use super::{UnsizedByteArray, MAX_STRING_LENGTH};
use byteorder::{BigEndian, WriteBytesExt};
use std::{collections::HashMap, io::Write};

// TODO: get rid of Writable and use McBufWritable everywhere

pub trait Writable: Write {
    fn write_list<F, T>(&mut self, list: &[T], writer: F) -> Result<(), std::io::Error>
    where
        F: FnOnce(&mut Self, &T) -> Result<(), std::io::Error> + Copy,
    {
        self.write_varint(list.len() as i32)?;
        for item in list {
            writer(self, item)?;
        }
        Ok(())
    }

    fn write_int_id_list(&mut self, list: &[i32]) -> Result<(), std::io::Error> {
        self.write_list(list, |buf, n| buf.write_varint(*n))
    }

    fn write_map<KF, VF, KT, VT>(
        &mut self,
        map: Vec<(KT, VT)>,
        key_writer: KF,
        value_writer: VF,
    ) -> Result<(), std::io::Error>
    where
        KF: Fn(&mut Self, KT) -> Result<(), std::io::Error> + Copy,
        VF: Fn(&mut Self, VT) -> Result<(), std::io::Error> + Copy,
    {
        self.write_varint(map.len() as i32)?;
        for (key, value) in map {
            key_writer(self, key)?;
            value_writer(self, value)?;
        }
        Ok(())
    }

    fn write_byte(&mut self, n: u8) -> Result<(), std::io::Error> {
        WriteBytesExt::write_u8(self, n)
    }

    fn write_bytes(&mut self, bytes: &[u8]) -> Result<(), std::io::Error> {
        self.write_all(bytes)?;
        Ok(())
    }

    fn write_varint(&mut self, mut value: i32) -> Result<(), std::io::Error> {
        let mut buffer = [0];
        if value == 0 {
            self.write_all(&buffer).unwrap();
        }
        while value != 0 {
            buffer[0] = (value & 0b0111_1111) as u8;
            value = (value >> 7) & (i32::max_value() >> 6);
            if value != 0 {
                buffer[0] |= 0b1000_0000;
            }
            self.write_all(&buffer)?;
        }
        Ok(())
    }

    fn write_utf_with_len(&mut self, string: &str, len: usize) -> Result<(), std::io::Error> {
        if string.len() > len {
            panic!(
                "String too big (was {} bytes encoded, max {})",
                string.len(),
                len
            );
        }
        self.write_varint(string.len() as i32)?;
        self.write_bytes(string.as_bytes())
    }

    fn write_utf(&mut self, string: &str) -> Result<(), std::io::Error> {
        self.write_utf_with_len(string, MAX_STRING_LENGTH.into())
    }

    fn write_short(&mut self, n: i16) -> Result<(), std::io::Error> {
        WriteBytesExt::write_i16::<BigEndian>(self, n)
    }

    fn write_byte_array(&mut self, bytes: &[u8]) -> Result<(), std::io::Error> {
        self.write_varint(bytes.len() as i32)?;
        self.write_bytes(bytes)
    }

    fn write_int(&mut self, n: i32) -> Result<(), std::io::Error> {
        WriteBytesExt::write_i32::<BigEndian>(self, n)
    }

    fn write_boolean(&mut self, b: bool) -> Result<(), std::io::Error> {
        self.write_byte(if b { 1 } else { 0 })
    }

    fn write_long(&mut self, n: i64) -> Result<(), std::io::Error> {
        WriteBytesExt::write_i64::<BigEndian>(self, n)
    }

    fn write_float(&mut self, n: f32) -> Result<(), std::io::Error> {
        WriteBytesExt::write_f32::<BigEndian>(self, n)
    }

    fn write_double(&mut self, n: f64) -> Result<(), std::io::Error> {
        WriteBytesExt::write_f64::<BigEndian>(self, n)
    }
}

impl<W: Write + ?Sized> Writable for W {}

pub trait McBufWritable {
    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error>;
}

pub trait McBufVarWritable {
    fn var_write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error>;
}

impl McBufWritable for i32 {
    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        Writable::write_int(buf, *self)
    }
}

impl McBufVarWritable for i32 {
    fn var_write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        buf.write_varint(*self)
    }
}

impl McBufWritable for UnsizedByteArray {
    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        buf.write_bytes(self)
    }
}

impl<T: McBufWritable> McBufWritable for Vec<T> {
    default fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        buf.write_list(self, |buf, i| T::write_into(i, buf))
    }
}

impl<K: McBufWritable, V: McBufWritable> McBufWritable for HashMap<K, V> {
    default fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        u32::var_write_into(&(self.len() as u32), buf)?;
        for (key, value) in self {
            key.write_into(buf)?;
            value.write_into(buf)?;
        }

        Ok(())
    }
}

impl<K: McBufWritable, V: McBufVarWritable> McBufVarWritable for HashMap<K, V> {
    default fn var_write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        u32::var_write_into(&(self.len() as u32), buf)?;
        for (key, value) in self {
            key.write_into(buf)?;
            value.var_write_into(buf)?;
        }

        Ok(())
    }
}

impl McBufWritable for Vec<u8> {
    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        buf.write_byte_array(self)
    }
}

impl McBufWritable for String {
    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        buf.write_utf(self)
    }
}

impl McBufWritable for u32 {
    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        i16::write_into(&(*self as i16), buf)
    }
}

impl McBufVarWritable for u32 {
    fn var_write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        i32::var_write_into(&(*self as i32), buf)
    }
}

impl McBufVarWritable for i64 {
    fn var_write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        let mut buffer = [0];
        let mut value = *self;
        while value != 0 {
            buffer[0] = (value & 0b0111_1111) as u8;
            value = (value >> 7) & (i64::max_value() >> 6);
            if value != 0 {
                buffer[0] |= 0b1000_0000;
            }
            // this only writes a single byte, so write_all isn't necessary
            // the let _ = is so clippy doesn't complain
            let _ = buf.write(&buffer)?;
        }
        Ok(())
    }
}

impl McBufVarWritable for u64 {
    fn var_write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        i64::var_write_into(&(*self as i64), buf)
    }
}

impl McBufWritable for u16 {
    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        i16::write_into(&(*self as i16), buf)
    }
}

impl McBufVarWritable for u16 {
    fn var_write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        i32::var_write_into(&(*self as i32), buf)
    }
}

impl<T: McBufVarWritable> McBufVarWritable for Vec<T> {
    fn var_write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        u32::var_write_into(&(self.len() as u32), buf)?;
        for i in self {
            i.var_write_into(buf)?;
        }
        Ok(())
    }
}

impl McBufWritable for u8 {
    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        buf.write_byte(*self)
    }
}

impl McBufWritable for i16 {
    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        Writable::write_short(buf, *self)
    }
}

impl McBufWritable for i64 {
    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        Writable::write_long(buf, *self)
    }
}

impl McBufWritable for u64 {
    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        i64::write_into(&(*self as i64), buf)
    }
}

impl McBufWritable for bool {
    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        buf.write_boolean(*self)
    }
}

impl McBufWritable for i8 {
    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        buf.write_byte(*self as u8)
    }
}

impl McBufWritable for f32 {
    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        buf.write_float(*self)
    }
}

impl McBufWritable for f64 {
    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        buf.write_double(*self)
    }
}

impl<T: McBufWritable> McBufWritable for Option<T> {
    default fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        if let Some(s) = self {
            buf.write_boolean(true)?;
            s.write_into(buf)?;
        } else {
            buf.write_boolean(false)?;
        };
        Ok(())
    }
}

impl<T: McBufVarWritable> McBufVarWritable for Option<T> {
    default fn var_write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        if let Some(s) = self {
            buf.write_boolean(true)?;
            s.var_write_into(buf)?;
        } else {
            buf.write_boolean(false)?;
        };
        Ok(())
    }
}

// [T; N]
impl<T: McBufWritable, const N: usize> McBufWritable for [T; N] {
    default fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
        for i in self {
            i.write_into(buf)?;
        }
        Ok(())
    }
}