package core

import (
	"bufio"
	"io"
	"net"
	"time"
)

var (
	// connReadDeadline specifies the connection read deadline
	connReadDeadline time.Duration

	// connWriteDeadline specifies the connection write deadline
	connWriteDeadline time.Duration

	// connReadMax specifies the connection read max (in bytes)
	connReadMax int
)

// deadlineConn wraps net.Conn to set the read / write deadlines on each access
type deadlineConn struct {
	conn net.Conn
}

// Read wraps the underlying net.Conn read function, setting read deadline on each access
func (c *deadlineConn) Read(b []byte) (int, error) {
	c.conn.SetReadDeadline(time.Now().Add(connReadDeadline))
	return c.conn.Read(b)
}

// Read wraps the underlying net.Conn write function, setting write deadline on each access
func (c *deadlineConn) Write(b []byte) (int, error) {
	c.conn.SetWriteDeadline(time.Now().Add(connWriteDeadline))
	return c.conn.Write(b)
}

// Close directly wraps underlying net.Conn close function
func (c *deadlineConn) Close() error {
	return c.conn.Close()
}

// Conn wraps a DeadlineConn with a buffer
type conn struct {
	br *bufio.Reader
	bw *bufio.Writer
	cl io.Closer
}

// wrapConn wraps a net.Conn in deadlineConn, then within conn and returns the result
func wrapConn(c net.Conn) *conn {
	deadlineConn := &deadlineConn{c}
	return &conn{
		br: connBufferedReaderPool.Get(deadlineConn),
		bw: connBufferedWriterPool.Get(deadlineConn),
		cl: deadlineConn,
	}
}

// ReadLine reads a single line and returns the result, or nil and error
func (c *conn) ReadLine() ([]byte, Error) {
	// return slice
	var b []byte

	// Read! Use this method so we can
	// ensure we don't perform some insanely
	// long read
	for len(b) < connReadMax {
		// read the line
		line, isPrefix, err := c.br.ReadLine()
		if err != nil {
			return nil, WrapError(ConnReadErr, err)
		}

		// append line contents to return slice
		b = append(b, line...)

		// if finished reading, break out
		if !isPrefix {
			break
		}
	}

	return b, nil
}

// WriteBytes writes a byte slice to the buffer and returns error status
func (c *conn) Write(b []byte) Error {
	_, err := c.bw.Write(b)
	if err != nil {
		return WrapError(ConnWriteErr, err)
	}
	return nil
}

// ReadFrom writes to the buffer from a reader and returns error status
func (c *conn) ReadFrom(r io.Reader) Error {
	// Since this buffer wraps deadlineConn, which DOES NOT have
	// a ReadFrom method implemented, it will force the buffer to
	// use it's own internal byte buffer along with the deadlineConn's
	// Write implementation (forcing the deadline to be regularly updated)
	_, err := c.bw.ReadFrom(r)
	if err != nil {
		return WrapError(ConnWriteErr, err)
	}
	return nil
}

// Writer returns the underlying buffer wrapped conn writer
func (c *conn) Writer() io.Writer {
	return c.bw
}

// Close flushes the underlying buffer, closes the conn then puts
// the sync.Pool conn buffers back
func (c *conn) Close() Error {
	// Flush + close
	err1 := c.bw.Flush()
	err2 := c.cl.Close()

	// Put buffers back
	connBufferedReaderPool.Put(c.br)
	connBufferedWriterPool.Put(c.bw)

	// If either errors, wrap. Else return none
	if err2 != nil {
		return WrapError(ConnCloseErr, err2)
	}
	if err1 != nil {
		return WrapError(ConnWriteErr, err1)
	}
	return nil
}