use anyhow::Context;
use std::io::{Read, Write};

pub trait Sink {
    fn put<V: Ser>(&mut self, value: V) -> anyhow::Result<()>;
}
pub trait Source {
    fn get<V: Ser>(&mut self) -> anyhow::Result<V>;
}

impl<T: Write> Sink for T {
    fn put<V: Ser>(&mut self, value: V) -> anyhow::Result<()> {
        value.write(self)
    }
}
impl<T: Read> Source for T {
    fn get<V: Ser>(&mut self) -> anyhow::Result<V> {
        V::read(self)
    }
}

pub trait Ser: Sized {
    fn write(&self, sink: &mut impl Write) -> anyhow::Result<()>;
    fn read(source: &mut impl Read) -> anyhow::Result<Self>;
}

impl<A: Ser, B: Ser> Ser for (A, B) {
    fn write(&self, sink: &mut impl Write) -> anyhow::Result<()> {
        self.0.write(sink).context("first tuple field")?;
        self.1.write(sink).context("second tuple field")?;
        Ok(())
    }

    fn read(source: &mut impl Read) -> anyhow::Result<Self> {
        Ok((A::read(source)?, B::read(source)?))
    }
}
impl<A: Ser, B: Ser, C: Ser> Ser for (A, B, C) {
    fn write(&self, sink: &mut impl Write) -> anyhow::Result<()> {
        self.0.write(sink).context("first tuple field")?;
        self.1.write(sink).context("second tuple field")?;
        self.2.write(sink).context("third tuple field")?;
        Ok(())
    }

    fn read(source: &mut impl Read) -> anyhow::Result<Self> {
        Ok((A::read(source)?, B::read(source)?, C::read(source)?))
    }
}

impl<A: Ser, const N: usize> Ser for [A; N] {
    fn write(&self, sink: &mut impl Write) -> anyhow::Result<()> {
        for e in self {
            e.write(sink).context("some array")?;
        }
        Ok(())
    }

    fn read(source: &mut impl Read) -> anyhow::Result<Self> {
        let mut k: [A; N] = unsafe { std::mem::zeroed() };
        for i in 0..N {
            k[i] = A::read(source)?;
        }
        Ok(k)
    }
}

impl<T: Ser> Ser for Vec<T> {
    fn write(&self, sink: &mut impl Write) -> anyhow::Result<()> {
        self.len().write(sink)?;
        for e in self {
            e.write(sink).context("some vec")?;
        }
        Ok(())
    }

    fn read(source: &mut impl Read) -> anyhow::Result<Self> {
        let mut v = vec![];
        for _ in 0..usize::read(source)? {
            v.push(T::read(source)?)
        }
        Ok(v)
    }
}

impl Ser for u8 {
    fn write(&self, sink: &mut impl Write) -> anyhow::Result<()> {
        Ok(sink.write_all(&[*self]).context("write u8")?)
    }
    fn read(source: &mut impl Read) -> anyhow::Result<Self> {
        let mut buf = [0u8; 1];
        source.read_exact(&mut buf)?;
        Ok(buf[0])
    }
}
impl Ser for u16 {
    fn write(&self, sink: &mut impl Write) -> anyhow::Result<()> {
        Ok(sink
            .write_all(&unsafe { std::mem::transmute_copy::<_, [u8; 2]>(self) })
            .context("write 16")?)
    }
    fn read(source: &mut impl Read) -> anyhow::Result<Self> {
        let mut buf = [0u8; 2];
        source.read_exact(&mut buf)?;
        Ok(unsafe { std::mem::transmute_copy(&buf) })
    }
}
impl Ser for u32 {
    fn write(&self, sink: &mut impl Write) -> anyhow::Result<()> {
        Ok(sink
            .write_all(&unsafe { std::mem::transmute_copy::<_, [u8; 4]>(self) })
            .context("write u32")?)
    }
    fn read(source: &mut impl Read) -> anyhow::Result<Self> {
        let mut buf = [0u8; 4];
        source.read_exact(&mut buf)?;
        Ok(unsafe { std::mem::transmute_copy(&buf) })
    }
}
impl Ser for u64 {
    fn write(&self, sink: &mut impl Write) -> anyhow::Result<()> {
        Ok(sink
            .write_all(&unsafe { std::mem::transmute_copy::<_, [u8; 8]>(self) })
            .context("write u64")?)
    }
    fn read(source: &mut impl Read) -> anyhow::Result<Self> {
        let mut buf = [0u8; 8];
        source.read_exact(&mut buf)?;
        Ok(unsafe { std::mem::transmute_copy(&buf) })
    }
}
impl Ser for usize {
    fn write(&self, sink: &mut impl Write) -> anyhow::Result<()> {
        Ok(sink
            .write_all(&unsafe { std::mem::transmute_copy::<_, [u8; 8]>(self) })
            .context("write usize")?)
    }
    fn read(source: &mut impl Read) -> anyhow::Result<Self> {
        let mut buf = [0u8; 8];
        source.read_exact(&mut buf)?;
        Ok(unsafe { std::mem::transmute_copy(&buf) })
    }
}
impl Ser for isize {
    fn write(&self, sink: &mut impl Write) -> anyhow::Result<()> {
        Ok(sink
            .write_all(&unsafe { std::mem::transmute_copy::<_, [u8; 8]>(self) })
            .context("write isize")?)
    }
    fn read(source: &mut impl Read) -> anyhow::Result<Self> {
        let mut buf = [0u8; 8];
        source.read_exact(&mut buf)?;
        Ok(unsafe { std::mem::transmute_copy(&buf) })
    }
}
impl Ser for f32 {
    fn write(&self, sink: &mut impl Write) -> anyhow::Result<()> {
        Ok(sink
            .write_all(&unsafe { std::mem::transmute_copy::<_, [u8; 4]>(self) })
            .context("write f32")?)
    }
    fn read(source: &mut impl Read) -> anyhow::Result<Self> {
        let mut buf = [0u8; 4];
        source.read_exact(&mut buf)?;
        Ok(unsafe { std::mem::transmute_copy(&buf) })
    }
}
impl Ser for f64 {
    fn write(&self, sink: &mut impl Write) -> anyhow::Result<()> {
        Ok(sink
            .write_all(&unsafe { std::mem::transmute_copy::<_, [u8; 8]>(self) })
            .context("write f64")?)
    }
    fn read(source: &mut impl Read) -> anyhow::Result<Self> {
        let mut buf = [0u8; 8];
        source.read_exact(&mut buf)?;
        Ok(unsafe { std::mem::transmute_copy(&buf) })
    }
}

#[cfg(test)]
mod test {
    use super::{Ser, Sink};
    use crate::header::Header;
    use crate::ser::Source;
    use crate::vec2::Vec2;
    use std::fmt::Debug;
    use std::io::Cursor;

    fn test_ser<T: PartialEq + Ser + Debug + Clone>(value: T) {
        let mut buf = vec![];
        Cursor::new(&mut buf).put(value.clone()).unwrap();
        assert_eq!(value, Cursor::new(&mut buf).get().unwrap());
    }

    #[test]
    fn simple() {
        let mut buf = vec![];
        Cursor::new(&mut buf).put(10usize).unwrap();
        assert_eq!(10usize, Cursor::new(&mut buf).get().unwrap());
    }
    #[test]
    fn tuple() {
        let mut buf = vec![];
        Cursor::new(&mut buf).put((10usize, 5u8, 3u16)).unwrap();
        assert_eq!((10usize, 5u8, 3u16), Cursor::new(&mut buf).get().unwrap());
    }
    #[test]
    fn header() {
        test_ser(Header {
            frame_count: 123,
            resolution: Vec2 { x: 13, y: 37 },
        });
    }
    #[test]
    fn vec() {
        test_ser(vec![1u16, 2, 3, 4]);
    }
    #[test]
    fn array() {
        test_ser([1u16, 2, 3, 4]);
    }
}