//
// Sysinfo
//
// Copyright (c) 2017 Guillaume Gomez
//

use crate::Pid;
#[cfg(not(any(target_os = "windows", target_os = "unknown", target_arch = "wasm32")))]
use std::ffi::OsStr;
#[cfg(not(any(target_os = "windows", target_os = "unknown", target_arch = "wasm32")))]
use std::os::unix::ffi::OsStrExt;
#[cfg(not(any(target_os = "windows", target_os = "unknown", target_arch = "wasm32")))]
use std::path::Path;

#[allow(clippy::useless_conversion)]
#[cfg(not(any(
    target_os = "windows",
    target_os = "unknown",
    target_arch = "wasm32",
    target_os = "macos",
    target_os = "ios"
)))]
pub fn realpath(original: &Path) -> std::path::PathBuf {
    use libc::{c_char, lstat, stat, S_IFLNK, S_IFMT};
    use std::fs;
    use std::mem::MaybeUninit;
    use std::path::PathBuf;

    fn and(x: u32, y: u32) -> u32 {
        x & y
    }

    // let ori = Path::new(original.to_str().unwrap());
    // Right now lstat on windows doesn't work quite well
    // if cfg!(windows) {
    //     return PathBuf::from(ori);
    // }
    let result = PathBuf::from(original);
    let mut result_s = result.to_str().unwrap_or("").as_bytes().to_vec();
    result_s.push(0);
    let mut buf = MaybeUninit::<stat>::uninit();
    let res = unsafe { lstat(result_s.as_ptr() as *const c_char, buf.as_mut_ptr()) };
    let buf = unsafe { buf.assume_init() };
    if res < 0 || and(buf.st_mode.into(), S_IFMT.into()) != S_IFLNK.into() {
        PathBuf::new()
    } else {
        match fs::read_link(&result) {
            Ok(f) => f,
            Err(_) => PathBuf::new(),
        }
    }
}

/* convert a path to a NUL-terminated Vec<u8> suitable for use with C functions */
#[cfg(not(any(target_os = "windows", target_os = "unknown", target_arch = "wasm32")))]
pub fn to_cpath(path: &Path) -> Vec<u8> {
    let path_os: &OsStr = path.as_ref();
    let mut cpath = path_os.as_bytes().to_vec();
    cpath.push(0);
    cpath
}

/// Returns the pid for the current process.
///
/// `Err` is returned in case the platform isn't supported.
///
/// ```no_run
/// use sysinfo::get_current_pid;
///
/// match get_current_pid() {
///     Ok(pid) => {
///         println!("current pid: {}", pid);
///     }
///     Err(e) => {
///         eprintln!("failed to get current pid: {}", e);
///     }
/// }
/// ```
#[allow(clippy::unnecessary_wraps)]
pub fn get_current_pid() -> Result<Pid, &'static str> {
    cfg_if::cfg_if! {
        if #[cfg(not(any(target_os = "windows", target_os = "unknown", target_arch = "wasm32")))] {
            fn inner() -> Result<Pid, &'static str> {
                unsafe { Ok(::libc::getpid()) }
            }
        } else if #[cfg(target_os = "windows")] {
            fn inner() -> Result<Pid, &'static str> {
                use winapi::um::processthreadsapi::GetCurrentProcessId;

                unsafe { Ok(GetCurrentProcessId() as Pid) }
            }
        } else if #[cfg(target_os = "unknown")] {
            fn inner() -> Result<Pid, &'static str> {
                Err("Unavailable on this platform")
            }
        } else {
            fn inner() -> Result<Pid, &'static str> {
                Err("Unknown platform")
            }
        }
    }
    inner()
}

/// Converts the value into a parallel iterator (if the multithread feature is enabled)
/// Uses the rayon::iter::IntoParallelIterator trait
#[cfg_attr(any(target_os = "ios", feature = "apple-app-store"), allow(dead_code))]
#[cfg(feature = "multithread")]
pub fn into_iter<T>(val: T) -> T::Iter
where
    T: rayon::iter::IntoParallelIterator,
{
    val.into_par_iter()
}

/// Converts the value into a sequential iterator (if the multithread feature is disabled)
/// Uses the std::iter::IntoIterator trait
#[cfg_attr(any(target_os = "ios", feature = "apple-app-store"), allow(dead_code))]
#[cfg(not(feature = "multithread"))]
pub fn into_iter<T>(val: T) -> T::IntoIter
where
    T: IntoIterator,
{
    val.into_iter()
}