use crate::ffi::CStr;
use crate::io as std_io;

unsafe extern "C" {
    #[thread_local]
    #[link_name = "errno"]
    static mut libc_errno: libc::c_int;
}

pub fn errno() -> i32 {
    unsafe { libc_errno as i32 }
}

pub fn set_errno(val: i32) {
    unsafe {
        libc_errno = val;
    }
}

#[inline]
pub fn is_interrupted(errno: i32) -> bool {
    errno == libc::EINTR
}

pub fn decode_error_kind(errno: i32) -> std_io::ErrorKind {
    use std_io::ErrorKind::*;
    match errno as libc::c_int {
        libc::E2BIG => ArgumentListTooLong,
        libc::EADDRINUSE => AddrInUse,
        libc::EADDRNOTAVAIL => AddrNotAvailable,
        libc::EBUSY => ResourceBusy,
        libc::ECONNABORTED => ConnectionAborted,
        libc::ECONNREFUSED => ConnectionRefused,
        libc::ECONNRESET => ConnectionReset,
        libc::EDEADLK => Deadlock,
        libc::EDQUOT => QuotaExceeded,
        libc::EEXIST => AlreadyExists,
        libc::EFBIG => FileTooLarge,
        libc::EHOSTUNREACH => HostUnreachable,
        libc::EINTR => Interrupted,
        libc::EINVAL => InvalidInput,
        libc::EISDIR => IsADirectory,
        libc::ELOOP => FilesystemLoop,
        libc::ENOENT => NotFound,
        libc::ENOMEM => OutOfMemory,
        libc::ENOSPC => StorageFull,
        libc::ENOSYS => Unsupported,
        libc::EMLINK => TooManyLinks,
        libc::ENAMETOOLONG => InvalidFilename,
        libc::ENETDOWN => NetworkDown,
        libc::ENETUNREACH => NetworkUnreachable,
        libc::ENOTCONN => NotConnected,
        libc::ENOTDIR => NotADirectory,
        libc::EPIPE => BrokenPipe,
        libc::EROFS => ReadOnlyFilesystem,
        libc::ESPIPE => NotSeekable,
        libc::ESTALE => StaleNetworkFileHandle,
        libc::ETIMEDOUT => TimedOut,
        libc::ETXTBSY => ExecutableFileBusy,
        libc::EXDEV => CrossesDevices,
        libc::EINPROGRESS => InProgress,
        libc::EOPNOTSUPP => Unsupported,
        libc::EACCES | libc::EPERM => PermissionDenied,
        libc::EWOULDBLOCK => WouldBlock,

        _ => Uncategorized,
    }
}

pub fn error_string(errno: i32) -> String {
    let mut buf = [0 as libc::c_char; 1024];

    let p = buf.as_mut_ptr();
    unsafe {
        if libc::strerror_r(errno as libc::c_int, p, buf.len()) < 0 {
            panic!("strerror_r failure");
        }
        str::from_utf8(CStr::from_ptr(p).to_bytes()).unwrap().to_owned()
    }
}