$fn = 64;

// --- Parametric Variables ---
arch_width = 70;         // Total width of the arch structure
arch_depth = 30;         // Depth (thickness) of the arch
pillar_height = 30;      // Height of the straight vertical pillars
opening_width = 30;      // Width of the passage for cables
base_height = 5;         // Height of the widened base plates

// Calculated dimensions
pillar_w = (arch_width - opening_width) / 2;

module medieval_cable_arch() {
    union() {
        difference() {
            // --- Main Solid Geometry ---
            union() {
                // Vertical pillars
                translate([0, 0, pillar_height / 2])
                    cube([arch_width, arch_depth, pillar_height], center=true);

                // Top arch curve
                translate([0, 0, pillar_height])
                    rotate([90, 0, 0])
                        cylinder(d=arch_width, h=arch_depth, center=true);

                // Widened base plates for stability
                base_w = pillar_w + 4;
                translate([-(opening_width / 2 + base_w / 2), 0, base_height / 2])
                    cube([base_w, arch_depth + 8, base_height], center=true);
                translate([(opening_width / 2 + base_w / 2), 0, base_height / 2])
                    cube([base_w, arch_depth + 8, base_height], center=true);

                // Keystone detail at the top center
                translate([0, 0, pillar_height + arch_width / 2])
                    hull() {
                        translate([0, 0, 2]) cube([16, arch_depth + 4, 4], center=true);
                        translate([0, 0, -8]) cube([10, arch_depth + 4, 4], center=true);
                    }
            }

            // --- Subtractions (Holes & Details) ---
            
            // Inner opening (straight vertical part)
            translate([0, 0, pillar_height / 2])
                cube([opening_width, arch_depth + 10, pillar_height + 0.1], center=true);

            // Inner opening (curved arch part)
            translate([0, 0, pillar_height])
                rotate([90, 0, 0])
                    cylinder(d=opening_width, h=arch_depth + 10, center=true);

            // Clean bottom cut to ensure flat printing surface
            translate([0, 0, -5])
                cube([arch_width + 20, arch_depth + 20, 10], center=true);

            // Horizontal stone grooves on the pillars
            for (z = [base_height + 6 : 6 : pillar_height - 2]) {
                translate([0, 0, z])
                    cube([arch_width + 5, arch_depth + 5, 1.2], center=true);
            }

            // Radial stone grooves on the arch
            translate([0, 0, pillar_height]) {
                for (a = [15 : 15 : 165]) {
                    // Skip 90 degrees to avoid cutting the keystone in half
                    if (a != 90) {
                        rotate([0, a, 0])
                            translate([25, 0, 0])
                                cube([22, arch_depth + 5, 1.2], center=true);
                    }
                }
            }
        }

        // --- Additions (Pillar Caps) ---
        // Added outside the difference so their slight inner overhang is preserved
        cap_w = pillar_w + 4;
        translate([-(opening_width / 2 + pillar_w / 2), 0, pillar_height])
            cube([cap_w, arch_depth + 4, 3], center=true);
        translate([(opening_width / 2 + pillar_w / 2), 0, pillar_height])
            cube([cap_w, arch_depth + 4, 3], center=true);
    }
}

// Render the object
medieval_cable_arch();