// Copyright 2015 Nathan Sizemore <nathanrsizemore@gmail.com>
//
// This Source Code Form is subject to the terms of the
// Mozilla Public License, v. 2.0. If a copy of the MPL was not
// distributed with this file, You can obtain one at
// http://mozilla.org/MPL/2.0/.

use std::{
    io::{self, Read, Write},
    marker::PhantomData,
    mem,
};

use openssl::ssl::{ErrorCode, SslStream};

use crate::{
    frame::{Frame, FrameBuilder},
    Blocking, NonBlocking,
};

const BUF_SIZE: usize = 1024;

/// OpenSSL backed stream.
pub struct Secure<S, FB>
where
    S: io::Read + io::Write,
    FB: FrameBuilder,
{
    inner: SslStream<S>,
    rx_buf: Vec<u8>,
    tx_buf: Vec<u8>,
    phantom: PhantomData<FB>,
}

impl<S, FB> Secure<S, FB>
where
    S: io::Read + io::Write,
    FB: FrameBuilder,
{
    /// Creates a new secured stream.
    pub fn new(stream: SslStream<S>) -> Secure<S, FB> {
        Secure {
            inner: stream,
            rx_buf: Vec::<u8>::with_capacity(BUF_SIZE),
            tx_buf: Vec::<u8>::with_capacity(BUF_SIZE),
            phantom: PhantomData,
        }
    }
}

impl<S, FB> Blocking for Secure<S, FB>
where
    S: io::Read + io::Write,
    FB: FrameBuilder,
{
    fn b_recv(&mut self) -> io::Result<Box<dyn Frame>> {
        // Empty anything that is in our buffer already from any previous reads
        match FB::from_bytes(&mut self.rx_buf) {
            Some(boxed_frame) => {
                debug!("Complete frame read");
                return Ok(boxed_frame);
            }
            None => {}
        };

        loop {
            let mut buf = [0u8; BUF_SIZE];
            let read_result = self.inner.read(&mut buf);
            if read_result.is_err() {
                let err = read_result.unwrap_err();
                return Err(err);
            }

            let num_read = read_result.unwrap();
            trace!("Read {} byte(s)", num_read);
            self.rx_buf.extend_from_slice(&buf[0..num_read]);

            match FB::from_bytes(&mut self.rx_buf) {
                Some(boxed_frame) => {
                    debug!("Complete frame read");
                    return Ok(boxed_frame);
                }
                None => {}
            };
        }
    }

    fn b_send(&mut self, frame: &dyn Frame) -> io::Result<()> {
        let out_buf = frame.to_bytes();
        let write_result = self.inner.write(&out_buf[..]);
        if write_result.is_err() {
            let err = write_result.unwrap_err();
            return Err(err);
        }

        trace!("Wrote {} byte(s)", write_result.unwrap());

        Ok(())
    }
}

impl<S, FB> NonBlocking for Secure<S, FB>
where
    S: io::Read + io::Write,
    FB: FrameBuilder,
{
    fn nb_recv(&mut self) -> io::Result<Vec<Box<dyn Frame>>> {
        loop {
            let mut buf = [0u8; BUF_SIZE];
            let read_result = self.inner.ssl_read(&mut buf);
            if read_result.is_err() {
                let e = read_result.unwrap_err();
                match e.code() {
                    ErrorCode::ZERO_RETURN => {
                        return Err(io::Error::new(
                            io::ErrorKind::UnexpectedEof,
                            "UnexpectedEof",
                        ));
                    }
                    ErrorCode::WANT_READ => {
                        break;
                    }

                    ErrorCode::WANT_WRITE => {
                        return Err(io::Error::new(io::ErrorKind::Other, "WantWrite"));
                    }

                    ErrorCode::SYSCALL => {
                        return Err(io::Error::new(io::ErrorKind::Other, "Syscall"));
                    }

                    ErrorCode::SSL => {
                        return Err(io::Error::new(io::ErrorKind::Other, "SSL"));
                    }
                    _ => {
                        // Other error types should not be thrown from this operation
                        return Err(io::Error::new(
                            io::ErrorKind::Other,
                            "Unknown error during ssl_read",
                        ));
                    }
                };
            }

            let num_read = read_result.unwrap();
            trace!("Read {} byte(s)", num_read);
            self.rx_buf.extend_from_slice(&buf[0..num_read]);
        }

        let mut ret_buf = Vec::<Box<dyn Frame>>::with_capacity(5);
        while let Some(boxed_frame) = FB::from_bytes(&mut self.rx_buf) {
            info!("Complete frame read");
            ret_buf.push(boxed_frame);
        }

        if ret_buf.len() > 0 {
            info!("Read {} frame(s)", ret_buf.len());
            return Ok(ret_buf);
        }

        Err(io::Error::new(io::ErrorKind::WouldBlock, "WouldBlock"))
    }

    fn nb_send(&mut self, frame: &dyn Frame) -> io::Result<()> {
        self.tx_buf.extend_from_slice(&frame.to_bytes()[..]);

        let mut out_buf = Vec::<u8>::with_capacity(BUF_SIZE);
        mem::swap(&mut self.tx_buf, &mut out_buf);

        let write_result = self.inner.ssl_write(&out_buf[..]);
        if write_result.is_err() {
            let err = write_result.unwrap_err();
            match err.code() {
                ErrorCode::ZERO_RETURN => {
                    return Err(io::Error::new(
                        io::ErrorKind::UnexpectedEof,
                        "UnexpectedEof",
                    ));
                }
                ErrorCode::WANT_WRITE => {
                    return Err(io::Error::new(io::ErrorKind::WouldBlock, "WouldBlock"));
                }
                ErrorCode::SYSCALL => {
                    return Err(io::Error::new(io::ErrorKind::Other, "Syscall"));
                }

                ErrorCode::SSL => {
                    return Err(io::Error::new(io::ErrorKind::Other, "SSL"));
                }
                _ => {
                    // Other error types should not be thrown from this operation
                    return Err(io::Error::new(
                        io::ErrorKind::Other,
                        "Unknown error during ssl_write",
                    ));
                }
            };
        }

        let num_written = write_result.unwrap();
        if num_written == 0 {
            return Err(io::Error::new(io::ErrorKind::Other, "Write returned zero"));
        }

        trace!(
            "Tried to write {} byte(s) wrote {} byte(s)",
            out_buf.len(),
            num_written
        );

        if num_written < out_buf.len() {
            let out_buf_len = out_buf.len();
            self.tx_buf
                .extend_from_slice(&out_buf[num_written..out_buf_len]);

            return Err(io::Error::new(io::ErrorKind::WouldBlock, "WouldBlock"));
        }

        Ok(())
    }
}