use std::path::{Path, PathBuf};

use anyhow::{Context, anyhow};

fn generate<F>(generate: F) -> anyhow::Result<String>
where
    F: FnOnce() -> anyhow::Result<String> + Send + 'static,
{
    std::thread::Builder::new()
        .stack_size(256 * 1024 * 1024)
        .spawn(generate)
        .context("spawn generator thread")?
        .join()
        .map_err(|_| anyhow!("openapi generation panicked (stack overflow?)"))?
}

fn check_file(path: &Path, json: &str) -> anyhow::Result<()> {
    let existing =
        std::fs::read_to_string(path).with_context(|| format!("reading {}", path.display()))?;
    if existing.trim_end() != json.trim_end() {
        eprintln!(
            "{} is out of date; run `cargo run -p openapi` to regenerate",
            path.display()
        );
        std::process::exit(1);
    }
    Ok(())
}

fn main() -> anyhow::Result<()> {
    let web = generate(|| {
        let doc = webapi::openapi::api_doc();
        doc.to_pretty_json().context("serializing web openapi doc")
    })?;

    let crate_dir = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
    let root = crate_dir
        .ancestors()
        .nth(2)
        .ok_or_else(|| anyhow!("workspace root not found above {}", crate_dir.display()))?;
    let web_path = root.join("openapi.json");

    let check = std::env::args().nth(1).as_deref() == Some("--check");
    if check {
        check_file(&web_path, &web)?;
        println!("openapi.json is up to date");
        return Ok(());
    }

    std::fs::write(&web_path, web).with_context(|| format!("writing {}", web_path.display()))?;
    println!("wrote {}", web_path.display());
    Ok(())
}