#![allow(missing_docs, nonstandard_style)]

use crate::ffi::{OsStr, OsString};
use crate::io::ErrorKind;
use crate::os::windows::ffi::{OsStrExt, OsStringExt};
use crate::path::PathBuf;
use crate::time::Duration;

pub use self::rand::hashmap_random_keys;
pub use libc::strlen;

#[macro_use]
pub mod compat;

pub mod alloc;
pub mod args;
pub mod c;
pub mod cmath;
pub mod condvar;
pub mod env;
pub mod fs;
pub mod handle;
pub mod io;
pub mod memchr;
pub mod mutex;
pub mod net;
pub mod os;
pub mod os_str;
pub mod path;
pub mod pipe;
pub mod process;
pub mod rand;
pub mod rwlock;
pub mod thread;
pub mod thread_local_dtor;
pub mod thread_local_key;
pub mod thread_parker;
pub mod time;
cfg_if::cfg_if! {
    if #[cfg(not(target_vendor = "uwp"))] {
        pub mod stdio;
        pub mod stack_overflow;
    } else {
        pub mod stdio_uwp;
        pub mod stack_overflow_uwp;
        pub use self::stdio_uwp as stdio;
        pub use self::stack_overflow_uwp as stack_overflow;
    }
}

// SAFETY: 在运行时初始化期间只能调用一次。
// NOTE: 这不能保证运行，例如在外部调用 Rust 代码时。
pub unsafe fn init(_argc: isize, _argv: *const *const u8) {
    stack_overflow::init();
}

// SAFETY: 在运行时清理期间只能调用一次。
// NOTE: 这不能保证运行，例如当程序中止时。
pub unsafe fn cleanup() {
    net::cleanup();
}

pub fn decode_error_kind(errno: i32) -> ErrorKind {
    use ErrorKind::*;

    match errno as c::DWORD {
        c::ERROR_ACCESS_DENIED => return PermissionDenied,
        c::ERROR_ALREADY_EXISTS => return AlreadyExists,
        c::ERROR_FILE_EXISTS => return AlreadyExists,
        c::ERROR_BROKEN_PIPE => return BrokenPipe,
        c::ERROR_FILE_NOT_FOUND => return NotFound,
        c::ERROR_PATH_NOT_FOUND => return NotFound,
        c::ERROR_NO_DATA => return BrokenPipe,
        c::ERROR_INVALID_PARAMETER => return InvalidInput,
        c::ERROR_NOT_ENOUGH_MEMORY | c::ERROR_OUTOFMEMORY => return OutOfMemory,
        c::ERROR_SEM_TIMEOUT
        | c::WAIT_TIMEOUT
        | c::ERROR_DRIVER_CANCEL_TIMEOUT
        | c::ERROR_OPERATION_ABORTED
        | c::ERROR_SERVICE_REQUEST_TIMEOUT
        | c::ERROR_COUNTER_TIMEOUT
        | c::ERROR_TIMEOUT
        | c::ERROR_RESOURCE_CALL_TIMED_OUT
        | c::ERROR_CTX_MODEM_RESPONSE_TIMEOUT
        | c::ERROR_CTX_CLIENT_QUERY_TIMEOUT
        | c::FRS_ERR_SYSVOL_POPULATE_TIMEOUT
        | c::ERROR_DS_TIMELIMIT_EXCEEDED
        | c::DNS_ERROR_RECORD_TIMED_OUT
        | c::ERROR_IPSEC_IKE_TIMED_OUT
        | c::ERROR_RUNLEVEL_SWITCH_TIMEOUT
        | c::ERROR_RUNLEVEL_SWITCH_AGENT_TIMEOUT => return TimedOut,
        c::ERROR_CALL_NOT_IMPLEMENTED => return Unsupported,
        c::ERROR_HOST_UNREACHABLE => return HostUnreachable,
        c::ERROR_NETWORK_UNREACHABLE => return NetworkUnreachable,
        c::ERROR_DIRECTORY => return NotADirectory,
        c::ERROR_DIRECTORY_NOT_SUPPORTED => return IsADirectory,
        c::ERROR_DIR_NOT_EMPTY => return DirectoryNotEmpty,
        c::ERROR_WRITE_PROTECT => return ReadOnlyFilesystem,
        c::ERROR_DISK_FULL | c::ERROR_HANDLE_DISK_FULL => return StorageFull,
        c::ERROR_SEEK_ON_DEVICE => return NotSeekable,
        c::ERROR_DISK_QUOTA_EXCEEDED => return FilesystemQuotaExceeded,
        c::ERROR_FILE_TOO_LARGE => return FileTooLarge,
        c::ERROR_BUSY => return ResourceBusy,
        c::ERROR_POSSIBLE_DEADLOCK => return Deadlock,
        c::ERROR_NOT_SAME_DEVICE => return CrossesDevices,
        c::ERROR_TOO_MANY_LINKS => return TooManyLinks,
        c::ERROR_FILENAME_EXCED_RANGE => return FilenameTooLong,
        _ => {}
    }

    match errno {
        c::WSAEACCES => PermissionDenied,
        c::WSAEADDRINUSE => AddrInUse,
        c::WSAEADDRNOTAVAIL => AddrNotAvailable,
        c::WSAECONNABORTED => ConnectionAborted,
        c::WSAECONNREFUSED => ConnectionRefused,
        c::WSAECONNRESET => ConnectionReset,
        c::WSAEINVAL => InvalidInput,
        c::WSAENOTCONN => NotConnected,
        c::WSAEWOULDBLOCK => WouldBlock,
        c::WSAETIMEDOUT => TimedOut,
        c::WSAEHOSTUNREACH => HostUnreachable,
        c::WSAENETDOWN => NetworkDown,
        c::WSAENETUNREACH => NetworkUnreachable,

        _ => Uncategorized,
    }
}

pub fn unrolled_find_u16s(needle: u16, haystack: &[u16]) -> Option<usize> {
    let ptr = haystack.as_ptr();
    let mut start = &haystack[..];

    // 出于性能原因，将循环展开八次。
    while start.len() >= 8 {
        macro_rules! if_return {
            ($($n:literal,)+) => {
                $(
                    if start[$n] == needle {
                        return Some((&start[$n] as *const u16 as usize - ptr as usize) / 2);
                    }
                )+
            }
        }

        if_return!(0, 1, 2, 3, 4, 5, 6, 7,);

        start = &start[8..];
    }

    for c in start {
        if *c == needle {
            return Some((c as *const u16 as usize - ptr as usize) / 2);
        }
    }
    None
}

pub fn to_u16s<S: AsRef<OsStr>>(s: S) -> crate::io::Result<Vec<u16>> {
    fn inner(s: &OsStr) -> crate::io::Result<Vec<u16>> {
        let mut maybe_result: Vec<u16> = s.encode_wide().collect();
        if unrolled_find_u16s(0, &maybe_result).is_some() {
            return Err(crate::io::Error::new_const(
                ErrorKind::InvalidInput,
                &"strings passed to WinAPI cannot contain NULs",
            ));
        }
        maybe_result.push(0);
        Ok(maybe_result)
    }
    inner(s.as_ref())
}

// 许多 Windows API 遵循一种模式，将缓冲区交给我们，然后它们会向我们报告缓冲区应该有多大或缓冲区中当前有多少字节。
// 通过使这些函数更易于调用，该函数是这些函数的抽象。
//
// 第一个回调 `f1` 产生了 (指针，len) 对，该对可以传递给系统调用。`ptr` 对 `len` 项 (在这种情况下为 u16) 有效。
// 预计闭包将返回系统调用返回的内容，此函数将对此进行解释，以确定是否需要再次调用系统调用 (具有更多的缓冲区空间)。
//
//
// 一旦系统调用完成 (错误可以尽早解决)，第二个闭包就会产生从系统调用中读取的数据。
// 该闭包的返回值就是函数的返回值。
//
//
//
//
//
fn fill_utf16_buf<F1, F2, T>(mut f1: F1, f2: F2) -> crate::io::Result<T>
where
    F1: FnMut(*mut u16, c::DWORD) -> c::DWORD,
    F2: FnOnce(&[u16]) -> T,
{
    // 从栈缓冲区开始，但如果最终需要更多空间，则溢出到堆中。
    //
    let mut stack_buf = [0u16; 512];
    let mut heap_buf = Vec::new();
    unsafe {
        let mut n = stack_buf.len();
        loop {
            let buf = if n <= stack_buf.len() {
                &mut stack_buf[..]
            } else {
                let extra = n - heap_buf.len();
                heap_buf.reserve(extra);
                heap_buf.set_len(n);
                &mut heap_buf[..]
            };

            // 通常在 windows API 函数上调用此函数，该函数将返回正确的字符串长度，但是这些函数也会在出错时返回 `0`。
            //
            // 但是，在某些情况下，返回的 "correct length" 实际上可能为 0!
            //
            // 为了处理这种情况，我们调用 `SetLastError` 将其重置为 0，然后再次检查是否获得 "0 error value"。
            // 如果 "last error" 仍为 0，则我们将其解释为长度为 0 的缓冲区，而不是实际错误。
            //
            //
            //
            c::SetLastError(0);
            let k = match f1(buf.as_mut_ptr(), n as c::DWORD) {
                0 if c::GetLastError() == 0 => 0,
                0 => return Err(crate::io::Error::last_os_error()),
                n => n,
            } as usize;
            if k == n && c::GetLastError() == c::ERROR_INSUFFICIENT_BUFFER {
                n *= 2;
            } else if k >= n {
                n = k;
            } else {
                return Ok(f2(&buf[..k]));
            }
        }
    }
}

fn os2path(s: &[u16]) -> PathBuf {
    PathBuf::from(OsString::from_wide(s))
}

pub fn truncate_utf16_at_nul(v: &[u16]) -> &[u16] {
    match unrolled_find_u16s(0, v) {
        // 不要包含 0
        Some(i) => &v[..i],
        None => v,
    }
}

pub trait IsZero {
    fn is_zero(&self) -> bool;
}

macro_rules! impl_is_zero {
    ($($t:ident)*) => ($(impl IsZero for $t {
        fn is_zero(&self) -> bool {
            *self == 0
        }
    })*)
}

impl_is_zero! { i8 i16 i32 i64 isize u8 u16 u32 u64 usize }

pub fn cvt<I: IsZero>(i: I) -> crate::io::Result<I> {
    if i.is_zero() { Err(crate::io::Error::last_os_error()) } else { Ok(i) }
}

pub fn dur2timeout(dur: Duration) -> c::DWORD {
    // 请注意，持续时间是 (u64，u32) (秒，纳秒) 对，并且 windows API 中的超时通常为 u32 毫秒。
    // 要翻译，我们需要注意以下两点:
    //
    // * 纳秒精度舍入
    // * 大于 u32::MAX 毫秒 (50 天) 的值会四舍五入为 INFINITE (永远不会超时)。
    //
    //
    dur.as_secs()
        .checked_mul(1000)
        .and_then(|ms| ms.checked_add((dur.subsec_nanos() as u64) / 1_000_000))
        .and_then(|ms| ms.checked_add(if dur.subsec_nanos() % 1_000_000 > 0 { 1 } else { 0 }))
        .map(|ms| if ms > <c::DWORD>::MAX as u64 { c::INFINITE } else { ms as c::DWORD })
        .unwrap_or(c::INFINITE)
}

/// 使用 `__fastfail` 中止该进程
///
/// 这与 libpanic_abort 的 `__rust_start_panic` 中的实现相同。
/// 有关 `__fastfail` 的更多信息，请参见该函数。
#[allow(unreachable_code)]
pub fn abort_internal() -> ! {
    const FAST_FAIL_FATAL_APP_EXIT: usize = 7;
    unsafe {
        cfg_if::cfg_if! {
            if #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] {
                asm!("int $$0x29", in("ecx") FAST_FAIL_FATAL_APP_EXIT);
                crate::intrinsics::unreachable();
            } else if #[cfg(all(target_arch = "arm", target_feature = "thumb-mode"))] {
                asm!(".inst 0xDEFB", in("r0") FAST_FAIL_FATAL_APP_EXIT);
                crate::intrinsics::unreachable();
            } else if #[cfg(target_arch = "aarch64")] {
                asm!("brk 0xF003", in("x0") FAST_FAIL_FATAL_APP_EXIT);
                crate::intrinsics::unreachable();
            }
        }
    }
    crate::intrinsics::abort();
}