// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
//
// Copyright 2016 The Go-MySQL-Driver Authors. All rights reserved.
//
// 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/.

package mysql

import (
	"database/sql/driver"
	"errors"
	"net"
	"testing"
	"time"
)

var (
	errConnClosed        = errors.New("connection is closed")
	errConnTooManyReads  = errors.New("too many reads")
	errConnTooManyWrites = errors.New("too many writes")
)

// struct to mock a net.Conn for testing purposes
type mockConn struct {
	laddr     net.Addr
	raddr     net.Addr
	data      []byte
	closed    bool
	read      int
	written   int
	reads     int
	writes    int
	maxReads  int
	maxWrites int
}

func (m *mockConn) Read(b []byte) (n int, err error) {
	if m.closed {
		return 0, errConnClosed
	}

	m.reads++
	if m.maxReads > 0 && m.reads > m.maxReads {
		return 0, errConnTooManyReads
	}

	n = copy(b, m.data)
	m.read += n
	m.data = m.data[n:]
	return
}
func (m *mockConn) Write(b []byte) (n int, err error) {
	if m.closed {
		return 0, errConnClosed
	}

	m.writes++
	if m.maxWrites > 0 && m.writes > m.maxWrites {
		return 0, errConnTooManyWrites
	}

	n = len(b)
	m.written += n
	return
}
func (m *mockConn) Close() error {
	m.closed = true
	return nil
}
func (m *mockConn) LocalAddr() net.Addr {
	return m.laddr
}
func (m *mockConn) RemoteAddr() net.Addr {
	return m.raddr
}
func (m *mockConn) SetDeadline(t time.Time) error {
	return nil
}
func (m *mockConn) SetReadDeadline(t time.Time) error {
	return nil
}
func (m *mockConn) SetWriteDeadline(t time.Time) error {
	return nil
}

// make sure mockConn implements the net.Conn interface
var _ net.Conn = new(mockConn)

func TestReadPacketSingleByte(t *testing.T) {
	conn := new(mockConn)
	mc := &mysqlConn{
		buf: newBuffer(conn),
	}

	conn.data = []byte{0x01, 0x00, 0x00, 0x00, 0xff}
	conn.maxReads = 1
	packet, err := mc.readPacket()
	if err != nil {
		t.Fatal(err)
	}
	if len(packet) != 1 {
		t.Fatalf("unexpected packet lenght: expected %d, got %d", 1, len(packet))
	}
	if packet[0] != 0xff {
		t.Fatalf("unexpected packet content: expected %x, got %x", 0xff, packet[0])
	}
}

func TestReadPacketWrongSequenceID(t *testing.T) {
	conn := new(mockConn)
	mc := &mysqlConn{
		buf: newBuffer(conn),
	}

	// too low sequence id
	conn.data = []byte{0x01, 0x00, 0x00, 0x00, 0xff}
	conn.maxReads = 1
	mc.sequence = 1
	_, err := mc.readPacket()
	if err != ErrPktSync {
		t.Errorf("expected ErrPktSync, got %v", err)
	}

	// reset
	conn.reads = 0
	mc.sequence = 0
	mc.buf = newBuffer(conn)

	// too high sequence id
	conn.data = []byte{0x01, 0x00, 0x00, 0x42, 0xff}
	_, err = mc.readPacket()
	if err != ErrPktSyncMul {
		t.Errorf("expected ErrPktSyncMul, got %v", err)
	}
}

func TestReadPacketSplit(t *testing.T) {
	conn := new(mockConn)
	mc := &mysqlConn{
		buf: newBuffer(conn),
	}

	data := make([]byte, maxPacketSize*2+4*3)
	const pkt2ofs = maxPacketSize + 4
	const pkt3ofs = 2 * (maxPacketSize + 4)

	// case 1: payload has length maxPacketSize
	data = data[:pkt2ofs+4]

	// 1st packet has maxPacketSize length and sequence id 0
	// ff ff ff 00 ...
	data[0] = 0xff
	data[1] = 0xff
	data[2] = 0xff

	// mark the payload start and end of 1st packet so that we can check if the
	// content was correctly appended
	data[4] = 0x11
	data[maxPacketSize+3] = 0x22

	// 2nd packet has payload length 0 and squence id 1
	// 00 00 00 01
	data[pkt2ofs+3] = 0x01

	conn.data = data
	conn.maxReads = 3
	packet, err := mc.readPacket()
	if err != nil {
		t.Fatal(err)
	}
	if len(packet) != maxPacketSize {
		t.Fatalf("unexpected packet lenght: expected %d, got %d", maxPacketSize, len(packet))
	}
	if packet[0] != 0x11 {
		t.Fatalf("unexpected payload start: expected %x, got %x", 0x11, packet[0])
	}
	if packet[maxPacketSize-1] != 0x22 {
		t.Fatalf("unexpected payload end: expected %x, got %x", 0x22, packet[maxPacketSize-1])
	}

	// case 2: payload has length which is a multiple of maxPacketSize
	data = data[:cap(data)]

	// 2nd packet now has maxPacketSize length
	data[pkt2ofs] = 0xff
	data[pkt2ofs+1] = 0xff
	data[pkt2ofs+2] = 0xff

	// mark the payload start and end of the 2nd packet
	data[pkt2ofs+4] = 0x33
	data[pkt2ofs+maxPacketSize+3] = 0x44

	// 3rd packet has payload length 0 and squence id 2
	// 00 00 00 02
	data[pkt3ofs+3] = 0x02

	conn.data = data
	conn.reads = 0
	conn.maxReads = 5
	mc.sequence = 0
	packet, err = mc.readPacket()
	if err != nil {
		t.Fatal(err)
	}
	if len(packet) != 2*maxPacketSize {
		t.Fatalf("unexpected packet lenght: expected %d, got %d", 2*maxPacketSize, len(packet))
	}
	if packet[0] != 0x11 {
		t.Fatalf("unexpected payload start: expected %x, got %x", 0x11, packet[0])
	}
	if packet[2*maxPacketSize-1] != 0x44 {
		t.Fatalf("unexpected payload end: expected %x, got %x", 0x44, packet[2*maxPacketSize-1])
	}

	// case 3: payload has a length larger maxPacketSize, which is not an exact
	// multiple of it
	data = data[:pkt2ofs+4+42]
	data[pkt2ofs] = 0x2a
	data[pkt2ofs+1] = 0x00
	data[pkt2ofs+2] = 0x00
	data[pkt2ofs+4+41] = 0x44

	conn.data = data
	conn.reads = 0
	conn.maxReads = 4
	mc.sequence = 0
	packet, err = mc.readPacket()
	if err != nil {
		t.Fatal(err)
	}
	if len(packet) != maxPacketSize+42 {
		t.Fatalf("unexpected packet lenght: expected %d, got %d", maxPacketSize+42, len(packet))
	}
	if packet[0] != 0x11 {
		t.Fatalf("unexpected payload start: expected %x, got %x", 0x11, packet[0])
	}
	if packet[maxPacketSize+41] != 0x44 {
		t.Fatalf("unexpected payload end: expected %x, got %x", 0x44, packet[maxPacketSize+41])
	}
}

func TestReadPacketFail(t *testing.T) {
	conn := new(mockConn)
	mc := &mysqlConn{
		buf: newBuffer(conn),
	}

	// illegal empty (stand-alone) packet
	conn.data = []byte{0x00, 0x00, 0x00, 0x00}
	conn.maxReads = 1
	_, err := mc.readPacket()
	if err != driver.ErrBadConn {
		t.Errorf("expected ErrBadConn, got %v", err)
	}

	// reset
	conn.reads = 0
	mc.sequence = 0
	mc.buf = newBuffer(conn)

	// fail to read header
	conn.closed = true
	_, err = mc.readPacket()
	if err != driver.ErrBadConn {
		t.Errorf("expected ErrBadConn, got %v", err)
	}

	// reset
	conn.closed = false
	conn.reads = 0
	mc.sequence = 0
	mc.buf = newBuffer(conn)

	// fail to read body
	conn.maxReads = 1
	_, err = mc.readPacket()
	if err != driver.ErrBadConn {
		t.Errorf("expected ErrBadConn, got %v", err)
	}
}