// SPDX-FileCopyrightText: 2022 Matteo Settenvini <matteo.settenvini@montecristosoftware.eu>
// SPDX-License-Identifier: GPL-3.0-or-later

#![allow(non_upper_case_globals)]
#![allow(non_camel_case_types)]
#![allow(non_snake_case)]
#![allow(dead_code)]

use std::str::FromStr;

include!(concat!(env!("OUT_DIR"), "/bindings.rs"));

use {
    anyhow::{anyhow, bail, ensure, Result},
    libc::{freeaddrinfo, gai_strerror, getaddrinfo},
    nix::sys::socket::{SockaddrLike as _, SockaddrStorage},
    std::env,
    std::ffi::{CStr, CString},
    std::net::{IpAddr, Ipv4Addr, Ipv6Addr},
    std::path::PathBuf,
    std::process::Command,
    std::sync::Once,
};

pub type Eai = EaiRetcode;

static SETUP: Once = Once::new();

pub fn setup() -> Result<()> {
    let out_dir = PathBuf::from(env!("OUT_DIR"));
    let nss_config_status = unsafe {
        SETUP.call_once(|| {
            let library_path = test_cdylib::build_current_project();
            let mut library_filename = library_path.file_name().unwrap().to_owned();
            library_filename.push(".2"); // required for NSS modules

            let dest = out_dir.join(library_filename);
            std::fs::copy(library_path, dest).unwrap();
        });

        let db = CString::new("hosts").unwrap();
        let resolvers = CString::new("malcontent dns").unwrap();
        __nss_configure_lookup(db.as_ptr(), resolvers.as_ptr())
    };

    ensure!(
        nss_config_status == 0,
        "Unable to configure NSS to load module: __nss_configure_lookup() returned {}",
        nss_config_status
    );

    Ok(())
}

pub fn system_resolve(host: &str) -> Result<IpAddr> {
    let process = Command::new("getent").arg("hosts").arg(host).output()?;
    ensure!(
        process.status.success(),
        "Failed to run getent to check host IP"
    );
    let output = String::from_utf8(process.stdout)?;
    let addr_string = output
        .as_str()
        .split(' ')
        .next()
        .ok_or(anyhow!("Unparseable output from getent"))?;
    Ok(IpAddr::from_str(&addr_string)?)
}

pub fn convert_addrinfo(sa: &SockaddrStorage) -> Result<IpAddr> {
    if let Some(addr) = sa.as_sockaddr_in() {
        Ok(IpAddr::V4(Ipv4Addr::from(addr.ip())))
    } else if let Some(addr) = sa.as_sockaddr_in6() {
        Ok(IpAddr::V6(Ipv6Addr::from(addr.ip())))
    } else {
        bail!("addrinfo is not either an IPv4 or IPv6 address")
    }
}

pub fn resolve_system_and_us(hostname: &str) -> Result<(IpAddr, IpAddr)> {
    setup()?;
    let ip_from_system = system_resolve(hostname)?;

    let c_hostname = CString::new(hostname).unwrap();
    unsafe {
        let mut addr = std::ptr::null_mut();
        let getaddrinfo_status = getaddrinfo(
            c_hostname.as_ptr(),
            std::ptr::null(),
            std::ptr::null(),
            &mut addr,
        );

        let error = CStr::from_ptr(gai_strerror(getaddrinfo_status));
        assert_eq!(
            getaddrinfo_status,
            Eai::Success.0,
            "Should have gotten hostname for {}, instead got {}",
            hostname,
            error.to_str().unwrap()
        );
        let addr_storage = SockaddrStorage::from_raw((*addr).ai_addr, Some((*addr).ai_addrlen))
            .ok_or(anyhow!("Garbled addrinfo from getaddrinfo()"))?;
        let ip_from_us = convert_addrinfo(&addr_storage)?;
        freeaddrinfo(addr);
        Ok((ip_from_system, ip_from_us))
    }
}