// Copyright 2018 gf Author(https://github.com/gogf/gf). All Rights Reserved.
//
// This Source Code Form is subject to the terms of the MIT License.
// If a copy of the MIT was not distributed with this file,
// You can obtain one at https://github.com/gogf/gf.

package gtcp

import (
	"bufio"
	"bytes"
	"crypto/tls"
	"io"
	"net"
	"time"
)

// TCP connection object.
type Conn struct {
	net.Conn                     // Underlying TCP connection object.
	reader         *bufio.Reader // Buffer reader for connection.
	recvDeadline   time.Time     // Timeout point for reading.
	sendDeadline   time.Time     // Timeout point for writing.
	recvBufferWait time.Duration // Interval duration for reading buffer.
}

const (
	// Default interval for reading buffer.
	gRECV_ALL_WAIT_TIMEOUT = time.Millisecond
)

// NewConn creates and returns a new connection with given address.
func NewConn(addr string, timeout ...time.Duration) (*Conn, error) {
	if conn, err := NewNetConn(addr, timeout...); err == nil {
		return NewConnByNetConn(conn), nil
	} else {
		return nil, err
	}
}

// NewConnTLS creates and returns a new TLS connection
// with given address and TLS configuration.
func NewConnTLS(addr string, tlsConfig *tls.Config) (*Conn, error) {
	if conn, err := NewNetConnTLS(addr, tlsConfig); err == nil {
		return NewConnByNetConn(conn), nil
	} else {
		return nil, err
	}
}

// NewConnKeyCrt creates and returns a new TLS connection
// with given address and TLS certificate and key files.
func NewConnKeyCrt(addr, crtFile, keyFile string) (*Conn, error) {
	if conn, err := NewNetConnKeyCrt(addr, crtFile, keyFile); err == nil {
		return NewConnByNetConn(conn), nil
	} else {
		return nil, err
	}
}

// NewConnByNetConn creates and returns a TCP connection object with given net.Conn object.
func NewConnByNetConn(conn net.Conn) *Conn {
	return &Conn{
		Conn:           conn,
		reader:         bufio.NewReader(conn),
		recvDeadline:   time.Time{},
		sendDeadline:   time.Time{},
		recvBufferWait: gRECV_ALL_WAIT_TIMEOUT,
	}
}

// Send writes data to remote address.
func (c *Conn) Send(data []byte, retry ...Retry) error {
	for {
		if _, err := c.Write(data); err != nil {
			// Connection closed.
			if err == io.EOF {
				return err
			}
			// Still failed even after retrying.
			if len(retry) == 0 || retry[0].Count == 0 {
				return err
			}
			if len(retry) > 0 {
				retry[0].Count--
				if retry[0].Interval == 0 {
					retry[0].Interval = gDEFAULT_RETRY_INTERVAL
				}
				time.Sleep(retry[0].Interval)
			}
		} else {
			return nil
		}
	}
}

// Recv receives and returns data from the connection.
//
// Note that,
// 1. If length = 0, which means it receives the data from current buffer and returns immediately.
// 2. If length < 0, which means it receives all data from connection and returns it until no data
//    from connection. Developers should notice the package parsing yourself if you decide receiving
//    all data from buffer.
// 3. If length > 0, which means it blocks reading data from connection until length size was received.
//    It is the most commonly used length value for data receiving.
func (c *Conn) Recv(length int, retry ...Retry) ([]byte, error) {
	var err error       // Reading error.
	var size int        // Reading size.
	var index int       // Received size.
	var buffer []byte   // Buffer object.
	var bufferWait bool // Whether buffer reading timeout set.

	if length > 0 {
		buffer = make([]byte, length)
	} else {
		buffer = make([]byte, gDEFAULT_READ_BUFFER_SIZE)
	}

	for {
		if length < 0 && index > 0 {
			bufferWait = true
			if err = c.SetReadDeadline(time.Now().Add(c.recvBufferWait)); err != nil {
				return nil, err
			}
		}
		size, err = c.reader.Read(buffer[index:])
		if size > 0 {
			index += size
			if length > 0 {
				// It reads til <length> size if <length> is specified.
				if index == length {
					break
				}
			} else {
				if index >= gDEFAULT_READ_BUFFER_SIZE {
					// If it exceeds the buffer size, it then automatically increases its buffer size.
					buffer = append(buffer, make([]byte, gDEFAULT_READ_BUFFER_SIZE)...)
				} else {
					// It returns immediately if received size is lesser than buffer size.
					if !bufferWait {
						break
					}
				}
			}
		}
		if err != nil {
			// Connection closed.
			if err == io.EOF {
				break
			}
			// Re-set the timeout when reading data.
			if bufferWait && isTimeout(err) {
				if err = c.SetReadDeadline(c.recvDeadline); err != nil {
					return nil, err
				}
				err = nil
				break
			}
			if len(retry) > 0 {
				// It fails even it retried.
				if retry[0].Count == 0 {
					break
				}
				retry[0].Count--
				if retry[0].Interval == 0 {
					retry[0].Interval = gDEFAULT_RETRY_INTERVAL
				}
				time.Sleep(retry[0].Interval)
				continue
			}
			break
		}
		// Just read once from buffer.
		if length == 0 {
			break
		}
	}
	return buffer[:index], err
}

// RecvLine reads data from the connection until reads char '\n'.
// Note that the returned result does not contain the last char '\n'.
func (c *Conn) RecvLine(retry ...Retry) ([]byte, error) {
	var err error
	var buffer []byte
	data := make([]byte, 0)
	for {
		buffer, err = c.Recv(1, retry...)
		if len(buffer) > 0 {
			if buffer[0] == '\n' {
				data = append(data, buffer[:len(buffer)-1]...)
				break
			} else {
				data = append(data, buffer...)
			}
		}
		if err != nil {
			break
		}
	}
	return data, err
}

// RecvTil reads data from the connection until reads bytes <til>.
// Note that the returned result contains the last bytes <til>.
func (c *Conn) RecvTil(til []byte, retry ...Retry) ([]byte, error) {
	var err error
	var buffer []byte
	data := make([]byte, 0)
	length := len(til)
	for {
		buffer, err = c.Recv(1, retry...)
		if len(buffer) > 0 {
			if length > 0 &&
				len(data) >= length-1 &&
				buffer[0] == til[length-1] &&
				bytes.EqualFold(data[len(data)-length+1:], til[:length-1]) {
				data = append(data, buffer...)
				break
			} else {
				data = append(data, buffer...)
			}
		}
		if err != nil {
			break
		}
	}
	return data, err
}

// RecvWithTimeout reads data from the connection with timeout.
func (c *Conn) RecvWithTimeout(length int, timeout time.Duration, retry ...Retry) (data []byte, err error) {
	if err := c.SetRecvDeadline(time.Now().Add(timeout)); err != nil {
		return nil, err
	}
	defer c.SetRecvDeadline(time.Time{})
	data, err = c.Recv(length, retry...)
	return
}

// SendWithTimeout writes data to the connection with timeout.
func (c *Conn) SendWithTimeout(data []byte, timeout time.Duration, retry ...Retry) (err error) {
	if err := c.SetSendDeadline(time.Now().Add(timeout)); err != nil {
		return err
	}
	defer c.SetSendDeadline(time.Time{})
	err = c.Send(data, retry...)
	return
}

// SendRecv writes data to the connection and blocks reading response.
func (c *Conn) SendRecv(data []byte, length int, retry ...Retry) ([]byte, error) {
	if err := c.Send(data, retry...); err == nil {
		return c.Recv(length, retry...)
	} else {
		return nil, err
	}
}

// SendRecvWithTimeout writes data to the connection and reads response with timeout.
func (c *Conn) SendRecvWithTimeout(data []byte, length int, timeout time.Duration, retry ...Retry) ([]byte, error) {
	if err := c.Send(data, retry...); err == nil {
		return c.RecvWithTimeout(length, timeout, retry...)
	} else {
		return nil, err
	}
}

func (c *Conn) SetDeadline(t time.Time) error {
	err := c.Conn.SetDeadline(t)
	if err == nil {
		c.recvDeadline = t
		c.sendDeadline = t
	}
	return err
}

func (c *Conn) SetRecvDeadline(t time.Time) error {
	err := c.SetReadDeadline(t)
	if err == nil {
		c.recvDeadline = t
	}
	return err
}

func (c *Conn) SetSendDeadline(t time.Time) error {
	err := c.SetWriteDeadline(t)
	if err == nil {
		c.sendDeadline = t
	}
	return err
}

// SetRecvBufferWait sets the buffer waiting timeout when reading all data from connection.
// The waiting duration cannot be too long which might delay receiving data from remote address.
func (c *Conn) SetRecvBufferWait(bufferWaitDuration time.Duration) {
	c.recvBufferWait = bufferWaitDuration
}