package Slic3r::Layer;
use Moo;

use Math::Clipper ':all';
use Slic3r::Geometry qw(polygon_lines points_coincide angle3points polyline_lines nearest_point
    line_length collinear X Y A B PI);
use Slic3r::Geometry::Clipper qw(safety_offset union_ex);
use XXX;

# a sequential number of layer, starting at 0
has 'id' => (
    is          => 'ro',
    #isa         => 'Int',
    required    => 1,
);

# collection of spare segments generated by slicing the original geometry;
# these need to be merged in continuos (closed) polylines
has 'lines' => (
    is      => 'rw',
    #isa     => 'ArrayRef[Slic3r::Line]',
    default => sub { [] },
);

# collection of surfaces generated by slicing the original geometry
has 'surfaces' => (
    is      => 'rw',
    #isa     => 'ArrayRef[Slic3r::Surface]',
    default => sub { [] },
);

# collection of surfaces representing bridges
has 'bridges' => (
    is      => 'rw',
    #isa     => 'ArrayRef[Slic3r::Surface::Bridge]',
    default => sub { [] },
);

# collection of surfaces to make perimeters for
has 'perimeter_surfaces' => (
    is      => 'rw',
    #isa     => 'ArrayRef[Slic3r::Surface]',
    default => sub { [] },
);

# ordered collection of extrusion paths to build all perimeters
has 'perimeters' => (
    is      => 'rw',
    #isa     => 'ArrayRef[Slic3r::ExtrusionLoop]',
    default => sub { [] },
);

# ordered collection of extrusion paths to build skirt loops
has 'skirts' => (
    is      => 'rw',
    #isa     => 'ArrayRef[Slic3r::ExtrusionLoop]',
    default => sub { [] },
);

# collection of surfaces generated by offsetting the innermost perimeter(s)
# they represent boundaries of areas to fill (grouped by original objects)
has 'fill_surfaces' => (
    is      => 'rw',
    #isa     => 'ArrayRef[ArrayRef[Slic3r::Surface]]',
    default => sub { [] },
);

# ordered collection of extrusion paths to fill surfaces
has 'fills' => (
    is      => 'rw',
    #isa     => 'ArrayRef[Slic3r::ExtrusionPath]',
    default => sub { [] },
);

# Z used for slicing
sub slice_z {
    my $self = shift;
    return ($self->id * $Slic3r::layer_height + $Slic3r::layer_height/2) / $Slic3r::resolution;
}

# Z used for printing
sub print_z {
    my $self = shift;
    return ($self->id + 1) * $Slic3r::layer_height / $Slic3r::resolution;
}

sub add_surface {
    my $self = shift;
    my (@vertices) = @_;
    
    # convert arrayref points to Point objects
    @vertices = map Slic3r::Point->new($_), @vertices;
    
    my $surface = Slic3r::Surface->new(
        contour => Slic3r::Polyline::Closed->new(points => \@vertices),
    );
    push @{ $self->surfaces }, $surface;
    
    # make sure our contour has its points in counter-clockwise order
    $surface->contour->make_counter_clockwise;
    
    return $surface;
}

sub add_line {
    my $self = shift;
    my ($line) = @_;
    
    return if $line->a->coincides_with($line->b);
    
    push @{ $self->lines }, $line;
    return $line;
}

# merge overlapping lines
sub cleanup_lines {
    my $self = shift;
    
    my $lines = $self->lines;
    my $line_count = @$lines;
    
    for (my $i = 0; $i <= $#$lines-1; $i++) {
        for (my $j = $i+1; $j <= $#$lines; $j++) {
            # lines are collinear and overlapping?
            next unless collinear($lines->[$i], $lines->[$j], 1);
            
            # lines have same orientation?
            next unless ($lines->[$i][A][X] <=> $lines->[$i][B][X]) == ($lines->[$j][A][X] <=> $lines->[$j][B][X])
                && ($lines->[$i][A][Y] <=> $lines->[$i][B][Y]) == ($lines->[$j][A][Y] <=> $lines->[$j][B][Y]);
            
            # resulting line
            my @x = sort { $a <=> $b } ($lines->[$i][A][X], $lines->[$i][B][X], $lines->[$j][A][X], $lines->[$j][B][X]);
            my @y = sort { $a <=> $b } ($lines->[$i][A][Y], $lines->[$i][B][Y], $lines->[$j][A][Y], $lines->[$j][B][Y]);
            my $new_line = Slic3r::Line->new([$x[0], $y[0]], [$x[-1], $y[-1]]);
            for (X, Y) {
                ($new_line->[A][$_], $new_line->[B][$_]) = ($new_line->[B][$_], $new_line->[A][$_])
                    if $lines->[$i][A][$_] > $lines->[$i][B][$_];
            }
            
            # save new line and remove found one
            $lines->[$i] = $new_line;
            splice @$lines, $j, 1;
            $j--;
        }
    }
    
    Slic3r::debugf "  merging %d lines resulted in %d lines\n", $line_count, scalar(@$lines);
}

# build polylines from lines
sub make_surfaces {
    my $self = shift;
    
    if (0) {
        require "Slic3r/SVG.pm";
        Slic3r::SVG::output(undef, "lines.svg",
            lines       => [ grep !$_->isa('Slic3r::Line::FacetEdge'), @{$self->lines} ],
            red_lines   => [ grep  $_->isa('Slic3r::Line::FacetEdge'), @{$self->lines} ],
        );
    }
    
    my (@polygons, %visited_lines, @discarded_lines, @discarded_polylines) = ();
    
    my $detect = sub {
        my @lines = @{$self->lines};
        (@polygons, %visited_lines, @discarded_lines, @discarded_polylines) = ();
        my $get_point_id = sub { sprintf "%.0f,%.0f", @{$_[0]} };
        
        my (%pointmap, @pointmap_keys) = ();
        foreach my $line (@lines) {
            my $point_id = $get_point_id->($line->[A]);
            if (!exists $pointmap{$point_id}) {
                $pointmap{$point_id} = [];
                push @pointmap_keys, $line->[A];
            }
            push @{ $pointmap{$point_id} }, $line;
        }
        
        my $n = 0;
        while (my $first_line = shift @lines) {
            next if $visited_lines{ $first_line->id };
            my @points = @$first_line;
            
            my @seen_lines = ($first_line);
            my %seen_points = map { $get_point_id->($points[$_]) => $_ } 0..1;
            
            CYCLE: while (1) {
                my $next_lines = $pointmap{ $get_point_id->($points[-1]) };
                
                # shouldn't we find the point, let's try with a slower algorithm
                # as approximation may make the coordinates differ
                if (!$next_lines) {
                    my $nearest_point = nearest_point($points[-1], \@pointmap_keys);
                    #printf "  we have a nearest point: %f,%f (%s)\n", @$nearest_point, $get_point_id->($nearest_point);
                    
                    if ($nearest_point) {
                        local $Slic3r::Geometry::epsilon = 1000000;
                        $next_lines = $pointmap{$get_point_id->($nearest_point)}
                            if points_coincide($points[-1], $nearest_point);
                    }
                }
                
                #Slic3r::SVG::output(undef, "lines.svg",
                #    lines       => [ map $_->p, grep !$_->isa('Slic3r::Line::FacetEdge'), @{$self->lines} ],
                #    red_lines   => [ map $_->p, grep  $_->isa('Slic3r::Line::FacetEdge'), @{$self->lines} ],
                #    points      => [ $points[-1] ],
                #    no_arrows => 1,
                #) if !$next_lines;
                
                $next_lines
                    or die sprintf("No lines start at point %s. This shouldn't happen. Please check the model for manifoldness.", $get_point_id->($points[-1]));
                last CYCLE if !@$next_lines;
                
                my @ordered_next_lines = sort 
                    { angle3points($points[-1], $points[-2], $next_lines->[$a][B]) <=> angle3points($points[-1], $points[-2], $next_lines->[$b][B]) } 
                    0..$#$next_lines;
                
                #if (@$next_lines > 1) {
                #    Slic3r::SVG::output(undef, "next_line.svg",
                #        lines        => $next_lines,
                #        red_lines    => [ polyline_lines([@points]) ],
                #        green_lines  => [ $next_lines->[ $ordered_next_lines[0] ] ],
                #    );
                #}
                
                my ($next_line) = splice @$next_lines, $ordered_next_lines[0], 1;
                push @seen_lines, $next_line;
                
                push @points, $next_line->[B];
                
                my $point_id = $get_point_id->($points[-1]);
                if ($seen_points{$point_id}) {
                    splice @points, 0, $seen_points{$point_id};
                    last CYCLE;
                }
                
                $seen_points{$point_id} = $#points;
            }
            
            if (@points < 4 || !points_coincide($points[0], $points[-1])) {
                # discarding polyline
                push @discarded_lines, @seen_lines;
                if (@points > 2) {
                    push @discarded_polylines, [@points];
                }
                next;
            }
            
            $visited_lines{ $_->id } = 1 for @seen_lines;
            pop @points;
            Slic3r::debugf "Discovered polygon of %d points\n", scalar(@points);
            push @polygons, Slic3r::Polygon->new(@points);
            $polygons[-1]->cleanup;
        }
    };
    
    $detect->();
    
    # Now, if we got a clean and manifold model then @polygons would contain everything
    # we need to draw our layer. In real life, sadly, things are different and it is likely
    # that the above algorithm wasn't able to detect every polygon. This may happen because
    # of non-manifoldness or because of many close lines, often overlapping; both situations
    # make a head-to-tail search difficult.
    # On the other hand, we can safely assume that every polygon we detected is correct, as 
    # the above algorithm is quite strict. We can take a brute force approach to connect any
    # other line.
    
    # So, let's first check what lines were not detected as part of polygons.
    if (@discarded_lines) {
        Slic3r::debugf "  %d lines out of %d were discarded and %d polylines were not closed\n",
            scalar(@discarded_lines), scalar(@{$self->lines}), scalar(@discarded_polylines);
        print "  Warning: errors while parsing this layer (dirty or non-manifold model).\n";
        print "  Retrying with slower algorithm.\n";
        
        if (0) {
            require "Slic3r/SVG.pm";
            Slic3r::SVG::output(undef, "layer" . $self->id . "_detected.svg",
                white_polygons => \@polygons,
            );
            Slic3r::SVG::output(undef, "layer" . $self->id . "_discarded_lines.svg",
                red_lines   => \@discarded_lines,
            );
            Slic3r::SVG::output(undef, "layer" . $self->id . "_discarded_polylines.svg",
                polylines   => \@discarded_polylines,
            );
            exit;
        }
        
        $self->cleanup_lines;
        $detect->();
        
        if (@discarded_lines) {
            print "  Warning: even slow detection algorithm throwed errors. Review the output before printing.\n";
        }
    }
    
    {
        my $expolygons = union_ex([ @polygons ]);
        Slic3r::debugf "  %d surface(s) having %d holes detected from %d polylines\n",
            scalar(@$expolygons), scalar(map $_->holes, @$expolygons), scalar(@polygons);
        
        push @{$self->surfaces},
            map Slic3r::Surface->cast_from_expolygon($_, surface_type => 'internal'),
                @$expolygons;
    }
    
    #use Slic3r::SVG;
    #Slic3r::SVG::output(undef, "surfaces.svg",
    #    polygons        => [ map $_->contour->p, @{$self->surfaces} ],
    #    red_polygons    => [ map $_->p, map @{$_->holes}, @{$self->surfaces} ],
    #);
}

sub remove_small_surfaces {
    my $self = shift;
    my @good_surfaces = ();
    
    my $surface_count = scalar @{$self->surfaces};
    foreach my $surface (@{$self->surfaces}) {
        next if !$surface->contour->is_printable;
        @{$surface->holes} = grep $_->is_printable, @{$surface->holes};
        push @good_surfaces, $surface;
    }
    
    @{$self->surfaces} = @good_surfaces;
    Slic3r::debugf "removed %d small surfaces at layer %d\n",
        ($surface_count - @good_surfaces), $self->id 
        if @good_surfaces != $surface_count;
}

sub remove_small_perimeters {
    my $self = shift;
    my @good_perimeters = grep $_->is_printable, @{$self->perimeters};
    Slic3r::debugf "removed %d unprintable perimeters at layer %d\n",
        (@{$self->perimeters} - @good_perimeters), $self->id
        if @good_perimeters != @{$self->perimeters};
    
    @{$self->perimeters} = @good_perimeters;
}

# make bridges printable
sub process_bridges {
    my $self = shift;
    return if $self->id == 0;
    
    # a bottom surface on a layer > 0 is either a bridge or a overhang 
    # or a combination of both
    
    my @bottom_surfaces     = grep $_->surface_type eq 'bottom',   @{$self->surfaces} or return;
    my @supporting_surfaces = grep $_->surface_type =~ /internal/, @{$self->surfaces};
    
    SURFACE: foreach my $surface (@bottom_surfaces) {
        # since we can't print concave bridges, we transform the surface
        # in a convex polygon; this will print thin membranes eventually
        my $surface_p = $surface->contour->p;
        
        # offset the surface a bit to avoid approximation issues when doing the
        # intersection below (this is to make sure we overlap with supporting
        # surfaces, otherwise a little gap will result from intersection)
        $surface_p = safety_offset([$surface_p])->[0];
        
            #use Slic3r::SVG;
            #Slic3r::SVG::output(undef, "bridge.svg",
            #    green_polygons  => [ map $_->p, @supporting_surfaces ],
            #    red_polygons    => [ $surface_p ],
            #);
        
        # find all supported edges (as polylines, thus keeping notion of 
        # consecutive supported edges)
        my @supported_polylines = ();
        {
            my @current_polyline = ();
            EDGE: foreach my $edge (Slic3r::Geometry::polygon_lines($surface_p)) {
                for my $supporting_surface (@supporting_surfaces) {
                    local $Slic3r::Geometry::epsilon = 1E+7;
                    if (Slic3r::Geometry::polygon_has_subsegment($supporting_surface->contour->p, $edge)) {
                        push @current_polyline, $edge;
                        next EDGE;
                    }
                }
                if (@current_polyline) {
                    push @supported_polylines, [@current_polyline];
                    @current_polyline = ();
                }
            }
            push @supported_polylines, [@current_polyline] if @current_polyline;
        }
        
        # defensive programming, this shouldn't happen
        if (@supported_polylines == 0) {
            Slic3r::debugf "Found bridge/overhang with no supports on layer %d; ignoring\n", $self->id;
            next SURFACE;
        }
        
        if (@supported_polylines == 1) {
            Slic3r::debugf "Found bridge/overhang with only one support on layer %d; ignoring\n", $self->id;
            next SURFACE;
        }
        
        # now connect the first point to the last of each polyline
        @supported_polylines = map [ $_->[0]->[0], $_->[-1]->[-1] ], @supported_polylines;
        # @supported_polylines becomes actually an array of lines
        
        # if we got more than two supports, get the longest two
        if (@supported_polylines > 2) {
            my %lengths = map { $_ => Slic3r::Geometry::line_length($_) } @supported_polylines;
            @supported_polylines = sort { $lengths{"$a"} <=> $lengths{"$b"} } @supported_polylines;
            @supported_polylines = @supported_polylines[-2,-1];
        }
        
        # connect the midpoints, that will give the the optimal infill direction
        my @midpoints = map Slic3r::Geometry::midpoint($_), @supported_polylines;
        my $bridge_angle = -Slic3r::Geometry::rad2deg(Slic3r::Geometry::line_atan(\@midpoints) + PI/2);
        Slic3r::debugf "Optimal infill angle of bridge on layer %d is %d degrees\n", $self->id, $bridge_angle;
        
        # detect which neighbor surfaces are now supporting our bridge
        my @supporting_neighbor_surfaces = ();
        foreach my $supporting_surface (@supporting_surfaces) {
            local $Slic3r::Geometry::epsilon = 1E+7;
            push @supporting_neighbor_surfaces, $supporting_surface 
                if grep Slic3r::Geometry::polygon_has_vertex($supporting_surface->contour->p, $_), 
                    map $_->[0], @supported_polylines;
        }
        
        # defensive programming, this shouldn't happen
        if (@supporting_neighbor_surfaces == 0) {
            Slic3r::debugf "Couldn't find supporting surfaces on layer %d; ignoring\n", $self->id;
            next SURFACE;
        }
        
        # now, extend our bridge by taking a portion of supporting surfaces
        {
            # offset the bridge by the specified amount of mm
            my $bridge_offset = ${ offset([$surface_p], $Slic3r::bridge_overlap / $Slic3r::resolution, $Slic3r::resolution * 100, JT_MITER, 2) }[0];
            
            # calculate the new bridge
            my $clipper = Math::Clipper->new;
            $clipper->add_subject_polygon($surface_p);
            $clipper->add_subject_polygons([ map $_->p, @supporting_neighbor_surfaces ]);
            $clipper->add_clip_polygon($bridge_offset);
            my $intersection = $clipper->execute(CT_INTERSECTION, PFT_NONZERO, PFT_NONZERO);
            
            push @{$self->bridges}, map Slic3r::Surface::Bridge->cast_from_polygon($_,
                surface_type => 'bottom',
                bridge_angle => $bridge_angle,
            ), @$intersection;
        }
    }
}

# generates a set of surfaces that will be used to make perimeters
# thus, we need to merge internal surfaces and bridges
sub detect_perimeter_surfaces {
    my $self = shift;
    
    # little optimization: skip the Clipper UNION if we have no bridges
    if (!@{$self->bridges}) {
        push @{$self->perimeter_surfaces}, @{$self->surfaces};
    } else {
        my $clipper = Math::Clipper->new;
        $clipper->add_subject_polygons([ map $_->p, grep $_->surface_type =~ /internal/, @{$self->surfaces} ]);
        $clipper->add_clip_polygons([ map $_->p, @{$self->bridges} ]);
        my $union = $clipper->ex_execute(CT_UNION, PFT_NONZERO, PFT_NONZERO);
        
        push @{$self->perimeter_surfaces}, 
            map Slic3r::Surface->cast_from_expolygon($_, surface_type => 'internal'), 
            @$union;
        
        push @{$self->perimeter_surfaces}, 
            grep $_->surface_type !~ /internal/ && ($_->surface_type ne 'bottom' || $self->id == 0), 
            @{$self->surfaces};
    }
}

# splits fill_surfaces in internal and bridge surfaces
sub split_bridges_fills {
    my $self = shift;
    
    my $clipper = Math::Clipper->new;
    foreach my $surfaces (@{$self->fill_surfaces}) {
        my @surfaces = @$surfaces;
        @$surfaces = ();
        
        # intersect fill_surfaces with bridges to get actual bridges
        foreach my $bridge (@{$self->bridges}) {
            $clipper->clear;
            $clipper->add_subject_polygons([ map $_->p, @surfaces ]);
            $clipper->add_clip_polygon($bridge->contour->p);
            my $intersection = $clipper->ex_execute(CT_INTERSECTION, PFT_NONZERO, PFT_NONZERO);
            push @$surfaces, map Slic3r::Surface::Bridge->cast_from_expolygon($_,
                surface_type => 'bottom',
                bridge_angle => $bridge->bridge_angle,
            ), @$intersection;
        }
        
        # difference between fill_surfaces and bridges are the other surfaces
        foreach my $surface (@surfaces) {
            $clipper->clear;
            $clipper->add_subject_polygons([ $surface->p ]);
            $clipper->add_clip_polygons([ map $_->contour->p, @{$self->bridges} ]);
            my $difference = $clipper->ex_execute(CT_DIFFERENCE, PFT_NONZERO, PFT_NONZERO);
            push @$surfaces, map Slic3r::Surface->cast_from_expolygon($_,
                surface_type => $surface->surface_type), @$difference;
        }
    }
}

1;