bramble-data 0.1.1

use crate::{constants::*, Error, Result};
use serde::{ser, Serialize};
use std::{convert::TryFrom, io::Write};

/// Serializes a value as BDF into a [`Vec`].
pub fn to_vec<T>(value: &T) -> Result<Vec<u8>>
where
    T: ?Sized + Serialize,
{
    let mut writer = Vec::new();
    to_writer(&mut writer, value)?;
    Ok(writer)
}

/// Serializes a value as BDF into a [`Write`](std::io::Write).
pub fn to_writer<W, T>(writer: W, value: &T) -> Result<()>
where
    W: Write,
    T: ?Sized + Serialize,
{
    let mut ser = Serializer::new(writer);
    value.serialize(&mut ser)
}

/// A serializer that outputs data as BDF.
pub struct Serializer<W>
where
    W: Write,
{
    writer: W,
}

impl<W> Serializer<W>
where
    W: Write,
{
    /// Creates a new serializer from a writer.
    pub fn new(writer: W) -> Self {
        Self { writer }
    }

    /// Consumes the serializer and returns the inner writer.
    pub fn into_inner(self) -> W {
        self.writer
    }
}

impl<'a, W> ser::Serializer for &'a mut Serializer<W>
where
    W: Write,
{
    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, value: bool) -> Result<()> {
        Ok(self.writer.write_all(&[TYPE_BOOLEAN | value as u8])?)
    }

    fn serialize_i8(self, value: i8) -> Result<()> {
        self.serialize_i64(value as i64)
    }

    fn serialize_i16(self, value: i16) -> Result<()> {
        self.serialize_i64(value as i64)
    }

    fn serialize_i32(self, value: i32) -> Result<()> {
        self.serialize_i64(value as i64)
    }

    fn serialize_i64(self, value: i64) -> Result<()> {
        write_integer(&mut self.writer, TYPE_INTEGER, value)
    }

    fn serialize_u8(self, value: u8) -> Result<()> {
        self.serialize_i64(value as i64)
    }

    fn serialize_u16(self, value: u16) -> Result<()> {
        self.serialize_i64(value as i64)
    }

    fn serialize_u32(self, value: u32) -> Result<()> {
        self.serialize_i64(value as i64)
    }

    fn serialize_u64(self, value: u64) -> Result<()> {
        self.serialize_i64(i64::try_from(value)?)
    }

    fn serialize_f32(self, value: f32) -> Result<()> {
        self.serialize_f64(value as f64)
    }

    fn serialize_f64(self, value: f64) -> Result<()> {
        self.writer.write_all(&[TYPE_FLOAT | 8])?;
        Ok(self.writer.write_all(&value.to_be_bytes())?)
    }

    fn serialize_char(self, value: char) -> Result<()> {
        self.serialize_i64(value as i64)
    }

    fn serialize_str(self, value: &str) -> Result<()> {
        write_integer(&mut self.writer, TYPE_STRING, value.len() as i64)?;
        Ok(self.writer.write_all(value.as_bytes())?)
    }

    fn serialize_bytes(self, value: &[u8]) -> Result<()> {
        write_integer(&mut self.writer, TYPE_RAW, value.len() as i64)?;
        Ok(self.writer.write_all(value)?)
    }

    fn serialize_unit(self) -> Result<()> {
        Ok(self.writer.write_all(&[TYPE_NULL])?)
    }

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

    fn serialize_unit_variant(
        self,
        _name: &'static str,
        variant_index: u32,
        _variant: &'static str,
    ) -> Result<()> {
        self.serialize_u32(variant_index)
    }

    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,
    {
        use ser::SerializeSeq;
        let mut seq = self.serialize_seq(Some(2))?;
        seq.serialize_element(&variant_index)?;
        seq.serialize_element(value)?;
        seq.end()
    }

    fn serialize_none(self) -> Result<()> {
        self.serialize_unit()
    }

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

    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq> {
        self.writer.write_all(&[TYPE_LIST])?;
        Ok(self)
    }

    fn serialize_tuple(self, len: usize) -> Result<Self::SerializeTuple> {
        self.serialize_seq(Some(len))
    }

    fn serialize_tuple_struct(
        self,
        _name: &'static str,
        len: usize,
    ) -> Result<Self::SerializeTupleStruct> {
        self.serialize_tuple(len)
    }

    fn serialize_tuple_variant(
        self,
        _name: &'static str,
        variant_index: u32,
        _variant: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeTupleVariant> {
        use ser::SerializeSeq;
        let mut seq = self.serialize_seq(None)?;
        seq.serialize_element(&variant_index)?;
        Ok(seq)
    }

    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap> {
        self.writer.write_all(&[TYPE_DICTIONARY])?;
        Ok(self)
    }

    fn serialize_struct(self, _name: &'static str, len: usize) -> Result<Self::SerializeStruct> {
        self.serialize_tuple(len)
    }

    fn serialize_struct_variant(
        self,
        name: &'static str,
        variant_index: u32,
        variant: &'static str,
        len: usize,
    ) -> Result<Self::SerializeStructVariant> {
        self.serialize_tuple_variant(name, variant_index, variant, len)
    }
}

impl<'a, W> ser::SerializeSeq for &'a mut Serializer<W>
where
    W: Write,
{
    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(self.writer.write_all(&[TYPE_END])?)
    }
}

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

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

    fn end(self) -> Result<()> {
        ser::SerializeSeq::end(self)
    }
}

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

    fn serialize_field<T>(&mut self, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        ser::SerializeSeq::serialize_element(self, value)
    }

    fn end(self) -> Result<()> {
        ser::SerializeSeq::end(self)
    }
}

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

    fn serialize_field<T>(&mut self, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        ser::SerializeSeq::serialize_element(self, value)
    }

    fn end(self) -> Result<()> {
        ser::SerializeSeq::end(self)
    }
}

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

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

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

    fn end(self) -> Result<()> {
        Ok(self.writer.write_all(&[TYPE_END])?)
    }
}

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

    fn serialize_field<T>(&mut self, _name: &'static str, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        ser::SerializeSeq::serialize_element(self, value)
    }

    fn end(self) -> Result<()> {
        ser::SerializeSeq::end(self)
    }
}

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

    fn serialize_field<T>(&mut self, name: &'static str, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        ser::SerializeStruct::serialize_field(self, name, value)
    }

    fn end(self) -> Result<()> {
        ser::SerializeSeq::end(self)
    }
}

fn write_integer<W>(writer: &mut W, typ: u8, value: i64) -> Result<()>
where
    W: Write,
{
    let len = if value >= i8::MIN as i64 && value <= i8::MAX as i64 {
        1
    } else if value >= i16::MIN as i64 && value <= i16::MAX as i64 {
        2
    } else if value >= i32::MIN as i64 && value <= i32::MAX as i64 {
        4
    } else {
        8
    };
    writer.write_all(&[typ | len as u8])?;
    let start = 8 - len as usize;
    let mut buf = [0u8; 8];
    buf[..len].copy_from_slice(&value.to_be_bytes()[start..]);
    Ok(writer.write_all(&buf[..len])?)
}

struct KeySerializer<'a, W>(&'a mut Serializer<W>)
where
    W: Write;

impl<'a, W> ser::Serializer for KeySerializer<'a, W>
where
    W: Write,
{
    type Ok = ();
    type Error = Error;

    type SerializeSeq = ser::Impossible<(), Error>;
    type SerializeTuple = ser::Impossible<(), Error>;
    type SerializeTupleStruct = ser::Impossible<(), Error>;
    type SerializeTupleVariant = ser::Impossible<(), Error>;
    type SerializeMap = ser::Impossible<(), Error>;
    type SerializeStruct = ser::Impossible<(), Error>;
    type SerializeStructVariant = ser::Impossible<(), Error>;

    fn serialize_bool(self, _value: bool) -> Result<()> {
        Err(Error::WrongType)
    }

    fn serialize_i8(self, _value: i8) -> Result<()> {
        Err(Error::WrongType)
    }

    fn serialize_i16(self, _value: i16) -> Result<()> {
        Err(Error::WrongType)
    }

    fn serialize_i32(self, _value: i32) -> Result<()> {
        Err(Error::WrongType)
    }

    fn serialize_i64(self, _value: i64) -> Result<()> {
        Err(Error::WrongType)
    }

    fn serialize_u8(self, _value: u8) -> Result<()> {
        Err(Error::WrongType)
    }

    fn serialize_u16(self, _value: u16) -> Result<()> {
        Err(Error::WrongType)
    }

    fn serialize_u32(self, _value: u32) -> Result<()> {
        Err(Error::WrongType)
    }

    fn serialize_u64(self, _value: u64) -> Result<()> {
        Err(Error::WrongType)
    }

    fn serialize_f32(self, _value: f32) -> Result<()> {
        Err(Error::WrongType)
    }

    fn serialize_f64(self, _value: f64) -> Result<()> {
        Err(Error::WrongType)
    }

    fn serialize_char(self, _value: char) -> Result<()> {
        Err(Error::WrongType)
    }

    fn serialize_str(self, value: &str) -> Result<()> {
        self.0.serialize_str(value)
    }

    fn serialize_bytes(self, _value: &[u8]) -> Result<()> {
        Err(Error::WrongType)
    }

    fn serialize_unit(self) -> Result<()> {
        Err(Error::WrongType)
    }

    fn serialize_unit_struct(self, _name: &'static str) -> Result<()> {
        Err(Error::WrongType)
    }

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

    fn serialize_newtype_struct<T>(self, _name: &'static str, _value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        Err(Error::WrongType)
    }

    fn serialize_newtype_variant<T>(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        _value: &T,
    ) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        Err(Error::WrongType)
    }

    fn serialize_none(self) -> Result<()> {
        Err(Error::WrongType)
    }

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

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

    fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple> {
        Err(Error::WrongType)
    }

    fn serialize_tuple_struct(
        self,
        _name: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeTupleStruct> {
        Err(Error::WrongType)
    }

    fn serialize_tuple_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeTupleVariant> {
        Err(Error::WrongType)
    }

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

    fn serialize_struct(self, _name: &'static str, _len: usize) -> Result<Self::SerializeStruct> {
        Err(Error::WrongType)
    }

    fn serialize_struct_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeStructVariant> {
        Err(Error::WrongType)
    }
}

#[cfg(test)]
mod test {
    use super::*;
    use hex_literal::hex;
    use serde::Serialize;
    use std::collections::BTreeMap;

    #[test]
    fn to_vec_maps() {
        let mut map = BTreeMap::new();
        map.insert("foo".to_string(), 123u32);
        map.insert("bar".to_string(), 456u32);
        let buf = to_vec(&map).unwrap();
        assert_eq!(
            hex!("70 4103626172 2201C8 4103666F6F 217B 80").as_ref(),
            buf.as_slice()
        );
    }

    #[test]
    fn to_vec_structs() {
        #[derive(Serialize)]
        struct Test {
            x: bool,
            y: u32,
            z: Vec<String>,
        }
        let s = Test {
            x: true,
            y: 17,
            z: vec!["foo".into(), "bar".into()],
        };
        let buf = to_vec(&s).unwrap();
        assert_eq!(
            hex!("60 11 2111 60 4103666F6F 4103626172 80 80").as_ref(),
            buf.as_slice()
        );
    }

    #[test]
    fn to_vec_enums() {
        #[derive(Serialize)]
        enum Test {
            UnitVariant,
            NewTypeVariant(u32),
            TupleVariant(bool, u32),
            StructVariant { x: bool, y: u32 },
        }
        let e = Test::UnitVariant;
        let buf = to_vec(&e).unwrap();
        assert_eq!(hex!("2100").as_ref(), buf.as_slice());

        let e = Test::NewTypeVariant(17);
        let buf = to_vec(&e).unwrap();
        assert_eq!(hex!("60 2101 2111 80").as_ref(), buf.as_slice());

        let e = Test::TupleVariant(true, 17);
        let buf = to_vec(&e).unwrap();
        assert_eq!(hex!("60 2102 11 2111 80").as_ref(), buf.as_slice());

        let e = Test::StructVariant { x: true, y: 17 };
        let buf = to_vec(&e).unwrap();
        assert_eq!(hex!("60 2103 11 2111 80").as_ref(), buf.as_slice());
    }

    #[test]
    fn to_vec_options() {
        let o: Option<u32> = None;
        let buf = to_vec(&o).unwrap();
        assert_eq!(hex!("00").as_ref(), buf.as_slice());

        let o = Some(17);
        let buf = to_vec(&o).unwrap();
        assert_eq!(hex!("2111").as_ref(), buf.as_slice());
    }
}