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use std::cell::UnsafeCell;
use std::marker::PhantomData;

use serde::{Deserialize, Deserializer, Serialize, Serializer};

#[derive(Debug)]
pub struct Swear<T, K> {
    inner: UnsafeCell<T>,
    key: PhantomData<K>,
}

impl<T, K> Swear<T, K> {
    #[inline]
    pub fn new(value: T) -> Self {
        Self {
            inner: UnsafeCell::new(value),
            key: PhantomData::default(),
        }
    }

    #[inline]
    pub fn swear(&self, _key: K) -> &mut T {
        self.as_mut()
    }

    #[allow(clippy::mut_from_ref)]
    #[inline]
    fn as_mut(&self) -> &mut T {
        unsafe { &mut *self.inner.get() }
    }
}

impl<T, K> From<T> for Swear<T, K> {
    #[inline]
    fn from(value: T) -> Self {
        Self::new(value)
    }
}

impl<T, K> AsRef<T> for Swear<T, K> {
    #[inline]
    fn as_ref(&self) -> &T {
        unsafe { &*self.inner.get() }
    }
}

impl<T, K> Serialize for Swear<T, K>
where
    T: Serialize,
{
    #[inline]
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        self.as_mut().serialize(serializer)
    }
}

impl<'de, T, K> Deserialize<'de> for Swear<T, K>
where
    T: Deserialize<'de>,
{
    #[inline]
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'de>,
    {
        Ok(Self::new(T::deserialize(deserializer)?))
    }
}

impl<T, K> Default for Swear<T, K>
where
    T: Default,
{
    #[inline]
    fn default() -> Self {
        Self {
            inner: T::default().into(),
            key: PhantomData::default(),
        }
    }
}

unsafe impl<T, K> Send for Swear<T, K> where T: Send {}
unsafe impl<T, K> Sync for Swear<T, K> where T: Sync {}