#[cfg(target_os = "linux")]
use std::ffi::c_int;
use std::path::PathBuf;

use anyhow::Context;
use sparse_05_common::messages::{Capabilities, OperatingSystem, TransportType};

#[derive(Debug)]
pub struct SrvCapabilities {
    pub operating_system: OperatingSystem,
    pub docker_container: bool,
    pub docker_breakout: bool,
    pub setuid: bool,
    pub root: bool,
    pub service: bool,
    pub userent: Option<String>,
    pub transport: TransportType,
    pub hostname: Option<String>,
}

impl SrvCapabilities {
    pub fn to_capabilities(&self) -> Capabilities {
        Capabilities {
            cwd: PathBuf::from("/"),
            docker_breakout: self.docker_breakout,
            docker_container: self.docker_container,
            hostname: self.hostname.clone(),
            operating_system: self.operating_system.clone(),
            root: self.root,
            setuid: self.setuid,
            service: self.service,
            transport: self.transport,
            userent: self.userent.clone(),
        }
    }
}

#[cfg(target_os = "linux")]
const CAP_SETUID: u32 = 1 << 7;
#[cfg(target_os = "linux")]
const CAP_NET_RAW: u32 = 1 << 13;
#[cfg(target_os = "linux")]
const SYS_CAPGET: i64 = 125;

#[cfg(target_os = "linux")]
#[allow(non_camel_case_types)]
#[repr(C)]
#[derive(Debug)]
struct cap_user_header_t {
    version: u32,
    pid: c_int,
}

#[cfg(target_os = "linux")]
#[allow(non_camel_case_types)]
#[repr(C)]
#[derive(Debug)]
struct cap_user_data_t {
    effective: u32,
    permitted: u32,
    inheritable: u32,
}

#[cfg(any(target_os = "linux", target_os = "freebsd"))]
fn get_username(uid: u32) -> anyhow::Result<Option<String>> {
    let passwd = std::fs::read_to_string("/etc/passwd")?;

    Ok(passwd.split("\n").find_map(|row| -> Option<String> {
        let mut entries = row.split(":");

        let name = entries.next()?;
        entries.next()?;
        let euid = entries.next()?.parse::<u32>().ok()?;

        if euid == uid {
            Some(name.to_string())
        } else {
            None
        }
    }))
}

#[cfg(target_os = "windows")]
fn get_username(_uid: u32) -> anyhow::Result<Option<String>> {
    Ok(std::env::var("USERNAME").ok())
}

#[cfg(target_os = "linux")]
fn get_current_capabilities() -> anyhow::Result<SrvCapabilities> {
    let mut header = cap_user_header_t {
        version: 0x20080522,
        pid: 0,
    };
    let mut data = cap_user_data_t {
        effective: 0,
        permitted: 0,
        inheritable: 0,
    };
    let oscapabilities =
        unsafe { libc::syscall(SYS_CAPGET, &mut header as *const _, &mut data as *mut _) };

    if oscapabilities == -1 {
        return Err(std::io::Error::last_os_error())?;
    }

    let docker_container = std::fs::read_to_string("/proc/1/cgroup")? != "0::/\n";
    let docker_breakout = false;
    let uid = unsafe { libc::getuid() };
    let root = uid == 0;
    let setuid = data.effective & CAP_SETUID != 0;
    let transport = if data.effective & CAP_NET_RAW != 0 || root {
        TransportType::RawUdp
    } else {
        TransportType::Udp
    };
    let userent = get_username(uid)?;
    let hostname = std::fs::read_to_string("/etc/hostname")
        .map(|s| s.trim().to_string())
        .ok();

    Ok(SrvCapabilities {
        operating_system: OperatingSystem::Linux,
        docker_container,
        docker_breakout,
        setuid,
        root,
        service: false,
        userent,
        transport,
        hostname,
    })
}

#[cfg(target_os = "windows")]
fn get_current_capabilities() -> anyhow::Result<SrvCapabilities> {
    let userent = get_username(0)?;
    let hostname = std::env::var("COMPUTERNAME").ok();
    let service_name = hostname.clone().map(|name| format!("{name}$"));

    Ok(SrvCapabilities {
        operating_system: OperatingSystem::Windows,
        docker_container: false,
        docker_breakout: false,
        setuid: false,
        service: userent.as_deref() == service_name.as_deref(),
        root: userent.as_deref() == Some("Administrator"),
        userent: userent.clone(),
        transport: TransportType::RawUdp,
        hostname,
    })
}

#[cfg(target_os = "freebsd")]
fn get_current_capabilities() -> anyhow::Result<SrvCapabilities> {
    let uid = unsafe { libc::getuid() };
    let root = uid == 0;
    let userent = get_username(uid)?;
    let hostname = std::fs::read_to_string("/etc/rc.conf")?
        .split("\n")
        .map(|line| line.split("=").collect::<Vec<_>>())
        .find(|line| line.get(0) == Some(&"hostname"))
        .map(|line| line.get(1).map(|name| name.to_string()))
        .flatten();

    Ok(SrvCapabilities {
        operating_system: OperatingSystem::FreeBSD,
        docker_container: false,
        docker_breakout: false,
        setuid: false,
        service: false,
        root,
        userent: userent.clone(),
        transport: TransportType::RawUdp,
        hostname,
    })
}

pub fn get_capabilities() -> anyhow::Result<SrvCapabilities> {
    get_current_capabilities()
}