package messaging

import (
	"time"

	"git.espin.casa/albert/whippet/proto"
	flatbuffers "github.com/google/flatbuffers/go"
	"github.com/google/uuid"
)

type MetaData map[string]string

var builder *flatbuffers.Builder

func Init() {
	builder = flatbuffers.NewBuilder(1024)
}

func BuildDataMessage(topic string, payload []byte, metadata MetaData) []byte {
	//
	builder.Reset()
	// auto generate message id
	id := uuid.New().String()

	idOffset := builder.CreateString(id)
	topicOffset := builder.CreateString(topic)
	payloadOffset := builder.CreateByteVector(payload)

	var kvOffsets []flatbuffers.UOffsetT

	for k, v := range metadata {
		key := builder.CreateString(k)
		val := builder.CreateString(v)

		proto.KeyValueStart(builder)
		proto.KeyValueAddKey(builder, key)
		proto.KeyValueAddValue(builder, val)

		kvOffsets = append(kvOffsets, proto.KeyValueEnd(builder))
	}

	proto.DataMessageStartMetadataVector(builder, len(kvOffsets))

	for i := len(kvOffsets) - 1; i >= 0; i-- {
		builder.PrependUOffsetT(kvOffsets[i])
	}

	metadataVec := builder.EndVector(len(kvOffsets))

	proto.DataMessageStart(builder)
	proto.DataMessageAddId(builder, idOffset)
	proto.DataMessageAddTopic(builder, topicOffset)
	proto.DataMessageAddTimestamp(builder, uint64(time.Now().UnixNano()))
	proto.DataMessageAddPayload(builder, payloadOffset)
	proto.DataMessageAddMetadata(builder, metadataVec)

	dataMsg := proto.DataMessageEnd(builder)

	proto.EnvelopeStart(builder)
	proto.EnvelopeAddType(builder, proto.MessageTypeDATA)
	proto.EnvelopeAddMessage(builder, dataMsg)
	envelope := proto.EnvelopeEnd(builder)

	builder.Finish(envelope)

	return builder.FinishedBytes()

}

func BuildAckMessage(ackedID string) []byte {
	builder.Reset()

	ackedIDOffset := builder.CreateString(ackedID)

	proto.AckMessageStart(builder)
	proto.AckMessageAddAckedId(builder, ackedIDOffset)
	proto.AckMessageAddTimestamp(builder, uint64(time.Now().UnixNano()))

	ackMsg := proto.AckMessageEnd(builder)

	proto.EnvelopeStart(builder)
	proto.EnvelopeAddType(builder, proto.MessageTypeACK)
	proto.EnvelopeAddMessage(builder, ackMsg)
	envelope := proto.EnvelopeEnd(builder)

	builder.Finish(envelope)

	return builder.FinishedBytes()

}

func BuildHeartBeatMessage(clientID string) []byte {
	builder.Reset()

	clientIDOffset := builder.CreateString(clientID)

	proto.HeartBeatMessageStart(builder)
	proto.HeartBeatMessageAddClientId(builder, clientIDOffset)
	proto.HeartBeatMessageAddTimestamp(builder, uint64(time.Now().UnixNano()))
	heartMsg := proto.HeartBeatMessageEnd(builder)

	proto.EnvelopeStart(builder)
	proto.EnvelopeAddType(builder, proto.MessageTypeHEARTBEAT)
	proto.EnvelopeAddMessage(builder, heartMsg)

	envelope := proto.EnvelopeEnd(builder)

	builder.Finish(envelope)

	return builder.FinishedBytes()

}