// User Configurable Dimensions
inlet_outer_diameter = 40;  // mm
inlet_inner_diameter = 35;  // mm (This is the taper start width)
elbow_length = 70;          // mm (Length of the straight section)
width_at_elbow = 32.1;      // mm (Target width at elbow)
wall_thickness = 3;         // mm (Base wall thickness)

// Geometry Generation
inlet_len = 10;
taper_len = inlet_len;

// Calculate Inner Radius at various points
// Point 0 (y=0): 32.1mm width (0.16)
// Point 1 (y=10): 30mm width (0.15)
// Point 2 (y=70): 32.1mm width (0.16)
r_in_0 = width_at_elbow / 2;
r_in_end = 30 / 2;
r_in_70 = width_at_elbow / 2;

// Calculate Outer Radius (add wall thickness)
// Start: 35mm ID -> 32.1mm width. Wall is 2.9mm.
r_out_0 = inlet_outer_diameter / 2;
r_out_end = (30 + wall_thickness) / 2; // Inner is 30, Wall is 3 -> Outer is 33mm

// Create a function to get the Radius at any given distance 'y'
function get_radius(y) = (y <= inlet_len) ?
    linear_interpolate(0, inlet_len, r_in_0, r_in_end, y) :
    linear_interpolate(inlet_len, elbow_length, r_in_end, r_in_70, y);

function get_outer_radius(y) = get_radius(y) + wall_thickness;

// Syntax Error Here
/* 
//old code
// Generate points for the profile
profile_points = [
    [0, r_out_0]
];
for (y = [0.1 : 0.5 : inlet_len])
    profile_points = concat(profile_points, [[y, get_radius(y)]]);
   
for (y = [inlet_len : 0.5 : elbow_length])
    profile_points = concat(profile_points, [[y, get_radius(y)]]);
*/

// revised code
// Generate points for the profile
profile_points = [
    [0, r_out_0],
    for (y = [0.1 : 0.5 : inlet_len]) [y, get_radius(y)],
    for (y = [inlet_len : 0.5 : elbow_length]) [y, get_radius(y)]
];



// --- SECTION E: The Main Shape Generator ---
module create_adapter() {
    // Inlet (Bottom)
    polygon(profile_points);
   
    // Elbow (Top)
    // We need to rotate the profile so the bottom (inlet) points down and top points right.
    // Let's define a pivot point at the end of the inlet.
    pivot_x = inlet_len;
    pivot_y = get_radius(inlet_len); // The radius at the bend point
   
    // Create a new set of points for the elbow section
    // We offset the elbow section so its origin (0,0) is at the pivot
    elbow_points = [
        for (i = [0:1:len(profile_points)-1])
            [profile_points[i][0] - pivot_x, profile_points[i][1] - pivot_y]
    ];
   
    // Rotate the elbow
    rotate([0, 0, 90]) {
        translate([0, 0, -elbow_radius]) {
            polygon(elbow_points);
        }
    }
   
    // Extrude to make it a tube
    // We need to create a closed loop for extrusion.
    // The polygon is just the top half. We need to mirror it for the bottom.
    // Actually, for `linear_extrude`, we should define a closed shape.
    // The top points are [x, y]. The bottom points are [x, -y].

// Another Syntax Error Here
/* 
//old code
    closed_shape = concat(
        for (p = profile_points) [p[0], -p[1]],
        profile_points
    );
*/

//revised code    
    closed_shape = concat(
    [ for (p = profile_points) [p[0], -p[1]] ], 
    profile_points
    );
   
    linear_extrude(height = 50) {
        polygon(closed_shape);
    }
}

function linear_interpolate(y0, y1, r0, r1, y) = r0 + (r1 - r0) * (y - y0) / (y1 - y0);

create_adapter();