// Print-in-Place Hinge with Alternating Knuckles
// Modeled in the open (flat) position

/* [Hinge Dimensions] */
// Total length of the hinge along the hinge axis
hinge_length = 60.0; // [30:1:150]

// Width of each leaf flap measured from the hinge pin centerline
leaf_width = 20.0; // [15:1:50]

// Thickness of each leaf
leaf_thickness = 3.0; // [2:0.5:6]

// Total number of alternating knuckles along the hinge
knuckle_count = 5; // [3:2:11]

// Outer diameter of the hinge knuckles
knuckle_diameter = 8.0; // [6:0.5:14]

/* [Pin and Tolerances] */
// Diameter of the central hinge pin
pin_diameter = 4.0; // [2.5:0.5:8]

// Print-in-place clearance gap between moving parts
clearance = 0.4; // [0.2:0.05:0.8]

/* [Screw Holes] */
// Through-hole diameter for mounting screws
screw_hole_diameter = 3.5; // [2:0.5:6]

// Top diameter of the 90-degree countersunk screw head
screw_head_diameter = 7.0; // [4:0.5:12]

// Corner radius on the outer corners of the leaves
corner_radius = 2.5; // [0:0.5:8]

/* [Colors] */
// Color of Leaf A (including pin and odd knuckles)
leaf_a_color = "SteelBlue";

// Color of Leaf B (even knuckles)
leaf_b_color = "DarkOrange";

/* [Quality] */
$fn = 60;

// --- Derived Calculations ---
pin_radius = pin_diameter / 2;
knuckle_radius = knuckle_diameter / 2;
center_z = knuckle_radius; // Knuckles and leaves sit flush at Z = 0 on print bed

// Axial spacing for knuckles
total_axial_gap = (knuckle_count - 1) * clearance;
knuckle_length = (hinge_length - total_axial_gap) / knuckle_count;
knuckle_pitch = knuckle_length + clearance;

// Screw hole positions
hole_x = (knuckle_radius + clearance + leaf_width) / 2;
hole_y1 = hinge_length * 0.25;
hole_y2 = hinge_length * 0.75;
countersink_depth = (screw_head_diameter - screw_hole_diameter) / 2;

// --- Main Assembly ---
color(leaf_a_color)
    leaf_a();

color(leaf_b_color)
    leaf_b();

// --- Module Definitions ---

// Leaf A: Contains knuckles 0, 2, 4 (indices 0, 2, 4) and the central pin
module leaf_a() {
    difference() {
        union() {
            // Flat leaf plate
            leaf_plate_body(x_sign = 1);

            // Knuckles 0, 2, 4 with transition bridges to leaf plate
            for (i = [0 : 2 : knuckle_count - 1]) {
                knuckle_with_bridge(i * knuckle_pitch, knuckle_length, x_sign = 1);
            }

            // Continuous central hinge pin
            translate([0, 0, center_z])
                rotate([-90, 0, 0])
                cylinder(r = pin_radius, h = hinge_length);
        }

        // Screw holes
        translate([hole_x, hole_y1, 0])
            countersunk_hole();
        translate([hole_x, hole_y2, 0])
            countersunk_hole();
    }
}

// Leaf B: Contains knuckles 1, 3 (indices 1, 3) with bore for the central pin
module leaf_b() {
    difference() {
        union() {
            // Flat leaf plate
            leaf_plate_body(x_sign = -1);

            // Knuckles 1, 3 with transition bridges to leaf plate
            for (i = [1 : 2 : knuckle_count - 1]) {
                knuckle_with_bridge(i * knuckle_pitch, knuckle_length, x_sign = -1);
            }
        }

        // Through-bore for the central pin (pin radius + radial clearance)
        translate([0, -1, center_z])
            rotate([-90, 0, 0])
            cylinder(r = pin_radius + clearance, h = hinge_length + 2);

        // Screw holes
        translate([-hole_x, hole_y1, 0])
            countersunk_hole();
        translate([-hole_x, hole_y2, 0])
            countersunk_hole();
    }
}

// Flat leaf plate with rounded outer corners
module leaf_plate_body(x_sign = 1) {
    inner_x = knuckle_radius + clearance;
    outer_x = leaf_width;
    plate_w = outer_x - inner_x;

    linear_extrude(height = leaf_thickness) {
        if (x_sign > 0) {
            translate([inner_x, 0])
                hull() {
                    // Straight inner edge
                    square([0.1, hinge_length]);
                    // Rounded outer corners
                    translate([plate_w - corner_radius, corner_radius])
                        circle(r = corner_radius, $fn = 32);
                    translate([plate_w - corner_radius, hinge_length - corner_radius])
                        circle(r = corner_radius, $fn = 32);
                }
        } else {
            translate([-outer_x, 0])
                hull() {
                    // Rounded outer corners
                    translate([corner_radius, corner_radius])
                        circle(r = corner_radius, $fn = 32);
                    translate([corner_radius, hinge_length - corner_radius])
                        circle(r = corner_radius, $fn = 32);
                    // Straight inner edge
                    translate([plate_w - 0.1, 0])
                        square([0.1, hinge_length]);
                }
        }
    }
}

// Knuckle cylinder with smooth transition bridge to the leaf plate
module knuckle_with_bridge(y_pos, len, x_sign = 1) {
    overlap = 0.2; // Overlap with leaf plate to ensure seamless union
    bridge_width = knuckle_radius + clearance + overlap;

    hull() {
        // Full knuckle cylinder
        translate([0, y_pos, center_z])
            rotate([-90, 0, 0])
            cylinder(r = knuckle_radius, h = len);

        // Lower bridge extending toward the leaf plate
        if (x_sign > 0) {
            translate([0, y_pos, 0])
                cube([bridge_width, len, leaf_thickness]);
        } else {
            translate([-bridge_width, y_pos, 0])
                cube([bridge_width, len, leaf_thickness]);
        }
    }
}

// Standard 90-degree countersunk screw hole
module countersunk_hole() {
    // Cylindrical through-hole
    translate([0, 0, -1])
        cylinder(d = screw_hole_diameter, h = leaf_thickness + 2, $fn = 32);

    // 90-degree countersink cone (top face is at Z = leaf_thickness)
    translate([0, 0, leaf_thickness - countersink_depth])
        cylinder(
            d1 = screw_hole_diameter,
            d2 = screw_head_diameter,
            h = countersink_depth + 0.01,
            $fn = 32
        );

    // Clearance above the top surface for a clean boolean cut
    translate([0, 0, leaf_thickness])
        cylinder(d = screw_head_diameter, h = 2, $fn = 32);
}