/*
Copyright 2016 The Transicator Authors

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.
*/
package pgclient

import (
	"bytes"
	"errors"
	"regexp"
	"strconv"

	log "github.com/Sirupsen/logrus"
)

/*
ParseError looks at an input message that represents an error and returns
a Go error.
*/
func ParseError(m *InputMessage) error {
	if m.Type() != ErrorResponse {
		return errors.New("Message type is not Error")
	}
	msg, err := ParseNotice(m)
	if err == nil {
		log.Debugf("Received error: %s", msg)
		return errors.New(msg)
	}
	return err
}

/*
ParseNotice looks at an input message that's an error or a "notice" message
(both have the same format) and returns the text.
*/
func ParseNotice(m *InputMessage) (string, error) {
	if m.Type() != NoticeResponse && m.Type() != ErrorResponse {
		return "", errors.New("Mismatched message type")
	}

	msg := &bytes.Buffer{}
	for {
		code, err := m.ReadByte()
		if err != nil {
			return "", errors.New("Invalid message format")
		}

		if code == 0 {
			return msg.String(), nil
		}
		txt, err := m.ReadString()
		if err != nil {
			return "", errors.New("Invalid message format")
		}
		msg.WriteString(txt)
		msg.WriteString(" ")
	}
}

// ParseCopyOutResponse parses the response from the CopyData message
func ParseCopyOutResponse(m *InputMessage) (info *CopyResponseInfo, err error) {
	if m.Type() != CopyOutResponse {
		err = errors.New("Message type is not CopyOutResponse")
		return
	}

	i8, err := m.ReadInt8()
	if err != nil {
		return
	}
	log.Debugf("copy format (raw): %d", i8)
	copyFmt := GetCopyFormat(int(i8))

	i16, err := m.ReadInt16()
	if err != nil {
		return
	}
	numCol := int(i16)
	var colFmts = make([]int, numCol)
	for i := 0; i < numCol; i++ {
		var f int16
		f, err = m.ReadInt16()
		if err != nil {
			return
		}
		colFmts[i] = int(f)
	}
	info = &CopyResponseInfo{
		format:  copyFmt,
		numCol:  numCol,
		colFmts: colFmts,
	}
	return info, nil
}

/*
ParseCopyData looks at a CopyData message and then parses it again as
another message.
*/
func ParseCopyData(m *InputMessage) (*InputMessage, error) {
	if m.Type() != CopyData {
		return nil, errors.New("Mismatched message type")
	}

	buf := m.buf.Bytes()
	typeByte := buf[0]
	return NewInputMessage(PgInputType(typeByte), buf[1:]), nil
}

// ParseRowDescription looks at a RowDescription message and parses it
func ParseRowDescription(m *InputMessage) ([]ColumnInfo, error) {
	if m.Type() != RowDescription {
		return nil, errors.New("Message type is not Row Description")
	}

	var cols []ColumnInfo
	numFields, err := m.ReadInt16()
	if err != nil {
		return nil, err
	}

	nf := int(numFields)
	log.Debugf("Row description has %d fields", nf)
	for i := 0; i < nf; i++ {
		col := ColumnInfo{}
		col.Name, _ = m.ReadString()
		m.ReadInt32() // Table OID
		m.ReadInt16() // Attribute number
		ct, _ := m.ReadInt32()
		col.Type = PgType(ct)
		m.ReadInt16() // Type size
		m.ReadInt32() // Type modifier
		fmtCode, _ := m.ReadInt16()
		col.Binary = (fmtCode == 1)
		cols = append(cols, col)
	}

	return cols, nil
}

// ParseParameterDescription looks at a Parameter description and returns
// a list of types.
func ParseParameterDescription(m *InputMessage) ([]PgType, error) {
	if m.Type() != ParameterDescription {
		return nil, errors.New("Message type is not ParameterDescription")
	}

	var types []PgType
	numCols, err := m.ReadInt16()
	if err != nil {
		return nil, err
	}

	nf := int(numCols)
	for i := 0; i < nf; i++ {
		ct, err := m.ReadInt32()
		if err != nil {
			return nil, err
		}
		types = append(types, PgType(ct))
	}

	return types, nil
}

// ParseDataRow turns a single DataRow message to a list of buffers
func ParseDataRow(m *InputMessage) ([][]byte, error) {
	if m.Type() != DataRow {
		return nil, errors.New("Message type is not DataRow")
	}

	var fields [][]byte

	numFields, err := m.ReadInt16()
	if err != nil {
		return nil, err
	}

	nf := int(numFields)
	log.Debugf("Row has %d columns", nf)
	for i := 0; i < nf; i++ {
		len, _ := m.ReadInt32()
		if len > 0 {
			buf, _ := m.ReadBytes(int(len))
			fields = append(fields, buf)
		} else {
			fields = append(fields, nil)
		}
	}
	return fields, nil
}

// ParseCommandComplete parses the CommandComplete message and returns
// the row count that it contains
func ParseCommandComplete(m *InputMessage) (int64, error) {
	if m.Type() != CommandComplete {
		return 0, errors.New("Message type is not CommandComplete")
	}

	s, err := m.ReadString()
	if err != nil {
		return 0, err
	}
	log.Debugf("CommandComplete %s", s)

	return parseRowCount(s), nil
}

var insertCompleteRe = regexp.MustCompile("^INSERT [0-9]+ ([0-9]+)$")
var otherCompleteRe = regexp.MustCompile("^[A-Z]+ ([0-9]+)$")

func parseRowCount(completeMsg string) int64 {
	match := insertCompleteRe.FindStringSubmatch(completeMsg)
	if match == nil {
		match = otherCompleteRe.FindStringSubmatch(completeMsg)
	}
	if match == nil {
		return 0
	}

	ret, err := strconv.ParseInt(match[1], 10, 64)
	if err == nil {
		return ret
	}
	return 0
}

// ParseParameterStatus parses the ParameterStatus message
func ParseParameterStatus(m *InputMessage) (string, error) {
	if m.Type() != ParameterStatus {
		return "", errors.New("Message type is not ParameterStatus")
	}

	s, err := m.ReadString()
	if err != nil {
		return "", err
	}

	s2, err := m.ReadString()
	if err != nil {
		return "", err
	}

	return s + " " + s2, nil
}