// SPDX-License-Identifier: CC0-1.0

//! Bitcoin serde utilities.
//!
//! This module is for special serde serializations.
//!

pub(crate) struct SerializeBytesAsHex<'a>(pub(crate) &'a [u8]);

impl<'a> serde::Serialize for SerializeBytesAsHex<'a> {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: serde::Serializer,
    {
        use hex::DisplayHex;

        serializer.collect_str(&format_args!("{:x}", self.0.as_hex()))
    }
}

pub mod btreemap_byte_values {
    //! Module for serialization of BTreeMaps with hex byte values.
    #![allow(missing_docs)]

    // NOTE: This module can be exactly copied to use with HashMap.

    use hex::FromHex;

    use crate::prelude::*;

    pub fn serialize<S, T>(v: &BTreeMap<T, Vec<u8>>, s: S) -> Result<S::Ok, S::Error>
    where
        S: serde::Serializer,
        T: serde::Serialize + core::hash::Hash + Eq + Ord,
    {
        use serde::ser::SerializeMap;

        // Don't do anything special when not human readable.
        if !s.is_human_readable() {
            serde::Serialize::serialize(v, s)
        } else {
            let mut map = s.serialize_map(Some(v.len()))?;
            for (key, value) in v.iter() {
                map.serialize_entry(key, &super::SerializeBytesAsHex(value))?;
            }
            map.end()
        }
    }

    pub fn deserialize<'de, D, T>(d: D) -> Result<BTreeMap<T, Vec<u8>>, D::Error>
    where
        D: serde::Deserializer<'de>,
        T: serde::Deserialize<'de> + core::hash::Hash + Eq + Ord,
    {
        use core::marker::PhantomData;

        struct Visitor<T>(PhantomData<T>);
        impl<'de, T> serde::de::Visitor<'de> for Visitor<T>
        where
            T: serde::Deserialize<'de> + core::hash::Hash + Eq + Ord,
        {
            type Value = BTreeMap<T, Vec<u8>>;

            fn expecting(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
                write!(f, "a map with hexadecimal values")
            }

            fn visit_map<A: serde::de::MapAccess<'de>>(
                self,
                mut a: A,
            ) -> Result<Self::Value, A::Error> {
                let mut ret = BTreeMap::new();
                while let Some((key, value)) = a.next_entry()? {
                    ret.insert(key, FromHex::from_hex(value).map_err(serde::de::Error::custom)?);
                }
                Ok(ret)
            }
        }

        // Don't do anything special when not human readable.
        if !d.is_human_readable() {
            serde::Deserialize::deserialize(d)
        } else {
            d.deserialize_map(Visitor(PhantomData))
        }
    }
}

pub mod btreemap_as_seq {
    //! Module for serialization of BTreeMaps as lists of sequences because
    //! serde_json will not serialize hashmaps with non-string keys be default.
    #![allow(missing_docs)]

    // NOTE: This module can be exactly copied to use with HashMap.

    use crate::prelude::*;

    pub fn serialize<S, T, U>(v: &BTreeMap<T, U>, s: S) -> Result<S::Ok, S::Error>
    where
        S: serde::Serializer,
        T: serde::Serialize + core::hash::Hash + Eq + Ord,
        U: serde::Serialize,
    {
        use serde::ser::SerializeSeq;

        // Don't do anything special when not human readable.
        if !s.is_human_readable() {
            serde::Serialize::serialize(v, s)
        } else {
            let mut seq = s.serialize_seq(Some(v.len()))?;
            for pair in v.iter() {
                seq.serialize_element(&pair)?;
            }
            seq.end()
        }
    }

    pub fn deserialize<'de, D, T, U>(d: D) -> Result<BTreeMap<T, U>, D::Error>
    where
        D: serde::Deserializer<'de>,
        T: serde::Deserialize<'de> + core::hash::Hash + Eq + Ord,
        U: serde::Deserialize<'de>,
    {
        use core::marker::PhantomData;

        struct Visitor<T, U>(PhantomData<(T, U)>);
        impl<'de, T, U> serde::de::Visitor<'de> for Visitor<T, U>
        where
            T: serde::Deserialize<'de> + core::hash::Hash + Eq + Ord,
            U: serde::Deserialize<'de>,
        {
            type Value = BTreeMap<T, U>;

            fn expecting(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
                write!(f, "a sequence of pairs")
            }

            fn visit_seq<A: serde::de::SeqAccess<'de>>(
                self,
                mut a: A,
            ) -> Result<Self::Value, A::Error> {
                let mut ret = BTreeMap::new();
                while let Some((key, value)) = a.next_element()? {
                    ret.insert(key, value);
                }
                Ok(ret)
            }
        }

        // Don't do anything special when not human readable.
        if !d.is_human_readable() {
            serde::Deserialize::deserialize(d)
        } else {
            d.deserialize_seq(Visitor(PhantomData))
        }
    }
}

pub mod btreemap_as_seq_byte_values {
    //! Module for serialization of BTreeMaps as lists of sequences because
    //! serde_json will not serialize hashmaps with non-string keys be default.
    #![allow(missing_docs)]

    // NOTE: This module can be exactly copied to use with HashMap.

    use crate::prelude::*;

    /// A custom key-value pair type that serialized the bytes as hex.
    #[derive(Debug, Deserialize)]
    #[serde(crate = "actual_serde")]
    struct OwnedPair<T>(
        T,
        #[serde(deserialize_with = "crate::serde_utils::hex_bytes::deserialize")] Vec<u8>,
    );

    /// A custom key-value pair type that serialized the bytes as hex.
    #[derive(Debug, Serialize)]
    #[serde(crate = "actual_serde")]
    struct BorrowedPair<'a, T: 'static>(
        &'a T,
        #[serde(serialize_with = "crate::serde_utils::hex_bytes::serialize")] &'a [u8],
    );

    pub fn serialize<S, T>(v: &BTreeMap<T, Vec<u8>>, s: S) -> Result<S::Ok, S::Error>
    where
        S: serde::Serializer,
        T: serde::Serialize + core::hash::Hash + Eq + Ord + 'static,
    {
        use serde::ser::SerializeSeq;

        // Don't do anything special when not human readable.
        if !s.is_human_readable() {
            serde::Serialize::serialize(v, s)
        } else {
            let mut seq = s.serialize_seq(Some(v.len()))?;
            for (key, value) in v.iter() {
                seq.serialize_element(&BorrowedPair(key, value))?;
            }
            seq.end()
        }
    }

    pub fn deserialize<'de, D, T>(d: D) -> Result<BTreeMap<T, Vec<u8>>, D::Error>
    where
        D: serde::Deserializer<'de>,
        T: serde::Deserialize<'de> + core::hash::Hash + Eq + Ord,
    {
        use core::marker::PhantomData;

        struct Visitor<T>(PhantomData<T>);
        impl<'de, T> serde::de::Visitor<'de> for Visitor<T>
        where
            T: serde::Deserialize<'de> + core::hash::Hash + Eq + Ord,
        {
            type Value = BTreeMap<T, Vec<u8>>;

            fn expecting(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
                write!(f, "a sequence of pairs")
            }

            fn visit_seq<A: serde::de::SeqAccess<'de>>(
                self,
                mut a: A,
            ) -> Result<Self::Value, A::Error> {
                let mut ret = BTreeMap::new();
                while let Option::Some(OwnedPair(key, value)) = a.next_element()? {
                    ret.insert(key, value);
                }
                Ok(ret)
            }
        }

        // Don't do anything special when not human readable.
        if !d.is_human_readable() {
            serde::Deserialize::deserialize(d)
        } else {
            d.deserialize_seq(Visitor(PhantomData))
        }
    }
}

pub mod hex_bytes {
    //! Module for serialization of byte arrays as hex strings.
    #![allow(missing_docs)]

    use hex::FromHex;

    pub fn serialize<T, S>(bytes: &T, s: S) -> Result<S::Ok, S::Error>
    where
        T: serde::Serialize + AsRef<[u8]>,
        S: serde::Serializer,
    {
        // Don't do anything special when not human readable.
        if !s.is_human_readable() {
            serde::Serialize::serialize(bytes, s)
        } else {
            serde::Serialize::serialize(&super::SerializeBytesAsHex(bytes.as_ref()), s)
        }
    }

    pub fn deserialize<'de, D, B>(d: D) -> Result<B, D::Error>
    where
        D: serde::Deserializer<'de>,
        B: serde::Deserialize<'de> + FromHex,
    {
        struct Visitor<B>(core::marker::PhantomData<B>);

        impl<'de, B: FromHex> serde::de::Visitor<'de> for Visitor<B> {
            type Value = B;

            fn expecting(&self, formatter: &mut core::fmt::Formatter) -> core::fmt::Result {
                formatter.write_str("an ASCII hex string")
            }

            fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
            where
                E: serde::de::Error,
            {
                if let Ok(hex) = core::str::from_utf8(v) {
                    FromHex::from_hex(hex).map_err(E::custom)
                } else {
                    return Err(E::invalid_value(serde::de::Unexpected::Bytes(v), &self));
                }
            }

            fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
            where
                E: serde::de::Error,
            {
                FromHex::from_hex(v).map_err(E::custom)
            }
        }

        // Don't do anything special when not human readable.
        if !d.is_human_readable() {
            serde::Deserialize::deserialize(d)
        } else {
            d.deserialize_str(Visitor(core::marker::PhantomData))
        }
    }
}

macro_rules! serde_string_serialize_impl {
    ($name:ty, $expecting:literal) => {
        impl $crate::serde::Serialize for $name {
            fn serialize<S>(&self, serializer: S) -> core::result::Result<S::Ok, S::Error>
            where
                S: $crate::serde::Serializer,
            {
                serializer.collect_str(&self)
            }
        }
    };
}

macro_rules! serde_string_deserialize_impl {
    ($name:ty, $expecting:literal) => {
        impl<'de> $crate::serde::Deserialize<'de> for $name {
            fn deserialize<D>(deserializer: D) -> core::result::Result<$name, D::Error>
            where
                D: $crate::serde::de::Deserializer<'de>,
            {
                use core::fmt::Formatter;

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

                    fn expecting(&self, f: &mut Formatter) -> core::fmt::Result {
                        f.write_str($expecting)
                    }

                    fn visit_str<E>(self, v: &str) -> core::result::Result<Self::Value, E>
                    where
                        E: $crate::serde::de::Error,
                    {
                        v.parse::<$name>().map_err(E::custom)
                    }
                }

                deserializer.deserialize_str(Visitor)
            }
        }
    };
}

macro_rules! serde_string_impl {
    ($name:ty, $expecting:literal) => {
        $crate::serde_utils::serde_string_deserialize_impl!($name, $expecting);
        $crate::serde_utils::serde_string_serialize_impl!($name, $expecting);
    };
}
pub(crate) use {serde_string_deserialize_impl, serde_string_impl, serde_string_serialize_impl};

/// A combination macro where the human-readable serialization is done like
/// serde_string_impl and the non-human-readable impl is done as a struct.
macro_rules! serde_struct_human_string_impl {
    ($name:ident, $expecting:literal, $($fe:ident),*) => (
        impl<'de> $crate::serde::Deserialize<'de> for $name {
            fn deserialize<D>(deserializer: D) -> core::result::Result<$name, D::Error>
            where
                D: $crate::serde::de::Deserializer<'de>,
            {
                if deserializer.is_human_readable() {
                    use core::fmt::Formatter;
                    use core::str::FromStr;

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

                        fn expecting(&self, f: &mut Formatter) -> core::fmt::Result {
                            f.write_str($expecting)
                        }

                        fn visit_str<E>(self, v: &str) -> core::result::Result<Self::Value, E>
                        where
                            E: $crate::serde::de::Error,
                        {
                            $name::from_str(v).map_err(E::custom)
                        }

                    }

                    deserializer.deserialize_str(Visitor)
                } else {
                    use core::fmt::Formatter;
                    use $crate::serde::de::IgnoredAny;

                    #[allow(non_camel_case_types)]
                    enum Enum { Unknown__Field, $($fe),* }

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

                        fn expecting(&self, f: &mut Formatter) -> core::fmt::Result {
                            f.write_str("a field name")
                        }

                        fn visit_str<E>(self, v: &str) -> core::result::Result<Self::Value, E>
                        where
                            E: $crate::serde::de::Error,
                        {
                            match v {
                                $(
                                stringify!($fe) => Ok(Enum::$fe)
                                ),*,
                                _ => Ok(Enum::Unknown__Field)
                            }
                        }
                    }

                    impl<'de> $crate::serde::Deserialize<'de> for Enum {
                        fn deserialize<D>(deserializer: D) -> core::result::Result<Self, D::Error>
                        where
                            D: $crate::serde::de::Deserializer<'de>,
                        {
                            deserializer.deserialize_str(EnumVisitor)
                        }
                    }

                    struct Visitor;

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

                        fn expecting(&self, f: &mut Formatter) -> core::fmt::Result {
                            f.write_str("a struct")
                        }

                        fn visit_seq<V>(self, mut seq: V) -> core::result::Result<Self::Value, V::Error>
                        where
                            V: $crate::serde::de::SeqAccess<'de>,
                        {
                            use $crate::serde::de::Error;

                            let length = 0;
                            $(
                                let $fe = seq.next_element()?.ok_or_else(|| {
                                    Error::invalid_length(length, &self)
                                })?;
                                #[allow(unused_variables)]
                                let length = length + 1;
                            )*

                            let ret = $name {
                                $($fe),*
                            };

                            Ok(ret)
                        }

                        fn visit_map<A>(self, mut map: A) -> core::result::Result<Self::Value, A::Error>
                        where
                            A: $crate::serde::de::MapAccess<'de>,
                        {
                            use $crate::serde::de::Error;

                            $(let mut $fe = None;)*

                            loop {
                                match map.next_key::<Enum>()? {
                                    Some(Enum::Unknown__Field) => {
                                        map.next_value::<IgnoredAny>()?;
                                    }
                                    $(
                                        Some(Enum::$fe) => {
                                            $fe = Some(map.next_value()?);
                                        }
                                    )*
                                    None => { break; }
                                }
                            }

                            $(
                                let $fe = match $fe {
                                    Some(x) => x,
                                    None => return Err(A::Error::missing_field(stringify!($fe))),
                                };
                            )*

                            let ret = $name {
                                $($fe),*
                            };

                            Ok(ret)
                        }
                    }
                    // end type defs

                    static FIELDS: &'static [&'static str] = &[$(stringify!($fe)),*];

                    deserializer.deserialize_struct(stringify!($name), FIELDS, Visitor)
                }
            }
        }

        impl $crate::serde::Serialize for $name {
            fn serialize<S>(&self, serializer: S) -> core::result::Result<S::Ok, S::Error>
            where
                S: $crate::serde::Serializer,
            {
                if serializer.is_human_readable() {
                    serializer.collect_str(&self)
                } else {
                    use $crate::serde::ser::SerializeStruct;

                    // Only used to get the struct length.
                    static FIELDS: &'static [&'static str] = &[$(stringify!($fe)),*];

                    let mut st = serializer.serialize_struct(stringify!($name), FIELDS.len())?;

                    $(
                        st.serialize_field(stringify!($fe), &self.$fe)?;
                    )*

                    st.end()
                }
            }
        }
    )
}
pub(crate) use serde_struct_human_string_impl;
