arr is running

//! Resolve the SPA bundle embedded by `web.rs` via `include_dir!`.
//!
//! Three modes, in order:
//!
//! * `ARR_WEB_DIST` set — a prebuilt bundle (Nix, CI, release pipeline) is
//!   embedded as-is. Missing or empty means a broken pipeline: fail.
//! * pnpm available — the default developer path: build `web/` and embed
//!   `web/dist`. Failures in the build itself fail loudly.
//! * pnpm missing, debug profile — embed a generated placeholder page and
//!   warn. This keeps `cargo clippy`/`cargo test` working on runners with no
//!   node toolchain (the CI rust job, DESIGN.md §12).
//!
//! A release build never gets the placeholder: shipping a binary whose UI is
//! an apology defeats the single-binary acceptance test, so that combination
//! panics instead.

use std::env;
use std::path::PathBuf;
use std::process::Command;

fn main() {
    println!("cargo:rerun-if-env-changed=ARR_WEB_DIST");

    let dist = match env::var_os("ARR_WEB_DIST") {
        Some(prebuilt) => PathBuf::from(prebuilt),
        None => build_or_placeholder(),
    };

    let index = dist.join("index.html");
    let bundled = std::fs::metadata(&index).is_ok_and(|m| m.is_file() && m.len() > 0);
    assert!(
        bundled,
        "no SPA bundle at {} (missing or empty index.html) — check the vite \
         outDir or the ARR_WEB_DIST override",
        index.display()
    );

    // `include_dir!` expands `$VAR` against the env rustc is invoked with,
    // which is what `cargo:rustc-env` sets.
    println!("cargo:rustc-env=ARR_WEB_BUNDLE_DIR={}", dist.display());
}

fn build_or_placeholder() -> PathBuf {
    let manifest_dir =
        PathBuf::from(env::var("CARGO_MANIFEST_DIR").expect("cargo sets CARGO_MANIFEST_DIR"));
    let web_dir = manifest_dir.join("../../web");

    // Rebuild only when a frontend input changes, not on unrelated Rust
    // recompiles. The dist watch matters too: the inputs decide whether this
    // script reruns, but `include_dir!` reads dist, and without this watch an
    // incremental build can regenerate dist yet keep the old bytes embedded.
    for rel in [
        "src",
        "index.html",
        "package.json",
        "pnpm-lock.yaml",
        "pnpm-workspace.yaml",
        "vite.config.ts",
        "tsconfig.json",
        "dist",
    ] {
        println!("cargo:rerun-if-changed={}", web_dir.join(rel).display());
    }

    if !tool_works("pnpm") {
        let profile = env::var("PROFILE").unwrap_or_default();
        assert!(
            profile != "release",
            "arr embeds the web SPA at build time and needs pnpm + node for a \
             release build. Install them, or point ARR_WEB_DIST at a prebuilt \
             bundle."
        );
        println!(
            "cargo:warning=pnpm not found; embedding a placeholder page instead of \
             the web SPA (debug builds only)"
        );
        return write_placeholder();
    }

    run(
        Command::new("pnpm")
            .args(["install", "--frozen-lockfile"])
            .current_dir(&web_dir),
        "pnpm install --frozen-lockfile",
    );
    run(
        Command::new("pnpm").arg("build").current_dir(&web_dir),
        "pnpm build",
    );

    web_dir.join("dist")
}

fn write_placeholder() -> PathBuf {
    let out = PathBuf::from(env::var("OUT_DIR").expect("cargo sets OUT_DIR")).join("placeholder");
    std::fs::create_dir_all(&out).expect("create placeholder dir");
    std::fs::write(out.join("index.html"), PLACEHOLDER_HTML).expect("write placeholder");
    out
}

fn tool_works(tool: &str) -> bool {
    Command::new(tool)
        .arg("--version")
        .output()
        .is_ok_and(|o| o.status.success())
}

fn run(cmd: &mut Command, label: &str) {
    let status = cmd
        .status()
        .unwrap_or_else(|e| panic!("failed to spawn `{label}`: {e}"));
    assert!(status.success(), "`{label}` failed with {status}");
}

const PLACEHOLDER_HTML: &str = r#"<!doctype html>
<meta charset="utf-8">
<title>arr — web bundle not built</title>
<style>
  body { font-family: ui-sans-serif, system-ui, sans-serif; max-width: 40em;
         margin: 4em auto; padding: 0 1em; line-height: 1.5; }
  code { background: #eee; padding: 0.1em 0.3em; border-radius: 3px; }
</style>
<h1>arr is running</h1>
<p>but this binary was built without the web bundle (no pnpm on the build
machine). Rebuild with pnpm + node installed, or set <code>ARR_WEB_DIST</code>
to a prebuilt bundle.</p>
"#;