//! Unix 和许多其他系统上的底层 OsString/OsStr 实现：只是一个 `Vec<u8>`/`[u8]`。
//!

use crate::borrow::Cow;
use crate::collections::TryReserveError;
use crate::fmt;
use crate::fmt::Write;
use crate::mem;
use crate::rc::Rc;
use crate::str;
use crate::sync::Arc;
use crate::sys_common::{AsInner, IntoInner};

use core::str::Utf8Chunks;

#[cfg(test)]
#[path = "../unix/os_str/tests.rs"]
mod tests;

#[derive(Hash)]
#[repr(transparent)]
pub struct Buf {
    pub inner: Vec<u8>,
}

#[repr(transparent)]
pub struct Slice {
    pub inner: [u8],
}

impl fmt::Debug for Slice {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::Debug::fmt(&Utf8Chunks::new(&self.inner).debug(), f)
    }
}

impl fmt::Display for Slice {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        // 如果我们是空字符串，那么我们的迭代器实际上不会产生任何结果，因此请手动执行格式化
        //
        if self.inner.is_empty() {
            return "".fmt(f);
        }

        for chunk in Utf8Chunks::new(&self.inner) {
            let valid = chunk.valid();
            // 如果我们成功地将整个块解码为有效字符串，那么我们可以返回字符串的直接格式，如果可能的话，该格式也将遵循各种格式标志。
            //
            //
            if chunk.invalid().is_empty() {
                return valid.fmt(f);
            }

            f.write_str(valid)?;
            f.write_char(char::REPLACEMENT_CHARACTER)?;
        }
        Ok(())
    }
}

impl fmt::Debug for Buf {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::Debug::fmt(self.as_slice(), formatter)
    }
}

impl fmt::Display for Buf {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::Display::fmt(self.as_slice(), formatter)
    }
}

impl Clone for Buf {
    #[inline]
    fn clone(&self) -> Self {
        Buf { inner: self.inner.clone() }
    }

    #[inline]
    fn clone_from(&mut self, source: &Self) {
        self.inner.clone_from(&source.inner)
    }
}

impl IntoInner<Vec<u8>> for Buf {
    fn into_inner(self) -> Vec<u8> {
        self.inner
    }
}

impl AsInner<[u8]> for Buf {
    #[inline]
    fn as_inner(&self) -> &[u8] {
        &self.inner
    }
}

impl Buf {
    pub fn from_string(s: String) -> Buf {
        Buf { inner: s.into_bytes() }
    }

    #[inline]
    pub fn with_capacity(capacity: usize) -> Buf {
        Buf { inner: Vec::with_capacity(capacity) }
    }

    #[inline]
    pub fn clear(&mut self) {
        self.inner.clear()
    }

    #[inline]
    pub fn capacity(&self) -> usize {
        self.inner.capacity()
    }

    #[inline]
    pub fn reserve(&mut self, additional: usize) {
        self.inner.reserve(additional)
    }

    #[inline]
    pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> {
        self.inner.try_reserve(additional)
    }

    #[inline]
    pub fn reserve_exact(&mut self, additional: usize) {
        self.inner.reserve_exact(additional)
    }

    #[inline]
    pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), TryReserveError> {
        self.inner.try_reserve_exact(additional)
    }

    #[inline]
    pub fn shrink_to_fit(&mut self) {
        self.inner.shrink_to_fit()
    }

    #[inline]
    pub fn shrink_to(&mut self, min_capacity: usize) {
        self.inner.shrink_to(min_capacity)
    }

    #[inline]
    pub fn as_slice(&self) -> &Slice {
        // SAFETY: 切片仅包裹 [u8]，而 &* self.inner 是 &[u8]，因此将 &[u8] 转换为 &Slice 是安全的。
        //
        //
        unsafe { mem::transmute(&*self.inner) }
    }

    #[inline]
    pub fn as_mut_slice(&mut self) -> &mut Slice {
        // SAFETY: 切片仅包裹 [u8]，而 &mut *self.inner 是 &mut [u8]，因此将 &mut [u8] 转换为 &mut 切片是安全的。
        //
        //
        unsafe { mem::transmute(&mut *self.inner) }
    }

    pub fn into_string(self) -> Result<String, Buf> {
        String::from_utf8(self.inner).map_err(|p| Buf { inner: p.into_bytes() })
    }

    pub fn push_slice(&mut self, s: &Slice) {
        self.inner.extend_from_slice(&s.inner)
    }

    #[inline]
    pub fn into_box(self) -> Box<Slice> {
        unsafe { mem::transmute(self.inner.into_boxed_slice()) }
    }

    #[inline]
    pub fn from_box(boxed: Box<Slice>) -> Buf {
        let inner: Box<[u8]> = unsafe { mem::transmute(boxed) };
        Buf { inner: inner.into_vec() }
    }

    #[inline]
    pub fn into_arc(&self) -> Arc<Slice> {
        self.as_slice().into_arc()
    }

    #[inline]
    pub fn into_rc(&self) -> Rc<Slice> {
        self.as_slice().into_rc()
    }
}

impl Slice {
    #[inline]
    fn from_u8_slice(s: &[u8]) -> &Slice {
        unsafe { mem::transmute(s) }
    }

    #[inline]
    pub fn from_str(s: &str) -> &Slice {
        Slice::from_u8_slice(s.as_bytes())
    }

    pub fn to_str(&self) -> Option<&str> {
        str::from_utf8(&self.inner).ok()
    }

    pub fn to_string_lossy(&self) -> Cow<'_, str> {
        String::from_utf8_lossy(&self.inner)
    }

    pub fn to_owned(&self) -> Buf {
        Buf { inner: self.inner.to_vec() }
    }

    pub fn clone_into(&self, buf: &mut Buf) {
        self.inner.clone_into(&mut buf.inner)
    }

    #[inline]
    pub fn into_box(&self) -> Box<Slice> {
        let boxed: Box<[u8]> = self.inner.into();
        unsafe { mem::transmute(boxed) }
    }

    pub fn empty_box() -> Box<Slice> {
        let boxed: Box<[u8]> = Default::default();
        unsafe { mem::transmute(boxed) }
    }

    #[inline]
    pub fn into_arc(&self) -> Arc<Slice> {
        let arc: Arc<[u8]> = Arc::from(&self.inner);
        unsafe { Arc::from_raw(Arc::into_raw(arc) as *const Slice) }
    }

    #[inline]
    pub fn into_rc(&self) -> Rc<Slice> {
        let rc: Rc<[u8]> = Rc::from(&self.inner);
        unsafe { Rc::from_raw(Rc::into_raw(rc) as *const Slice) }
    }

    #[inline]
    pub fn make_ascii_lowercase(&mut self) {
        self.inner.make_ascii_lowercase()
    }

    #[inline]
    pub fn make_ascii_uppercase(&mut self) {
        self.inner.make_ascii_uppercase()
    }

    #[inline]
    pub fn to_ascii_lowercase(&self) -> Buf {
        Buf { inner: self.inner.to_ascii_lowercase() }
    }

    #[inline]
    pub fn to_ascii_uppercase(&self) -> Buf {
        Buf { inner: self.inner.to_ascii_uppercase() }
    }

    #[inline]
    pub fn is_ascii(&self) -> bool {
        self.inner.is_ascii()
    }

    #[inline]
    pub fn eq_ignore_ascii_case(&self, other: &Self) -> bool {
        self.inner.eq_ignore_ascii_case(&other.inner)
    }
}