toio 0.1.4

use bytes::BufMut;
use derive_new::new;
use serde::{ser, Serialize};
use std::fmt::{self, Display};
use std::io::prelude::*;

pub type Result<T> = std::result::Result<T, Error>;

pub fn encode<T: Serialize, W: Write>(mut buf: W, msg: T) -> anyhow::Result<()> {
    let mut ser = Serializer::new();
    msg.serialize(&mut ser)?;
    buf.write(&ser.buf)?;
    Ok(())
}

#[derive(Clone, Debug, PartialEq)]
pub struct Error(String);

impl From<std::io::Error> for Error {
    fn from(e: std::io::Error) -> Self {
        Self(e.to_string())
    }
}

impl ser::Error for Error {
    fn custom<T: Display>(msg: T) -> Self {
        Error(msg.to_string())
    }
}

impl Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", self.0)
    }
}

impl std::error::Error for Error {}

#[derive(new)]
pub struct Serializer {
    #[new(default)]
    buf: Vec<u8>,
}

impl<'a> ser::Serializer for &'a mut Serializer {
    type Ok = ();
    type Error = Error;

    type SerializeSeq = Self;
    type SerializeTuple = Self;
    type SerializeTupleStruct = Self;
    type SerializeTupleVariant = Self;
    type SerializeMap = Self;
    type SerializeStruct = Self;
    type SerializeStructVariant = Self;

    fn serialize_bool(self, v: bool) -> Result<()> {
        Ok(self.buf.put_u8(v as u8))
    }

    fn serialize_i8(self, v: i8) -> Result<()> {
        Ok(self.buf.put_i8(v))
    }

    fn serialize_i16(self, v: i16) -> Result<()> {
        Ok(self.buf.put_i16_le(v))
    }

    fn serialize_i32(self, v: i32) -> Result<()> {
        Ok(self.buf.put_i32_le(v))
    }

    fn serialize_i64(self, v: i64) -> Result<()> {
        Ok(self.buf.put_i64_le(v))
    }

    fn serialize_u8(self, v: u8) -> Result<()> {
        Ok(self.buf.put_u8(v))
    }

    fn serialize_u16(self, v: u16) -> Result<()> {
        Ok(self.buf.put_u16_le(v))
    }

    fn serialize_u32(self, v: u32) -> Result<()> {
        Ok(self.buf.put_u32_le(v))
    }

    fn serialize_u64(self, v: u64) -> Result<()> {
        Ok(self.buf.put_u64_le(v))
    }

    fn serialize_f32(self, _v: f32) -> Result<()> {
        unreachable!()
    }

    fn serialize_f64(self, _v: f64) -> Result<()> {
        unreachable!()
    }

    fn serialize_char(self, _v: char) -> Result<()> {
        unreachable!()
    }

    fn serialize_str(self, v: &str) -> Result<()> {
        self.buf.write(v.as_bytes())?;
        Ok(())
    }

    fn serialize_bytes(self, _v: &[u8]) -> Result<()> {
        unreachable!()
    }

    fn serialize_none(self) -> Result<()> {
        unreachable!()
    }

    fn serialize_some<T>(self, _value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        unreachable!()
    }

    fn serialize_unit(self) -> Result<()> {
        unreachable!()
    }

    fn serialize_unit_struct(self, _name: &'static str) -> Result<()> {
        unreachable!()
    }

    fn serialize_unit_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
    ) -> Result<()> {
        unreachable!()
    }

    fn serialize_newtype_struct<T>(self, _name: &'static str, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(self)
    }

    fn serialize_newtype_variant<T>(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        value: &T,
    ) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(&mut *self)?;
        Ok(())
    }

    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq> {
        Ok(self)
    }

    fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple> {
        self.serialize_seq(None)
    }

    fn serialize_tuple_struct(
        self,
        _name: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeTupleStruct> {
        self.serialize_seq(None)
    }

    fn serialize_tuple_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeTupleVariant> {
        self.serialize_seq(None)
    }

    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap> {
        Ok(self)
    }

    fn serialize_struct(self, _name: &'static str, _len: usize) -> Result<Self::SerializeStruct> {
        self.serialize_map(None)
    }

    fn serialize_struct_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeStructVariant> {
        self.serialize_map(None)
    }
}

impl<'a> ser::SerializeSeq for &'a mut Serializer {
    type Ok = ();
    type Error = Error;

    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(&mut **self)
    }

    fn end(self) -> Result<()> {
        Ok(())
    }
}

impl<'a> ser::SerializeTuple for &'a mut Serializer {
    type Ok = ();
    type Error = Error;

    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(&mut **self)
    }

    fn end(self) -> Result<()> {
        Ok(())
    }
}

impl<'a> ser::SerializeTupleStruct for &'a mut Serializer {
    type Ok = ();
    type Error = Error;

    fn serialize_field<T>(&mut self, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(&mut **self)
    }

    fn end(self) -> Result<()> {
        Ok(())
    }
}

impl<'a> ser::SerializeTupleVariant for &'a mut Serializer {
    type Ok = ();
    type Error = Error;

    fn serialize_field<T>(&mut self, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(&mut **self)
    }

    fn end(self) -> Result<()> {
        Ok(())
    }
}

impl<'a> ser::SerializeMap for &'a mut Serializer {
    type Ok = ();
    type Error = Error;

    fn serialize_key<T>(&mut self, _key: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        Ok(())
    }

    fn serialize_value<T>(&mut self, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(&mut **self)
    }

    fn end(self) -> Result<()> {
        Ok(())
    }
}

impl<'a> ser::SerializeStruct for &'a mut Serializer {
    type Ok = ();
    type Error = Error;

    fn serialize_field<T>(&mut self, _key: &'static str, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(&mut **self)
    }

    fn end(self) -> Result<()> {
        Ok(())
    }
}

impl<'a> ser::SerializeStructVariant for &'a mut Serializer {
    type Ok = ();
    type Error = Error;

    fn serialize_field<T>(&mut self, _key: &'static str, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(&mut **self)
    }

    fn end(self) -> Result<()> {
        Ok(())
    }
}