// Copyright (c) The Diem Core Contributors
// SPDX-License-Identifier: Apache-2.0

//! The following macros are slightly modified from rust-bitcoin. The original file may be found
//! here:
//!
//! https://github.com/rust-bitcoin/rust-bitcoin/blob/master/src/internal_macros.rs

macro_rules! impl_array_newtype {
    ($thing:ident, $ty:ty, $len:expr) => {
        impl<'a> From<&'a [$ty]> for $thing {
            fn from(data: &'a [$ty]) -> $thing {
                assert_eq!(data.len(), $len);
                let mut ret = [0; $len];
                ret.copy_from_slice(data);
                $thing(ret)
            }
        }

        impl ::std::ops::Index<usize> for $thing {
            type Output = $ty;

            #[inline]
            fn index(&self, index: usize) -> &$ty {
                precondition!(index < $len);
                let &$thing(ref dat) = self;
                &dat[index]
            }
        }

        impl_index_newtype!($thing, $ty);

        impl PartialEq for $thing {
            #[inline]
            fn eq(&self, other: &$thing) -> bool {
                &self[..] == &other[..]
            }
        }

        impl Eq for $thing {}

        impl PartialOrd for $thing {
            #[inline]
            fn partial_cmp(&self, other: &$thing) -> Option<::std::cmp::Ordering> {
                Some(self.cmp(&other))
            }
        }

        impl Ord for $thing {
            #[inline]
            fn cmp(&self, other: &$thing) -> ::std::cmp::Ordering {
                // manually implement comparison to get little-endian ordering
                // (we need this for our numeric diem_types; non-numeric ones shouldn't
                // be ordered anyway except to put them in BTrees or whatever, and
                // they don't care how we order as long as we're consistent).
                for i in 0..$len {
                    if self[$len - 1 - i] < other[$len - 1 - i] {
                        return ::std::cmp::Ordering::Less;
                    }
                    if self[$len - 1 - i] > other[$len - 1 - i] {
                        return ::std::cmp::Ordering::Greater;
                    }
                }
                ::std::cmp::Ordering::Equal
            }
        }

        #[cfg_attr(feature = "clippy", allow(expl_impl_clone_on_copy))] // we don't define the `struct`, we have to explicitly impl
        impl Clone for $thing {
            #[inline]
            fn clone(&self) -> $thing {
                $thing::from(&self[..])
            }
        }

        impl Copy for $thing {}

        impl ::std::hash::Hash for $thing {
            #[inline]
            fn hash<H>(&self, state: &mut H)
            where
                H: ::std::hash::Hasher,
            {
                (&self[..]).hash(state);
            }

            fn hash_slice<H>(data: &[$thing], state: &mut H)
            where
                H: ::std::hash::Hasher,
            {
                for d in data.iter() {
                    (&d[..]).hash(state);
                }
            }
        }
    };
}

macro_rules! impl_array_newtype_encodable {
    ($thing:ident, $ty:ty, $len:expr) => {
        #[cfg(feature = "serde")]
        impl<'de> $crate::serde::Deserialize<'de> for $thing {
            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
            where
                D: $crate::serde::Deserializer<'de>,
            {
                use $crate::std::fmt::{self, Formatter};

                struct Visitor;
                impl<'de> $crate::serde::de::Visitor<'de> for Visitor {
                    type Value = $thing;

                    fn expecting(&self, formatter: &mut Formatter) -> fmt::Result {
                        formatter.write_str("a fixed size array")
                    }

                    #[inline]
                    fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
                    where
                        A: $crate::serde::de::SeqAccess<'de>,
                    {
                        let mut ret: [$ty; $len] = [0; $len];
                        for item in ret.iter_mut() {
                            *item = match seq.next_element()? {
                                Some(c) => c,
                                None => {
                                    return Err($crate::serde::de::Error::custom("end of stream"))
                                }
                            };
                        }
                        Ok($thing(ret))
                    }
                }

                deserializer.deserialize_seq(Visitor)
            }
        }

        #[cfg(feature = "serde")]
        impl $crate::serde::Serialize for $thing {
            fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
            where
                S: $crate::serde::Serializer,
            {
                let &$thing(ref dat) = self;
                (&dat[..]).serialize(serializer)
            }
        }
    };
}

macro_rules! impl_array_newtype_show {
    ($thing:ident) => {
        impl ::std::fmt::Debug for $thing {
            fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
                write!(f, concat!(stringify!($thing), "({:?})"), &self[..])
            }
        }
    };
}

macro_rules! impl_index_newtype {
    ($thing:ident, $ty:ty) => {
        impl ::std::ops::Index<::std::ops::Range<usize>> for $thing {
            type Output = [$ty];

            #[inline]
            fn index(&self, index: ::std::ops::Range<usize>) -> &[$ty] {
                &self.0[index]
            }
        }

        impl ::std::ops::Index<::std::ops::RangeTo<usize>> for $thing {
            type Output = [$ty];

            #[inline]
            fn index(&self, index: ::std::ops::RangeTo<usize>) -> &[$ty] {
                &self.0[index]
            }
        }

        impl ::std::ops::Index<::std::ops::RangeFrom<usize>> for $thing {
            type Output = [$ty];

            #[inline]
            fn index(&self, index: ::std::ops::RangeFrom<usize>) -> &[$ty] {
                &self.0[index]
            }
        }

        impl ::std::ops::Index<::std::ops::RangeFull> for $thing {
            type Output = [$ty];

            #[inline]
            fn index(&self, _: ::std::ops::RangeFull) -> &[$ty] {
                &self.0[..]
            }
        }
    };
}