package packets

import (
	"bufio"
	"bytes"
	"errors"
	"io"
	"strings"

	"badat.dev/maeqtt/v2/mqtt/properties"
	"badat.dev/maeqtt/v2/mqtt/types"
)

type Topic struct {
	Fields []string
}

var multiLevelWildcardNotLast = errors.New("Multi level wildcard isn't the field in a topic")

func ParseTopic(topic_name string) (Topic, error) {
	topic := Topic{}
	fields := strings.Split(topic_name, "/")
	for i, field := range fields {
		if field == "#" && len(fields) > i+1 {
			return topic, multiLevelWildcardNotLast
		}
	}
	topic.Fields = fields

	return topic, nil
}

type TopicFilter struct {
	Topic             Topic
	MaxQoS            uint
	NoLocal           bool
	RetainAsPublished bool
	RetainHandling    uint
}

func parseTopicFilter(r *bufio.Reader) (TopicFilter, error) {
	filter := TopicFilter{}
	var err error

	topic_str, err := types.DecodeUTF8String(r)
	if err != nil {
		return filter, err
	}

	filter.Topic, err = ParseTopic(topic_str)
	if err != nil {
		return filter, err
	}

	options, err := types.DecodeBits(r)
	if err != nil {
		return filter, err
	}
	filter.MaxQoS = types.BoolsToUint(options[0], options[1])
	filter.NoLocal = options[2]
	filter.RetainAsPublished = options[3]
	filter.RetainHandling = types.BoolsToUint(options[4], options[5])
	return filter, nil
}

type SubscribePacket struct {
	PacketId     uint16
	TopicFilters []TopicFilter
	Properties   properties.SubscribePacketProperties
}

func parseSubscribePacket(control controlPacket) (SubscribePacket, error) {
	if control.packetType != PacketTypeSubscribe {
		panic("Wrong packet type for parseSubscribePacket")
	}

	packet := SubscribePacket{}

	r := bufio.NewReader(control.reader)

	if control.flags != 2 {
		return packet, errors.New("Malformed subscription packet")
	}

	var err error
	packet.PacketId, err = types.DecodeUint16(r)
	if err != nil {
		return packet, err
	}

	err = properties.ParseProperties(r, packet.Properties.ArrayOf())
	if err != nil {
		return packet, err
	}

	for err != io.EOF {
		filter, err := parseTopicFilter(r)
		packet.TopicFilters = append(packet.TopicFilters, filter)
		if err != nil {
			return packet, err
		}
		_, err = r.Peek(1)
		if err != nil && err != io.EOF {
			return packet, err
		}
		if err == io.EOF {
			return packet, nil
		}
	}

	return packet, nil
}

func (p SubscribePacket) Visit(v PacketVisitor) {
	v.VisitSubscribe(p)
}

type SubackReasonCode byte

const (
	SubackReasonGrantedQoSZero         SubackReasonCode = 0
	SubackReasonGrantedQoSOne          SubackReasonCode = 1
	SubackReasonGrantedQoSTwo          SubackReasonCode = 2
	SubackReasonUnspecified            SubackReasonCode = 128
	SubackReasonImplSpecificError      SubackReasonCode = 131
	SubackReasonNotAuthorized          SubackReasonCode = 135
	SubackReasonTopicFilterInvalid     SubackReasonCode = 143
	SubackReasonPacketIDInUse          SubackReasonCode = 145
	SubackReasonQuotaExceeded          SubackReasonCode = 151
	SubackReasonSharedSubNotSupported  SubackReasonCode = 158
	SubackReasonSubIDUnsupported       SubackReasonCode = 161
	SubackReasonWildcardSubUnsupported SubackReasonCode = 162
)

type SubAckPacket struct {
	PacketID   uint16
	Properties properties.SubackPacketProperties
	Reason     SubackReasonCode
}

func (p SubAckPacket) Write(w io.Writer) error {
	buf := bytes.NewBuffer([]byte{})
	err := types.WriteUint16(buf, p.PacketID)
	if err != nil {
		return err
	}

	err = properties.WriteProps(buf, p.Properties.ArrayOf())
	if err != nil {
		return err
	}

	err = buf.WriteByte(byte(p.Reason))
	if err != nil {
		return err
	}

	conPack := controlPacket{
		packetType: PacketTypeSuback,
		flags:      0,
		reader:     buf,
	}
	return conPack.write(w)
}

type UnsubscribePacket struct {
	PacketID   uint16
	Topics     []Topic
	Properties properties.UnsubscribePacketProperties
}

func parseUnsubscribePacket(control controlPacket) (UnsubscribePacket, error) {
	if control.packetType != PacketTypeUnsubscribe {
		panic("Wrong packet type for parseSubscribePacket")
	}

	packet := UnsubscribePacket{}
	r := bufio.NewReader(control.reader)

	if control.flags != 2 {
		return packet, errors.New("Malformed subscription packet")
	}

	var err error
	packet.PacketID, err = types.DecodeUint16(r)
	if err != nil {
		return packet, err
	}

	err = properties.ParseProperties(r, packet.Properties.ArrayOf())
	if err != nil {
		return packet, err
	}

	for err != io.EOF {
		topic_str, err := types.DecodeUTF8String(r)
		if err != nil && err != io.EOF {
			return packet, err
		} else if err == io.EOF {
			return packet, nil
		}

		filter, err := ParseTopic(topic_str)
		if err != nil {
			return packet, err
		}

		packet.Topics = append(packet.Topics, filter)
	}

	return packet, nil
}

func (p UnsubscribePacket) Visit(v PacketVisitor) {
	v.VisitUnsubscribe(p)
}

type UnsubackReasonCode byte

const (
	UnsubackReasonSuccess            UnsubackReasonCode = 0
	UnSubackReasonUnspecified        UnsubackReasonCode = 128
	UnSubackReasonImplSpecificError  UnsubackReasonCode = 131
	UnSubackReasonNotAuthorized      UnsubackReasonCode = 135
	UnSubackReasonTopicFilterInvalid UnsubackReasonCode = 143
	UnSubackReasonPacketIDInUse      UnsubackReasonCode = 145
)

type UnsubAckPacket struct {
	PacketID   uint16
	Properties properties.UnsubackPacketProperties
	Reason     UnsubackReasonCode
}

func (p UnsubAckPacket) Write(w io.Writer) error {
	buf := bytes.NewBuffer([]byte{})
	err := types.WriteUint16(buf, p.PacketID)
	if err != nil {
		return err
	}

	err = properties.WriteProps(buf, p.Properties.ArrayOf())
	if err != nil {
		return err
	}

	err = buf.WriteByte(byte(p.Reason))
	if err != nil {
		return err
	}

	conPack := controlPacket{
		packetType: PacketTypeUnsuback,
		flags:      0,
		reader:     buf,
	}
	return conPack.write(w)
}