// Package event define real time data evnet operation functions
package event

import (
	"context"
	"encoding/json"

	"eventRT/constants"
	"eventRT/database"
	"eventRT/logger"
	"eventRT/mq"

	amqp "github.com/rabbitmq/amqp091-go"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/propagation"
)

// amqpHeaderCarrier adapts amqp.Table to propagation.TextMapCarrier for trace context extraction.
type amqpHeaderCarrier amqp.Table

func (c amqpHeaderCarrier) Get(key string) string {
	val, ok := amqp.Table(c)[key]
	if !ok {
		return ""
	}
	str, _ := val.(string)
	return str
}

func (c amqpHeaderCarrier) Set(key, value string) {
	amqp.Table(c)[key] = value
}

func (c amqpHeaderCarrier) Keys() []string {
	keys := make([]string, 0, len(c))
	for k := range c {
		keys = append(keys, k)
	}
	return keys
}

var _ propagation.TextMapCarrier = amqpHeaderCarrier{}

const (
	queueName    = "event-up-down-queue"
	exchangeName = "event-exchange"
)

// ReceiptUpDownLimitAlarm define func to receipt up down limit alarm event from modelRT service and process the event alarm
func ReceiptUpDownLimitAlarm(ctx context.Context) {
	conn := mq.GetConn()
	if conn == nil {
		logger.Error(ctx, "get rabbitMQ connection for receiving alarms failed")
		return
	}

	channel, err := conn.Channel()
	if err != nil {
		logger.Error(ctx, "open rabbitMQ channel for consumer failed", "error", err)
		return
	}
	defer channel.Close()

	uiChannel, err := initUIEventChannel(ctx)
	if err != nil {
		logger.Error(ctx, "init UI event channel failed", "error", err)
		return
	}
	defer uiChannel.Close()

	err = channel.QueueBind(
		queueName, // 队列名
		"event.#.updown.*",
		exchangeName, // 交换机名
		false,
		nil,
	)
	if err != nil {
		logger.Error(ctx, "channel bind queue and exchange failed", "error", err)
		return
	}

	err = channel.Qos(1, 0, false)
	if err != nil {
		logger.Error(ctx, "set rabbitMQ Qos config failed", "error", err)
	}

	// registered consumer
	msgs, err := channel.Consume(
		queueName, // queue
		"",        // consumer tag
		false,     // auto-ack
		false,     // exclusive
		false,     // no-local
		false,     // no-wait
		nil,       // args
	)
	if err != nil {
		logger.Error(ctx, "failed to register a consumer", "error", err)
		return
	}

	logger.Info(ctx, "started receiving up-down limit alarms from rabbitMQ")

	for {
		select {
		case <-ctx.Done():
			logger.Info(ctx, "receipt up-down limit alarm stopped by context cancel")
			return
		case msg, ok := <-msgs:
			if !ok {
				logger.Error(ctx, "message channel closed, exiting consumer loop")
				return
			}
			processAlarmEventMessage(ctx, msg, uiChannel)
		}
	}
}

func processAlarmEventMessage(ctx context.Context, msg amqp.Delivery, uiCh *amqp.Channel) {
	// extract upstream trace context injected by modelRT into AMQP headers
	ctx = otel.GetTextMapPropagator().Extract(ctx, amqpHeaderCarrier(msg.Headers))
	ctx, span := otel.Tracer("eventRT/event").Start(ctx, "processAlarmEventMessage")
	defer span.End()

	logger.Info(ctx, "received event alarm from modelRT up and down limit compute process")
	mongodbClient := database.GetMongoClient()

	var alarmEvent EventRecord
	if err := json.Unmarshal(msg.Body, &alarmEvent); err != nil {
		logger.Error(ctx, "unmarshal alarm event message failed", "error", err)
		return
	}

	alarmEvent.IsPersisted = true
	alarmEvent.Status = constants.EventStatusReported

	result, err := mongodbClient.Database(constants.EventDBName).Collection(constants.EventCollectionName).InsertOne(ctx, alarmEvent)
	if err != nil {
		logger.Error(ctx, "failed to insert alarm event into database", "error", err)
		return
	}
	logger.Info(ctx, "alarm event inserted into database", "result", result)

	if err := msg.Ack(false); err != nil {
		logger.Error(ctx, "ack alarm event message failed", "error", err)
		return
	}

	if err := PublishEventToUI(ctx, uiCh, &alarmEvent); err != nil {
		logger.Error(ctx, "publish alarm event to UI failed", "event_uuid", alarmEvent.EventUUID, "error", err)
	}
}