#[cfg(any(
    target_has_atomic = "8",
    target_has_atomic = "16",
    target_has_atomic = "32",
    target_has_atomic = "64",
))]
mod atomic;
mod niching;

use core::{
    cell::{Cell, UnsafeCell},
    hash::{Hash, Hasher},
    hint::unreachable_unchecked,
    marker::PhantomData,
    num::{
        NonZeroI128, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI8,
        NonZeroIsize, NonZeroU128, NonZeroU16, NonZeroU32, NonZeroU64,
        NonZeroU8, NonZeroUsize,
    },
};

use munge::munge;
use rancor::{Fallible, Source};

use crate::{
    boxed::{ArchivedBox, BoxResolver},
    niche::{
        niched_option::NichedOption,
        niching::{DefaultNiche, Niching},
        option_nonzero::{
            ArchivedOptionNonZeroI128, ArchivedOptionNonZeroI16,
            ArchivedOptionNonZeroI32, ArchivedOptionNonZeroI64,
            ArchivedOptionNonZeroI8, ArchivedOptionNonZeroIsize,
            ArchivedOptionNonZeroU128, ArchivedOptionNonZeroU16,
            ArchivedOptionNonZeroU32, ArchivedOptionNonZeroU64,
            ArchivedOptionNonZeroU8, ArchivedOptionNonZeroUsize,
        },
    },
    option::ArchivedOption,
    primitive::{FixedNonZeroIsize, FixedNonZeroUsize},
    ser::{Allocator, Writer},
    string::{ArchivedString, StringResolver},
    traits::NoUndef,
    vec::{ArchivedVec, VecResolver},
    with::{
        ArchiveWith, AsBox, AsString, AsVec, DeserializeWith, Identity, Inline,
        InlineAsBox, Map, MapNiche, Niche, NicheInto, SerializeWith, Skip,
        Unsafe,
    },
    Archive, ArchiveUnsized, Deserialize, Place, Serialize, SerializeUnsized,
};

// This is used by various internal impls, but isn't something we want to make a
// public API. However, in some build configurations there end up being no uses
// of this helper at all. So the most straightforward way to solve this is to
// just allow this code to be unused.
#[allow(dead_code)]
// Wrapper for O so that we have an Archive and Serialize implementation
// and ArchivedVec::serialize_from_* is happy about the bound
// constraints
pub struct RefWrapper<'o, A, O>(pub &'o O, pub PhantomData<A>);

impl<A: ArchiveWith<O>, O> Archive for RefWrapper<'_, A, O> {
    type Archived = <A as ArchiveWith<O>>::Archived;
    type Resolver = <A as ArchiveWith<O>>::Resolver;

    fn resolve(&self, resolver: Self::Resolver, out: Place<Self::Archived>) {
        A::resolve_with(self.0, resolver, out)
    }
}

impl<A, O, S> Serialize<S> for RefWrapper<'_, A, O>
where
    A: ArchiveWith<O> + SerializeWith<O, S>,
    S: Fallible + ?Sized,
{
    fn serialize(&self, s: &mut S) -> Result<Self::Resolver, S::Error> {
        A::serialize_with(self.0, s)
    }
}

impl<A, O: Hash> Hash for RefWrapper<'_, A, O> {
    fn hash<H: Hasher>(&self, state: &mut H) {
        self.0.hash(state)
    }
}

impl<A, O: PartialEq> PartialEq for RefWrapper<'_, A, O> {
    fn eq(&self, other: &Self) -> bool {
        self.0 == other.0
    }
}

impl<A, O: Eq> Eq for RefWrapper<'_, A, O> {}

// InlineAsBox

impl<F: ArchiveUnsized + ?Sized> ArchiveWith<&F> for InlineAsBox {
    type Archived = ArchivedBox<F::Archived>;
    type Resolver = BoxResolver;

    fn resolve_with(
        field: &&F,
        resolver: Self::Resolver,
        out: Place<Self::Archived>,
    ) {
        ArchivedBox::resolve_from_ref(*field, resolver, out);
    }
}

impl<F, S> SerializeWith<&F, S> for InlineAsBox
where
    F: SerializeUnsized<S> + ?Sized,
    S: Fallible + ?Sized,
{
    fn serialize_with(
        field: &&F,
        serializer: &mut S,
    ) -> Result<Self::Resolver, S::Error> {
        ArchivedBox::serialize_from_ref(*field, serializer)
    }
}

// AsString

impl ArchiveWith<&str> for AsString {
    type Archived = ArchivedString;
    type Resolver = StringResolver;

    fn resolve_with(
        field: &&str,
        resolver: Self::Resolver,
        out: Place<Self::Archived>,
    ) {
        ArchivedString::resolve_from_str(field, resolver, out);
    }
}

impl<S> SerializeWith<&str, S> for AsString
where
    str: SerializeUnsized<S>,
    S: Fallible + ?Sized,
    S::Error: Source,
{
    fn serialize_with(
        field: &&str,
        serializer: &mut S,
    ) -> Result<Self::Resolver, S::Error> {
        ArchivedString::serialize_from_str(field, serializer)
    }
}

// AsVec

impl<T: Archive> ArchiveWith<&[T]> for AsVec {
    type Archived = ArchivedVec<T::Archived>;
    type Resolver = VecResolver;

    fn resolve_with(
        field: &&[T],
        resolver: Self::Resolver,
        out: Place<Self::Archived>,
    ) {
        ArchivedVec::resolve_from_len(field.len(), resolver, out);
    }
}

impl<T, S> SerializeWith<&[T], S> for AsVec
where
    T: Serialize<S>,
    S: Fallible + Allocator + Writer + ?Sized,
{
    fn serialize_with(
        field: &&[T],
        serializer: &mut S,
    ) -> Result<Self::Resolver, S::Error> {
        ArchivedVec::serialize_from_slice(field, serializer)
    }
}

// AsBox

impl<F: ArchiveUnsized + ?Sized> ArchiveWith<F> for AsBox {
    type Archived = ArchivedBox<F::Archived>;
    type Resolver = BoxResolver;

    fn resolve_with(
        field: &F,
        resolver: Self::Resolver,
        out: Place<Self::Archived>,
    ) {
        ArchivedBox::resolve_from_ref(field, resolver, out);
    }
}

impl<F, S> SerializeWith<F, S> for AsBox
where
    F: SerializeUnsized<S> + ?Sized,
    S: Fallible + ?Sized,
{
    fn serialize_with(
        field: &F,
        serializer: &mut S,
    ) -> Result<Self::Resolver, S::Error> {
        ArchivedBox::serialize_from_ref(field, serializer)
    }
}

impl<F, D> DeserializeWith<ArchivedBox<F::Archived>, F, D> for AsBox
where
    F: Archive,
    F::Archived: Deserialize<F, D>,
    D: Fallible + ?Sized,
{
    fn deserialize_with(
        field: &ArchivedBox<F::Archived>,
        deserializer: &mut D,
    ) -> Result<F, D::Error> {
        field.get().deserialize(deserializer)
    }
}

// Map

// Copy-paste from Option's impls for the most part
impl<A, O> ArchiveWith<Option<O>> for Map<A>
where
    A: ArchiveWith<O>,
{
    type Archived = ArchivedOption<<A as ArchiveWith<O>>::Archived>;
    type Resolver = Option<<A as ArchiveWith<O>>::Resolver>;

    fn resolve_with(
        field: &Option<O>,
        resolver: Self::Resolver,
        out: Place<Self::Archived>,
    ) {
        match resolver {
            None => {
                let out = unsafe {
                    out.cast_unchecked::<ArchivedOptionVariantNone>()
                };
                munge!(let ArchivedOptionVariantNone(tag) = out);
                tag.write(ArchivedOptionTag::None);
            }
            Some(resolver) => {
                let out = unsafe {
                    out.cast_unchecked::<ArchivedOptionVariantSome<
                        <A as ArchiveWith<O>>::Archived,
                    >>()
                };
                munge!(let ArchivedOptionVariantSome(tag, out_value) = out);
                tag.write(ArchivedOptionTag::Some);

                let value = if let Some(value) = field.as_ref() {
                    value
                } else {
                    unsafe {
                        unreachable_unchecked();
                    }
                };

                A::resolve_with(value, resolver, out_value);
            }
        }
    }
}

impl<A, O, S> SerializeWith<Option<O>, S> for Map<A>
where
    S: Fallible + ?Sized,
    A: ArchiveWith<O> + SerializeWith<O, S>,
{
    fn serialize_with(
        field: &Option<O>,
        s: &mut S,
    ) -> Result<Self::Resolver, S::Error> {
        field
            .as_ref()
            .map(|value| A::serialize_with(value, s))
            .transpose()
    }
}

impl<A, O, D>
    DeserializeWith<
        ArchivedOption<<A as ArchiveWith<O>>::Archived>,
        Option<O>,
        D,
    > for Map<A>
where
    D: Fallible + ?Sized,
    A: ArchiveWith<O> + DeserializeWith<<A as ArchiveWith<O>>::Archived, O, D>,
{
    fn deserialize_with(
        field: &ArchivedOption<<A as ArchiveWith<O>>::Archived>,
        d: &mut D,
    ) -> Result<Option<O>, D::Error> {
        match field {
            ArchivedOption::Some(value) => {
                Ok(Some(A::deserialize_with(value, d)?))
            }
            ArchivedOption::None => Ok(None),
        }
    }
}

#[repr(u8)]
enum ArchivedOptionTag {
    None,
    Some,
}

// SAFETY: `ArchivedOptionTag` is `repr(u8)` and so always consists of a single
// well-defined byte.
unsafe impl NoUndef for ArchivedOptionTag {}

#[repr(C)]
struct ArchivedOptionVariantNone(ArchivedOptionTag);

#[repr(C)]
struct ArchivedOptionVariantSome<T>(ArchivedOptionTag, T);

// [O; N]

impl<A, O, const N: usize> ArchiveWith<[O; N]> for Map<A>
where
    A: ArchiveWith<O>,
{
    type Archived = [A::Archived; N];
    type Resolver = [A::Resolver; N];

    fn resolve_with(
        field: &[O; N],
        resolver: Self::Resolver,
        out: Place<Self::Archived>,
    ) {
        for (i, (value, resolver)) in field.iter().zip(resolver).enumerate() {
            A::resolve_with(value, resolver, unsafe { out.index(i) })
        }
    }
}

impl<A, O, S, const N: usize> SerializeWith<[O; N], S> for Map<A>
where
    S: Fallible + ?Sized,
    A: ArchiveWith<O> + SerializeWith<O, S>,
{
    fn serialize_with(
        field: &[O; N],
        serializer: &mut S,
    ) -> Result<Self::Resolver, S::Error> {
        let mut result = core::mem::MaybeUninit::<Self::Resolver>::uninit();
        let result_ptr = result.as_mut_ptr().cast::<A::Resolver>();
        for (i, value) in field.iter().enumerate() {
            let serialized = A::serialize_with(value, serializer)?;
            unsafe { result_ptr.add(i).write(serialized) };
        }
        Ok(unsafe { result.assume_init() })
    }
}

impl<O, A, D, const N: usize> DeserializeWith<[A::Archived; N], [O; N], D>
    for Map<A>
where
    D: Fallible + ?Sized,
    A: ArchiveWith<O> + DeserializeWith<A::Archived, O, D>,
{
    fn deserialize_with(
        field: &[A::Archived; N],
        deserializer: &mut D,
    ) -> Result<[O; N], <D as Fallible>::Error> {
        let mut result = core::mem::MaybeUninit::<[O; N]>::uninit();
        let result_ptr = result.as_mut_ptr().cast::<O>();
        for (i, value) in field.iter().enumerate() {
            let deserialized = A::deserialize_with(value, deserializer)?;
            unsafe { result_ptr.add(i).write(deserialized) };
        }
        Ok(unsafe { result.assume_init() })
    }
}

// Niche

macro_rules! impl_nonzero_niche {
    ($ar:ty, $nz:ty, $ne:ty) => {
        impl ArchiveWith<Option<$nz>> for Niche {
            type Archived = $ar;
            type Resolver = ();

            #[inline]
            fn resolve_with(
                field: &Option<$nz>,
                _: Self::Resolver,
                out: Place<Self::Archived>,
            ) {
                <$ar>::resolve_from_option(*field, out);
            }
        }

        impl<S: Fallible + ?Sized> SerializeWith<Option<$nz>, S> for Niche {
            fn serialize_with(
                _: &Option<$nz>,
                _: &mut S,
            ) -> Result<Self::Resolver, S::Error> {
                Ok(())
            }
        }

        impl<D> DeserializeWith<$ar, Option<$nz>, D> for Niche
        where
            D: Fallible + ?Sized,
        {
            fn deserialize_with(
                field: &$ar,
                _: &mut D,
            ) -> Result<Option<$nz>, D::Error> {
                Ok(field.as_ref().map(|x| (*x).into()))
            }
        }
    };
}

impl_nonzero_niche!(ArchivedOptionNonZeroI8, NonZeroI8, i8);
impl_nonzero_niche!(ArchivedOptionNonZeroI16, NonZeroI16, i16);
impl_nonzero_niche!(ArchivedOptionNonZeroI32, NonZeroI32, i32);
impl_nonzero_niche!(ArchivedOptionNonZeroI64, NonZeroI64, i64);
impl_nonzero_niche!(ArchivedOptionNonZeroI128, NonZeroI128, i128);

impl_nonzero_niche!(ArchivedOptionNonZeroU8, NonZeroU8, u8);
impl_nonzero_niche!(ArchivedOptionNonZeroU16, NonZeroU16, u16);
impl_nonzero_niche!(ArchivedOptionNonZeroU32, NonZeroU32, u32);
impl_nonzero_niche!(ArchivedOptionNonZeroU64, NonZeroU64, u64);
impl_nonzero_niche!(ArchivedOptionNonZeroU128, NonZeroU128, u128);

impl ArchiveWith<Option<NonZeroIsize>> for Niche {
    type Archived = ArchivedOptionNonZeroIsize;
    type Resolver = ();

    #[inline]
    fn resolve_with(
        field: &Option<NonZeroIsize>,
        _: Self::Resolver,
        out: Place<Self::Archived>,
    ) {
        let f = field.as_ref().map(|&x| x.try_into().unwrap());
        ArchivedOptionNonZeroIsize::resolve_from_option(f, out);
    }
}

impl<S: Fallible + ?Sized> SerializeWith<Option<NonZeroIsize>, S> for Niche {
    fn serialize_with(
        _: &Option<NonZeroIsize>,
        _: &mut S,
    ) -> Result<Self::Resolver, S::Error> {
        Ok(())
    }
}

impl<D> DeserializeWith<ArchivedOptionNonZeroIsize, Option<NonZeroIsize>, D>
    for Niche
where
    D: Fallible + ?Sized,
{
    fn deserialize_with(
        field: &ArchivedOptionNonZeroIsize,
        _: &mut D,
    ) -> Result<Option<NonZeroIsize>, D::Error> {
        // This conversion is necessary with archive_be and archive_le
        #[allow(clippy::useless_conversion)]
        Ok(field
            .as_ref()
            .map(|x| FixedNonZeroIsize::from(*x).try_into().unwrap()))
    }
}

impl ArchiveWith<Option<NonZeroUsize>> for Niche {
    type Archived = ArchivedOptionNonZeroUsize;
    type Resolver = ();

    #[inline]
    fn resolve_with(
        field: &Option<NonZeroUsize>,
        _: Self::Resolver,
        out: Place<Self::Archived>,
    ) {
        let f = field.as_ref().map(|&x| x.try_into().unwrap());
        ArchivedOptionNonZeroUsize::resolve_from_option(f, out);
    }
}

impl<S: Fallible + ?Sized> SerializeWith<Option<NonZeroUsize>, S> for Niche {
    fn serialize_with(
        _: &Option<NonZeroUsize>,
        _: &mut S,
    ) -> Result<Self::Resolver, S::Error> {
        Ok(())
    }
}

impl<D> DeserializeWith<ArchivedOptionNonZeroUsize, Option<NonZeroUsize>, D>
    for Niche
where
    D: Fallible + ?Sized,
{
    fn deserialize_with(
        field: &ArchivedOptionNonZeroUsize,
        _: &mut D,
    ) -> Result<Option<NonZeroUsize>, D::Error> {
        // This conversion is necessary with archive_be and archive_le
        #[allow(clippy::useless_conversion)]
        Ok(field
            .as_ref()
            .map(|x| FixedNonZeroUsize::from(*x).try_into().unwrap()))
    }
}

// NicheInto

impl<T, N> ArchiveWith<Option<T>> for NicheInto<N>
where
    T: Archive,
    N: Niching<T::Archived> + ?Sized,
{
    type Archived = NichedOption<T::Archived, N>;
    type Resolver = Option<T::Resolver>;

    fn resolve_with(
        field: &Option<T>,
        resolver: Self::Resolver,
        out: Place<Self::Archived>,
    ) {
        NichedOption::<T::Archived, N>::resolve_from_option(
            field.as_ref(),
            resolver,
            out,
        );
    }
}

impl<T, N, S> SerializeWith<Option<T>, S> for NicheInto<N>
where
    T: Serialize<S>,
    N: Niching<T::Archived> + ?Sized,
    S: Fallible + ?Sized,
{
    fn serialize_with(
        field: &Option<T>,
        serializer: &mut S,
    ) -> Result<Self::Resolver, S::Error> {
        NichedOption::<T::Archived, N>::serialize_from_option(
            field.as_ref(),
            serializer,
        )
    }
}

impl<T, N, D> DeserializeWith<NichedOption<T::Archived, N>, Option<T>, D>
    for NicheInto<N>
where
    T: Archive<Archived: Deserialize<T, D>>,
    N: Niching<T::Archived> + ?Sized,
    D: Fallible + ?Sized,
{
    fn deserialize_with(
        field: &NichedOption<T::Archived, N>,
        deserializer: &mut D,
    ) -> Result<Option<T>, D::Error> {
        Deserialize::deserialize(field, deserializer)
    }
}

impl<T, N, D> Deserialize<Option<T>, D> for NichedOption<T::Archived, N>
where
    T: Archive<Archived: Deserialize<T, D>>,
    N: Niching<T::Archived> + ?Sized,
    D: Fallible + ?Sized,
{
    fn deserialize(&self, deserializer: &mut D) -> Result<Option<T>, D::Error> {
        match self.as_ref() {
            Some(value) => value.deserialize(deserializer).map(Some),
            None => Ok(None),
        }
    }
}

// MapNiche

impl<T, W, N> ArchiveWith<Option<T>> for MapNiche<W, N>
where
    W: ArchiveWith<T> + ?Sized,
    N: Niching<<W as ArchiveWith<T>>::Archived> + ?Sized,
{
    type Archived = NichedOption<<W as ArchiveWith<T>>::Archived, N>;
    type Resolver = Option<<W as ArchiveWith<T>>::Resolver>;

    fn resolve_with(
        field: &Option<T>,
        resolver: Self::Resolver,
        out: Place<Self::Archived>,
    ) {
        let out = NichedOption::munge_place(out);
        match field {
            Some(value) => {
                let resolver = resolver.expect("non-niched resolver");
                W::resolve_with(value, resolver, out);
            }
            None => N::resolve_niched(out),
        }
    }
}

impl<T, W, N, S> SerializeWith<Option<T>, S> for MapNiche<W, N>
where
    W: SerializeWith<T, S> + ?Sized,
    N: Niching<<W as ArchiveWith<T>>::Archived> + ?Sized,
    S: Fallible + ?Sized,
{
    fn serialize_with(
        field: &Option<T>,
        serializer: &mut S,
    ) -> Result<Self::Resolver, S::Error> {
        match field {
            Some(value) => W::serialize_with(value, serializer).map(Some),
            None => Ok(None),
        }
    }
}

impl<T, W, N, D>
    DeserializeWith<
        NichedOption<<W as ArchiveWith<T>>::Archived, N>,
        Option<T>,
        D,
    > for MapNiche<W, N>
where
    W: ArchiveWith<T> + DeserializeWith<<W as ArchiveWith<T>>::Archived, T, D>,
    N: Niching<<W as ArchiveWith<T>>::Archived> + ?Sized,
    D: Fallible + ?Sized,
{
    fn deserialize_with(
        field: &NichedOption<<W as ArchiveWith<T>>::Archived, N>,
        deserializer: &mut D,
    ) -> Result<Option<T>, D::Error> {
        field
            .as_ref()
            .map(|value| W::deserialize_with(value, deserializer))
            .transpose()
    }
}

// DefaultNiche

impl<T> ArchiveWith<Option<T>> for DefaultNiche
where
    T: Archive,
    Self: Niching<T::Archived>,
{
    type Archived = NichedOption<T::Archived, Self>;
    type Resolver = Option<T::Resolver>;

    fn resolve_with(
        field: &Option<T>,
        resolver: Self::Resolver,
        out: Place<Self::Archived>,
    ) {
        NicheInto::<Self>::resolve_with(field, resolver, out);
    }
}

impl<T, S> SerializeWith<Option<T>, S> for DefaultNiche
where
    T: Serialize<S>,
    Self: Niching<T::Archived>,
    S: Fallible + ?Sized,
{
    fn serialize_with(
        field: &Option<T>,
        serializer: &mut S,
    ) -> Result<Self::Resolver, S::Error> {
        NicheInto::<Self>::serialize_with(field, serializer)
    }
}

impl<T, D> DeserializeWith<NichedOption<T::Archived, Self>, Option<T>, D>
    for DefaultNiche
where
    T: Archive<Archived: Deserialize<T, D>>,
    Self: Niching<T::Archived>,
    D: Fallible + ?Sized,
{
    fn deserialize_with(
        field: &NichedOption<T::Archived, Self>,
        deserializer: &mut D,
    ) -> Result<Option<T>, D::Error> {
        NicheInto::<Self>::deserialize_with(field, deserializer)
    }
}

// Inline

impl<F: Archive> ArchiveWith<&F> for Inline {
    type Archived = F::Archived;
    type Resolver = F::Resolver;

    fn resolve_with(
        field: &&F,
        resolver: Self::Resolver,
        out: Place<Self::Archived>,
    ) {
        field.resolve(resolver, out);
    }
}

impl<F: Serialize<S>, S: Fallible + ?Sized> SerializeWith<&F, S> for Inline {
    fn serialize_with(
        field: &&F,
        serializer: &mut S,
    ) -> Result<Self::Resolver, S::Error> {
        field.serialize(serializer)
    }
}

// Unsafe

impl<F: Archive> ArchiveWith<UnsafeCell<F>> for Unsafe {
    type Archived = F::Archived;
    type Resolver = F::Resolver;

    fn resolve_with(
        field: &UnsafeCell<F>,
        resolver: Self::Resolver,
        out: Place<Self::Archived>,
    ) {
        let value = unsafe { &*field.get() };
        F::resolve(value, resolver, out);
    }
}

impl<F, S> SerializeWith<UnsafeCell<F>, S> for Unsafe
where
    F: Serialize<S>,
    S: Fallible + ?Sized,
{
    fn serialize_with(
        field: &UnsafeCell<F>,
        serializer: &mut S,
    ) -> Result<Self::Resolver, S::Error> {
        unsafe { (*field.get()).serialize(serializer) }
    }
}

impl<F, D> DeserializeWith<F::Archived, UnsafeCell<F>, D> for Unsafe
where
    F: Archive,
    F::Archived: Deserialize<F, D>,
    D: Fallible + ?Sized,
{
    fn deserialize_with(
        field: &F::Archived,
        deserializer: &mut D,
    ) -> Result<UnsafeCell<F>, D::Error> {
        field.deserialize(deserializer).map(|x| UnsafeCell::new(x))
    }
}

impl<F: Archive> ArchiveWith<Cell<F>> for Unsafe {
    type Archived = F::Archived;
    type Resolver = F::Resolver;

    fn resolve_with(
        field: &Cell<F>,
        resolver: Self::Resolver,
        out: Place<Self::Archived>,
    ) {
        let value = unsafe { &*field.as_ptr() };
        F::resolve(value, resolver, out);
    }
}

impl<F, S> SerializeWith<Cell<F>, S> for Unsafe
where
    F: Serialize<S>,
    S: Fallible + ?Sized,
{
    fn serialize_with(
        field: &Cell<F>,
        serializer: &mut S,
    ) -> Result<Self::Resolver, S::Error> {
        unsafe { (*field.as_ptr()).serialize(serializer) }
    }
}

impl<F, D> DeserializeWith<F::Archived, Cell<F>, D> for Unsafe
where
    F: Archive,
    F::Archived: Deserialize<F, D>,
    D: Fallible + ?Sized,
{
    fn deserialize_with(
        field: &F::Archived,
        deserializer: &mut D,
    ) -> Result<Cell<F>, D::Error> {
        field.deserialize(deserializer).map(|x| Cell::new(x))
    }
}

// Skip

impl<F> ArchiveWith<F> for Skip {
    type Archived = ();
    type Resolver = ();

    fn resolve_with(_: &F, _: Self::Resolver, _: Place<Self::Archived>) {}
}

impl<F, S: Fallible + ?Sized> SerializeWith<F, S> for Skip {
    fn serialize_with(_: &F, _: &mut S) -> Result<(), S::Error> {
        Ok(())
    }
}

impl<F: Default, D: Fallible + ?Sized> DeserializeWith<(), F, D> for Skip {
    fn deserialize_with(_: &(), _: &mut D) -> Result<F, D::Error> {
        Ok(Default::default())
    }
}

// Identity

impl<F: Archive> ArchiveWith<F> for Identity {
    type Archived = F::Archived;
    type Resolver = F::Resolver;

    fn resolve_with(
        field: &F,
        resolver: Self::Resolver,
        out: Place<Self::Archived>,
    ) {
        field.resolve(resolver, out)
    }
}

impl<F: Serialize<S>, S: Fallible + ?Sized> SerializeWith<F, S> for Identity {
    fn serialize_with(
        field: &F,
        serializer: &mut S,
    ) -> Result<Self::Resolver, S::Error> {
        field.serialize(serializer)
    }
}

impl<F, T, D> DeserializeWith<F, T, D> for Identity
where
    F: Deserialize<T, D>,
    D: Fallible + ?Sized,
{
    fn deserialize_with(
        field: &F,
        deserializer: &mut D,
    ) -> Result<T, <D as Fallible>::Error> {
        field.deserialize(deserializer)
    }
}

#[cfg(test)]
mod tests {
    use core::f32;

    use crate::{
        api::test::{deserialize, roundtrip, roundtrip_with, to_archived},
        niche::niching::{NaN, Zero},
        rancor::Fallible,
        ser::Writer,
        with::{
            ArchiveWith, AsBox, AsString, AsVec, DeserializeWith, Identity,
            Inline, InlineAsBox, Map, Niche, NicheInto, SerializeWith, Unsafe,
            With,
        },
        Archive, Archived, Deserialize, Place, Serialize,
    };

    struct AsFloat;

    impl ArchiveWith<i32> for AsFloat {
        type Archived = Archived<f32>;
        type Resolver = ();

        fn resolve_with(
            value: &i32,
            _: Self::Resolver,
            out: Place<Self::Archived>,
        ) {
            out.write(Archived::<f32>::from_native(*value as f32));
        }
    }

    impl<S> SerializeWith<i32, S> for AsFloat
    where
        S: Fallible + Writer + ?Sized,
    {
        fn serialize_with(
            _: &i32,
            _: &mut S,
        ) -> Result<Self::Resolver, S::Error> {
            Ok(())
        }
    }

    impl<D> DeserializeWith<Archived<f32>, i32, D> for AsFloat
    where
        D: Fallible + ?Sized,
    {
        fn deserialize_with(
            value: &Archived<f32>,
            _: &mut D,
        ) -> Result<i32, D::Error> {
            Ok(value.to_native() as i32)
        }
    }

    #[test]
    fn with_struct() {
        #[derive(Archive, Serialize, Deserialize, Debug, PartialEq)]
        #[rkyv(crate, derive(Debug))]
        struct Test {
            #[rkyv(with = AsFloat)]
            value: i32,
            other: i32,
        }

        let value = Test {
            value: 10,
            other: 10,
        };
        roundtrip_with(&value, |_, archived| {
            assert_eq!(archived.value, 10.0);
            assert_eq!(archived.other, 10);
        });
    }

    #[test]
    fn with_tuple_struct() {
        #[derive(Archive, Serialize, Deserialize, Debug, PartialEq)]
        #[rkyv(crate, derive(Debug))]
        struct Test(#[rkyv(with = AsFloat)] i32, i32);

        let value = Test(10, 10);
        roundtrip_with(&value, |_, archived| {
            assert_eq!(archived.0, 10.0);
            assert_eq!(archived.1, 10);
        });
    }

    #[test]
    fn with_enum() {
        #[derive(Archive, Serialize, Deserialize, Debug, PartialEq)]
        #[rkyv(crate, derive(Debug))]
        enum Test {
            A {
                #[rkyv(with = AsFloat)]
                value: i32,
                other: i32,
            },
            B(#[rkyv(with = AsFloat)] i32, i32),
        }

        let value = Test::A {
            value: 10,
            other: 10,
        };
        roundtrip_with(&value, |_, archived| {
            if let ArchivedTest::A { value, other } = archived {
                assert_eq!(*value, 10.0);
                assert_eq!(*other, 10);
            } else {
                panic!("expected variant A");
            }
        });

        let value = Test::B(10, 10);
        roundtrip_with(&value, |_, archived| {
            if let ArchivedTest::B(value, other) = archived {
                assert_eq!(*value, 10.0);
                assert_eq!(*other, 10);
            } else {
                panic!("expected variant B");
            }
        });
    }

    #[test]
    fn with_wrapper() {
        to_archived(With::<_, AsFloat>::cast(&10), |archived| {
            assert_eq!(archived.to_native(), 10.0);
            let original = deserialize(With::<_, AsFloat>::cast(&*archived));
            assert_eq!(original, 10);
        });
    }

    #[test]
    fn with_inline() {
        #[derive(Archive, Serialize, Deserialize)]
        #[rkyv(crate)]
        struct Test<'a> {
            #[rkyv(with = Inline)]
            value: &'a i32,
        }

        let a = 42;
        let value = Test { value: &a };
        to_archived(&value, |archived| {
            assert_eq!(archived.value, 42);
        });
    }

    #[test]
    fn with_boxed() {
        #[derive(Archive, Serialize, Deserialize)]
        #[rkyv(crate)]
        struct Test {
            #[rkyv(with = AsBox)]
            value: i32,
        }

        let value = Test { value: 42 };
        to_archived(&value, |archived| {
            assert_eq!(archived.value.get(), &42);
        });
    }

    #[test]
    fn with_boxed_inline() {
        #[derive(Archive, Serialize, Deserialize)]
        #[rkyv(crate)]
        struct Test<'a> {
            #[rkyv(with = InlineAsBox)]
            value: &'a str,
        }

        let a = "hello world";
        let value = Test { value: &a };
        to_archived(&value, |archived| {
            assert_eq!(archived.value.as_ref(), "hello world");
        });
    }

    #[test]
    fn with_str() {
        #[derive(Archive, Serialize, Deserialize)]
        #[rkyv(crate)]
        struct Test<'a> {
            #[rkyv(with = AsString)]
            value: &'a str,
        }

        let a = "hello world";
        let value = Test { value: a };
        to_archived(&value, |archived| {
            assert_eq!(archived.value.as_str(), "hello world");
        });
    }

    #[test]
    fn with_slice() {
        #[derive(Archive, Serialize, Deserialize)]
        #[rkyv(crate)]
        struct Test<'a> {
            #[rkyv(with = AsVec)]
            value: &'a [bool],
        }

        let a: &[bool] = &[true, true, false, true];
        let value = Test { value: a };
        to_archived(&value, |archived| {
            assert_eq!(archived.value.as_slice(), &[true, true, false, true]);
        });
    }

    #[test]
    fn with_niche_nonzero() {
        use core::{
            mem::size_of,
            num::{
                NonZeroI32, NonZeroI8, NonZeroIsize, NonZeroU32, NonZeroU8,
                NonZeroUsize,
            },
        };

        #[derive(Archive, Serialize, Deserialize)]
        #[rkyv(crate)]
        struct TestNiche {
            #[rkyv(with = Niche)]
            a: Option<NonZeroI8>,
            #[rkyv(with = Niche)]
            b: Option<NonZeroI32>,
            #[rkyv(with = Niche)]
            c: Option<NonZeroIsize>,
            #[rkyv(with = Niche)]
            d: Option<NonZeroU8>,
            #[rkyv(with = Niche)]
            e: Option<NonZeroU32>,
            #[rkyv(with = Niche)]
            f: Option<NonZeroUsize>,
        }

        #[derive(Archive, Serialize, Deserialize)]
        #[rkyv(crate)]
        struct TestZeroNiche {
            #[rkyv(with = NicheInto<Zero>)]
            a: Option<NonZeroI8>,
            #[rkyv(with = NicheInto<Zero>)]
            b: Option<NonZeroI32>,
            #[rkyv(with = NicheInto<Zero>)]
            c: Option<NonZeroIsize>,
            #[rkyv(with = NicheInto<Zero>)]
            d: Option<NonZeroU8>,
            #[rkyv(with = NicheInto<Zero>)]
            e: Option<NonZeroU32>,
            #[rkyv(with = NicheInto<Zero>)]
            f: Option<NonZeroUsize>,
        }

        #[derive(Archive, Serialize, Deserialize)]
        #[rkyv(crate)]
        struct TestNoNiching {
            a: Option<NonZeroI8>,
            b: Option<NonZeroI32>,
            c: Option<NonZeroIsize>,
            d: Option<NonZeroU8>,
            e: Option<NonZeroU32>,
            f: Option<NonZeroUsize>,
        }

        let value = TestNiche {
            a: Some(NonZeroI8::new(10).unwrap()),
            b: Some(NonZeroI32::new(10).unwrap()),
            c: Some(NonZeroIsize::new(10).unwrap()),
            d: Some(NonZeroU8::new(10).unwrap()),
            e: Some(NonZeroU32::new(10).unwrap()),
            f: Some(NonZeroUsize::new(10).unwrap()),
        };
        to_archived(&value, |archived| {
            assert!(archived.a.is_some());
            assert_eq!(archived.a.as_ref().unwrap().get(), 10);
            assert!(archived.b.is_some());
            assert_eq!(archived.b.as_ref().unwrap().get(), 10);
            assert!(archived.c.is_some());
            assert_eq!(archived.c.as_ref().unwrap().get(), 10);
            assert!(archived.d.is_some());
            assert_eq!(archived.d.as_ref().unwrap().get(), 10);
            assert!(archived.e.is_some());
            assert_eq!(archived.e.as_ref().unwrap().get(), 10);
            assert!(archived.f.is_some());
            assert_eq!(archived.f.as_ref().unwrap().get(), 10);
        });

        let value = TestNiche {
            a: None,
            b: None,
            c: None,
            d: None,
            e: None,
            f: None,
        };
        to_archived(&value, |archived| {
            assert!(archived.a.is_none());
            assert!(archived.b.is_none());
            assert!(archived.c.is_none());
            assert!(archived.d.is_none());
            assert!(archived.e.is_none());
            assert!(archived.f.is_none());
        });

        assert!(
            size_of::<Archived<TestNiche>>()
                < size_of::<Archived<TestNoNiching>>()
        );

        let value = TestZeroNiche {
            a: Some(NonZeroI8::new(10).unwrap()),
            b: Some(NonZeroI32::new(10).unwrap()),
            c: Some(NonZeroIsize::new(10).unwrap()),
            d: Some(NonZeroU8::new(10).unwrap()),
            e: Some(NonZeroU32::new(10).unwrap()),
            f: Some(NonZeroUsize::new(10).unwrap()),
        };
        to_archived(&value, |archived| {
            assert!(archived.a.is_some());
            assert_eq!(archived.a.as_ref().unwrap().get(), 10);
            assert!(archived.b.is_some());
            assert_eq!(archived.b.as_ref().unwrap().get(), 10);
            assert!(archived.c.is_some());
            assert_eq!(archived.c.as_ref().unwrap().get(), 10);
            assert!(archived.d.is_some());
            assert_eq!(archived.d.as_ref().unwrap().get(), 10);
            assert!(archived.e.is_some());
            assert_eq!(archived.e.as_ref().unwrap().get(), 10);
            assert!(archived.f.is_some());
            assert_eq!(archived.f.as_ref().unwrap().get(), 10);
        });

        let value = TestZeroNiche {
            a: None,
            b: None,
            c: None,
            d: None,
            e: None,
            f: None,
        };
        to_archived(&value, |archived| {
            assert!(archived.a.is_none());
            assert!(archived.b.is_none());
            assert!(archived.c.is_none());
            assert!(archived.d.is_none());
            assert!(archived.e.is_none());
            assert!(archived.f.is_none());
        });

        assert!(
            size_of::<Archived<TestZeroNiche>>()
                < size_of::<Archived<TestNoNiching>>()
        );
    }

    #[test]
    fn with_niche_float_nan() {
        #[derive(Archive, Serialize, Deserialize)]
        #[rkyv(crate)]
        struct Test {
            #[rkyv(with = NicheInto<NaN>)]
            a: Option<f32>,
            #[rkyv(with = NicheInto<NaN>)]
            b: Option<f64>,
        }

        #[derive(Archive, Serialize, Deserialize)]
        #[rkyv(crate)]
        struct TestNoNiching {
            a: Option<f32>,
            b: Option<f64>,
        }

        let value = Test {
            a: Some(123.45),
            b: Some(123.45),
        };
        to_archived(&value, |archived| {
            assert!(archived.a.is_some());
            assert_eq!(archived.a.as_ref().unwrap().to_native(), 123.45);
            assert!(archived.b.is_some());
            assert_eq!(archived.b.as_ref().unwrap().to_native(), 123.45);
        });

        let value = Test {
            a: Some(f32::NAN),
            b: Some(f64::NAN),
        };
        to_archived(&value, |archived| {
            assert!(archived.a.is_none());
            assert!(archived.b.is_none());
        });

        let value = Test { a: None, b: None };
        to_archived(&value, |archived| {
            assert!(archived.a.is_none());
            assert!(archived.b.is_none());
        });

        assert!(
            size_of::<Archived<Test>>() < size_of::<Archived<TestNoNiching>>()
        );
    }

    #[test]
    fn with_unsafe() {
        use core::cell::Cell;

        #[derive(Archive, Debug, Deserialize, Serialize, PartialEq)]
        #[rkyv(crate, derive(Debug))]
        struct Test {
            #[rkyv(with = Unsafe)]
            inner: Cell<u32>,
        }

        impl PartialEq<Test> for ArchivedTest {
            fn eq(&self, other: &Test) -> bool {
                self.inner == other.inner.get()
            }
        }

        let value = Test {
            inner: Cell::new(100),
        };
        roundtrip(&value);
    }

    #[test]
    fn with_identity() {
        #[derive(Archive, Serialize, Deserialize, Debug, PartialEq)]
        #[rkyv(crate, derive(Debug))]
        struct Test {
            #[rkyv(with = Identity)]
            value: i32,
            other: i32,
        }

        let value = Test {
            value: 10,
            other: 10,
        };
        roundtrip_with(&value, |_, archived| {
            assert_eq!(archived.value, 10);
            assert_eq!(archived.other, 10);
        });
    }

    #[test]
    fn with_map_array() {
        #[derive(Archive, Serialize, Deserialize, Debug, PartialEq)]
        #[rkyv(crate, derive(Debug))]
        struct Test {
            #[rkyv(with = Map<AsFloat>)]
            value: [i32; 2],
            other: [i32; 2],
        }

        let value = Test {
            value: [1, 2],
            other: [1, 2],
        };
        roundtrip_with(&value, |_, archived| {
            assert_eq!(archived.value, [1.0, 2.0]);
            assert_eq!(archived.other, [1, 2]);
        });
    }

    #[test]
    fn with_map_nested_array() {
        #[derive(Archive, Serialize, Deserialize, Debug, PartialEq)]
        #[rkyv(crate, derive(Debug))]
        struct Test {
            #[rkyv(with = Map<Map<AsFloat>>)]
            value: [[i32; 2]; 3],
            other: [[i32; 2]; 3],
        }

        let value = Test {
            value: [[1, 2], [3, 4], [5, 6]],
            other: [[1, 2], [3, 4], [5, 6]],
        };
        roundtrip_with(&value, |_, archived| {
            assert_eq!(archived.value, [[1.0, 2.0], [3.0, 4.0], [5.0, 6.0]]);
            assert_eq!(archived.other, [[1, 2], [3, 4], [5, 6]]);
        });
    }
}
