// -*- C -*-

cover_ysz = 45;
cover_len = 70;

attach_tube_dia = 18;

attach_cx = -15;
attach_cdy = -5;
attach_w = 25;

attach_inrad = 25; ///
attach_hole_dist = 5; ///
attach_hole_dia = 4 + 0.5; ///
attach_ang = 45;

// calculated

cover_lcircle_r = cover_ysz / (1 + 1/sqrt(2));

base_len = cover_len - cover_lcircle_r;

attach_straight_len =
  attach_inrad + attach_tube_dia + attach_hole_dist + attach_hole_dia/2
  - attach_w / 2 + attach_hole_dist;

attach_down = tube_dia + attach_hole_dist;

module RearSideTemplate(){
  polygon([[0.1,0],
	   [-base_len,0],
	   [-base_len,-cover_ysz],
	   [0.1,      -cover_ysz]]);
  translate([-base_len, -cover_ysz + cover_lcircle_r])
    circle(r=cover_lcircle_r);
}

module AttachTemplate(){
  hull(){
    polygon([[0,   0],
	     [-0.1, 0],
	     [-0.1, -cover_ysz],
	     [0,    -cover_ysz]]);
    translate([attach_cx, -attach_cdy]) rotate([0,0,-attach_ang]) {
      polygon([[-attach_cx,          attach_w/2],
	       [0,                   -attach_w/2],
	       [attach_straight_len, -attach_w/2],
	       [attach_straight_len, attach_w/2]]);
      translate([attach_straight_len, 0])
	circle(r=attach_w/2);
    }
  }
}

module BodyPositive(){
  color("blue") linear_extrude(height=60) RearSideTemplate();
  translate([0,0,-attach_down]) linear_extrude(height=100) AttachTemplate();
}

module Tube(){
  %translate([attach_cx, -attach_cdy, -20]) {
    rotate_extrude(convexity=10) {
      translate([attach_inrad + attach_tube_dia/2, 0])
	circle(r=attach_tube_dia/2);
    }
  }
}

module Bolt(){
  %translate([0,0,-50]) linear_extrude(height=80) {
    circle(r=attach_hole_dia/2, $fn=20);
  }
  %translate([0,0,10]) linear_extrude(height=20) {
    circle(r=attach_hole_dia/2 * 2, $fn=20);
  }
}

module Bolts(){
  translate([attach_cx, -attach_cdy]) rotate([0,0,-attach_ang]) {
    translate([attach_inrad - attach_hole_dist - attach_hole_dia/2, 0])
      Bolt();
    translate([attach_inrad + attach_tube_dia
	       +attach_hole_dist + attach_hole_dia/2, 0])
      Bolt();
  }
}

Tube();
Bolts();
BodyPositive();