// embeds assets/Icon.svg into the windows .exe via rsvg-convert, magick, llvm-windres, and rustc-link-arg-bins.

fn main() {
    let target_os = std::env::var("CARGO_CFG_TARGET_OS").unwrap_or_default();
    if target_os != "windows" {
        return;
    }

    let svg = "assets/Icon.svg";
    let out_dir = std::env::var("OUT_DIR").expect("cargo OUT_DIR");
    let tmp = format!("{out_dir}/icon_tmp");
    let ico = format!("{out_dir}/icon.ico");
    let rc = format!("{out_dir}/icon.rc");
    let res = format!("{out_dir}/icon.res");

    println!("cargo:rerun-if-changed={svg}");
    println!("cargo:rerun-if-changed=build.rs");

    if !std::path::Path::new(svg).exists() {
        println!("cargo:warning=no {svg} — skipping windows icon embed");
        return;
    }

    let _ = std::fs::create_dir_all(&tmp);
    let sizes = [16, 24, 32, 48, 64, 128, 256];
    let mut pngs: Vec<String> = Vec::new();
    for size in sizes {
        let out = format!("{tmp}/icon_{size}.png");
        let s = size.to_string();
        if !run(&["rsvg-convert", "--width", &s, "--height", &s, svg, "-o", &out]) {
            println!("cargo:warning=rsvg-convert failed — windows icon not embedded (brew install librsvg)");
            let _ = std::fs::remove_dir_all(&tmp);
            return;
        }
        pngs.push(out);
    }

    let mut magick_args: Vec<&str> = pngs.iter().map(|s| s.as_str()).collect();
    magick_args.push(&ico);
    if !run_vec("magick", &magick_args) {
        println!("cargo:warning=magick failed — windows icon not embedded (brew install imagemagick)");
        let _ = std::fs::remove_dir_all(&tmp);
        return;
    }
    let _ = std::fs::remove_dir_all(&tmp);

    if std::fs::write(&rc, "1 ICON \"icon.ico\"\r\n").is_err() {
        println!("cargo:warning=could not write {rc} — windows icon not embedded");
        return;
    }

    let Some(windres) = locate_llvm_windres() else {
        println!("cargo:warning=llvm-windres not found — windows icon not embedded (brew install llvm)");
        return;
    };
    if !run(&[&windres, "-I", &out_dir, &rc, "-o", &res]) {
        println!("cargo:warning=llvm-windres failed — windows icon not embedded");
        return;
    }

    println!("cargo:rustc-link-arg-bins={res}");
}

/// resolves llvm-windres from $LLVM_WINDRES, Homebrew's keg-only llvm prefix on Apple Silicon and Intel, or $PATH.
fn locate_llvm_windres() -> Option<String> {
    if let Ok(p) = std::env::var("LLVM_WINDRES") {
        if std::path::Path::new(&p).exists() {
            return Some(p);
        }
    }
    let candidates = [
        "/opt/homebrew/opt/llvm/bin/llvm-windres",
        "/usr/local/opt/llvm/bin/llvm-windres",
    ];
    for c in candidates {
        if std::path::Path::new(c).exists() {
            return Some(c.to_string());
        }
    }
    if run(&["sh", "-c", "command -v llvm-windres"]) {
        return Some("llvm-windres".to_string());
    }
    None
}

fn run(args: &[&str]) -> bool {
    std::process::Command::new(args[0])
        .args(&args[1..])
        .status()
        .map(|s| s.success())
        .unwrap_or(false)
}

fn run_vec(cmd: &str, args: &[&str]) -> bool {
    std::process::Command::new(cmd)
        .args(args)
        .status()
        .map(|s| s.success())
        .unwrap_or(false)
}