use <threads.scad>

// Body parameters
length_above = 25;
top_diameter = 11.6;    // Original: 11.6 mm

pinch_length = 8;
pinch_gap = 1;
pinch_diameter_difference = 0.5;
pinch_minimum_diameter = 7;

screw_outer_diameter = 12;
screw_inner_diameter = 8.5;
screw_start_height = 9;
screw_pitch = ThreadPitch(screw_outer_diameter);

// Tolerances for threads
thread_gap = 0.3;

// Pen hole
pen_hole_diameter = 6.1;

nut_bottom_diameter = 15;
nut_top_diameter = 10;
nut_knurl_height = 10;  // > screw_thread_length
nut_knurl_size = 0.5;
nut_knurl_count = 36;
nut_thread_extend = 1;

hook_width_shrink = 0.3;    // Shrink original size
hook_squeeze = 0.25;

$fn = 48;
$eps = 0.1;

screw_thread_length = length_above - pinch_length - screw_start_height;

module holder() {
    difference() {
        union() {
            // Base shape
            rotate_extrude()
            polygon([
                [0, -4.8],
                [9.25 / 2, -4.8],
                [9.55 / 2, -4.8],
                [9.55 / 2, -hook_squeeze],
                [top_diameter / 2, (top_diameter - 9.55) / 2 - hook_squeeze],  // 45° draft
                [top_diameter / 2, screw_start_height - nut_thread_extend],
                [screw_inner_diameter / 2, screw_start_height - nut_thread_extend],
                [screw_inner_diameter / 2, length_above - pinch_length],
                [pinch_minimum_diameter / 2 + pinch_diameter_difference / 4, length_above],
                [0, length_above]
            ]);

            // Retention hooks
            intersection() {
                rotate_extrude()
                polygon([
                    [9.55 / 2, -4.8],
                    [11.3 / 2, (11.3 - 9.55) / 2 - 4.8],
                    [11.3 / 2, 2.4 - 4.8],
                    [9.55 / 2 + 0.3, 2.4 - 4.8],
                    [9.55 / 2, 2.4 - 0.3 - 4.8]
                ]);
                
                cube([20, 4.5 - hook_width_shrink, length_above + 4.8], true);
            }
            
            // Outer thread
            translate([0, 0, screw_start_height - nut_thread_extend])
            ScrewThread(screw_outer_diameter - thread_gap / 2, screw_thread_length + nut_thread_extend, pitch = screw_pitch);
            
        }

        // Pen hole
        union() {
            translate([0, 0, -4.8 - $eps])
            cylinder(d = pen_hole_diameter, h = length_above + 4.8 - pinch_length + 2 * $eps);
            translate([0, 0, length_above - pinch_length])
            cylinder(h = pinch_length + $eps, d1 = pen_hole_diameter, d2 = pen_hole_diameter - pinch_diameter_difference / 2);
        }
        
        for(angle = [0, 90]) {
            translate([0, 0, length_above + $eps])
            rotate([-90, 0, angle])
            linear_extrude(screw_outer_diameter + $eps, center = true)
            polygon([
                [pinch_gap / 2, 0],
                [0, pinch_length + $eps],
                [-pinch_gap / 2, 0]
            ]);
        }
    }
}

module nut() {
    ScrewHole(screw_outer_diameter + thread_gap / 2, screw_thread_length + nut_thread_extend, pitch=screw_pitch)
    rotate_extrude()
    polygon([
        [screw_inner_diameter / 2, 0],
        [nut_bottom_diameter / 2, 0],
        [nut_bottom_diameter / 2, nut_knurl_height],
        [nut_top_diameter / 2, screw_thread_length + pinch_length],
        [pinch_minimum_diameter / 2, screw_thread_length + pinch_length],
        [screw_outer_diameter / 2, screw_thread_length],
        [screw_inner_diameter / 2, screw_thread_length],
    ]);
    for(i = [0:nut_knurl_count - 1]) {
        rotate([0, 0, i * 360 / nut_knurl_count])
        translate([-nut_knurl_size / 2, nut_bottom_diameter / 2 - nut_knurl_size / 2, 0])
        cube([nut_knurl_size, nut_knurl_size, nut_knurl_height]);
    }
}


// nut();
holder();

//difference() {
//    union() {
//        holder();
//        translate([0, 0, screw_start_height])
//        nut();
//    }
//    cube([100, 100, 100]);
//}