// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

#![expect(clippy::unwrap_used, reason = "OK in build scripts.")]

use std::env;

const BINDINGS: &str = "bindings.rs";

#[cfg(feature = "gecko")]
fn clang_args() -> Vec<String> {
    use mozbuild::{config::BINDGEN_SYSTEM_FLAGS, TOPOBJDIR};

    let mut flags: Vec<String> = BINDGEN_SYSTEM_FLAGS.iter().map(|s| s.to_string()).collect();

    flags.push(String::from("-include"));
    flags.push(
        TOPOBJDIR
            .join("dist")
            .join("include")
            .join("mozilla-config.h")
            .to_str()
            .unwrap()
            .to_string(),
    );
    flags
}

#[cfg(not(feature = "gecko"))]
const fn clang_args() -> Vec<String> {
    Vec::new()
}

fn bindgen() {
    let target_os = env::var("CARGO_CFG_TARGET_OS").expect("CARGO_CFG_TARGET_OS was not set");

    // Platforms currently not supported.
    //
    // See <https://github.com/mozilla/mtu/issues/82>.
    if matches!(target_os.as_str(), "ios" | "tvos" | "visionos") {
        return;
    }

    if target_os == "windows" {
        return;
    }

    let bindings = if matches!(target_os.as_str(), "linux" | "android") {
        bindgen::Builder::default()
            .header_contents("rtnetlink.h", "#include <linux/rtnetlink.h>")
            // Only generate bindings for the following types
            .allowlist_type("rtattr|rtmsg|ifinfomsg|nlmsghdr")
    } else {
        bindgen::Builder::default()
        .header_contents(
            "route.h",
            "#include <sys/types.h>\n#include <sys/socket.h>\n#include <net/route.h>\n#include <net/if.h>",
        )
        // Only generate bindings for the following types and items
        .allowlist_type("rt_msghdr|rt_metrics|if_data")
        .allowlist_item("RTAX_MAX|RTM_GET|RTM_VERSION|RTA_DST|RTA_IFP")
    };

    let bindings = bindings
        .clang_args(clang_args())
        // Tell cargo to invalidate the built crate whenever any of the
        // included header files changed.
        .parse_callbacks(Box::new(bindgen::CargoCallbacks::new()))
        // Constants should be generated as &CStr instead of &[u8].
        .generate_cstr(true)
        // Always emit explicit padding fields.
        .explicit_padding(true)
        // Default trait should be derived when possible
        .derive_default(true)
        // Finish the builder and generate the bindings.
        .generate()
        // Unwrap the Result and panic on failure.
        .expect("Unable to generate bindings");

    // Write the bindings to the $OUT_DIR/$BINDINGS file.
    let out_path = std::path::PathBuf::from(env::var("OUT_DIR").unwrap()).join(BINDINGS);
    bindings
        .write_to_file(out_path.clone())
        .expect("Couldn't write bindings!");
    println!("cargo:rustc-env=BINDINGS={}", out_path.display());
}

fn main() {
    // Setup cfg aliases
    cfg_aliases::cfg_aliases! {
        bsd: {
            any(
                target_os = "freebsd",
                target_os = "openbsd",
                target_os = "netbsd",
                target_os = "solaris"
            )
        }
    }

    bindgen();
}