$fn = 64;

// --- Parameters ---
rail_length = 400;
rail_height = 40;
rail_thickness = 10;
corner_radius = 5;

num_hooks = 5;
hook_length = 35;
hook_base_dia = 12;
hook_cap_dia = 20;
hook_cap_height = 12;

hole_dia = 4.5; // Sized for standard wood/drywall screws
countersink_dia = 9.5;
countersink_depth = 4;

// --- Modules ---
module rounded_board() {
    hull() {
        translate([corner_radius, corner_radius, 0]) 
            cylinder(r=corner_radius, h=rail_thickness);
        translate([rail_length - corner_radius, corner_radius, 0]) 
            cylinder(r=corner_radius, h=rail_thickness);
        translate([rail_length - corner_radius, rail_height - corner_radius, 0]) 
            cylinder(r=corner_radius, h=rail_thickness);
        translate([corner_radius, rail_height - corner_radius, 0]) 
            cylinder(r=corner_radius, h=rail_thickness);
    }
}

module printable_peg() {
    trunk_height = hook_length - hook_cap_height;
    
    // Sturdy base trunk
    cylinder(d1=hook_base_dia + 6, d2=hook_base_dia, h=trunk_height);
    
    // Diamond-profile knob (designed for 3D printing without supports)
    translate([0, 0, trunk_height]) {
        cylinder(d1=hook_base_dia, d2=hook_cap_dia, h=hook_cap_height/2);
        translate([0, 0, hook_cap_height/2])
            cylinder(d1=hook_cap_dia, d2=hook_base_dia - 2, h=hook_cap_height/2);
    }
}

module mounting_hole() {
    // Main screw clearance hole
    translate([0, 0, -1])
        cylinder(d=hole_dia, h=rail_thickness + 2);
    
    // Countersink for screw head
    translate([0, 0, rail_thickness - countersink_depth])
        cylinder(d1=hole_dia, d2=countersink_dia, h=countersink_depth + 0.1);
        
    // Clean top cutout for countersink
    translate([0, 0, rail_thickness])
        cylinder(d=countersink_dia, h=2);
}

// --- Main Assembly ---
difference() {
    union() {
        // Main wall rail
        rounded_board();
        
        // Add hooks
        hook_spacing = rail_length / num_hooks;
        for (i = [1 : num_hooks]) {
            x_pos = (i - 0.5) * hook_spacing;
            translate([x_pos, rail_height / 2, rail_thickness - 0.1])
                printable_peg();
        }
    }
    
    // Subtract mounting holes (placed evenly between hooks)
    hole_spacing = rail_length / num_hooks;
    for (i = [1 : num_hooks - 1]) {
        x_pos = i * hole_spacing;
        translate([x_pos, rail_height / 2, 0])
            mounting_hole();
    }
}