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use crate::types::{Encode, HeaderRaw, IndexKinds, Vec2, Vec3, Vec4, VertexIndexKinds};
use std::convert::TryFrom;
use std::fs::File;
use std::io::{BufReader, Error, Read};
use std::path::Path;

macro_rules! read_bin {
    ($F:ident,$T:ty) => {
        pub(crate) fn $F(&mut self) -> $T {
            let mut buf = [0_u8; std::mem::size_of::<$T>()];
            self.inner.read_exact(&mut buf).unwrap();
            <$T>::from_le_bytes(buf)
        }
    };
}

pub(crate) struct BinaryReader<R: Read> {
    inner: BufReader<R>,
}
impl BinaryReader<File> {
    pub(crate) fn open<P: AsRef<Path>>(path: P) -> Result<Self, Error> {
        let file = File::open(&path);

        match file {
            Ok(file) => {
                let inner = BufReader::new(file);
                Ok(BinaryReader { inner })
            }
            Err(err) => Err(err),
        }
    }
}
impl<R: Read> BinaryReader<R> {
    pub(crate) fn from_reader(r: R) -> Self {
        Self {
            inner: BufReader::new(r),
        }
    }
    pub(crate) fn read_vec(&mut self, n: usize) -> Vec<u8> {
        let mut v = vec![0; n];
        self.inner.read_exact(&mut v).unwrap();
        v
    }
    pub(crate) fn read_text_buf(&mut self, encode: Encode) -> String {
        let length = self.read_i32();
        let v = self.read_vec(usize::try_from(length).unwrap());
        match encode {
            Encode::UTF8 => String::from_utf8(v).unwrap(),
            Encode::Utf16Le => encoding_rs::UTF_16LE.decode(&v).0.to_string(),
        }
    }

    pub(crate) fn read_vertex_index(&mut self, types: VertexIndexKinds) -> i32 {
        match types {
            VertexIndexKinds::U8 => i32::from(self.read_u8()),
            VertexIndexKinds::U16 => i32::from(self.read_u16()),
            VertexIndexKinds::I32 => self.read_i32(),
        }
    }

    pub(crate) fn read_sized(&mut self, types: IndexKinds) -> i32 {
        match types {
            IndexKinds::I8 => i32::from(self.read_i8()),
            IndexKinds::I16 => i32::from(self.read_i16()),
            IndexKinds::I32 => self.read_i32(),
        }
    }

    pub(crate) fn read_vec4(&mut self) -> Vec4 {
        [
            self.read_f32(),
            self.read_f32(),
            self.read_f32(),
            self.read_f32(),
        ]
    }
    pub(crate) fn read_vec3(&mut self) -> Vec3 {
        [self.read_f32(), self.read_f32(), self.read_f32()]
    }
    pub(crate) fn read_vec2(&mut self) -> Vec2 {
        [self.read_f32(), self.read_f32()]
    }
    pub(crate) fn read_raw_header(&mut self) -> HeaderRaw {
        let mut header = HeaderRaw {
            magic: [0; 4],
            version: 0.0,
            length: 0,
            config: [0; 8],
        };
        header.magic.iter_mut().for_each(|c| *c = self.read_u8());
        header.version = self.read_f32();
        header.length = self.read_u8();
        header.config.iter_mut().for_each(|c| *c = self.read_u8());
        header
    }

    read_bin!(read_f32, f32);
    read_bin!(read_i32, i32);
    read_bin!(read_i16, i16);
    read_bin!(read_u16, u16);
    read_bin!(read_i8, i8);
    read_bin!(read_u8, u8);
    /// read `0_u8` as `false`, `1_u8` as `true`
    pub(crate) fn read_bool(&mut self) -> Option<bool> {
        match self.read_u8() {
            0 => Some(false),
            1 => Some(true),
            _ => None,
        }
    }
}