/*
 * Parametric enclosure for the Adafruit ESP32 Feather V2 and FeatherWings.
 *
 * Coordinate system:
 *   X: USB-C wall (0) toward the rear of the case
 *   Y: non-battery side (0) toward the battery/JST side
 *   Z: outside bottom (0) upward
 *
 * Board coordinates are derived from Adafruit's Eagle PCB files:
 *   https://github.com/adafruit/Adafruit-ESP32-Feather-V2-PCB
 *   https://github.com/adafruit/Adafruit-OLED-FeatherWing-PCB
 */

/* [Output] */
part = "assembly"; // [assembly,body,lid,buttons,insert_coupon,switch_coupon,fit_coupon]
exploded_view = 8; // [0:1:20]
show_references = true;

/* [Stack] */
top_profile = "generic"; // [generic,gps,oled128x64]
wing_count = 1; // [1:1:8]
wing_pitch = 12.25; // [7:0.1:16]
stack_height_override = 0; // [0:0.1:100]
generic_component_height = 3; // [0:0.1:30]
generic_top_gap = 2; // [0.5:0.1:10]
gps_antenna_height = 6;
gps_top_gap = 5;
oled_component_height = 2.4;
oled_display_height = 1.5;
oled_face_gap = 0.8;

/* [OLED controls] */
button_a = true;
button_b = true;
button_c = true;
button_reset = false;
button_projection = 1.5; // [0.5:0.1:3]
button_cap_size = [5, 3.2];
button_flange_size = [6.6, 3.6];
button_flange_thickness = 0.9;
button_travel = 0.5;
button_contact_extension = 0.7;

/* [Battery and switch] */
battery_enabled = false;
battery_length = 69;
battery_diameter = 18;
battery_radial_clearance = 0.6;
battery_end_clearance = 1;
switch_hole_diameter = 12;
switch_hole_compensation = 0.3;
switch_cap_diameter = 8;
switch_flange_diameter = 16.2;
switch_body_length = 24;
switch_body_diameter = 12;
switch_wire_allowance = 3;

/* [Tripod mount] */
tripod_insert_enabled = false;
tripod_insert_length = 6.4;
tripod_insert_hole_diameter = 8.8;
tripod_thread_clearance_diameter = 6.8;
tripod_boss_diameter = 14;

/* [M2.5 inserts] */
m25_insert_length = 4;
m25_insert_hole_diameter = 3.7;
m25_screw_clearance = 2.8;
m25_boss_diameter = 7;
insert_entry_chamfer = 0.6;
insert_melt_relief = 0.8;

/* [Shell and fit] */
wall_thickness = 2.4;
floor_thickness = 2.4;
lid_thickness = 3.2;
corner_radius = 4;
board_bottom_clearance = 5.4;
board_side_clearance = 7;
board_rear_clearance = 4;
usb_board_wall_gap = 2;
lid_lip_depth = 2.4;
lid_lip_thickness = 1.2;
fit_clearance = 0.35;
cutout_min_web = 1.2;
hole_compensation = 0.2;
lid_screw_head_diameter = 5.2;
lid_screw_head_height = 2.5;

/* [USB-C opening] */
usb_opening_enabled = true;
usb_guide_enabled = true;
usb_connector_overhang = 2;
usb_guide_wall_thickness = 1.2;
usb_guide_end_gap = 1;
usb_opening_width = 12.5;
usb_opening_height = 7;
usb_opening_radius = 1.5;
usb_vertical_offset = 0;

/* [Custom wall cutouts] */
// Entry format: [face, shape, u, z, width, height, radius]
// face: front, rear, left, right. u is Y on front/rear and X on left/right.
// shape: circle, rect, roundrect, slot. Circle uses width as its diameter.
extra_cutouts = [];

/* [Calibration] */
coupon_steps = [-0.3, -0.15, 0, 0.15, 0.3];

$fn = $preview ? 36 : 72;
eps = 0.02;

// Adafruit Feather mechanical reference, millimetres.
feather_length = 50.8;
feather_width = 22.86;
board_thickness = 1.6;
mount_x = [2.54, 48.26];
mount_y = [2.54, 20.32];
usb_center_y = 11.43;

// Official 128x64 OLED FeatherWing geometry in Feather-board coordinates.
oled_visible_min = [11.42, 3.78];
oled_visible_size = [30, 15.3];
oled_button_a_xy = [4.318, 15.875];
oled_button_b_xy = [4.318, 11.43];
oled_button_c_xy = [4.318, 6.985];
oled_button_reset_xy = [7.366, 20.828];

effective_floor = tripod_insert_enabled
    ? max(floor_thickness, tripod_insert_length + insert_melt_relief + 1.2)
    : floor_thickness;
effective_board_clearance = max(
    board_bottom_clearance,
    m25_insert_length + insert_melt_relief + 0.6
);

board_origin_x = wall_thickness + usb_board_wall_gap;
board_origin_y = wall_thickness + board_side_clearance;
board_bottom_z = effective_floor + effective_board_clearance;
board_top_z = board_bottom_z + board_thickness;
usb_center_u = board_origin_y + usb_center_y;
usb_center_z = board_top_z + 1.6 + usb_vertical_offset;
usb_inner_width = usb_opening_width + hole_compensation;
usb_inner_height = usb_opening_height + hole_compensation;
usb_guide_length = max(
    0,
    usb_board_wall_gap - usb_connector_overhang - usb_guide_end_gap
);
usb_guide_active = usb_opening_enabled && usb_guide_enabled
    && usb_guide_length > 0;
usb_reserved_width = usb_inner_width
    + (usb_guide_active ? 2 * usb_guide_wall_thickness : 0);
usb_reserved_height = usb_inner_height
    + (usb_guide_active ? 2 * usb_guide_wall_thickness : 0);

computed_top_pcb_z = board_top_z + wing_count * wing_pitch;
top_pcb_z = stack_height_override > 0
    ? board_top_z + stack_height_override
    : computed_top_pcb_z;
profile_component_height =
    top_profile == "gps" ? gps_antenna_height :
    top_profile == "oled128x64" ? oled_component_height :
    generic_component_height;
profile_top_gap =
    top_profile == "gps" ? gps_top_gap :
    top_profile == "oled128x64" ? oled_face_gap :
    generic_top_gap;

partition_y = board_origin_y + feather_width + 1;
battery_center_y = partition_y + wall_thickness + battery_radial_clearance
    + battery_diameter / 2;
battery_start_x = board_origin_x + battery_end_clearance;
battery_end_x = battery_start_x + battery_length;
switch_center_x = battery_end_x + max(
    switch_body_diameter / 2 + 0.8,
    switch_flange_diameter / 2 + 0.5
);

case_length_plain = board_origin_x + feather_length
    + board_rear_clearance + wall_thickness;
case_length_battery = switch_center_x + switch_flange_diameter / 2
    + 1.2 + wall_thickness;
case_length = battery_enabled ? max(case_length_plain, case_length_battery)
    : case_length_plain;

case_width_plain = board_origin_y + feather_width
    + board_side_clearance + wall_thickness;
case_width_battery = battery_center_y + battery_diameter / 2
    + battery_radial_clearance + wall_thickness;
case_width = battery_enabled ? max(case_width_plain, case_width_battery)
    : case_width_plain;

battery_center_z = effective_floor + battery_radial_clearance
    + battery_diameter / 2;
switch_center_z = max(
    effective_floor + switch_flange_diameter / 2 + 1,
    battery_center_z
);
electronics_ceiling_z = top_pcb_z + profile_component_height + profile_top_gap;
battery_ceiling_z = battery_enabled
    ? max(
        battery_center_z + battery_diameter / 2 + battery_radial_clearance,
        switch_center_z + switch_flange_diameter / 2 + 1
    )
    : 0;
body_height = max(electronics_ceiling_z, battery_ceiling_z);

lid_boss_r = m25_boss_diameter / 2;
lid_boss_wall_overlap = 0.6;
lid_boss_xy = [
    [
        wall_thickness + lid_boss_r - lid_boss_wall_overlap,
        wall_thickness + lid_boss_r - lid_boss_wall_overlap
    ],
    [
        case_length - wall_thickness - lid_boss_r + lid_boss_wall_overlap,
        wall_thickness + lid_boss_r - lid_boss_wall_overlap
    ],
    [
        wall_thickness + lid_boss_r - lid_boss_wall_overlap,
        case_width - wall_thickness - lid_boss_r + lid_boss_wall_overlap
    ],
    [
        case_length - wall_thickness - lid_boss_r + lid_boss_wall_overlap,
        case_width - wall_thickness - lid_boss_r + lid_boss_wall_overlap
    ]
];

assert(wing_count >= 1, "wing_count must be at least one");
assert(top_profile == "generic" || top_profile == "gps"
    || top_profile == "oled128x64", "Unsupported top_profile");
assert(wall_thickness >= 1.2, "wall_thickness is too small for 0.6 mm FDM");
assert(lid_lip_thickness >= 1.2, "lid lip needs at least two 0.6 mm lines");
assert(m25_boss_diameter > m25_insert_hole_diameter + 2,
    "M2.5 boss does not have enough radial material");
assert(!tripod_insert_enabled
    || tripod_boss_diameter > tripod_insert_hole_diameter + 3,
    "Tripod insert boss does not have enough radial material");
assert(usb_opening_enabled || !usb_guide_enabled,
    "USB guide requires the USB opening");

function clamp(v, lo, hi) = min(max(v, lo), hi);
function cutout_height(entry) = len(entry) > 5 ? entry[5] : entry[4];
function cutouts_separated(first, second, web) =
    abs(first[2] - second[2])
        >= (first[4] + second[4]) / 2 + web
    || abs(first[3] - second[3])
        >= (cutout_height(first) + cutout_height(second)) / 2 + web;
function cutout_clear_of_usb(entry, web) =
    abs(entry[2] - usb_center_u)
        >= (entry[4] + usb_reserved_width) / 2 + web
    || abs(entry[3] - usb_center_z)
        >= (cutout_height(entry) + usb_reserved_height) / 2 + web;

module validate_cutout_spacing() {
    if (len(extra_cutouts) > 1)
        for (first = [0 : len(extra_cutouts) - 2],
             second = [first + 1 : len(extra_cutouts) - 1])
            if (extra_cutouts[first][0] == extra_cutouts[second][0])
                assert(
                    cutouts_separated(
                        extra_cutouts[first],
                        extra_cutouts[second],
                        cutout_min_web
                    ),
                    "Custom cutouts are too close on the same wall"
                );
    if (usb_opening_enabled)
        for (entry = extra_cutouts)
            if (entry[0] == "front")
                assert(
                    cutout_clear_of_usb(entry, cutout_min_web),
                    "Front cutout is too close to the USB opening or guide"
                );
}

module rounded_rect_2d(size, radius) {
    r = clamp(radius, 0.01, min(size[0], size[1]) / 2 - 0.01);
    hull() {
        for (x = [r, size[0] - r], y = [r, size[1] - r])
            translate([x, y]) circle(r = r);
    }
}

module centered_rounded_rect_2d(size, radius) {
    translate([-size[0] / 2, -size[1] / 2])
        rounded_rect_2d(size, radius);
}

module centered_rounded_prism(size, height, radius) {
    linear_extrude(height = height)
        centered_rounded_rect_2d(size, radius);
}

module rounded_box(size, radius) {
    linear_extrude(height = size[2])
        rounded_rect_2d([size[0], size[1]], radius);
}

module insert_pocket(diameter, depth, entry_z, downward = true) {
    bore_d = diameter + hole_compensation;
    if (downward) {
        translate([0, 0, entry_z - depth])
            cylinder(h = depth + eps, d = bore_d);
        translate([0, 0, entry_z - insert_entry_chamfer])
            cylinder(
                h = insert_entry_chamfer + eps,
                d1 = bore_d,
                d2 = bore_d + 2 * insert_entry_chamfer
            );
    } else {
        translate([0, 0, entry_z - eps])
            cylinder(h = depth + eps, d = bore_d);
        translate([0, 0, entry_z - eps])
            cylinder(
                h = insert_entry_chamfer + eps,
                d1 = bore_d + 2 * insert_entry_chamfer,
                d2 = bore_d
            );
    }
}

module face_rounded_cutout(face, u, z, width, height, radius) {
    r = clamp(radius, 0.01, min(width, height) / 2);
    depth = wall_thickness + 2 * eps;
    if (face == "front" || face == "rear") {
        x0 = face == "front" ? -eps : case_length - wall_thickness - eps;
        hull()
            for (yy = [u - width / 2 + r, u + width / 2 - r],
                 zz = [z - height / 2 + r, z + height / 2 - r])
                translate([x0, yy, zz])
                    rotate([0, 90, 0]) cylinder(h = depth, r = r);
    } else if (face == "left" || face == "right") {
        y0 = face == "left" ? -eps : case_width - wall_thickness - eps;
        hull()
            for (xx = [u - width / 2 + r, u + width / 2 - r],
                 zz = [z - height / 2 + r, z + height / 2 - r])
                translate([xx, y0, zz])
                    rotate([-90, 0, 0]) cylinder(h = depth, r = r);
    }
}

module face_circle_cutout(face, u, z, diameter) {
    depth = wall_thickness + 2 * eps;
    if (face == "front")
        translate([-eps, u, z])
            rotate([0, 90, 0]) cylinder(h = depth, d = diameter);
    else if (face == "rear")
        translate([case_length - wall_thickness - eps, u, z])
            rotate([0, 90, 0]) cylinder(h = depth, d = diameter);
    else if (face == "left")
        translate([u, -eps, z])
            rotate([-90, 0, 0]) cylinder(h = depth, d = diameter);
    else if (face == "right")
        translate([u, case_width - wall_thickness - eps, z])
            rotate([-90, 0, 0]) cylinder(h = depth, d = diameter);
}

module x_rounded_prism(x, length, u, z, width, height, radius) {
    r = clamp(radius, 0.01, min(width, height) / 2 - 0.01);
    hull()
        for (yy = [u - width / 2 + r, u + width / 2 - r],
             zz = [z - height / 2 + r, z + height / 2 - r])
            translate([x, yy, zz])
                rotate([0, 90, 0]) cylinder(h = length, r = r);
}

module usb_guide_shell() {
    outer_width = usb_inner_width + 2 * usb_guide_wall_thickness;
    outer_height = usb_inner_height + 2 * usb_guide_wall_thickness;
    difference() {
        x_rounded_prism(
            wall_thickness - eps,
            usb_guide_length + 2 * eps,
            usb_center_u,
            usb_center_z,
            outer_width,
            outer_height,
            usb_opening_radius + usb_guide_wall_thickness
        );
        x_rounded_prism(
            wall_thickness - 2 * eps,
            usb_guide_length + 4 * eps,
            usb_center_u,
            usb_center_z,
            usb_inner_width,
            usb_inner_height,
            usb_opening_radius
        );
    }
}

module custom_wall_cutout(entry) {
    face = entry[0];
    shape = entry[1];
    u = entry[2];
    z = entry[3];
    width = entry[4];
    height = len(entry) > 5 ? entry[5] : width;
    radius = len(entry) > 6 ? entry[6] : min(width, height) / 2;
    assert(face == "front" || face == "rear"
        || face == "left" || face == "right", "Invalid cutout face");
    assert(shape == "circle" || shape == "rect"
        || shape == "roundrect" || shape == "slot", "Invalid cutout shape");
    assert(z - height / 2 >= effective_floor,
        "Cutout intersects the floor");
    assert(z + height / 2 <= body_height - lid_lip_depth,
        "Cutout intersects the lid locating lip");
    assert(
        (face == "front" || face == "rear")
            ? u - width / 2 >= 0 && u + width / 2 <= case_width
            : u - width / 2 >= 0 && u + width / 2 <= case_length,
        "Cutout extends beyond its wall"
    );

    if (shape == "circle")
        face_circle_cutout(face, u, z, width);
    else
        face_rounded_cutout(
            face, u, z, width, height,
            shape == "rect" ? 0.02 :
            shape == "slot" ? min(width, height) / 2 : radius
        );
}

module board_standoffs() {
    for (mx = mount_x, my = mount_y)
        translate([
            board_origin_x + mx,
            board_origin_y + my,
            effective_floor - eps
        ])
            cylinder(
                h = effective_board_clearance + eps,
                d = m25_boss_diameter
            );
}

module lid_bosses() {
    for (p = lid_boss_xy)
        translate([p[0], p[1], effective_floor - eps])
            cylinder(
                h = body_height - effective_floor + eps,
                d = m25_boss_diameter
            );
}

module battery_cradle() {
    partition_height = min(
        body_height - lid_lip_depth - 0.5,
        battery_center_z + battery_diameter / 2 + 1.5
    );
    rib_width = 2.4;
    rib_positions = [
        battery_start_x + 4,
        (battery_start_x + battery_end_x) / 2,
        battery_end_x - 4
    ];

    // Board/battery partition, with a lead-routing notch near the JST end.
    difference() {
        translate([wall_thickness, partition_y, effective_floor - eps])
            cube([
                battery_end_x - wall_thickness + battery_end_clearance,
                wall_thickness,
                partition_height - effective_floor + eps
            ]);
        translate([
            board_origin_x + 6.5,
            partition_y - eps,
            effective_floor + 1.5
        ])
            cube([9, wall_thickness + 2 * eps, 6]);
    }

    // Three low curved ribs cradle the protected cylindrical pack.
    for (x = rib_positions)
        difference() {
            translate([
                x - rib_width / 2,
                battery_center_y - battery_diameter / 2
                    - battery_radial_clearance,
                effective_floor - eps
            ])
                cube([
                    rib_width,
                    battery_diameter + 2 * battery_radial_clearance,
                    battery_diameter / 2 + battery_radial_clearance + eps
                ]);
            translate([x - rib_width, battery_center_y, battery_center_z])
                rotate([0, 90, 0])
                    cylinder(
                        h = rib_width * 2,
                        d = battery_diameter + 2 * battery_radial_clearance
                    );
        }

    // End stops remain below the cell center so the lid can remove vertically.
    for (x = [
        battery_start_x - battery_end_clearance - wall_thickness,
        battery_end_x + battery_end_clearance
    ])
        translate([
            x,
            battery_center_y - battery_diameter / 2 - battery_radial_clearance,
            effective_floor - eps
        ])
            cube([
                wall_thickness,
                battery_diameter + 2 * battery_radial_clearance,
                battery_diameter / 2 + 1 + eps
            ]);

    // Rear cross-strip separates the side-mounted switch body from the cell.
    translate([
        battery_end_x + battery_end_clearance,
        partition_y,
        effective_floor - eps
    ])
        cube([
            case_length - wall_thickness - battery_end_x - battery_end_clearance,
            case_width - wall_thickness - partition_y,
            min(body_height - effective_floor, switch_center_z
                + switch_body_diameter / 2 + switch_wire_allowance
                - effective_floor) + eps
        ]);
}

module body_positive() {
    union() {
        difference() {
            rounded_box([case_length, case_width, body_height], corner_radius);
            translate([wall_thickness, wall_thickness, effective_floor])
                rounded_box([
                    case_length - 2 * wall_thickness,
                    case_width - 2 * wall_thickness,
                    body_height - effective_floor + eps
                ], max(0.6, corner_radius - wall_thickness));
        }
        board_standoffs();
        lid_bosses();
        if (battery_enabled)
            battery_cradle();
        if (tripod_insert_enabled)
            translate([case_length / 2, case_width / 2, 0])
                cylinder(h = effective_floor, d = tripod_boss_diameter);
        if (usb_guide_active)
            usb_guide_shell();
    }
}

module body_cutouts() {
    // Board mounting insert pockets, loaded from above before the Feather.
    for (mx = mount_x, my = mount_y)
        translate([board_origin_x + mx, board_origin_y + my, 0])
            insert_pocket(
                m25_insert_hole_diameter,
                m25_insert_length + insert_melt_relief,
                board_bottom_z
            );

    // Lid insert pockets, loaded from the top of the body.
    for (p = lid_boss_xy)
        translate([p[0], p[1], 0])
            insert_pocket(
                m25_insert_hole_diameter,
                m25_insert_length + insert_melt_relief,
                body_height
            );

    // USB-C cable opening. Connector center is from the official ESP32 V2 PCB.
    if (usb_opening_enabled)
        face_rounded_cutout(
            "front",
            usb_center_u,
            usb_center_z,
            usb_inner_width,
            usb_inner_height,
            usb_opening_radius
        );

    if (battery_enabled) {
        face_circle_cutout(
            "right",
            switch_center_x,
            switch_center_z,
            switch_hole_diameter + switch_hole_compensation
        );
        // Clear the switch body and its prewired terminals through the rear bay.
        translate([
            switch_center_x,
            case_width - wall_thickness + eps,
            switch_center_z
        ])
            rotate([90, 0, 0])
                cylinder(
                    h = switch_body_length + switch_wire_allowance
                        + wall_thickness + eps,
                    d = switch_body_diameter + 2 * fit_clearance
                );
    }

    if (tripod_insert_enabled) {
        translate([case_length / 2, case_width / 2, 0]) {
            translate([0, 0, -eps])
                cylinder(
                    h = effective_floor + 2 * eps,
                    d = tripod_thread_clearance_diameter + hole_compensation
                );
            insert_pocket(
                tripod_insert_hole_diameter,
                tripod_insert_length + insert_melt_relief,
                effective_floor
            );
        }
    }

    for (entry = extra_cutouts)
        custom_wall_cutout(entry);
}

module body() {
    difference() {
        body_positive();
        body_cutouts();
    }
}

module lid_plate_positive() {
    union() {
        rounded_box([case_length, case_width, lid_thickness], corner_radius);
        // Inset rim: exported pointing upward so the outer lid face prints flat.
        translate([
            wall_thickness + fit_clearance,
            wall_thickness + fit_clearance,
            lid_thickness
        ])
            linear_extrude(height = lid_lip_depth)
                difference() {
                    rounded_rect_2d([
                        case_length - 2 * (wall_thickness + fit_clearance),
                        case_width - 2 * (wall_thickness + fit_clearance)
                    ], max(0.6, corner_radius - wall_thickness));
                    translate([lid_lip_thickness, lid_lip_thickness])
                        rounded_rect_2d([
                            case_length - 2 * (
                                wall_thickness + fit_clearance
                                + lid_lip_thickness
                            ),
                            case_width - 2 * (
                                wall_thickness + fit_clearance
                                + lid_lip_thickness
                            )
                        ], max(0.5, corner_radius - wall_thickness
                            - lid_lip_thickness));
                }
    }
}

module beveled_oled_window() {
    inner_size = oled_visible_size;
    outer_size = [oled_visible_size[0] + 3, oled_visible_size[1] + 3];
    center = [
        board_origin_x + oled_visible_min[0] + oled_visible_size[0] / 2,
        board_origin_y + oled_visible_min[1] + oled_visible_size[1] / 2
    ];
    hull() {
        translate([center[0], center[1], -eps])
            linear_extrude(height = eps)
                centered_rounded_rect_2d(outer_size, 1.5);
        translate([center[0], center[1], lid_thickness - eps])
            linear_extrude(height = 2 * eps)
                centered_rounded_rect_2d(inner_size, 0.8);
    }
}

module oled_button_lid_cutout(xy) {
    center = [board_origin_x + xy[0], board_origin_y + xy[1]];
    shaft_size = [
        button_cap_size[0] + fit_clearance * 2,
        button_cap_size[1] + fit_clearance * 2
    ];
    recess_size = [
        button_flange_size[0] + fit_clearance * 2,
        button_flange_size[1] + fit_clearance * 2
    ];
    recess_depth = button_flange_thickness + button_travel;
    translate([center[0], center[1], -eps])
        centered_rounded_prism(
            shaft_size,
            lid_thickness + 2 * eps,
            shaft_size[1] / 2
        );
    translate([center[0], center[1], lid_thickness - recess_depth])
        centered_rounded_prism(
            recess_size,
            recess_depth + lid_lip_depth + eps,
            recess_size[1] / 2
        );
}

module lid_cutouts() {
    // Through holes plus shallow counterbores for flush M2.5 socket heads.
    for (p = lid_boss_xy) {
        translate([p[0], p[1], -eps])
            cylinder(
                h = lid_thickness + lid_lip_depth + 2 * eps,
                d = m25_screw_clearance + hole_compensation
            );
        translate([p[0], p[1], -eps])
            cylinder(
                h = lid_screw_head_height + eps,
                d = lid_screw_head_diameter + hole_compensation
            );
    }

    if (top_profile == "oled128x64") {
        beveled_oled_window();
        if (button_a) oled_button_lid_cutout(oled_button_a_xy);
        if (button_b) oled_button_lid_cutout(oled_button_b_xy);
        if (button_c) oled_button_lid_cutout(oled_button_c_xy);
        if (button_reset) oled_button_lid_cutout(oled_button_reset_xy);
    }
}

module lid() {
    difference() {
        lid_plate_positive();
        lid_cutouts();
    }
}

module one_oled_button() {
    recess_depth = button_flange_thickness + button_travel;
    stem_height = lid_thickness - recess_depth + button_projection;
    // Print outer cap face down. The flange and contact nub build upward.
    centered_rounded_prism(
        button_cap_size,
        stem_height,
        button_cap_size[1] / 2
    );
    translate([0, 0, stem_height])
        centered_rounded_prism(
            button_flange_size,
            button_flange_thickness,
            button_flange_size[1] / 2
        );
    translate([0, 0, stem_height + button_flange_thickness])
        cylinder(h = button_contact_extension, d = 3);
}

module buttons() {
    enabled = [
        button_a,
        button_b,
        button_c,
        button_reset
    ];
    count_enabled = len([for (v = enabled) if (v) 1]);
    if (count_enabled == 0)
        echo("No OLED buttons are enabled.");
    for (i = [0 : len(enabled) - 1])
        if (enabled[i])
            translate([i * (button_flange_size[0] + 3), 0, 0])
                one_oled_button();
}

module reference_board() {
    color([0.05, 0.25, 0.55, 0.75])
        translate([board_origin_x, board_origin_y, board_bottom_z])
            rounded_box([feather_length, feather_width, board_thickness], 2.54);
    color([0.12, 0.45, 0.75, 0.45])
        for (i = [1 : wing_count])
            translate([
                board_origin_x,
                board_origin_y,
                board_top_z + i * wing_pitch - board_thickness
            ])
                rounded_box(
                    [feather_length, feather_width, board_thickness], 2.54
                );
}

module reference_top_feature() {
    if (top_profile == "gps")
        color([0.92, 0.78, 0.35, 0.8])
            translate([
                board_origin_x + 31,
                board_origin_y + (feather_width - 15) / 2,
                top_pcb_z
            ])
                cube([15, 15, gps_antenna_height]);
    else if (top_profile == "oled128x64") {
        color([0.12, 0.12, 0.12, 0.9])
            translate([
                board_origin_x + oled_visible_min[0],
                board_origin_y + oled_visible_min[1],
                top_pcb_z
            ])
                cube([
                    oled_visible_size[0],
                    oled_visible_size[1],
                    oled_display_height
                ]);
        color([0.6, 0.6, 0.6, 0.9])
            for (xy = [
                oled_button_a_xy,
                oled_button_b_xy,
                oled_button_c_xy,
                oled_button_reset_xy
            ])
                translate([
                    board_origin_x + xy[0],
                    board_origin_y + xy[1],
                    top_pcb_z
                ])
                    cylinder(h = 1.6, d = 2.1);
    } else
        color([0.3, 0.65, 0.35, 0.6])
            translate([
                board_origin_x + 10,
                board_origin_y + 4,
                top_pcb_z
            ])
                cube([
                    feather_length - 20,
                    feather_width - 8,
                    generic_component_height
                ]);
}

module reference_battery_and_switch() {
    if (battery_enabled) {
        color([0.35, 0.18, 0.55, 0.75])
            translate([battery_start_x, battery_center_y, battery_center_z])
                rotate([0, 90, 0])
                    cylinder(h = battery_length, d = battery_diameter);
        color([0.8, 0.15, 0.1, 0.65])
            translate([
                switch_center_x,
                case_width - wall_thickness,
                switch_center_z
            ])
                rotate([90, 0, 0]) {
                    cylinder(h = switch_body_length, d = switch_body_diameter);
                    translate([0, 0, -1.5])
                        cylinder(h = 1.5, d = switch_flange_diameter);
                    translate([0, 0, -3])
                        cylinder(h = 3, d = switch_cap_diameter);
                }
    }
}

module assembly() {
    color([0.82, 0.84, 0.88, 1]) body();
    if ($preview && show_references) {
        reference_board();
        reference_top_feature();
        reference_battery_and_switch();
    }
    // Printable lid is mirrored into its installed orientation and exploded up.
    color([0.92, 0.92, 0.95, 0.88])
        translate([0, case_width, body_height + lid_thickness + exploded_view])
            rotate([180, 0, 0])
                lid();
}

module coupon_hole(x, y, diameter, depth) {
    translate([x, y, -eps]) cylinder(h = depth + 2 * eps, d = diameter);
}

module insert_coupon() {
    spacing = 15;
    coupon_length = spacing * len(coupon_steps) + 8;
    coupon_width = 32;
    coupon_height = max(
        m25_insert_length + insert_melt_relief + 1.2,
        tripod_insert_length + insert_melt_relief + 1.2
    );
    difference() {
        rounded_box([coupon_length, coupon_width, coupon_height], 3);
        for (i = [0 : len(coupon_steps) - 1]) {
            x = 7 + i * spacing;
            coupon_hole(
                x, 8,
                m25_insert_hole_diameter + coupon_steps[i],
                m25_insert_length + insert_melt_relief
            );
            coupon_hole(
                x, 23,
                tripod_insert_hole_diameter + coupon_steps[i],
                tripod_insert_length + insert_melt_relief
            );
        }
    }
}

module switch_coupon() {
    spacing = 18;
    coupon_length = spacing * len(coupon_steps) + 6;
    coupon_width = 24;
    coupon_height = wall_thickness;
    difference() {
        rounded_box([coupon_length, coupon_width, coupon_height], 3);
        for (i = [0 : len(coupon_steps) - 1])
            translate([6 + i * spacing, coupon_width / 2, -eps])
                cylinder(
                    h = coupon_height + 2 * eps,
                    d = switch_hole_diameter + coupon_steps[i]
                );
    }
}

module fit_coupon() {
    segment_length = 34;
    base_width = 16;
    base_height = 6;
    cavity_size = [segment_length - 8, base_width - 8];
    male_size = [
        cavity_size[0] - 2 * fit_clearance,
        cavity_size[1] - 2 * fit_clearance
    ];
    difference() {
        rounded_box([segment_length, base_width, base_height], 2);
        translate([4, 4, 2])
            cube([segment_length - 8, base_width - 8, base_height]);
    }
    translate([segment_length + 5, 0, 0])
        union() {
            cube([segment_length, base_width, lid_thickness]);
            translate([
                4 + fit_clearance,
                4 + fit_clearance,
                lid_thickness - eps
            ])
                linear_extrude(height = lid_lip_depth + eps)
                    difference() {
                        rounded_rect_2d(male_size, 1);
                        translate([lid_lip_thickness, lid_lip_thickness])
                            rounded_rect_2d([
                                male_size[0] - 2 * lid_lip_thickness,
                                male_size[1] - 2 * lid_lip_thickness
                            ], 0.5);
                    }
        }
}

validate_cutout_spacing();

if (part == "assembly")
    assembly();
else if (part == "body")
    body();
else if (part == "lid")
    lid();
else if (part == "buttons")
    buttons();
else if (part == "insert_coupon")
    insert_coupon();
else if (part == "switch_coupon")
    switch_coupon();
else if (part == "fit_coupon")
    fit_coupon();
else
    assert(false, str("Unknown part: ", part));