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extern crate byteorder;

use types::*;
use self::byteorder::{ByteOrder, BigEndian};
use std::borrow::{Borrow};
use std::io;
use std::io::{Write};
use std::marker::PhantomData;
use std::{u8, u64, usize};


#[derive(Debug)]
pub struct FrameWriter<W: Write>(PhantomData<W>);
impl<W: Write> FrameWriter<W> {
    pub fn write(frame: &Frame, writer: &mut W) -> io::Result<()> {
        let mut fw = FrameWriter(PhantomData);
        let mut result = Ok(frame);
        result = fw.write_flags(result, writer);
        result = fw.write_size(result, writer);
        result = fw.write_body(result, writer);
        result.map(|_| ())
    }

    fn write_flags<'l>(&mut self,
                       result: io::Result<&'l Frame>,
                       writer: &mut W) -> io::Result<&'l Frame> {
        let frame = try!{ result };
        let mut flags: u8 = 0b0000_0000;
        flags |= match *frame.get_kind() {
            FrameKind::Cmd => 0b100,
            FrameKind::Msg => 0b000,
        };
        flags |= match *frame.get_size() {
            Size::Short(_) => 0b000,
            Size::Long(_)  => 0b010,
        };
        flags |= !frame.get_is_last() as u8;
        assert_eq!(try!{ writer.write(&[flags]) },  1);
        Ok(frame)
    }

    fn write_size<'l>(&mut self,
                      result: io::Result<&'l Frame>,
                      writer: &mut W) -> io::Result<&'l Frame> {
        let frame = try!{ result };
        match *frame.get_size() {
            Size::Short(size) =>
                assert_eq!(try!{ writer.write(&[size]) },  1),
            Size::Long(size) => {
                let mut bytes = [0; BYTES_PER_U64 as usize];
                BigEndian::write_u64(&mut bytes, size);
                assert_eq!(try!{ writer.write(&bytes) }, BYTES_PER_U64);
            },
        };
        Ok(frame)
    }

    fn write_body<'l>(&mut self,
                      result: io::Result<&'l Frame>,
                      writer: &mut W) -> io::Result<&'l Frame> {
        let frame = try!{ result };
        writer.write(frame.view_body()).map(|size| {
            assert_eq!(size,  frame.body_len());
            frame
        })
    }
}

#[derive(Debug)]
pub struct CommandWriter<W: Write>(PhantomData<W>);
impl<W: Write> CommandWriter<W> {
    pub fn write(cmd: &Command, writer: &mut W) -> io::Result<()> {
        let mut frame = Frame::new()
            .kind(FrameKind::Cmd)
            .is_last(true);
        let mut cmd_writer = CommandWriter::<W>(PhantomData);
        match cmd.get_name_str().borrow() {
            "READY" => {
                frame = cmd_writer.write_size(cmd, frame);
                frame = cmd_writer.write_name(cmd, frame);
                frame = cmd_writer.write_metadata(cmd, frame);
            },
            _ => {
                frame = cmd_writer.write_size(cmd, frame);
                frame = cmd_writer.write_name(cmd, frame);
                frame = cmd_writer.write_data(cmd, frame);
            },
        };
        FrameWriter::write(&frame, writer)
    }

    fn write_size(&mut self, cmd: &Command, frame: Frame) -> Frame {
        frame.set_size(match cmd.size().as_usize() {
            size @ 0...0xFF => Size::Short(size as u8),
            size            => Size::Long(size as u64),
        })
    }

    fn write_name(&mut self, cmd: &Command, mut frame: Frame) -> Frame {
        let cmd_name = cmd.get_name();
        frame.edit_body().push(cmd_name.len() as u8);
        frame.edit_body().extend_from_slice(cmd_name);
        frame
    }

    fn write_data(&mut self, cmd: &Command, mut frame: Frame) -> Frame {
        frame.edit_body().extend_from_slice(&cmd.get_data());
        frame
    }

    fn write_metadata(&mut self, cmd: &Command, mut frame: Frame) -> Frame {
        for (name, val) in cmd.get_metadata().iter() {
            let name_bytes = name.as_bytes();
            let name_len = name_bytes.len();
            assert!(1 <= name_len && name_len <= 255);
            let val_len = val.len() as u32;
            let mut val_len_bytes = [0 as u8; 4];
            BigEndian::write_u32(&mut val_len_bytes, val_len);
            frame.edit_body().extend_from_slice(&[name_len as u8]);
            frame.edit_body().extend_from_slice(name_bytes);
            frame.edit_body().extend_from_slice(&val_len_bytes);
            frame.edit_body().extend_from_slice(val);
        }
        frame
    }
}

#[derive(Debug)]
pub struct MessageWriter<W: Write>(PhantomData<W>);
impl<W: Write> MessageWriter<W> {
    pub fn write(msg: &Message, writer: &mut W) -> io::Result<()> {
        let mut result = Ok(());
        for frame in msg.frame_iter() {
            result = FrameWriter::write(&frame, writer);
            if result.is_err() { break }
        }
        result
    }
}

#[derive(Debug)]
pub struct GreetingWriter<W: Write>(PhantomData<W>);
impl<W: Write> GreetingWriter<W> {
    pub fn write(g: &Greeting, writer: &mut W) -> io::Result<()> {
        try!{ Self::write_signature(g, writer) }
        try!{ Self::write_version(  g, writer) }
        try!{ Self::write_mechanism(g, writer) }
        try!{ Self::write_as_server(g, writer) }
        try!{ Self::write_filler(   g, writer) }
        Ok(assert_eq!(try!{ writer.flush() }, ()))
    }

    pub fn write_signature(g: &Greeting, writer: &mut W) -> io::Result<()> {
        Ok(assert_eq!(try!{ writer.write(&g.signature) },  g.signature.len()))
    }

    pub fn write_version(g: &Greeting, writer: &mut W) -> io::Result<()> {
        let (major, minor) = g.version;
        Ok(assert_eq!(try!{ writer.write(&[major, minor]) },  2))
    }

    pub fn write_mechanism(g: &Greeting, writer: &mut W) -> io::Result<()> {
        Ok(assert_eq!(try!{ writer.write(&g.mechanism) },   g.mechanism.len()))
    }

    pub fn write_as_server(g: &Greeting, writer: &mut W) -> io::Result<()> {
        Ok(assert_eq!(try!{ writer.write(&[g.as_server as u8]) },  1))
    }

    pub fn write_filler(g: &Greeting, writer: &mut W) -> io::Result<()> {
        Ok(assert_eq!(try!{ writer.write(&g.filler) },  g.filler.len()))
    }
}

#[derive(Debug)]
pub struct TrafficWriter<W: Write>(PhantomData<W>);
impl<W: Write> TrafficWriter<W> {
    pub fn write(traffic: &Traffic, writer: &mut W) -> io::Result<()> {
        let mut result = Ok(());
        for item in traffic.items() {
            result = match *item {
                TrafficItem::Cmd(ref cmd) => CommandWriter::write(cmd, writer),
                TrafficItem::Msg(ref msg) => MessageWriter::write(msg, writer),
            };
            if result.is_err() { break }
        }
        result
    }
}