use image;

fn main() {
    let out_path = "/tmp/composite_output.png";
    let ref_path = "_images/_test_images/example3/Example3-mini.png";

    if !std::path::Path::new(out_path).exists() || !std::path::Path::new(ref_path).exists() {
        println!("Images not found.");
        return;
    }

    let out_img = image::open(out_path).unwrap().to_rgba8();
    let ref_img = image::open(ref_path).unwrap().to_rgba8();

    if out_img.width() != ref_img.width() || out_img.height() != ref_img.height() {
        println!("Dimensions differ: out={}x{}, ref={}x{}", out_img.width(), out_img.height(), ref_img.width(), ref_img.height());
        return;
    }

    let mut diffs = Vec::new();
    for y in 0..out_img.height() {
        for x in 0..out_img.width() {
            let p1 = out_img.get_pixel(x, y);
            let p2 = ref_img.get_pixel(x, y);
            let dr = (p1[0] as i32 - p2[0] as i32).abs();
            let dg = (p1[1] as i32 - p2[1] as i32).abs();
            let db = (p1[2] as i32 - p2[2] as i32).abs();
            let da = (p1[3] as i32 - p2[3] as i32).abs();
            let total = dr + dg + db + da;
            if total > 0 {
                diffs.push((x, y, p1.0, p2.0, total));
            }
        }
    }

    diffs.sort_by_key(|d| std::cmp::Reverse(d.4));

    println!("Total differing pixels: {} / {}", diffs.len(), out_img.width() * out_img.height());
    println!("\nTop 50 worst pixels:");
    for i in 0..50.min(diffs.len()) {
        let (x, y, p1, p2, total) = diffs[i];
        println!("  at ({:4}, {:4}): out={:?}, ref={:?}, sum_diff={}", x, y, p1, p2, total);
    }
}