// Copyright 2015 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Copyright 2013 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/.

// The MIT License (MIT)
//
// Copyright (c) 2014 wandoulabs
// Copyright (c) 2014 siddontang
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

package dump

import (
	"encoding/binary"
	"time"

	"github.com/pingcap/tidb/pkg/parser/mysql"
	"github.com/pingcap/tidb/pkg/types"
)

// LengthEncodedString dumps a string as length encoded byte slice.
func LengthEncodedString(buffer []byte, bytes []byte) []byte {
	buffer = LengthEncodedInt(buffer, uint64(len(bytes)))
	buffer = append(buffer, bytes...)
	return buffer
}

// LengthEncodedInt dumps an integer as length encoded byte slice.
func LengthEncodedInt(buffer []byte, n uint64) []byte {
	switch {
	case n <= 250:
		return append(buffer, byte(n))

	case n <= 0xffff:
		return append(buffer, 0xfc, byte(n), byte(n>>8))

	case n <= 0xffffff:
		return append(buffer, 0xfd, byte(n), byte(n>>8), byte(n>>16))

	case n <= 0xffffffffffffffff:
		return append(buffer, 0xfe, byte(n), byte(n>>8), byte(n>>16), byte(n>>24),
			byte(n>>32), byte(n>>40), byte(n>>48), byte(n>>56))
	}

	return buffer
}

// Uint16 dumps an uint16 as byte slice.
func Uint16(buffer []byte, n uint16) []byte {
	return binary.LittleEndian.AppendUint16(buffer, n)
}

// Uint32 dumps an uint32 as byte slice.
func Uint32(buffer []byte, n uint32) []byte {
	return binary.LittleEndian.AppendUint32(buffer, n)
}

// Uint64 dumps an uint64 as byte slice.
func Uint64(buffer []byte, n uint64) []byte {
	return binary.LittleEndian.AppendUint64(buffer, n)
}

// BinaryTime dumps a time as binary byte slice.
func BinaryTime(dur time.Duration) (data []byte) {
	if dur == 0 {
		return []byte{0}
	}
	data = make([]byte, 13)
	data[0] = 12
	if dur < 0 {
		data[1] = 1
		dur = -dur
	}
	days := dur / (24 * time.Hour)
	dur -= days * 24 * time.Hour //nolint:durationcheck
	data[2] = byte(days)
	hours := dur / time.Hour
	dur -= hours * time.Hour //nolint:durationcheck
	data[6] = byte(hours)
	minutes := dur / time.Minute
	dur -= minutes * time.Minute //nolint:durationcheck
	data[7] = byte(minutes)
	seconds := dur / time.Second
	dur -= seconds * time.Second //nolint:durationcheck
	data[8] = byte(seconds)
	if dur == 0 {
		data[0] = 8
		return data[:9]
	}
	binary.LittleEndian.PutUint32(data[9:13], uint32(dur/time.Microsecond))
	return
}

// BinaryDateTime dumps a datetime as binary byte slice.
func BinaryDateTime(data []byte, t types.Time) []byte {
	year, mon, day := t.Year(), t.Month(), t.Day()
	switch t.Type() {
	case mysql.TypeTimestamp, mysql.TypeDatetime:
		if t.IsZero() {
			// All zero.
			data = append(data, 0)
		} else if t.Microsecond() != 0 {
			// Has micro seconds.
			data = append(data, 11)
			data = Uint16(data, uint16(year))
			data = append(data, byte(mon), byte(day), byte(t.Hour()), byte(t.Minute()), byte(t.Second()))
			data = Uint32(data, uint32(t.Microsecond()))
		} else if t.Hour() != 0 || t.Minute() != 0 || t.Second() != 0 {
			// Has HH:MM:SS
			data = append(data, 7)
			data = Uint16(data, uint16(year))
			data = append(data, byte(mon), byte(day), byte(t.Hour()), byte(t.Minute()), byte(t.Second()))
		} else {
			// Only YY:MM:DD
			data = append(data, 4)
			data = Uint16(data, uint16(year))
			data = append(data, byte(mon), byte(day))
		}
	case mysql.TypeDate:
		if t.IsZero() {
			data = append(data, 0)
		} else {
			data = append(data, 4)
			data = Uint16(data, uint16(year)) // year
			data = append(data, byte(mon), byte(day))
		}
	}
	return data
}