use anyhow::Result;

fn main() -> Result<()> {
    #[cfg(feature = "runtime")]
    loopdev()?;

    #[cfg(feature = "seccomp")]
    generate_seccomp()?;

    Ok(())
}

#[cfg(feature = "seccomp")]
fn generate_seccomp() -> Result<()> {
    use anyhow::Context;
    use std::{env, fs, io::Write, path::PathBuf};

    let lines = bindgen::Builder::default()
        .header_contents("syscall.h", "#include <sys/syscall.h>")
        .allowlist_var("SYS_[0-9a-zA-Z_]+")
        .generate()
        .context("failed to generate syscall bindings")?
        .to_string();
    let lines: Vec<&str> = lines
        .lines()
        .filter(|s| s.starts_with("pub const SYS_"))
        .collect();

    let out_path = PathBuf::from(env::var("OUT_DIR")?);
    let mut f = fs::File::create(out_path.join("syscall_bindings.rs"))?;

    f.write_all(lines.join("\n").as_bytes())?;
    writeln!(f)?;
    writeln!(f)?;

    // Write static map that associates syscall strings with syscall numbers
    writeln!(f, "lazy_static::lazy_static! {{")?;
    writeln!(
        f,
        "    pub(super) static ref SYSCALL_MAP: std::collections::HashMap<&'static str, u32> = {{"
    )?;
    writeln!(f, "        let mut map = std::collections::HashMap::new();")?;
    lines.iter().try_for_each(|l| {
        let mut split = l.split_ascii_whitespace();
        let var = split.nth(2).unwrap().trim_end_matches(':');
        let name = var.replace("SYS_", "");
        writeln!(f, "        map.insert(\"{name}\", {var});")?;
        std::io::Result::Ok(())
    })?;
    writeln!(f, "        map")?;
    writeln!(f, "    }};")?;
    writeln!(f, "}}")?;

    let out_path = PathBuf::from(env::var("OUT_DIR")?);
    bindgen::Builder::default()
        .header_contents(
            "seccomp.h",
            r#"#include <linux/seccomp.h>
#include <linux/filter.h>
#include <linux/audit.h>"#,
        )
        .layout_tests(false)
        .allowlist_type("seccomp_data")
        .allowlist_type("sock_fprog")
        .allowlist_var("BPF_ABS")
        .allowlist_var("BPF_AND")
        .allowlist_var("BPF_ALU")
        .allowlist_var("BPF_IMM")
        .allowlist_var("BPF_IND")
        .allowlist_var("BPF_JEQ")
        .allowlist_var("BPF_JMP")
        .allowlist_var("BPF_NEG")
        .allowlist_var("BPF_K")
        .allowlist_var("BPF_LD")
        .allowlist_var("BPF_LDX")
        .allowlist_var("BPF_MEM")
        .allowlist_var("BPF_OR")
        .allowlist_var("BPF_RET")
        .allowlist_var("BPF_ST")
        .allowlist_var("BPF_W")
        .allowlist_var("BPF_MAXINSNS")
        .allowlist_var("AUDIT_ARCH_X86_64")
        .allowlist_var("AUDIT_ARCH_AARCH64")
        .generate()
        .context("failed to generate seccomp bindings")?
        .write_to_file(out_path.join("seccomp_bindings.rs"))?;
    Ok(())
}

#[cfg(feature = "runtime")]
fn loopdev() -> Result<()> {
    use anyhow::Context;
    use std::{env, path::PathBuf};

    let out_path = PathBuf::from(env::var("OUT_DIR")?);
    let bindings = bindgen::Builder::default()
        .header_contents("loopdev.h", "#include <linux/loop.h>")
        .derive_default(true)
        .generate()
        .context("failed to generated loopdev bindings")?;

    bindings
        .write_to_file(out_path.join("loopdev.rs"))
        .context("failed to generated loopdev bindings")
}