package Slic3r::ExtrusionPath;
use Moo;

require Exporter;
our @ISA = qw(Exporter);
our @EXPORT_OK = qw(EXTR_ROLE_PERIMETER EXTR_ROLE_EXTERNAL_PERIMETER 
    EXTR_ROLE_CONTOUR_INTERNAL_PERIMETER
    EXTR_ROLE_FILL EXTR_ROLE_SOLIDFILL EXTR_ROLE_TOPSOLIDFILL EXTR_ROLE_BRIDGE EXTR_ROLE_SKIRT 
    EXTR_ROLE_SUPPORTMATERIAL EXTR_ROLE_GAPFILL);
our %EXPORT_TAGS = (roles => \@EXPORT_OK);

use Slic3r::Geometry qw(PI X Y epsilon deg2rad rotate_points);

# the underlying Slic3r::Polyline objects holds the geometry
has 'polyline' => (
    is          => 'rw',
    required    => 1,
    handles     => [qw(merge_continuous_lines lines length reverse clip_end simplify)],
);

# height is the vertical thickness of the extrusion expressed in mm
has 'height'       => (is => 'rw');
has 'flow_spacing' => (is => 'rw');
has 'role'         => (is => 'rw', required => 1);

use constant EXTR_ROLE_PERIMETER                    => 0;
use constant EXTR_ROLE_EXTERNAL_PERIMETER           => 2;
use constant EXTR_ROLE_CONTOUR_INTERNAL_PERIMETER   => 3;
use constant EXTR_ROLE_FILL                         => 4;
use constant EXTR_ROLE_SOLIDFILL                    => 5;
use constant EXTR_ROLE_TOPSOLIDFILL                 => 6;
use constant EXTR_ROLE_BRIDGE                       => 7;
use constant EXTR_ROLE_SKIRT                        => 8;
use constant EXTR_ROLE_SUPPORTMATERIAL              => 9;
use constant EXTR_ROLE_GAPFILL                      => 10;

use constant PACK_FMT => 'ffca*';

# class or object method
sub pack {
    my $self = shift;
    my %args = @_;
    
    if (ref $self) {
        %args = map { $_ => $self->$_ } qw(height flow_spacing role polyline);
    }
    
    my $o = \ pack PACK_FMT,
        $args{height}       // -1,
        $args{flow_spacing} || -1,
        $args{role}         // (die "Missing mandatory attribute 'role'"), #/
        $args{polyline}->serialize;
    
    bless $o, 'Slic3r::ExtrusionPath::Packed';
    return $o;
}

# no-op, this allows to use both packed and non-packed objects in Collections
sub unpack { $_[0] }

sub clip_with_polygon {
    my $self = shift;
    my ($polygon) = @_;
    
    return $self->clip_with_expolygon(Slic3r::ExPolygon->new($polygon));
}

sub clip_with_expolygon {
    my $self = shift;
    my ($expolygon) = @_;
    
    my @paths = ();
    foreach my $polyline ($self->polyline->clip_with_expolygon($expolygon)) {
        push @paths, (ref $self)->new(
            polyline        => $polyline,
            height          => $self->height,
            flow_spacing    => $self->flow_spacing,
            role            => $self->role,
        );
    }
    return @paths;
}

sub points {
    my $self = shift;
    return $self->polyline;
}

sub endpoints {
    my $self = shift;
    return ($self->points->[0], $self->points->[-1]);
}

sub is_printable { 1 }

sub is_fill {
    my $self = shift;
    return $self->role == EXTR_ROLE_FILL
        || $self->role == EXTR_ROLE_SOLIDFILL
        || $self->role == EXTR_ROLE_TOPSOLIDFILL;
}

sub split_at_acute_angles {
    my $self = shift;
    
    # calculate angle limit
    my $angle_limit = abs(Slic3r::Geometry::deg2rad(40));
    my @points = @{$self->p};
    
    my @paths = ();
    
    # take first two points
    my @p = splice @points, 0, 2;
    
    # loop until we have one spare point
    while (my $p3 = shift @points) {
        my $angle = abs(Slic3r::Geometry::angle3points($p[-1], $p[-2], $p3));
        $angle = 2*PI - $angle if $angle > PI;
        
        if ($angle < $angle_limit) {
            # if the angle between $p[-2], $p[-1], $p3 is too acute
            # then consider $p3 only as a starting point of a new
            # path and stop the current one as it is
            push @paths, (ref $self)->new(
                polyline        => Slic3r::Polyline->new(\@p),
                role            => $self->role,
                height          => $self->height,
             );
            @p = ($p3);
            push @p, grep $_, shift @points or last;
        } else {
            push @p, $p3;
        }
    }
    push @paths, (ref $self)->new(
        polyline        => Slic3r::Polyline->new(\@p),
        role            => $self->role,
        height          => $self->height,
    ) if @p > 1;
    
    return @paths;
}

sub detect_arcs {
    my $self = shift;
    my ($max_angle, $len_epsilon) = @_;
    
    $max_angle = deg2rad($max_angle || 15);
    $len_epsilon ||= 10 / &Slic3r::SCALING_FACTOR;
    my $parallel_degrees_limit = abs(Slic3r::Geometry::deg2rad(3));
    
    my @points = @{$self->points};
    my @paths = ();
    
    # we require at least 3 consecutive segments to form an arc
    CYCLE: while (@points >= 4) {
        POINT: for (my $i = 0; $i <= $#points - 3; $i++) {
            my $s1 = Slic3r::Line->new($points[$i],   $points[$i+1]);
            my $s2 = Slic3r::Line->new($points[$i+1], $points[$i+2]);
            my $s3 = Slic3r::Line->new($points[$i+2], $points[$i+3]);
            my $s1_len = $s1->length;
            my $s2_len = $s2->length;
            my $s3_len = $s3->length;
            
            # segments must have the same length
            if (abs($s3_len - $s2_len) > $len_epsilon) {
                # optimization: skip a cycle
                $i++;
                next;
            }
            next if abs($s2_len - $s1_len) > $len_epsilon;
            
            # segments must have the same relative angle
            my $s1_angle = $s1->atan;
            my $s2_angle = $s2->atan;
            my $s3_angle = $s3->atan;
            $s1_angle += 2*PI if $s1_angle < 0;
            $s2_angle += 2*PI if $s2_angle < 0;
            $s3_angle += 2*PI if $s3_angle < 0;
            my $s1s2_angle = $s2_angle - $s1_angle;
            my $s2s3_angle = $s3_angle - $s2_angle;
            next if abs($s1s2_angle - $s2s3_angle) > $parallel_degrees_limit;
            next if abs($s1s2_angle) < $parallel_degrees_limit;     # ignore parallel lines
            next if $s1s2_angle > $max_angle;  # ignore too sharp vertices
            my @arc_points = ($points[$i], $points[$i+3]),  # first and last points
            
            # now look for more points
            my $last_line_angle = $s3_angle;
            my $last_j = $i+3;
            for (my $j = $i+3; $j < $#points; $j++) {
                my $line = Slic3r::Line->new($points[$j], $points[$j+1]);
                last if abs($line->length - $s1_len) > $len_epsilon;
                my $line_angle = $line->atan;
                $line_angle += 2*PI if $line_angle < 0;
                my $anglediff = $line_angle - $last_line_angle;
                last if abs($s1s2_angle - $anglediff) > $parallel_degrees_limit;
                
                # point $j+1 belongs to the arc
                $arc_points[-1] = $points[$j+1];
                $last_j = $j+1;
                
                $last_line_angle = $line_angle;
            }
            
            # s1, s2, s3 form an arc
            my $orientation = $s1->point_on_left($points[$i+2]) ? 'ccw' : 'cw';
            
            # to find the center, we intersect the perpendicular lines
            # passing by midpoints of $s1 and last segment
            # a better method would be to draw all the perpendicular lines
            # and find the centroid of the enclosed polygon, or to
            # intersect multiple lines and find the centroid of the convex hull
            # around the intersections
            my $arc_center;
            {
                my $s1_mid = $s1->midpoint;
                my $last_mid = Slic3r::Line->new($points[$last_j-1], $points[$last_j])->midpoint;
                my $rotation_angle = PI/2 * ($orientation eq 'ccw' ? -1 : 1);
                my $ray1     = Slic3r::Line->new($s1_mid,   rotate_points($rotation_angle, $s1_mid,   $points[$i+1]));
                my $last_ray = Slic3r::Line->new($last_mid, rotate_points($rotation_angle, $last_mid, $points[$last_j]));
                $arc_center = $ray1->intersection($last_ray, 0) or next POINT;
            }
            
            my $arc = Slic3r::ExtrusionPath::Arc->new(
                polyline    => Slic3r::Polyline->new(\@arc_points),
                role        => $self->role,
                orientation => $orientation,
                center      => $arc_center,
                radius      => $arc_center->distance_to($points[$i]),
            );
            
            # points 0..$i form a linear path
            push @paths, (ref $self)->new(
                polyline        => Slic3r::Polyline->new(@points[0..$i]),
                role            => $self->role,
                height          => $self->height,
            ) if $i > 0;
            
            # add our arc
            push @paths, $arc;
            Slic3r::debugf "ARC DETECTED\n";
            
            # remove arc points from path, leaving one
            splice @points, 0, $last_j, ();
            
            next CYCLE;
        }
        last;
    }
    
    # remaining points form a linear path
    push @paths, (ref $self)->new(
        polyline        => Slic3r::Polyline->new(\@points),
        role            => $self->role,
        height          => $self->height,
    ) if @points > 1;
    
    return @paths;
}

package Slic3r::ExtrusionPath::Packed;
sub unpack {
    my $self = shift;
    
    my ($height, $flow_spacing, $role, $polyline_s)
        = unpack Slic3r::ExtrusionPath::PACK_FMT, $$self;
    
    return Slic3r::ExtrusionPath->new(
        height          => ($height == -1) ? undef : $height,
        flow_spacing    => ($flow_spacing == -1) ? undef : $flow_spacing,
        role            => $role,
        polyline        => Slic3r::Polyline->deserialize($polyline_s),
    );
}

1;