use crate::{self as libc, util};

use alloc::boxed::Box;
use core::{ops::{Deref, DerefMut}, slice};

//pub struct FromBytesWithNulError {}

#[repr(transparent)]
pub struct CStr {
	inner: libc::c_char,
}

impl CStr {
	#[inline]
	pub unsafe fn from_ptr<'a>(p: *const libc::c_char) -> &'a CStr {
		&*p.cast()
	}

	#[inline]
	pub unsafe fn from_mut_ptr<'a>(p: *mut libc::c_char) -> &'a mut CStr {
		&mut *p.cast()
	}

	#[inline]
	pub unsafe fn from_bytes_with_nul_unchecked(bytes: &[u8]) -> &CStr {
		CStr::from_ptr(bytes.as_ptr().cast())
	}

	// TODO
	//pub fn from_bytes_with_nul(bytes: &[u8]) -> Result<&CStr, FromBytesWithNulError> {
	//}

	#[inline]
	pub fn len(&self) -> usize {
		unsafe { libc::strlen(self.as_ptr()) }
	}

	#[inline]
	pub const fn as_ptr(&self) -> *const libc::c_char {
		&self.inner
	}

	#[inline]
	pub fn as_mut_ptr(&mut self) -> *mut libc::c_char {
		&mut self.inner
	}

	#[inline]
	pub fn to_bytes(&self) -> &[u8] {
		unsafe { slice::from_raw_parts(self.as_ptr().cast(), self.len()) }
	}

	#[inline]
	pub fn to_mut_bytes(&mut self) -> &mut [u8] {
		unsafe { slice::from_raw_parts_mut(self.as_mut_ptr().cast(), self.len()) }
	}

	#[inline]
	pub fn to_str(&self) -> Result<&str, core::str::Utf8Error> {
		core::str::from_utf8(self.to_bytes())
	}

	#[inline]
	pub fn to_mut_str(&mut self) -> Result<&mut str, core::str::Utf8Error> {
		core::str::from_utf8_mut(self.to_mut_bytes())
	}

	#[inline]
	pub fn to_owned(self: &CStr) -> CString {
		CString::from(self)
	}
}

#[macro_export]
macro_rules! cstr {
	($s:expr) => {
		unsafe { $crate::string::CStr::from_bytes_with_nul_unchecked(concat!($s, "\0").as_bytes()) }
	};
}

pub struct CString {
	inner: Box<libc::c_char>,
}

impl CString {
	#[inline]
	pub unsafe fn from_raw(p: *mut libc::c_char) -> CString {
		CString {
			inner: Box::from_raw(p),
		}
	}

	#[inline]
	pub fn into_raw(self) -> *mut libc::c_char {
		Box::into_raw(self.inner)
	}
}

impl Deref for CString {
	type Target = CStr;

	#[inline]
	fn deref(&self) -> &CStr {
		unsafe { CStr::from_ptr(&*self.inner) }
	}
}

impl DerefMut for CString {
	#[inline]
	fn deref_mut(&mut self) -> &mut CStr {
		unsafe { CStr::from_mut_ptr(&mut *self.inner) }
	}
}

impl From<&[u8]> for CString {
	fn from(s: &[u8]) -> CString {
		unsafe {
			CString::from_raw(util::must_succeed(libc::strndup(
				s.as_ptr().cast(),
				s.len(),
			)))
		}
	}
}

impl From<&str> for CString {
	#[inline]
	fn from(s: &str) -> CString {
		CString::from(s.as_bytes())
	}
}

impl From<&CStr> for CString {
	#[inline]
	fn from(s: &CStr) -> CString {
		unsafe { CString::from_raw(util::must_succeed(libc::strdup(s.as_ptr()))) }
	}
}