$fn = 64;

// --- Parametric Variables ---
trellis_width = 120;
trellis_height = 220;
thickness = 4;
bar_width = 6;
grid_spacing = 25;
peg_length = 35;
tie_outer_dia = 12;
tie_inner_dia = 6;

module trellis() {
    difference() {
        union() {
            // Main Outer Frame
            difference() {
                cube([trellis_width, trellis_height, thickness]);
                
                // Inner Cutout (leaves a thick top header for stacking slots)
                translate([bar_width, bar_width, -1])
                    cube([
                        trellis_width - 2*bar_width, 
                        trellis_height - 2*bar_width - peg_length, 
                        thickness + 2
                    ]);
            }
            
            // Sturdy Diagonal Lattice
            intersection() {
                // Bounding box to keep lattice neatly inside the frame
                translate([bar_width, bar_width, 0])
                    cube([
                        trellis_width - 2*bar_width, 
                        trellis_height - 2*bar_width - peg_length, 
                        thickness
                    ]);
                
                union() {
                    for (i = [-trellis_height : grid_spacing : trellis_width + trellis_height]) {
                        // Right-leaning bars
                        translate([i, 0, 0]) rotate([0, 0, 45])
                            translate([-bar_width/2, -trellis_height, 0]) 
                                cube([bar_width, trellis_height*3, thickness]);
                        // Left-leaning bars
                        translate([i, 0, 0]) rotate([0, 0, -45])
                            translate([-bar_width/2, -trellis_height, 0]) 
                                cube([bar_width, trellis_height*3, thickness]);
                    }
                }
            }
            
            // Horizontal Stabilizer Bars
            for (y = [(trellis_height - peg_length)*0.33, (trellis_height - peg_length)*0.66]) {
                translate([0, y, 0])
                    cube([trellis_width, bar_width, thickness]);
            }

            // Bottom Stacking Pegs (Inserts into pot rings or another trellis)
            peg_w = bar_width * 1.5;
            spacing = trellis_width * 0.6;
            for (x = [trellis_width/2 - spacing/2, trellis_width/2 + spacing/2]) {
                translate([x - peg_w/2, -peg_length, 0]) {
                    // Main peg body
                    cube([peg_w, peg_length, thickness]);
                    // Snap-fit retention bumps
                    translate([-1.5, peg_length * 0.4, 0])
                        cube([peg_w + 3, 4, thickness]);
                }
            }
            
            // Integrated Tie Points (Loops on the outer edges)
            for (y = [trellis_height*0.2, trellis_height*0.45, trellis_height*0.7]) {
                // Left tie point
                translate([0, y, 0])
                    difference() {
                        cylinder(d=tie_outer_dia, h=thickness);
                        translate([0, 0, -1]) cylinder(d=tie_inner_dia, h=thickness+2);
                    }
                // Right tie point
                translate([trellis_width, y, 0])
                    difference() {
                        cylinder(d=tie_outer_dia, h=thickness);
                        translate([0, 0, -1]) cylinder(d=tie_inner_dia, h=thickness+2);
                    }
            }
        }
        
        // Top Slots for Stacking Extended Height Panels
        peg_w = bar_width * 1.5;
        spacing = trellis_width * 0.6;
        clearance = 0.8; // Generous clearance for easy fit after printing
        
        for (x = [trellis_width/2 - spacing/2, trellis_width/2 + spacing/2]) {
            translate([x - peg_w/2 - clearance/2, trellis_height - peg_length, -1]) {
                // Main slot cutout
                cube([peg_w + clearance, peg_length + 2, thickness + 2]);
                // Snap-fit bump cutout
                translate([-2, peg_length * 0.4 - 1, 0])
                    cube([peg_w + clearance + 4, 4 + 2, thickness + 2]);
            }
        }
    }
}

// Render the object
trellis();