLastPoint() );

    m_client.OnGeometryChange( *this );
}


void POLYGON_GEOM_MANAGER::Reset()
{
    m_lockedPoints.Clear();
    m_leaderPts.Clear();

    m_client.OnGeometryChange( *this );
}


void POLYGON_GEOM_MANAGER::updateLeaderPoints( const VECTOR2I& aEndPoint, LEADER_MODE aModifier )
{
    wxCHECK( m_lockedPoints.PointCount() > 0, /*void*/ );
    const VECTOR2I& last_pt = m_lockedPoints.CLastPoint();

    if( m_leaderMode == LEADER_MODE::DEG45 || aModifier == LEADER_MODE::DEG45 )
    {
        const VECTOR2I line_vec( aEndPoint - last_pt );
        // get a restricted 45/H/V line from the last fixed point to the cursor
        auto new_end = last_pt + GetVectorSnapped45( line_vec );
        OPT_VECTOR2I pt;

        if( m_lockedPoints.SegmentCount() > 1 )
        {
            const VECTOR2I& start_pt = m_lockedPoints.CPoint( 0 );
            VECTOR2I completed_vec( start_pt - new_end );

            if( completed_vec != GetVectorSnapped45( completed_vec ) )
            {
                SEG v_first( new_end, VECTOR2I( new_end.x, start_pt.y ) );
                SEG h_first( new_end, VECTOR2I( start_pt.x, new_end.y ) );

                SHAPE_LINE_CHAIN::INTERSECTIONS intersections;
                auto v_hits = m_lockedPoints.Intersect( v_first, intersections );
                v_hits += m_lockedPoints.Intersect( SEG( v_first.B, start_pt ), intersections );
                pt = v_first.B;

                if( v_hits > 0 )
                {
                    intersections.clear();
                    auto h_hits = m_lockedPoints.Intersect( h_first, intersections );
                    h_hits += m_lockedPoints.Intersect( SEG( h_first.B, start_pt ), intersections );

                    if( h_hits < v_hits )
                        pt = h_first.B;
                }
            }
        }

        m_leaderPts = SHAPE_LINE_CHAIN( { last_pt, new_end } );

        if( pt )
        {
            SEG drawn( last_pt, new_end );
            SEG completed( new_end, *pt );

            /*
             * Check for backtracking from the point to intersection.  If the snapped path to
             * completion is shorter than what the user actually drew, we want to discard the
             * drawn point and just use the snapped completion point.
             */
            if( drawn.Collinear( completed ) && drawn.SquaredLength() > completed.SquaredLength() )
                m_leaderPts = SHAPE_LINE_CHAIN( { last_pt, *pt } );
            else
                m_leaderPts.Append( *pt );
        }
    }
    else
    {
        // direct segment
        m_leaderPts = SHAPE_LINE_CHAIN( { last_pt, aEndPoint } );
    }

    m_client.OnGeometryChange( *this );
}