// Изменено: 2026-04-09
// ReceiveMessageV1 — получает сообщения из очереди тенанта с поддержкой long polling.
// Ловушка #4: long polling держит соединение до 20 сек — не прерываем принудительно.
package gosqs

import (
	"fmt"
	"net/http"
	"strings"
	"time"

	"github.com/google/uuid"

	"shared-sqs/app/interfaces"
	"shared-sqs/app/models"
	"shared-sqs/app/utils"

	"github.com/gorilla/mux"
	log "github.com/sirupsen/logrus"
)

func ReceiveMessageV1(req *http.Request) (int, interfaces.AbstractResponseBody) {
	requestBody := models.NewReceiveMessageRequest()
	ok := utils.REQUEST_TRANSFORMER(requestBody, req, false)
	if !ok {
		log.Error("Invalid Request - ReceiveMessageV1")
		return utils.CreateErrorResponseV1("InvalidParameterValue", true)
	}

	t := getTenantFromContext(req)
	if t == nil {
		return utils.CreateErrorResponseV1("InvalidClientTokenId", true)
	}

	maxNumberOfMessages := requestBody.MaxNumberOfMessages
	if maxNumberOfMessages == 0 {
		maxNumberOfMessages = 1
	}
	// Fix #8: clamp MaxNumberOfMessages к AWS лимиту 1–10
	maxNumberOfMessages = ClampInt(maxNumberOfMessages, MinNumberOfMessagesLimit, MaxNumberOfMessagesLimit)

	queueName := ""
	if requestBody.QueueUrl == "" {
		vars := mux.Vars(req)
		queueName = vars["queueName"]
	} else {
		uriSegments := strings.Split(requestBody.QueueUrl, "/")
		queueName = uriSegments[len(uriSegments)-1]
	}

	key := tenantQueueKey(t.AccessKey, queueName)

	if _, ok := models.SyncQueues.Queues[key]; !ok {
		return utils.CreateErrorResponseV1("QueueNotFound", true)
	}

	var messages []*models.ResultMessage
	respStruct := models.ReceiveMessageResponse{}

	waitTimeSeconds := requestBody.WaitTimeSeconds
	if waitTimeSeconds == 0 {
		models.SyncQueues.RLock()
		waitTimeSeconds = models.SyncQueues.Queues[key].ReceiveMessageWaitTimeSeconds
		models.SyncQueues.RUnlock()
	}
	// Fix #4: clamp WaitTimeSeconds к AWS лимиту 0–20
	waitTimeSeconds = ClampInt(waitTimeSeconds, 0, MaxReceiveMessageWaitTimeSeconds)

	if waitTimeSeconds > 0 {
		deadline := time.Now().Add(time.Duration(waitTimeSeconds) * time.Second)
		pollTicker := time.NewTicker(100 * time.Millisecond)
		defer pollTicker.Stop()

		for {
			models.SyncQueues.RLock()
			queue, queueFound := models.SyncQueues.Queues[key]
			if !queueFound {
				models.SyncQueues.RUnlock()
				return utils.CreateErrorResponseV1("QueueNotFound", true)
			}
			messageFound := queueHasReceivableMessages(queue)
			models.SyncQueues.RUnlock()
			if messageFound || time.Now().After(deadline) {
				break
			}

			select {
			case <-req.Context().Done():
				return http.StatusOK, models.ReceiveMessageResponse{
					Xmlns:    models.BaseXmlns,
					Result:   models.ReceiveMessageResult{},
					Metadata: models.BaseResponseMetadata,
				}
			case <-pollTicker.C:
			}
		}
	}
	log.Debugf("Getting Message from Queue:%s (tenant: %s)", queueName, t.ID)

	models.SyncQueues.Lock()
	defer models.SyncQueues.Unlock()

	if len(models.SyncQueues.Queues[key].Messages) > 0 {
		numMsg := 0
		messages = make([]*models.ResultMessage, 0)
		for i := range models.SyncQueues.Queues[key].Messages {
			if numMsg >= maxNumberOfMessages {
				break
			}

			if models.SyncQueues.Queues[key].Messages[i].ReceiptHandle != "" {
				continue
			}

			msg := &models.SyncQueues.Queues[key].Messages[i]
			if !msg.IsReadyForReceipt() {
				continue
			}

			if models.SyncQueues.Queues[key].IsFIFO {
				if models.SyncQueues.Queues[key].IsLocked(msg.GroupID) {
					continue
				}
				models.SyncQueues.Queues[key].LockGroup(msg.GroupID)
			}

			randomId := uuid.NewString()
			msg.ReceiptHandle = msg.Uuid + "#" + randomId
			msg.ReceiptTime = time.Now().UTC()

			if requestBody.VisibilityTimeout != 0 {
				msg.VisibilityTimeout = time.Now().Add(time.Duration(requestBody.VisibilityTimeout) * time.Second)
			} else {
				msg.VisibilityTimeout = time.Now().Add(time.Duration(models.SyncQueues.Queues[key].VisibilityTimeout) * time.Second)
			}

			messages = append(messages, buildResultMessage(msg))
			numMsg++
		}

		respStruct = models.ReceiveMessageResponse{
			"http://queue.amazonaws.com/doc/2012-11-05/",
			models.ReceiveMessageResult{Messages: messages},
			models.ResponseMetadata{RequestId: "00000000-0000-0000-0000-000000000000"},
		}
	} else {
		log.Warning("No messages in Queue:", queueName)
		respStruct = models.ReceiveMessageResponse{
			Xmlns:    "http://queue.amazonaws.com/doc/2012-11-05/",
			Result:   models.ReceiveMessageResult{},
			Metadata: models.ResponseMetadata{RequestId: "00000000-0000-0000-0000-000000000000"},
		}
	}

	return http.StatusOK, respStruct
}

func buildResultMessage(m *models.SqsMessage) *models.ResultMessage {
	return &models.ResultMessage{
		MessageId:              m.Uuid,
		Body:                   m.MessageBody,
		ReceiptHandle:          m.ReceiptHandle,
		MD5OfBody:              utils.GetMD5Hash(m.MessageBody),
		MD5OfMessageAttributes: m.MD5OfMessageAttributes,
		MessageAttributes:      m.MessageAttributes,
		Attributes: map[string]string{
			"ApproximateFirstReceiveTimestamp": fmt.Sprintf("%d", m.ReceiptTime.UnixNano()/int64(time.Millisecond)),
			"SenderId":                         models.CurrentEnvironment.AccountID,
			"ApproximateReceiveCount":          fmt.Sprintf("%d", m.NumberOfReceives+1),
			"SentTimestamp":                    fmt.Sprintf("%d", time.Now().UTC().UnixNano()/int64(time.Millisecond)),
		},
	}
}

func queueHasReceivableMessages(queue *models.Queue) bool {
	for i := range queue.Messages {
		msg := &queue.Messages[i]
		if msg.ReceiptHandle != "" {
			continue
		}
		if !msg.IsReadyForReceipt() {
			continue
		}
		if queue.IsFIFO && queue.IsLocked(msg.GroupID) {
			continue
		}
		return true
	}
	return false
}