package client

import (
	"encoding/binary"
	"fmt"
	"math"

	. "github.com/go-mysql-org/go-mysql/mysql"
	"github.com/pingcap/errors"
)

type Stmt struct {
	conn *Conn
	id   uint32

	params  int
	columns int
}

func (s *Stmt) ParamNum() int {
	return s.params
}

func (s *Stmt) ColumnNum() int {
	return s.columns
}

func (s *Stmt) Execute(args ...interface{}) (*Result, error) {
	if err := s.write(args...); err != nil {
		return nil, errors.Trace(err)
	}

	return s.conn.readResult(true)
}

func (s *Stmt) Close() error {
	if err := s.conn.writeCommandUint32(COM_STMT_CLOSE, s.id); err != nil {
		return errors.Trace(err)
	}

	return nil
}

func (s *Stmt) write(args ...interface{}) error {
	paramsNum := s.params

	if len(args) != paramsNum {
		return fmt.Errorf("argument mismatch, need %d but got %d", s.params, len(args))
	}

	paramTypes := make([]byte, paramsNum<<1)
	paramValues := make([][]byte, paramsNum)

	//NULL-bitmap, length: (num-params+7)
	nullBitmap := make([]byte, (paramsNum+7)>>3)

	length := 1 + 4 + 1 + 4 + ((paramsNum + 7) >> 3) + 1 + (paramsNum << 1)

	var newParamBoundFlag byte = 0

	for i := range args {
		if args[i] == nil {
			nullBitmap[i/8] |= (1 << (uint(i) % 8))
			paramTypes[i<<1] = MYSQL_TYPE_NULL
			continue
		}

		newParamBoundFlag = 1

		switch v := args[i].(type) {
		case int8:
			paramTypes[i<<1] = MYSQL_TYPE_TINY
			paramValues[i] = []byte{byte(v)}
		case int16:
			paramTypes[i<<1] = MYSQL_TYPE_SHORT
			paramValues[i] = Uint16ToBytes(uint16(v))
		case int32:
			paramTypes[i<<1] = MYSQL_TYPE_LONG
			paramValues[i] = Uint32ToBytes(uint32(v))
		case int:
			paramTypes[i<<1] = MYSQL_TYPE_LONGLONG
			paramValues[i] = Uint64ToBytes(uint64(v))
		case int64:
			paramTypes[i<<1] = MYSQL_TYPE_LONGLONG
			paramValues[i] = Uint64ToBytes(uint64(v))
		case uint8:
			paramTypes[i<<1] = MYSQL_TYPE_TINY
			paramTypes[(i<<1)+1] = 0x80
			paramValues[i] = []byte{v}
		case uint16:
			paramTypes[i<<1] = MYSQL_TYPE_SHORT
			paramTypes[(i<<1)+1] = 0x80
			paramValues[i] = Uint16ToBytes(v)
		case uint32:
			paramTypes[i<<1] = MYSQL_TYPE_LONG
			paramTypes[(i<<1)+1] = 0x80
			paramValues[i] = Uint32ToBytes(v)
		case uint:
			paramTypes[i<<1] = MYSQL_TYPE_LONGLONG
			paramTypes[(i<<1)+1] = 0x80
			paramValues[i] = Uint64ToBytes(uint64(v))
		case uint64:
			paramTypes[i<<1] = MYSQL_TYPE_LONGLONG
			paramTypes[(i<<1)+1] = 0x80
			paramValues[i] = Uint64ToBytes(v)
		case bool:
			paramTypes[i<<1] = MYSQL_TYPE_TINY
			if v {
				paramValues[i] = []byte{1}
			} else {
				paramValues[i] = []byte{0}
			}
		case float32:
			paramTypes[i<<1] = MYSQL_TYPE_FLOAT
			paramValues[i] = Uint32ToBytes(math.Float32bits(v))
		case float64:
			paramTypes[i<<1] = MYSQL_TYPE_DOUBLE
			paramValues[i] = Uint64ToBytes(math.Float64bits(v))
		case string:
			paramTypes[i<<1] = MYSQL_TYPE_STRING
			paramValues[i] = append(PutLengthEncodedInt(uint64(len(v))), v...)
		case []byte:
			paramTypes[i<<1] = MYSQL_TYPE_STRING
			paramValues[i] = append(PutLengthEncodedInt(uint64(len(v))), v...)
		default:
			return fmt.Errorf("invalid argument type %T", args[i])
		}

		length += len(paramValues[i])
	}

	data := make([]byte, 4, 4+length)

	data = append(data, COM_STMT_EXECUTE)
	data = append(data, byte(s.id), byte(s.id>>8), byte(s.id>>16), byte(s.id>>24))

	//flag: CURSOR_TYPE_NO_CURSOR
	data = append(data, 0x00)

	//iteration-count, always 1
	data = append(data, 1, 0, 0, 0)

	if s.params > 0 {
		data = append(data, nullBitmap...)

		//new-params-bound-flag
		data = append(data, newParamBoundFlag)

		if newParamBoundFlag == 1 {
			//type of each parameter, length: num-params * 2
			data = append(data, paramTypes...)

			//value of each parameter
			for _, v := range paramValues {
				data = append(data, v...)
			}
		}
	}

	s.conn.ResetSequence()

	return s.conn.WritePacket(data)
}

func (c *Conn) Prepare(query string) (*Stmt, error) {
	if err := c.writeCommandStr(COM_STMT_PREPARE, query); err != nil {
		return nil, errors.Trace(err)
	}

	data, err := c.ReadPacket()
	if err != nil {
		return nil, errors.Trace(err)
	}

	if data[0] == ERR_HEADER {
		return nil, c.handleErrorPacket(data)
	} else if data[0] != OK_HEADER {
		return nil, ErrMalformPacket
	}

	s := new(Stmt)
	s.conn = c

	pos := 1

	//for statement id
	s.id = binary.LittleEndian.Uint32(data[pos:])
	pos += 4

	//number columns
	s.columns = int(binary.LittleEndian.Uint16(data[pos:]))
	pos += 2

	//number params
	s.params = int(binary.LittleEndian.Uint16(data[pos:]))
	pos += 2

	//warnings
	//warnings = binary.LittleEndian.Uint16(data[pos:])

	if s.params > 0 {
		if err := s.conn.readUntilEOF(); err != nil {
			return nil, errors.Trace(err)
		}
	}

	if s.columns > 0 {
		if err := s.conn.readUntilEOF(); err != nil {
			return nil, errors.Trace(err)
		}
	}

	return s, nil
}