//! QEMU: boot a registry entry with qemu-system-x86_64 using direct kernel
//! boot (-kernel/-initrd).

use anyhow::{Context, Result, bail};
use std::process::Command;

use crate::registry::registry_dir;

pub(crate) fn run(name: &str) -> Result<()> {
    let reg_dir = registry_dir(name)?;
    let vmlinuz_path = reg_dir.join("vmlinuz");
    let initrd_path = reg_dir.join("initrd");
    if !vmlinuz_path.exists() || !initrd_path.exists() {
        bail!(
            "Registry missing vmlinuz/initrd for '{}'. Run `slim build` first.",
            name
        );
    }
    println!("Booting {} from registry: {}", name, reg_dir.display());
    println!(
        "  qemu-system-x86_64 -m 256 -nographic -kernel {} -initrd {} -append 'console=ttyS0'",
        vmlinuz_path.display(),
        initrd_path.display()
    );

    let cmdline = [
        "console=ttyS0,115200",
        "root=/dev/ram0",
        "rw",
        "earlyprintk=serial",
        "nokaslr",
        "raid=noautodetect",
    ]
    .join(" ");

    let status = Command::new("qemu-system-x86_64")
        .args(["-m", "1024M"])
        .arg("-kernel")
        .arg(vmlinuz_path.as_os_str())
        .arg("-initrd")
        .arg(initrd_path.as_os_str())
        .args(["-append", &cmdline])
        .args(["-nographic"])
        .status()
        .context("Failed to launch qemu-system-x86_64")?;

    match status.code() {
        Some(0) => println!("QEMU exited cleanly."),
        Some(126) | Some(127) => {
            bail!("Failed to start qemu-system-x86_64 (is it installed and in PATH?)")
        }
        Some(code) => bail!("QEMU exited with code {code}"),
        None => bail!("QEMU terminated by a signal"),
    }
    Ok(())
}