$fn = 64;

// --- Parametric Variables ---
clamp_gap = 12;         // Width of the slot to clamp onto pot/tray edge
arm_width = 16;         // Thickness (Z-height) of the arms
joint_radius = 10;      // Radius of the articulating joints
hole_dia = 5.5;         // Diameter of bolt holes (M5 clearance)
lower_arm_length = 100; // Length of the first arm segment
upper_arm_length = 80;  // Length of the second arm segment

// Note: The design uses support-free half-lap joints. 
// During assembly, simply flip every other part upside down to mate them.

// --- Layout for 3D Printing ---
translate([40, 0, 0]) clamp_base();
translate([0, 35, 0]) arm_segment(lower_arm_length);
translate([0, 65, 0]) arm_segment(upper_arm_length);
translate([0, 105, 0]) light_mount();

// --- Modules ---

// Standardized cutout to create the half-lap joint
module joint_cutout() {
    // 0.2mm tolerance added to prevent binding when tightened
    translate([0, 0, arm_width/2 - 0.2])
        cylinder(r=joint_radius + 1, h=arm_width/2 + 2);
}

// Base that clamps to the edge of a pot or tray
module clamp_base() {
    difference() {
        union() {
            // Main clamp body
            translate([-20, 0, arm_width/2])
                cube([40, 35, arm_width], center=true);
            // Joint cylinder
            cylinder(r=joint_radius, h=arm_width);
        }
        
        // Joint cutouts
        joint_cutout();
        translate([0, 0, -1]) cylinder(d=hole_dia, h=arm_width+2);

        // Slot for pot/tray edge
        translate([-25, 0, arm_width/2])
            cube([20, clamp_gap, arm_width + 2], center=true);
            
        // Set screw hole for tightening against the edge
        translate([-20, -17.5, arm_width/2])
            rotate([90, 0, 0])
            cylinder(d=hole_dia, h=25, center=true);
    }
}

// Reusable articulating arm segment
module arm_segment(length) {
    difference() {
        // Arm body
        hull() {
            cylinder(r=joint_radius, h=arm_width);
            translate([length, 0, 0]) cylinder(r=joint_radius, h=arm_width);
        }
        
        // Joint cutouts at both ends
        joint_cutout();
        translate([length, 0, 0]) joint_cutout();

        // Bolt holes
        translate([0, 0, -1]) cylinder(d=hole_dia, h=arm_width+2);
        translate([length, 0, -1]) cylinder(d=hole_dia, h=arm_width+2);
    }
}

// Flat plate for mounting the LED grow light
module light_mount() {
    difference() {
        union() {
            // Joint cylinder
            cylinder(r=joint_radius, h=arm_width);
            // Mounting plate
            translate([0, -25, 0]) cube([50, 50, 4]);
        }
        
        // Joint cutouts
        joint_cutout();
        translate([0, 0, -1]) cylinder(d=hole_dia, h=arm_width+2);

        // Mounting slots for zip-ties or screws
        for(y = [12, -12]) {
            hull() {
                translate([20, y, -1]) cylinder(d=hole_dia, h=10);
                translate([40, y, -1]) cylinder(d=hole_dia, h=10);
            }
        }
    }
}