// handler.go — обработчик MQTT-сообщений: envelope → SQS SendMessage.
package bridge

import (
	"context"
	"encoding/json"
	"log/slog"
	"strings"
	"time"

	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/service/sqs"
	mqtt "github.com/eclipse/paho.mqtt.golang"
)

// TelemetryEnvelope — сообщение, перекладываемое в SQS (разбирается consumer).
type TelemetryEnvelope struct {
	Namespace  string          `json:"namespace"`
	DeviceID   string          `json:"device_id"`
	Topic      string          `json:"topic"`
	Payload    json.RawMessage `json:"payload"`
	ReceivedAt string          `json:"received_at"`
}

// newMessageHandler возвращает обработчик MQTT-сообщений.
func newMessageHandler(ctx context.Context, sqsClient *sqs.Client, queueURL string, log *slog.Logger) mqtt.MessageHandler {
	return func(_ mqtt.Client, msg mqtt.Message) {
		topic := msg.Topic()
		payload := msg.Payload()

		// Топик: "{namespace}/telemetry/{deviceId}".
		parts := strings.SplitN(topic, "/", 3)
		if len(parts) != 3 {
			log.Warn("bridge: unexpected topic format, skipping", "topic", topic)
			return
		}
		ns := parts[0]
		deviceID := parts[2]

		// Не-JSON payload оборачиваем в строку.
		rawPayload := json.RawMessage(payload)
		if !json.Valid(payload) {
			quoted, _ := json.Marshal(string(payload))
			rawPayload = json.RawMessage(quoted)
		}

		envelope := TelemetryEnvelope{
			Namespace:  ns,
			DeviceID:   deviceID,
			Topic:      topic,
			Payload:    rawPayload,
			ReceivedAt: time.Now().UTC().Format(time.RFC3339),
		}
		body, err := json.Marshal(envelope)
		if err != nil {
			log.Error("bridge: marshal envelope", "topic", topic, "err", err)
			return
		}

		_, err = sqsClient.SendMessage(ctx, &sqs.SendMessageInput{
			QueueUrl:    aws.String(queueURL),
			MessageBody: aws.String(string(body)),
		})
		if err != nil {
			log.Error("bridge: SQS SendMessage failed", "topic", topic, "err", err)
			return
		}
		log.Info("bridge: forwarded telemetry to SQS",
			"mqtt_topic", topic, "namespace", ns, "device", deviceID)
	}
}