//////////////////////////////////////////////////////////////
// PARAMETRIC 120mm FAN‑MOUNTED DRIVE BRACKET
// 4× SAS (15mm) + 2× SATA (7mm) with 4mm air gaps
// HARD LIMIT: No geometry may extend more than 10mm
// below the fan-hole center (Y = 15 → min Y = 5)
// Spine rebuilt, arms extended, gussets restored, dual SSD holes
//////////////////////////////////////////////////////////////


//////////////////////////////////////////////////////////////
// CHUNK 1 — SPINE WITH REAL M5 FAN HOLES (REBUILT CLEANLY)
//////////////////////////////////////////////////////////////

spine_length     = 120;
fan_hole_spacing = 105;
spine_height     = 30;
spine_thickness  = 4;
m5_radius        = 2.8;

// Fan-hole center = 15 mm
// Allowed minimum Y = 5 mm
// Spine runs from Y = 5 → 35 (height = 30)

module spine() {
    // Spine bottom stays at Y = 5
    // Spine top must be Y = 25 (10mm above fan-hole center)
    // New spine height = 20mm
    translate([0, 5, 0])
        cube([spine_length, 20, spine_thickness], center=false);
}


module fan_mount_holes() {
    left_x  = (spine_length - fan_hole_spacing) / 2;
    right_x = left_x + fan_hole_spacing;

    // Fan-hole center at Y = 15
    translate([left_x, 15, -100])
        cylinder(h = 300, r = m5_radius, center = false, $fn = 64);

    translate([right_x, 15, -100])
        cylinder(h = 300, r = m5_radius, center = false, $fn = 64);
}


//////////////////////////////////////////////////////////////
// CHUNK 2 — ARM GEOMETRY (UPDATED FOR 50% GAP REDUCTION)
// Arm bottom must be EXACTLY Y = 5 mm
// First hole center: now 18.3mm from spine face (was 24.6)
// Second hole center: +76.6mm further out (unchanged spacing)
// Arm length shortened by 6.3mm (110 → 103.7)
//////////////////////////////////////////////////////////////

drop          = -6.25;
leg_width     = 10;
tip_Y         = 2.5;

// Arm shortened by 6.3 mm
arm_length    = 103.7;

m3_radius     = 1.6;

// Gusset geometry
gusset_height = 6;
gusset_length = 8;
gusset_thick  = 2;

// Updated hole positions
first_hole_z  = 18.3 - spine_thickness;     // 50% reduced gap
second_hole_z = first_hole_z + 76.6;        // preserve spacing

module one_arm() {

    // Vertical leg
    translate([-leg_width/2, -drop - tip_Y/2, 0])
        cube([leg_width, drop + tip_Y/2, spine_thickness]);

    // Left gusset
    translate([-leg_width/2, -drop - tip_Y/2, spine_thickness])
        polyhedron(
            points = [
                [0, 0, 0],
                [0, gusset_height, 0],
                [0, 0, gusset_length],
                [gusset_thick, 0, 0],
                [gusset_thick, gusset_height, 0],
                [gusset_thick, 0, gusset_length]
            ],
            faces = [
                [0,1,2],
                [3,5,4],
                [0,3,4,1],
                [1,4,5,2],
                [2,5,3,0]
            ]
        );

    // Right gusset
    translate([leg_width/2 - gusset_thick, -drop - tip_Y/2, spine_thickness])
        polyhedron(
            points = [
                [0, 0, 0],
                [0, gusset_height, 0],
                [0, 0, gusset_length],
                [gusset_thick, 0, 0],
                [gusset_thick, gusset_height, 0],
                [gusset_thick, 0, gusset_length]
            ],
            faces = [
                [0,1,2],
                [3,5,4],
                [0,3,4,1],
                [1,4,5,2],
                [2,5,3,0]
            ]
        );

    // Tip block with two through-holes
    translate([-leg_width/2, -drop - tip_Y/2, spine_thickness])
        difference() {
            cube([leg_width, tip_Y, arm_length], center = false);

            // First hole (reduced gap)
            translate([leg_width/2, -drop, first_hole_z])
                rotate([90, 0, 0])
                    cylinder(
                        h = 200,
                        r = m3_radius,
                        center = true,
                        $fn = 48
                    );

            // Second hole (same spacing)
            translate([leg_width/2, -drop, second_hole_z])
                rotate([90, 0, 0])
                    cylinder(
                        h = 200,
                        r = m3_radius,
                        center = true,
                        $fn = 48
                    );
        }
}



//////////////////////////////////////////////////////////////
// CHUNK 3 — PARAMETRIC ARM SPACING (MATCHES ORIGINAL)
//////////////////////////////////////////////////////////////

drive_thicknesses = [15,15,15,15,7,7];
air_gap           = 4;

function cum_thick(i) =
    i <= 0 ? 0 : drive_thicknesses[i-1] + cum_thick(i-1);

function total_thick() = cum_thick(len(drive_thicknesses));

function total_width() =
    total_thick() + (len(drive_thicknesses)-1) * air_gap;

fan_center_x = spine_length/2;  // = 60mm

function stack_left_x() =
    fan_center_x - total_width()/2;

function drive_center_x(i) =
    stack_left_x() + cum_thick(i) + i*air_gap + drive_thicknesses[i]/2;

function arm_center_x(i) = drive_center_x(i);

module arms_parametric() {
    for (i = [0 : len(drive_thicknesses)-1]) {
        translate([arm_center_x(i), 0, 0])
            one_arm();
    }
}


//////////////////////////////////////////////////////////////
// CHUNK 4 — FINAL ASSEMBLY
//////////////////////////////////////////////////////////////

difference() {
    union() {
        spine();
        arms_parametric();
    }
    fan_mount_holes();
}