package navicat

import (
	"encoding/binary"
	"fmt"
)

func putU32(n uint32) []byte {
	b := make([]byte, 4)
	binary.BigEndian.PutUint32(b, n)
	return b
}

func putU16(n uint16) []byte {
	b := make([]byte, 2)
	binary.BigEndian.PutUint16(b, n)
	return b
}

// AppendBlock encodes GetBlock() from ntunnel_mysql.php.
// NULL is not represented here; use AppendNull for row cells.
func AppendBlock(dst []byte, val []byte) []byte {
	if val == nil {
		val = []byte{}
	}
	n := len(val)
	if n < 254 {
		dst = append(dst, byte(n))
		return append(dst, val...)
	}
	dst = append(dst, markLong)
	dst = append(dst, putU32(uint32(n))...)
	return append(dst, val...)
}

func AppendNull(dst []byte) []byte {
	return append(dst, markNull)
}

func AppendHeader(dst []byte, version uint16, errno uint32) []byte {
	dst = append(dst, putU32(Magic)...)
	dst = append(dst, putU16(version)...)
	dst = append(dst, putU32(errno)...)
	dst = append(dst, 0, 0, 0, 0, 0, 0)
	return dst
}

func AppendResultSetHeader(dst []byte, errno, affected, insertID, numFields, numRows uint32) []byte {
	dst = append(dst, putU32(errno)...)
	dst = append(dst, putU32(affected)...)
	dst = append(dst, putU32(insertID)...)
	dst = append(dst, putU32(numFields)...)
	dst = append(dst, putU32(numRows)...)
	dst = append(dst, make([]byte, 12)...)
	return dst
}

func AppendField(dst []byte, name, table string, typ, flags, length uint32) []byte {
	dst = AppendBlock(dst, []byte(name))
	dst = AppendBlock(dst, []byte(table))
	dst = append(dst, putU32(typ)...)
	dst = append(dst, putU32(flags)...)
	dst = append(dst, putU32(length)...)
	return dst
}

func knownVersion(v uint16) bool {
	return v == Version202 || v == Version206
}

func fmtErrno(errno uint32, msg string) string {
	if msg == "" {
		return fmt.Sprintf("tunnel errno %d", errno)
	}
	return fmt.Sprintf("tunnel errno %d: %s", errno, msg)
}