links_count=6;
include_terminal=true;

//validation=1;
VALIDATE_INTERSECTION=1;

//xray=1;

use <BOSL/transforms.scad>
use <BOSL/shapes.scad>
include <BOSL/constants.scad>

function get_link_segment_size() = [15, 30, 5];
function get_link_pin_diameter() = 2;
function get_link_socket_slack() = [1, 4, 1];
function get_link_joiner_arm_size() = [get_link_segment_size().x - 2, 3, segment_size.z];
function get_link_socket_size() = [get_link_segment_size().z,
        get_link_segment_size().y - get_link_joiner_arm_size().y*2,
        get_link_segment_size().z];

echo("===============================");
echo(str("Strap length: ", (links_count * get_link_segment_size().x), " mm"));
echo("===============================");

assert(get_link_segment_size().x >= 10, "Link segment is too short.");
assert(get_link_segment_size().z >= (get_link_pin_diameter() + get_link_socket_slack().z + 1), "Link segment is too thin.");

module link(terminal=false) {
    segment_size=get_link_segment_size();
    module pin() {
        h=segment_size.y;
        d=get_link_pin_diameter();
        back(h/2) xrot(90) cylinder(h=h, d=d, $fn=$preview ? 10 : 30);
    }
    module pin_socket_area() {
        h=segment_size.y-get_link_socket_slack().y;
        d=segment_size.z;
        back(h/2) xrot(90) cylinder(h=h, d=d, $fn=$preview ? 10 : 30);
    }
    module pin_socket() {
        difference() {
            pin_socket_area();
            scaleup = [
                ((get_link_pin_diameter() + get_link_socket_slack().x) / get_link_pin_diameter()),
                ((get_link_pin_diameter() + get_link_socket_slack().y) / get_link_pin_diameter()),
                ((get_link_pin_diameter() + get_link_socket_slack().z) / get_link_pin_diameter())
            ];
            scale(scaleup) pin();
        }
    }
    module joiner() {
        gap=2;
        arm_size=get_link_joiner_arm_size();
        module arm() {
            fwd(segment_size.y/2 + arm_size.y/2 - 1) right(arm_size.x/2 - 1) cuboid(arm_size, fillet=1, edges=EDGES_FRONT + EDGES_Y_ALL);
        }
        module armFront() {
            arm();
        }
        module armBack() {
            scale([1, -1, 1]) arm();
        }
        module armJoiner() {
            joiner_size=[arm_size.x-get_link_socket_size().x, segment_size.y, segment_size.z];
            right(joiner_size.x/2 + get_link_socket_size().x/2 + gap) cuboid(joiner_size, fillet=1, edges=EDGES_Z_ALL + EDGES_BOTTOM);
        }
        module socketJoiner() {
            joiner_size=[segment_size.x-get_link_socket_size().x+get_link_socket_size().x*0.2,
                segment_size.y-4,
                segment_size.z];
            difference() {
                right(joiner_size.x/2 + 4.5) cuboid(joiner_size, fillet=1, edges=EDGES_Z_ALL + EDGES_BOTTOM);
                right(segment_size.x) scale([1, 2, 1]) pin_socket_area();
            }
        }
        module terminalArm() {
            left(5) {
                shift=arm_size.x - get_link_pin_diameter();
                right(segment_size.x + shift + gap/2) pin();
                right(segment_size.x + gap/2) {
                   armFront();
                   armBack();
                }
                right(arm_size.x - get_link_socket_size().x + gap) armJoiner();
            }
        }
        armFront();
        armBack();
        armJoiner();
        if (terminal) {
            terminalArm();
        } else {
            socketJoiner();
        }
    }
    
    pin();
    joiner();
    if (!terminal) {
        right(segment_size.x) pin_socket();
    }
}

segment_size=get_link_segment_size();
if (!is_undef(validation)) {
    if (validation==VALIDATE_INTERSECTION) {
        intersection() {
            right(0*segment_size.x) link();
            right(1*segment_size.x) link();
        }
        intersection() {
            right(1*segment_size.x) link();
            right(2*segment_size.x) link();
        }
    }
} else if (!is_undef(xray)) {
    intersection() {
        cube([1000, 1000, 1000]);
        for (i = [0:links_count-1]) {
            right(i*segment_size.x) link();
        }
    }
} else {
    for (i = [0:links_count-1]) {
        terminal=(i==links_count-1) && include_terminal;
        right(i*segment_size.x) link(terminal=terminal);
    }
}