fn main() {
    // Bake the short commit hash in for the About page. Falls back to "unknown"
    // in a non-git build (e.g. a source tarball). `logs/HEAD` is the reflog — it
    // gets a line on every commit/checkout, so watching it re-runs this script
    // when the hash changes (build.rs output is otherwise cached).
    let hash = std::process::Command::new("git")
        .args(["rev-parse", "--short", "HEAD"])
        .output()
        .ok()
        .filter(|o| o.status.success())
        .map(|o| String::from_utf8_lossy(&o.stdout).trim().to_string())
        .filter(|s| !s.is_empty())
        .unwrap_or_else(|| "unknown".to_string());
    println!("cargo:rustc-env=WA_GIT_HASH={hash}");
    println!("cargo:rerun-if-changed=../.git/logs/HEAD");

    // The `vulkan` build links `vulkan-1.dll` at load time, so the exe won't
    // launch on a machine that lacks the Vulkan loader (no GPU driver / bare VM).
    // Bundling the redistributable loader (Apache-2.0) next to the exe makes the
    // single universal installer start everywhere — with no GPU it simply reports
    // zero devices and we fall back to CPU. Copied both next to the built exe (so
    // `tauri dev`/`cargo run` work) and into the crate dir where the bundler picks
    // it up as a resource (see tauri.vulkan.conf.json).
    if std::env::var_os("CARGO_FEATURE_VULKAN").is_some() {
        stage_vulkan_loader();
    }

    tauri_build::build();
}

/// Locate `vulkan-1.dll` (Vulkan SDK first, then System32) and copy it beside
/// the compiled exe and into the crate dir for bundling. Warns rather than fails
/// so a dev build on a machine with the loader already on PATH still succeeds.
fn stage_vulkan_loader() {
    use std::path::{Path, PathBuf};

    let source = std::env::var_os("VULKAN_SDK")
        .map(|sdk| Path::new(&sdk).join("Bin").join("vulkan-1.dll"))
        .filter(|p| p.exists())
        .or_else(|| {
            let sys = PathBuf::from(r"C:\Windows\System32\vulkan-1.dll");
            sys.exists().then_some(sys)
        });
    let Some(source) = source else {
        println!(
            "cargo:warning=vulkan feature is on but vulkan-1.dll wasn't found \
             (set VULKAN_SDK); the installer won't bundle the Vulkan loader"
        );
        return;
    };

    // Beside the exe: OUT_DIR is target/<profile>/build/<pkg>-<hash>/out, so three
    // parents up is target/<profile> (correct even under CARGO_TARGET_DIR=C:\wt).
    if let Some(out_dir) = std::env::var_os("OUT_DIR") {
        if let Some(exe_dir) = Path::new(&out_dir).ancestors().nth(3) {
            let _ = std::fs::copy(&source, exe_dir.join("vulkan-1.dll"));
        }
    }
    // Into the crate dir for the bundler resource.
    let manifest_dir = std::env::var("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR");
    if let Err(e) = std::fs::copy(&source, Path::new(&manifest_dir).join("vulkan-1.dll")) {
        println!("cargo:warning=failed to stage vulkan-1.dll for bundling: {e}");
    }
}